July-Structure-2025

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STRUCTURE JULY 2025

NCSEA | CASE | SEI

NatureInspired Hybrid

INSIDE: Kresge College

20

Historic Hotel Conversion 24 Gilded Age Revival: The Frick Collection 28 Mass Timber and the Power of Reuse 34

RECORDS Eliminate the hassle of resubmitting your College transcripts Exams results Employment verifications Professional references each time you apply for licensure in an additional state.

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CIRCULATION

Anthony/CANFOR........................................................... 6 ASC Steel Deck................................................................. 7 ATLAS Tube......................................................................... 43 Computers & Structures Inc...................................................... Back Cover CRSI...................................................................................... 51 DEWALT.............................................................................. 17 Durafuse............................................................................... 13 ENERCALC......................................................................... 8 ICC........................................................................................ 12 IES......................................................................................... 3 LeJeune Bolt Company.................................................... 44 Nucor Vulcraft-Verco........................................................ 4 NCEES................................................................................. Inside Front Cover

July 2025 Digital Issue Available Only at

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EDITORIAL BOARD Chair John A. Dal Pino, S.E. Claremont Engineers Inc., Oakland, CA chair@STRUCTUREmag.org Kevin Adamson, PE Structural Focus, Gardena, CA Marshall Carman, PE, SE Schaefer, Cincinnati, Ohio Erin Conaway, PE AISC, Littleton, CO Sarah Evans, PE Walter P Moore, Houston, TX Linda M. Kaplan, PE Pennoni, Pittsburgh, PA

Publication of any article, image, or advertisement in STRUCTURE® magazine does not constitute endorsement

by NCSEA, CASE, SEI, the Publisher, or the Editorial Board. Authors, contributors, and advertisers retain sole responsibility for the content of their submissions.

STRUCTURE magazine is not a peer-reviewed publication.

Readers are encouraged to do their due diligence through personal research on topics.

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Nicholas Lang, PE Vice President Engineering & Advocacy, Masonry Concrete Masonry and Hardscapes Association (CMHA) Jessica Mandrick, PE, SE, LEED AP Gilsanz Murray Steficek, LLP, New York, NY Brian W. Miller Cast Connex Corporation, Davis, CA Evans Mountzouris, PE Retired, Milford, CT Kenneth Ogorzalek, PE, SE KPFF Consulting Engineers, San Francisco, CA (WI) John “Buddy” Showalter, PE International Code Council, Washington, DC Eytan Solomon, PE, LEED AP Silman, New York, NY

EDITORIAL STAFF Executive Editor Alfred Spada

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Audrey Schmook Tel: 312-649-4600 Ext. 213 aschmook@ncsea.com STRUCTURE magazine (ISSN 1536 4283) is published monthly by The ®

National Council of Structural Engineers Associations (a nonprofit Association), 20 N. Wacker Drive, Suite 750, Chicago, IL 60606 312.649.4600. Periodical postage paid at Chicago, Il, and at additional mailing offices. STRUCTURE magazine, Volume 32, Number 7, © 2025 by The National Council of Structural Engineers Associations, all rights reserved. Subscription services, back issues and subscription information tel: 312-649-4600, or write to STRUCTURE magazine Circulation, 20 N. Wacker Drive, Suite 750, Chicago, IL 60606.The publication is distributed to members of The National Council of Structural Engineers Associations through a resolution to its bylaws, and to members of CASE and SEI paid by each organization as nominal price subscription for its members as a benefit of their membership. Yearly Subscription in USA $75; $40 For Students; Canada $90; $60 for Canadian Students; Foreign $135, $90 for foreign students. Editorial Office: Send editorial mail to: STRUCTURE magazine, Attn: Editorial, 20 N. Wacker Drive, Suite 750, Chicago, IL 60606. POSTMASTER: Send Address changes to STRUCTURE magazine, 20 N. Wacker Drive, Suite 750, Chicago, IL 60606.

STRUCTURE is a registered trademark of the National Council of Structural Engineers Associations (NCSEA). Articles may not be reproduced in whole or in part without the written permission of the publisher.

JULY 2025

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Contents J U LY 2 0 25

NATURE-INSPIRED HYBRID

By Alex Wilson, PE, and Ian McFarlane, PE, SE

Kresge College’s new Academic Center advances mixed-material projects beyond typical hybrid-timber construction.

20

F E A T U R E S

24

TRIAL BY FIRE: STRUCTURAL ENGINEERING CHALLENGES IN A HISTORIC HOTEL CONVERSION

By Chelci E. Dell & Jeffrey D. Viano

The adaptive reuse project modified a 179-year-old academic building into a boutique hotel in Maryland.

28

GILDED AGE REVIVAL: THE FRICK COLLECTION

By Lauren Feinstein, PE, David Ribbans, PE, Kevin Poulin, PE, and Filippo Masetti, PE

Simpson Gumpertz & Heger engineered custom solutions for this historic New York mansion-turned-art-museum to achieve the architectural design intent while encountering a variety of archaic gravity systems from prior structural renovations.

34

MASS TIMBER AND THE POWER OF REUSE

By Sarah Evans, PE and Thomas Kostelak, PE

The University of Houston RAD Center combines architectural vision and structural ingenuity to maximize efficiency and sustainability.

40

SPECIAL SECTION: CONNECTIONS Real World Challenges Drive Innovation

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COLUMNS and D E PA RT M E N TS

9

Editorial

®

DELTAGRIP DG4

10

Seismic Shifts in Business

TM

By Jami Lorenz, PE

10

Structural Influencer

14

Structural Design

The Better Way of Connecting Steel Roof Deck at Sidelaps

Juliette Peyroux, PE, SE

Structural Engineering Considerations in Design of Secure Compounds Chris Heckmann, PE; Achraf Ayad, Ph.D, PE; Leslie Duffy, PE

Understanding Roof Systems of Metal Buildings Michael W. Seek, Ph.D, PE, and Vincent Sagan, PE

46

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18

Structural Design

14

Structural Forum

Why Structural Firms Should Adopt an InsideOut AI Strategy

By Dr. Mehdi Nourbakhsh and Dr. Sam Zolfagharian

48 Structural Forum

Australia Is Becoming Hotter: Climate Change and Its Impact on Long-term Monitoring of Structures

18 ● Lightest Pneumatic Sidelap Tool ● Increased Connection Strength ● Increased Connection Stiffness ● Increased Crimping Force ● Faster Cycle Time ● Improved Durability

By Parsa Ghannadi and Seyed Sina Kourehli

50 Historic Structures

Merchants' Bridge, St. Louis, Missouri, 1890

By Frank Griggs, Dist. M. ASCE

64

Codes and Standards FAQ on SEI Standards

By Jeannette Torrents, PE, SE

65 inSights

When Good Engineers Make Bad Business Decisions: A Risk Management Solution

By Mark Blankenship, CPCU, AIC, LEED AP

In Every Issue 3 Advertiser Index 52 SE News 58 SEI Update 60 NCSEA News 62 CASE in Point

Patent Number: 11,872,644

ascsd.com/dg4-tool J U LY 2 025

7

Project Title: Engineer: Project ID: Project Descr:

Wall Footing

Project Title: 1234 Central Avenue Engineer: CDJ Calculation:Continuous Footing Bearing, Overturning and Sliding Checks

1234 Central Ave CPD 123400 A Super Awesome Project

Dimensions

Project File: Excel vs ENERCALC - Marketing Campaign.ec6

LIC# : KW-06000215, Build:20.25.04.16

Licensed ENERCALC User

DESCRIPTION: Wall Footing Calc

Easy application of Codes & Standards Clear input

Code References Calculations per ACI 318-19, IBC 2024 Load Combinations Used : ASCE 7-22 / IBC 2024

General Information Material Properties f'c : Concrete 28 day strength fy : Rebar Yield Ec : Concrete Elastic Modulus Concrete Density M Values Flexure Shear Analysis Settings Min Steel % Bending Reinf.

Min Allow % Temp Reinf.

Min. Overturning Safety Factor Min. Sliding Safety Factor AutoCalc Footing Weight as DL :

3.0 ksi 60.0 ksi 3,122.0 ksi 145.0 pcf 0.90 0.750

= = = = = = = = = =

(c) ENERCALC, LLC 1982-2025

0.00180 1.50 : 1 1.50 : 1 Yes

Soil Design Values Allowable Soil Bearing Increase Bearing By Footing Weight Soil Passive Resistance (for Sliding) Soil/Concrete Friction Coeff.

= = = =

3.0 ksf No 250.0 pcf 0.30

Increases based on footing Depth Reference Depth below Surface Allow. Pressure Increase per foot of depth when base footing is below

= = =

ft ksf ft

Increases based on footing Width Allow. Pressure Increase per foot of width when footing is wider than

= =

ksf ft

Adjusted Allowable Bearing Pressure

=

3.0 ksf

Dimensions = =

2.50 ft 12.0 in

Wall center offset from center of footing

=

0 in

Footing Thickness = 12.0 in Rebar Centerline to Edge of Concrete... at Bottom of footing =

3.50 in

Bars along X-X Axis Bar spacing Reinforcing Bar Size

P : Column Load OB : Overburden

= =

D 1.20 0.30

L 0.80

S 1.0

V-x M-zz

= = =

0.60 0.30 0.40 24.0 in above top of footing

0.50

Vx applied

Lr 0.60

W

#

E

H

k k-ft

5

(D + L) (D + L + E/W)

250 psf 333 psf

(D + L) (D + L + E/W)

0.3 0.4

(D + L) (D + L + E/W)

Safety Factors Bearing = Overturning / Sliding =

ASD Load Combinations

=

k ksf 0.180

Coefficient of Soil/Concrete Friciton:

Load Combination

12.00

Applied Loads

Soil Density = 110 pcf Allowable Bearing Pressure: 3000 psf 4500 psf

Soil Passive Sliding Resistance:

DL = 450 plf DL,footing = 450 plf Shear Loads (Applied at T.O. Wall): Wind Loads: WL = 165 plf Seismic Load: EL = 135 plf

=

Responsive graphics and rich visuals

Soil Properties

3.0 ft 12.0 in 3 ft 12 in 3.5 in 0 in

Demands Vertical Loads: Dead Loads:

Reinforcing

Footing Width Wall Thickness

Footing Width, B = Footing Thickness, D = Wall Height, H = Wall Thickness, t = Rebar Centerline, d = Height of Soil Over Footing, h =

2 1.5

ASD Factored Loads Load Factors

Load Combination

IBC 2018, 16-12a: IBC 2018, 16-12b: IBC 2018, 16-13a: IBC 2018, 16-14: IBC 2018, 16-15: IBC 2018, 16-16:

1.00 1.00 1.00 1.00 0.60 0.60

DL + DL + DL + DL + DL + DL +

0.60 0.70 0.75 0.75 0.60 0.70

WL EL LL + LL + WL EL

Bearing Checks Load Combination IBC 2018, 16-12a: IBC 2018, 16-12b: IBC 2018, 16-13a: IBC 2018, 16-14: IBC 2018, 16-15: IBC 2018, 16-16:

qgravity 300 300 300 300 180 180

qlateral 264 252 198 189 264 252

qult 564 552 498 489 444 432

FS 8.0 >2 8.2 >2 9.0 >2 9.2 >2 10.1 >2 10.4 >2 Bearing Okay

Overturning Checks Load Combination

MOT

MR

IBC 2018, 16-12a: IBC 2018, 16-12b: IBC 2018, 16-13a: IBC 2018, 16-14: IBC 2018, 16-15: IBC 2018, 16-16:

396 378 297 284 396 378

1350 1350 1350 1350 810 810

0.45 WL 0.53 EL

FS 3.4 > 1.5 3.6 > 1.5 4.5 > 1.5 4.8 > 1.5 2.0 > 1.5 2.1 > 1.5 Overturning Okay

IBC 2018, 16-12a: IBC 2018, 16-12b: IBC 2018, 16-13a: IBC 2018, 16-14: IBC 2018, 16-15: IBC 2018, 16-16:

Sliding Checks Load Combination Fsliding IBC 2018, 16-12a: IBC 2018, 16-12b: IBC 2018, 16-13a: IBC 2018, 16-14: IBC 2018, 16-15: IBC 2018, 16-16:

99 95 74 71 99 95

DL

DL

Wall & Ftg

Soil

900 900 900 900 540 540

0 0 0 0 0 0

FR 1360 1360 1360 1360 1216 1216

W

E

99 74 99 -

0 95 0 71 0 95

FS 13.7 > 1.5 14.4 > 1.5 18.3 > 1.5 19.2 > 1.5 12.3 > 1.5 12.9 > 1.5 Sliding Okay

EDITORIAL Seismic Shifts in Business

By Jami Lorenz, PE

I

joined the NCSEA board in January 2020, and the profound shift that followed seemed to usher in a time of continuous change at an increasingly rapid pace. As I stepped into the NCSEA Presidency this April, I carry the lessons of those seismic shifts, not just personally, but for the future of our structural engineering profession.

Until recently, my career followed a traditional AEC pathway: from project engineer to project manager, then Principal and Shareholder of a new office, and eventually Principal in Charge of Corporate Business Development after a 2017 merger. In 2020, I would have confidently predicted a continued trajectory along this well-worn path. But what if the route to greater success in structural engineering isn’t the one we’ve always followed?

In 2023, after 18 years, I made the difficult, once unimaginable decision to leave my firm.

Our company had doubled in size and my extensive travel became unsustainable for my family. My two children, 12 and 14, were navigating a challenging adolescent period compounded by the pandemic’s lingering effects. Simultaneously, the office I had founded grew to 35 people, now managed by the next generation of leaders. It was time for a new course.

At its core, my decision was equally rooted in my desire for personal development that no longer aligned with the firm’s leadership opportunities. My business development role leveraged my personal strengths and passions—establishing deep connections with clients, colleagues and construction partners to build successful relationships and projects. I had envisioned that my corporate role would amplify my impact in these tenets of a healthy culture internally and externally. But with continued company growth and a corporate focus on independent office management structure, it became obvious that my influence could only reach so far.

Engineering schools provide technical prowess, but the nuanced art of fostering cohesive teams, building trust, and driving strategic growth often remains uncharted territory for both emerging and tenured leaders. I was formulating a belief that the true crux of success in an engineering consulting firm lies

STRUCTURE magazine

in cultivating a leadership-focused culture, aligned with clear core values, accountability, employee engagement, and professional development. Regardless of firm size, consistent leadership training at every level is essential for holistic thriving. Ask yourself: what leadership lessons do you wish you had learned sooner, and is there potential you can cultivate in your future leaders earlier in their careers?

Upon leaving my structural firm in 2023, I had the opportunity to test this theory and work with my favorite architectural client as the Director of Firm Development. They had grown from 20 to 40 employees and were grappling with the challenge of maintaining their unique culture, employee engagement, and client experience. I began working with a business coach employed by the firm—the same coach who had guided my previous firm a decade earlier after the 2012 economic downturn. She had pushed us to organize and evolve, achieving 20% profitability with a thriving culture. Re-engaging with her in my new role quickly reminded me of the transformative change that came from shedding the “this is how we’ve always done it” mentality.

No matter the size of a structural engineering firm, consistent leadership development is essential to holistically thrive.

As a non-billable leader with partner support at the architectural firm, I was given the bandwidth to objectively assess administrative and operational structures. Over two years, we established guiding principles for the future to collectively build a thriving community, clear career paths, and align our strategic vision.

We engaged all our employees with feedback surveys, 360 reviews, and semi-annual Town Halls—inviting them to the table to discuss ideas for culture, benefits, and professional development. These efforts have built the foundation for deeper connections across offices, among employees, with clients, and within project teams.

With these past experiences in mind, my

challenge to our industry leaders is this: be vulnerable to the opportunities brought by change; ask yourself if there is a different route to greater success. During a time of countless mergers and acquisitions, constant innovations in AI, more pressure on fees, schedules, and scope creep, what mindsets need to be changed to allow your business practices to continue to thrive? Embracing small movements can lead to transformation, starting with asking younger colleagues for their ideas, exploring current resources on leadership development, and engaging with peers that have started down that path. If you are a leader, I urge you to critically assess your firm’s trajectory and start a conversation with your people about how you can instill your core values into the firm’s culture, build community, and create a sense of shared purpose.

Like an earthquake, seismic shifts can be large or small, but each can leave a lasting impact. If this resonates with you, join us at the 2nd annual NCSEA Executive Retreat in 2026 to share your stories, struggles, and ideas with your fellow structural engineering executives. Bring one of your future trailblazers! By engaging your next generation, embracing innovation, and providing dedicated leadership development, you will define a roadmap to shared success. ■

Jami Lorenz, PE, is the current President of NCSEA. She is passionate about inspiring innovative mindsets and thriving employee cultures within the AEC industry.

JULY 2025

9

structural INFLUENCER Juliette Peyroux, PE, SE Juliette Peyroux, PE, SE, is a Principal at Magnusson Klemencic Associates and a member of the firm’s Aviation Specialist Group. Her work includes engineering and designing new and expanded airport terminals, such as San Diego (SAN) Terminal 1, Nashville (BNA) Expansion Concourse D and Terminal Wings, and San Francisco (SFO) Harvey Milk Terminal 1. Peyroux also leads MKA’s Earthquake Technical Specialist Team and teaches building safety evaluation classes.

STRUCTURE: Some of us know our careers from a very young age, and others stumble upon them later in life. Can you tell us about how you ended up as a structural engineer?

Peyroux: As a kid, I watched way too much CSI and wanted to be either a police detective or an FBI agent. However, my favorite subjects in school were math and science, and I quickly realized that my adolescent ideas for a career path probably weren’t the best fit for me. My dad was a computer science engineer, so I knew engineering was likely in my future. I had a great group of friends at the University of Washington (UW), and we all supported each other to get through the engineering pre-requisite classes. All seven of them decided to pursue civil engineering, and I decided to tag along to see what all the fuss was about. I ended up absolutely loving the technical aspects of structural engineering and the practical aspect of physically seeing what you design come to life. These sentiments were only reinforced by my time on the UW’s Steel Bridge Team.

STRUCTURE: What ought engineers be doing more of to educate and expose young people to the rewarding career opportunities in engineering?

Peyroux: Looking back at my personal experience, I was not exposed to engineering or construction careers and only happened to fall into structural engineering. I am embarrassed to admit that the first time I took a concrete class, I was shocked to learn that steel reinforcement was embedded in it! Luckily, it worked out for me, and I found something I love to do, but I worry that other people are missing opportunities. The Architecture Construction Engineering (ACE) Mentor Program for high school students is a wonderful opportunity for structural engineers to expose students to this industry and for the students to learn whether these career paths interest them. I volunteered for the program for many years and had multiple students I mentored end up in either structural engineering or construction careers, which was really rewarding.

The program also takes donations for scholarships to students for their college education. Another way for engineers to get involved is to go to your local high school’s Career Day or speak in their STEM classes. I think it is important to get students interested in this industry before they head to college so they have time to explore this career path further when they pick their curriculum.

Volunteering for ACE, donating to the program, or talking about structural engineering to your community’s students can make a big difference in providing much-needed exposure to our industry.

10 STRUCTURE magazine

STRUCTURE: Congratulations on being recognized on the 2021 Forty Under Forty list. In the published Q&A, you mentioned MKA’s John Hooper as having played an important role in your career. Would you mind telling STRUCTURE’s readers too and how you benefited?

Peyroux: Thank you—I was thrilled to be recognized for such a prestigious honor. John Hooper has been an instrumental part of my career because he has encouraged me to pursue my passion for seismic engineering. Early in my career, I worked on a project at the San Francisco International Airport with tricky site conditions and liquefiable soil. This project sparked my interest in seismic hazards, which John recognized and helped me further develop by helping me get involved in code development. Most of your readers probably think code development sounds really boring, but that is absolutely not the case! Take seismic hazards, for example; as an industry, we are constantly getting smarter about hazards and how they affect building design. The Multi-Period Response Spectrum introduced in ASCE 7-22 is a good example of updating the code to improve the accuracy of design ground motions and enhance their reliability based on the latest science.

By participating in code development, engineers become technical resources for their colleagues and can better explain the basis of changes to clients. I am very grateful to John for supporting my involvement in this endeavor.

STRUCTURE: We asked you about John Hooper earlier. Please tell us about someone else whose mentorship and coaching helped make you the person you are today.

Peyroux: I would not be where I am in my career without MKA’s Aviation Specialist Group Leader, Terry Palmer. Terry has been tremendously successful in growing the group from small terminal projects and hangars to major international airport terminal additions and expansions. I have learned a lot from him, including business development strategies, how to apply structural engineering principles to turn client ambitions into reality, and the effective management of large teams on long projects. He has constantly supported my career growth and given me opportunities, from presenting my design ideas directly to clients to managing multi-billion-dollar projects. It is hard to succeed in any career without the meaningful support of colleagues and peers, so I strive to provide my own team of engineers with similar coaching to help them grow and support their careers, as Terry has helped me with mine.

One of Juliette Peyroux's aviation projects was the new San Diego International Airport Terminal 1.

STRUCTURE: You are also involved in SEAW’s Disaster Preparedness and Response Committee. Can you tell us why you decided to join?

Peyroux: A few years into my career, I was looking for a way to get more involved in the Seattle structural engineering community. I knew that SEAW had several committees and was always open to new people joining, so I looked them up and found that Disaster Preparedness and Response interested me.

I had taken an ATC-20 course and found it fascinating how structural engineers can put our skills to use after a disaster to help communities bounce back by quickly evaluating buildings for safe occupancy. Studies have shown that the faster people can reoccupy buildings, the faster the community can recover. Through this committee, I have had the opportunity to help expand Washington State’s list of volunteer building safety evaluators (BSE) by training other structural engineers, building officials, and architects in WAsafe, Washington’s version of ATC-20.

Very few states have BSE registries that can be called upon after a disaster, so I think it is important and worthwhile to train as many people as possible and be ready to help our communities in the event of a large earthquake.

STRUCTURE: You have developed a specialty in aviation projects. Do you mind our asking what excites you about them?

Peyroux: What I love the most about aviation projects are the people who work on them, from the clients to the project managers, design teams, and contractors. The aviation industry is a close-knit community of people who all live and breathe airports. The projects tend to be complex, long, and costly, in addition to involving many people, so you need to maintain good relationships with everyone to be successful. Typically, aviation projects require some level of co-location, which I enjoy because it helps form deep bonds within the team.

The clients have owned and operated their buildings for decades, so they are truly invested in the outcome of the projects and care about supporting many aspects of their local communities. Our clients have admirable values, including promoting sustainability by requiring LEED certification and supporting equity and local businesses through DBE and WMBE programs. Many of the projects are design-build, which imparts a sense of teamwork between the design and contractor teams, and we all strive for mutual project success by bringing different ideas and perspectives to the table.

Working with the same design team for years means many celebrations, including the typical project milestones, but also retirement festivities, team dinners, baby showers, and the occasional backyard tiki party. The people involved in these projects keep me engaged and excited about the future.

I'm also proud to be part of the positive impact airports have on their communities. Airports allow people to travel for business, visit friends and family, and explore new places. I really love facilitating travel for others and connecting people to the rest of the world.

JULY 2025

11

There are so many technical aspects to structural engineering that once you find something that sparks your curiosity, discover more about it and become a subject matter expert for your peers. There is a lot of value in being a resource for others.

STRUCTURE: Every project type has its own unique difficult design issues. What is the most challenging aspect of aviation projects? How did you learn how to deal with them?

Peyroux: There is a saying in the aviation industry: “If you’ve worked on one airport, you’ve worked on one airport.” That is to say that each airport project is unique and comes with its own complex challenges. Some airports want expansions of existing terminals, which means retrofitting existing structures up to new codes and can be very challenging in high-seismic areas. Some airports want to remain operational under construction, so phasing is key to the construction process and must be considered in design. Some airports have a tough time making decisions because there are so many stakeholders involved, which can slow down the design process or cause big changes late in the project schedule. And most projects include some version of all these challenges. For structural engineers, it means that we are constantly adapting our designs to meet the project’s needs while also addressing many constraints. For example, retrofitting an

Juliette Peyroux said airport projects require structural engineers to constantly adapt designs to meet the project's needs while addressing many constraints.

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existing structure can require creative design to come up with the most structurally efficient solution that also works with phasing and airport operations.

Airports are also usually looking for future design flexibility because they are constantly moving concessions, updating restrooms, adjusting hold room spaces, and adding more mechanical equipment. Dealing with these challenges takes experience to anticipate constraints, listening to the stakeholders to understand their vision and their concerns, a strong team to work through them, and an open mind to develop innovative ideas. All these challenges keep designers on their toes and make every project feel fresh and interesting to tackle.

STRUCTURE: Starting a career at a major firm and competing to be successful in the long run isn’t easy. Ask anyone who has played competitive sports. If this seems like a daunting hill to climb, what advice would you give to young engineers just starting out?

Peyroux: I have two pieces of advice for engineers. First, I would tell engineers to find what they are passionate about and pursue that as part of their career. For example, there are so many technical aspects to structural engineering that once you find something that sparks your curiosity, discover more about it and become a subject matter expert for your peers. There is a lot of value in being a resource for others. Or, if you love a certain project type, then make sure to raise your hand and voice your interest when a new project comes along. Be an advocate for yourself, and when you get an opportunity, seize it and give it your all because often one opportunity leads to the next.

Second, MKA’s mission is to always strive for better. Everyone has areas where they could improve, and it can be daunting to push yourself outside of your comfort zone. I used to suffer from terrible stage fright and had a hard time speaking in public. To get past that, I signed up for MKA’s presentation training and started presenting WAsafe training courses. This helped me gain confidence with public speaking just in time to start making project presentations in front of clients. If your company has resources or there are other opportunities to help you with your weaknesses, don’t shy away from using them to improve yourself.

STRUCTURE: As a new parent, do you have any advice on balancing work and personal life?

Peyroux: This balance is something I am still working on myself, but I have found that it helps to have a strong team of engineers that is ready to support me. There comes a point in everyone’s career where you have to learn to delegate tasks to others and trust your team, which is easier said than done for a Type A personality like myself. Delegating tasks like coordination, managing other engineers, and documentation gives others opportunities to grow in their own careers. I think it is also important to set boundaries for yourself and be flexible.

There are times when extra effort needs to be spent at work to meet deadlines or prepare for a meeting but remember to also take advantage when there is a bit of a lull to take some personal time. One manager early on in my career was leaving work one day and said, “The work will still be here when I come back tomorrow,” which stuck with me, and I think it helps put some perspective on achieving a balanced lifestyle. ■

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JULY 2025

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structural DESIGN Structural Engineering Considerations in Design of Secure Compounds Many government facilities as well as private campuses are designed for physical security, which requires the buildings on site to be designed for deliberate threats, such as explosive devices or vehicle attacks. This poses unique challenges to structural engineers and often results in heavy buildings, typically constructed with conventionally reinforced concrete.

By Chris Heckmann, PE; Achraf Ayad, Ph.D, PE; Leslie Duffy, PE

O

n the morning of August 7, 1998, an unmarked truck drove up to the main gate of the United States embassy in Nairobi, Kenya. After a brief altercation between the men in the truck and the guards, the truck exploded, unleashing 2,000 pounds of TNT. The embassy was heavily damaged, and a neighboring building collapsed. At the same time, 500 miles away a similar truck drove a similar bomb to the gate of the U.S. embassy in Dar es Salaam, Tanzania, and detonated it.

The coordinated attacks killed 224 people and wounded thousands more. Combined with the 1995 bombing of the Oklahoma City Federal Building, the East Africa bombings kickstarted a serious look into how to protect structures against deliberate threats.

This article will provide an overview of the structural engineering principles behind designing a secure compound, including why it’s necessary and how structural designers account for physical security measures in their designs of these types of structures. A secure compound is a campus that is designed to protect the inhabitants from deliberate threats and attacks. These sites are typically large, spread out, and built away from dense city centers. Some common examples of secure compounds are embassies, certain military facilities, federal agency campuses, some aviation facilities, and courthouses.

Fig. 1. The U.S. Embassy site in Guatemala City is a modern example of a secure compound. (Photo by Gabe Border for the U.S. Department of State)

Why Do We Design for Extreme Events?

While it might seem uneconomical to design structures for seemingly rare events, attacks on government buildings and important structures are more common than one might think. The U.S. embassy in Beirut was bombed by Hezbollah in 1983, killing 63 people, including 17 Americans. The embassy was subsequently relocated to a new property in a suburban location. The following year, the new location was bombed as well, killing 23 more people. If we can design buildings to ensure the safety of occupants in extreme events like hurricanes and earthquakes, can we not design them to ensure safety in a terrorist attack as well?

Physical Security Physical security design can be broken down into four primary components: 1) secure perimeters, 2) blast resistant design, 3) progressive collapse mitigation, and 4) forced entry and ballistic resistance.

Secure Perimeters Fig. 2. Rubble of the U.S. embassy in Nairobi after the 1998 bombing.

(Source: IDF Spokesperson’s Unit)

14 STRUCTURE magazine

The secure perimeter of a site typically consists of a solid concrete wall or a concrete knee-wall with a steel fence atop. Two main aspects go into this design: anti-ram and anti-climb. The goal of anti-ram design is to prevent a vehicle from penetrating the secure perimeter. Numerous threat levels exist for vehicular

Fig. 3. Wedge barriers are a common staple of secure sites. (Photo courtesy of Hercules High Security, who installs and maintains all types of active vehicle barriers around the world.)

attacks, corresponding to various sizes and speeds of vehicle impact. The gold standard is the “K-12” barrier, which is tested and designed to stop a 15,000-pound vehicle traveling 50 mph. Examples of this would be a Ford F-350 towing its max capacity or a fully loaded box truck (think a large U-Haul).

Anti-ram barriers can be concrete walls, bollards, or wedge barriers. Anti-ram concrete walls are usually extended high enough above the ground to withstand vehicle impact and have a cantilevered retaining wall type footing designed to absorb the impact of the vehicle. Antiram bollards closely resemble standard traffic bollards, but the steel pipe is filled with concrete and features an extensive foundation. Bollards need to be closely spaced so that a vehicle cannot navigate through them, approximately 5-feet on-center.

Anti-ram wedge barriers are prefabricated products that allow for vehicular access control. A typical wedge barrier can be seen in Figure 3. The barrier is kept raised and only lowered when a vehicle is granted access to the site. Wedge barriers have an extensive concrete footing and are often combined with sliding gates or bi-fold gates, which serve as anti-climb protection.

Anti-climb means that the site perimeter must be designed so that someone cannot climb over the wall and gain access to the compound. Walls around secure compounds are typically both anti-ram and anti-climb.

Entrance pavilions, where pedestrians and vehicles enter the site, are also designed to be anti-climb.

Blast Resistant Design The goal of blast-resistant design is to prevent failure of structural and architectural components and to minimize injury to the building’s occupants should an explosive device be detonated nearby. This is accomplished through the hardening of structural elements, facade features, and architectural appendages that may become a hazard during a blast event (Figure 4). Blast design considerations include maintaining global stability of the structure, limiting damage, and mitigating flying debris.

Understanding the blast loading expected at each structure, namely blast overpressures (i.e., pressures exceeding atmospheric pressure) and their duration, is the foundational step. Loads are determined by considering a line

Fig. 4. The U.S. Consulate in Nogales, Mexico, features an impressive, cantilevered sunshade that was designed to withstand blast loading. (Photo by Patrick Coulie for the U.S. Department of State)

of threats around the site perimeter and enveloping the governing overpressures utilizing methodologies founded on empirical data or Computational Fluid Dynamics (CFD) analysis. In addition to explosive charge size and standoff distance, the geometry of a structure influences blast effects. Those with complex geometries typically create “confining” effects that produce higher design loads. Ultimately, the enveloped loads are implemented in a time-history analysis to verify the global and local response of the building structure and individual elements, respectively.

From a global standpoint, a blast event will induce base and story shear forces like wind or seismic loading. Blast story shears are developed considering the impulsive loads impacting a building surface area and the structure type. Forces are applied to the floor diaphragms based on surface tributary heights for each story down to the foundation, where the load attenuates. Coordination is required between the blast engineer and structural engineer to determine the governing lateral load for the building.

Ductile detailing for both architectural and structural components is incorporated into the design to induce plasticity in ductile failure mechanisms. For various architectural features, ductile detailing requirements are implemented when their response is not required to meet specific limits under blast (i.e., canopies, sunshades, railings, architectural fins, etc.). The standard of practice provides connections and anchorage that are designed to resist the ultimate flexural capacity of the element so that it will remain attached to the supporting structure.

Progressive Collapse Mitigation Progressive collapse refers to a structural failure mechanism where local damage to a load-bearing element triggers a chain reaction, leading to the disproportionate collapse of a structure. UFC 4-023-03, Design of Buildings to Resist Progressive Collapse, outlines strategies to enhance a building's robustness and limit such failures. The design philosophy focuses on redundancy, ductility, and continuity to ensure the structure can withstand localized damage.

Progressive collapse design is threat-independent, meaning that unlike blast design, the principles and methods are not tailored to specific threats like explosions or impacts. Instead, the design focuses on ensuring the structure can maintain its integrity regardless of the cause of localized damage. Per the UFC, only buildings three stories or more are required to be designed for progressive collapse.

The two design procedures for progressive collapse are the Tie Force Method and the Alternate Path Method. The Tie Force Method ensures that structural elements are interconnected to redistribute loads in the event of localized damage.

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This approach mandates robust connections in steel buildings and continuous reinforcement in concrete buildings within the structure. The Tie Force Method is typically applied to buildings with regular configurations, such as low-rise structures, where enhanced connectivity effectively mitigates localized damage.

The Alternate Path Method involves designing the structure to provide alternative load paths if a primary structural element fails. This method ensures stability by redirecting loads through other members, maintaining the overall integrity of the building. The Alternate Path Method is suitable for complex structures, mid to high-rise buildings, or facilities with higher risk profiles, where additional redundancy is necessary beyond the Tie Force Method.

The three common structural analysis procedures for designing and assessing buildings for progressive collapse are the Linear Static Procedure (LSP), the Nonlinear Static Procedure (NSP), and the Nonlinear Dynamic Procedure (NDP). The LSP applies static loads to a simplified linear model of the structure, assuming linear elastic material behavior. The LSP has lower computation demands but does not accurately capture nonlinear behaviors or dynamic effects, which are vital for accurate and not overly conservative progressive collapse calculations. The LSP is usually used in early design stages to gauge the building’s response to progressive collapse or for simple, redundant structures where detailed dynamic analysis is not critical.

The NSP, also known as pushover analysis, applies increasing static loads to a nonlinear model. This method accounts for material nonlinearity and inelastic behavior, providing a more realistic representation of the structure's response to extreme loading. It’s a more accurate representation of structural behavior than LSP, including post-yield response, but has increased computational demands.

The NDP involves time-history analysis using nonlinear models subjected to dynamic loads. This method captures both nonlinear material behavior and dynamic effects.

Of the three procedures, NDP offers the most accurate and comprehensive assessment of a structure's response to progressive collapse but also requires the highest level of model detail and is more computationally demanding.

By implementing these methods and procedures, the UFC 4-023-03 ensures that buildings can withstand local failures without experiencing total collapse. In the case where a threat cannot be eliminated, deferred, or stopped from damaging the building, designing for progressive collapse mitigation offers another way to limit catastrophic structural damage and save lives.

Forced Entry and Ballistic Resistance Incorporating Forced Entry and Ballistic Resistance (FEBR) provides increased security for building occupants under various levels of threats from individuals that may have already breached the secure perimeter or entered a building. FEBR requires the hardening of certain walls, doors, and windows throughout a compound.

The various levels of FEBR protection are defined by 16 STRUCTURE magazine

the site owner or governing body. Some common levels of FEBR protection are FE 5, FEBR 15, and FEBR 60 (FE 5 excludes ballistic resistance). The numbers define the amount of time in minutes that the barrier must theoretically withstand attack before being penetrated. FEBR wall, door, and window designs are based on individually tested assemblies. For a 5-minute FE assembly, the test involves two men swinging sledgehammers and other tools at the door for 5 minutes. FEBR 15 minute and FEBR 60 tests are similar but involve artillery fire and less readily available, heavy-duty tools like battering rams.

An example of an FEBR test is shown in Figure 5.

FEBR detailing is prescriptive, based on the tested configurations and usually requires no additional calculations from the structural engineer if preapproved configurations are implemented. FEBR walls are typically concrete walls, structural steel stud-walls, or glass curtain walls. Curtain walls are used where dictated by the architectural requirements of the building and usually consist of Fig. 5. Two men try to break through an FEBR door with sledgehammers in an FEBR test. (Photo courtesy of Protogetic thick glass windows supported and Ceco Doors)

by HSS steel mullions.

Consequences of Secure Design As described earlier, designing a site for physical security introduces many structural design considerations not common in conventional building design.

These protective designs have several major effects on the final building design.

Perhaps the most consequential effect on a building from protective design is the increased weight of structure that comes as a result of designing for blast, progressive collapse, anti-ram, and FEBR. Whereas conventional buildings rarely use solid concrete partition walls or exterior walls, a secure building will likely feature many. Despite the cascading effects of a heavier building, a concrete wall is often most economical when compared with steel or glass wall options.

Considering progressive collapse when designing a building often results in the need for concrete beams spanning between columns and walls. Flat slab systems are typically impractical given the quantity of reinforcing needed, and structural steel framing systems are often uneconomical due to the number of moment connections needed to create a frame of such redundancy. In turn, the additional dead weight leads to larger foundations and significant seismic base shears. On secure compounds, seismic loads often govern over wind loads even in regions of high wind and low seismicity. In regions of high seismicity, seismic forces can be significantly higher than a conventional building of the same size.

Exterior building elements like canopies or architectural features requiring structural backup framing are often complex and challenging when a building is designed for blast loading. These elements, such as canopies, are often constructed from structural steel, which requires ductile detailing and capacity design of connections. A canopy or other exterior feature on a building designed for blast loading can lead to significant added cost.

Similarly, when curtain walls, storefront, and doors/windows must meet blast loading requirements or FEBR requirements, the assemblies become complex and heavy. Curtain walls often feature thick glass with large structural steel mullions and significant embed plates cast into the base structure. Curtain wall design is usually delegated to a supplier and carried out at the beginning of the construction phase. Thus, the timing and sequencing of the design and installation of these embeds can pose a scheduling challenge to the contractor.

Lastly, as the building construction industry targets reducing embodied carbon

Fig. 6. The recently completed U.S. Consulate in Hermosillo, Mexico, shows that a secure design can be aesthetically appealing as well. (Photo by Gabe Border for the U.S. Department of State)

in design and construction of the built environment, hardening and strengthening the structure for physical security can be counterproductive to this goal, mostly due to the significant increase in concrete needed. To offset this, governments and owners can look to operational carbon reductions for their buildings, such as PV arrays and efficient mechanical operating systems.

Conclusion Designing a secure compound poses unique challenges for practicing structural engineers. From designing for vehicular impact to reducing risk of progressive collapse after the removal of a primary load bearing element, the structural engineer must take on a larger role and responsibility in the design of a secure compounds. With proper knowledge of the design methodologies discussed in this article, structural engineers can incorporate the requirements for a secure compound into their design without compromising architectural intent, function, or beauty of a site. ■

Chris Heckmann, PE, is a senior project manager with Ehlert Bryan in Washington, DC, specializing in overseas U.S. diplomatic facility design.

Achraf Ayad, PE, is an assistant project manager with Ehlert Bryan in Washington, DC, specializing in overseas U.S. diplomatic facility design.

Leslie Duffy, PE, is an associate with KPFF’s Protective Design team in San Francisco, CA, specializing in blast engineering.

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JULY 2025

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structural DESIGN Understanding Roof Systems of Metal Buildings

The Roof Framing Design Guide for Metal Building Systems, 2nd Edition, provides updates and additional guidance from the original Roof Framing Design Guide.

By Michael W. Seek, Ph.D, PE, and Vincent E. Sagan, PE

A

metal building is a system with complex behavior that, when properly accounted for, provides an efficient structural solution. To help the engineer properly design for this behavior, the Metal Building Manufacturers Association (MBMA) has recently released the Roof Framing Design Guide for Metal Building Systems, 2nd Edition (Roof Framing Design Guide).

A metal building roof system is comprised of primary frames, secondary framing, which includes roof purlins and wall girts, exterior cladding and additional bracing elements. These components work together to provide a structural system that can resist the various environmental loads while providing for large open spaces. An example of a metal building system that provides an open floor space for an industrial application is shown in Figure 1.

The interactions between the different roof system com- Fig. 1. The metal building roof system here provides an open floor space for industrial application. ponents and the resulting strength and stability benefits are not obvious and the mechanisms are not typically taught in under- behavior. This chapter provides a quick overview of these systems to graduate engineering programs. Therefore, it is the goal of the Roof help orient a designer who is unfamiliar with cold-formed steel purlin Framing Design Guide to thoroughly explain how a metal building supported roof systems. An example of a common configuration for roof system behaves and to provide guidance on how to design it. The roofing components is shown in Figure 2.

Roof Framing Design Guide provides updates and additional guidance Chapter 2, Design Method for Purlins: For the design of purlins, the from the first edition to reflect changes in standards and brings the flexural strength depends on the extent to which they are braced by the latest available information to the design of these systems. The origi- panels and any additional discrete braces. Chapter 2, Design Methods nal Design Guide for Cold-Formed Steel Purlin Roof Framing Systems, for Purlins, breaks down the design process into three distinct pathways AISI D111, was published in 2009 by the American Iron and Steel that account for these differences in bracing provided: through-fastened Institute (AISI). The new edition also incorporates the information systems, standing seam systems designed by the Base Test Method, and from another AISI design guide, A Guide for Designing with Standing discrete braced systems. Through-fastened panels effectively provide Seam Roof Panels, CF97-1. restraint from movement, so the process for the design of the purlin is The Roof Framing Design Guide provides a comprehensive simplified. Standing seam panels are typically more flexible, often by description of the design requirements of roof systems supported by design, to accommodate thermal expansion and contraction, so their cold-formed steel purlins, with emphasis on the design of the system design must account for this increased flexibility. A designer may take anchorage. All design provisions are aligned with the 2016 edition of a simplified approach ignoring the contribution of these panels altothe North American Specification for the Design of Cold-Formed Steel gether and design the purlins as discrete braced, relying solely on the Structural Members, AISI S100-16, referred to as AISI S100. stability provided by lateral braces along the span. A more sophisticated This second edition of the Roof Framing Design Guide, consisting approach for standing seam systems is to utilize full scale tests, known as of six chapters, was reorganized to highlight the nuances in design Base Tests, to determine the strength of the system. These tests account between systems clad with through-fastened panels versus those with for the complex forces at play and provide a more accurate method for standing seam panels, and to provide improved guidance on evaluat- determining the flexural strength of the purlin. ing the strength and stiffness contributions of these panels. Because The Base Test method is a standardized test outlined by AISI S908, the roof panels help stabilize the cold-formed steel purlins, a roof Test Standard for Determining the Flexural Strength Reduction Factor system constructed with cold-formed steel purlins and metal panels of Purlins Supporting a Standing Seam Roof System. Chapter 2 of the truly acts as a system.

Roof Framing Design Guide supplements this standard and provides Chapter 1, Introduction: Chapter 1 of the Roof Framing Design guidance developing a strategic test program with a reduced number Guide outlines the various components of the roof system includ- of required tests that can still accurately predict the strength of the ing types of bracing systems and how they contribute to the system system while still accounting for all of the potential variables that 18 STRUCTURE magazine

could be introduced. For example, AISI S908 requires that six tests be performed for each combination of purlin profile, panel profile, clip type, intermediate bracing configuration and loading. A manufacturer wishing to test a Z-section purlin with two flange widths in combination with a standing seam panel with two thicknesses and three possible clip types would be required to perform 72 tests (2 flange widths x 2 panel thicknesses x 3 clips x 6 tests).

By strategically addressing each variable in the tests, such a test program could be reduced to as few as nine tests. A Fig. 2. A common configuration of metal building roof components. detailed example outlining such a test program is provided.

Chapter 3, Continuous Purlin Design: This chapter guides the designer through the various design checks required for cold-formed steel purlin systems. Because purlins are typically lapped across supports to provide efficient continuity with simple connections, the purlin strength must be checked at many more locations. As a result of the slenderness of the cross section of cold-formed steel members, additional limit states must be checked that may not be familiar to engineers accustomed to designing hot-rolled steel. Guidance is provided for both gravity loading conditions as well as wind uplift conditions. Numerous flow charts assist designers to account for all applicable Fig. 3. Roof layout for a roof system with multiple anchors. limit states.

Chapter 4, Diaphragm Requirements: This is an entirely new chapter for this edition. It integrates much of the information multiple anchors for which a detailed design example is provided. originally published in A Guide for Designing with Standing Seam Chapter 6, Miscellaneous Topics: The Roof Framing Design Guide Roof Panels, CF97-1, and has been updated in accordance with AISI concludes with this new chapter that covers standing seam roofs on steel S100. The strength and stiffness of profiled panels is determined by joists and standing seam roofs with roof-top units or hanging loads.

AISI S907, Test Standard for Determining the Strength and Stiffness The Roof Framing Design Guide for Metal Building Systems, 2nd of Cold-Formed Steel Diaphragms by the Cantilever Method, known Edition, provides updates and additional guidance from the origias the cantilever test. Chapter 4 provides guidance for adapting the nal Roof Framing Design Guide to reflect changes in standards and diaphragm strength and stiffness quantified by the cantilever test brings the latest available information to the design of these systems. to roof systems. Most of the design methodologies for purlins rely It is an essential resource to understand how metal building roofs on the resistance provided by the diaphragm for strength, therefore work as a system. This publication went through a very thorough there are limits to the lateral deflection of the diaphragm. Also pro- review by metal building and cold-formed steel engineers. An MBMA vided are several methodologies with ranges of sophistication that steering group reviewed the allow the designer to predict the lateral deflections of the purlins to drafts of the guide, and comensure compliance with deflection limits. These special procedures ments were incorporated. are introduced and illustrated with examples.

It was then reviewed by the For cases where a diaphragm may not provide sufficient strength or AISI Education Committee stiffness to adequately stabilize a system of purlins, the system of purlins and AISI Subcommittee 4, may be designed as a discrete braced system as classified in Chapter Assemblies and Systems. These 2. The Roof Framing Design Guide provides guidance on calculating comments were incorporated these brace forces using the approximate method from Section C2.2.1 into the document, which was of AISI S100 or by using a more refined mechanics-based method. then published as an MBMA In addition, there is new guidance on the design of strut purlins as it design guide. relates to axial loads, along with a design example for a strut purlin The new Roof Framing Design in a standing seam system with discrete braces.

Guide is available as a free Chapter 5, System Anchorage Requirements: To complete the download from the Design design of the metal building roof structural system, bracing forces Resources page of the MBMA must be determined, and their load paths followed to the primary website, https://mbma.com/ frames. The transfer of these forces to the primary frames is referred design-resources. ■ to as anchorage. Chapter 5 describes and outlines the procedure in AISI S100 Section I6.4.1 to determine the anchorage forces in roof systems with varying bracing configurations. Additionally, alternative Michael Seek, Ph.D, PE, is an Associate Professor of Engineering Technology at methods to determine anchorage forces are explained, including the Old Dominion University in Norfolk, VA. Component Stiffness Method, and guidance is provided to model Vincent E. Sagan, PE, F.ASCE, is the Director of Codes & Standards for the Metal purlin systems either using frame element or shell finite element Building Manufacturing Association (MBMA) in Cleveland, OH. models. Numerous calculation examples are provided illustrating how to apply the various methods. Figure 3 is a plan of a roof system with JULY 2025

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NatureInspired Hybrid

20 STRUCTURE magazine

Kresge College’s new Academic Center advances mixedmaterial projects beyond typical hybrid-timber construction.

By Alex Wilson, PE, and Ian McFarlane, PE, SE

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estled among the redwoods on forested acreage marked by the ridges and ravines inherent to Northern California, the University of California, Santa Cruz’s (UCSC’s) new Kresge College Academic Center features a unique approach to hybrid design and construction different from the typical “steel-beams-and-timber-slab” hybrid model.

The largest of the 125,000-square-foot expansion’s four buildings, the Center’s below-grade concrete podium and retaining walls hold back the hillside, supporting an impressive “lobed” mass timber roof that celebrates the inherent beauty of exposed wood.

Light-frame wooden shear walls and a steel moment frame round out the design as the primary lateral Fig. 1. The new Kresge College Academic Center’s subtle curves let in more light than the College’s original campus buildings. (Photo by Jason O’Rear)

system of the roof structure. The Center’s CrossLaminated Timber (CLT) diaphragm is pushing the limits beyond what was formally codified at the time of design. Working collaboratively with the design architect and contractor, Magnusson Klemencic Associates (MKA) created a structural design that bridged the gap between vision and reality, historic and modern, and mass timber and hybrid systems.

‘Curvature and Porosity’ Design architect and architect of record Studio Gang envisioned Kresge’s four-building expansion— the Kresge College Academic Center and a trio of mass timber residence halls—as an opportunity to increase the College’s accessibility and better connect it with the surrounding natural ecology and the greater UCSC campus. The new buildings do not

Fig. 2. The renovation was sited and designed to minimize the removal of redwood trees, resulting in the Center’s four protruding wings—or lobes—inspired by the growth patterns of polypore fungi. (Photo by Jason O’Rear)

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Fig. 3. Typical hybrid construction utilizes steel and timber; MKA’s design included a new mix of structural materials where they work best. (Image by MKA)

replicate the original campus buildings designed by Charles Moore and William Turnbull in 1973, but rather “engage it in a dialogue that complements its rectilinear, angular language with a more organic one of curvature and porosity,” as described by Studio Gang.

The selection of wood was prioritized for sustainability, as wood construction produces less carbon emissions than steel or concrete, a critical driver for Studio Gang.

The eight-acre expansion site is small and features a steep, uneven hillside drop-off to the east, above which the Kresge College Academic Center is perched. All the new buildings were sited and designed to minimize the removal of redwood trees to preserve the natural environment whenever possible, resulting in the building’s

asymmetrical pod-like form inspired by the growth patterns of polypore fungi.

The Kresge College Academic Center includes four wings, or lobes, containing office, classroom, and lecture spaces connected to a large 600-seat lecture hall to the north at the primary upper-grade entry level. Here, the structural slab is lowered to accommodate a raised access floor. The raised floor provides a mechanical plenum and forms the tiered platforms and steps in the lecture hall and classrooms. The center of the building contains a triple-height atrium that shows off a curved, architectural concrete retaining wall and slender cast-in-place stairs that bring occupants down to the two lower levels, which terrace down, following the steep slope of the site.

Figs. 4–5. The Kresge College Academic Center’s large lecture hall, under construction (left) and complete, features an innovative mix of concrete, steel, light-frame, and mass timber. (Photos

by MKA [left] and Jason O’Rear [right])

22 STRUCTURE magazine

Choosing the Right Material While a concrete podium and retaining wall structure made sense for a large building built into the hillside above a ravine, UCSC chose exposed mass timber for the Center’s roof structure, where it could be most celebrated. The roof framing above the ground floor level consists of three- and five-ply CLT slabs spanning between glued-laminated timber (glulam) beams. Within the lobes of the building, glulam beams, ranging from 21–31½ inches deep, are gently curved upward to follow the geometry of the roof and rest on slender perimeter glulam columns designed to maximize window views. The CLT panels within the lobes are faceted to follow the curvature of the roof. This system provides flexibility for the variety of programs within each lobe, delivers an appealing exposed timber aesthetic, and maximizes views to the outside.

MKA utilized a light-frame wood shear wall lateral system and a single-bay steel moment frame to support the mass timber roof. The steel moment frame was selected to provide a 40-foot clear span at the south end of the large lecture hall, a critical aspect of the architectural vision, while efficiently integrating with the mass timber framing. The Center also utilizes a CLT diaphragm to distribute seismic loads to the shear walls and moment frame. MKA collaborated with WoodWorks on this unique diaphragm approach, which was vetted by a peer review process and ultimately resulted in cost savings by eliminating plywood sheathing and steel strapping.

Terracing down the steep grade of the site, a concrete podium was chosen for the lower two levels of the Kresge College Academic Center for its strength, stiffness, and durability. Concrete walls up to

The juxtaposition of concrete podium and timber roof highlights the Center's geometry.

18 inches thick and two stories tall support significant unbalanced permanent soil load. Below-grade slabs up to 12 inches thick were chosen based on compatibility with the retaining wall and the need to cantilever up to 15 feet at the atrium while minimizing structural depth. Concrete podium shear walls support the seismic and unbalanced soil load for strength and stiffness. The foundation system combines isolated spread footings and combined mat foundations.

The mat foundations were used to incorporate the building’s complex geometry (in plan and elevation) while minimizing the volume of concrete required.

The juxtaposition between the smooth, exposed concrete of the lower levels and the mass timber above met the architectural vision of embracing the natural ecology of the site without losing the practicality and strength of a concretesupported structure.

Naturally Unique In this timber project, the building’s beams, walls, and roof subtly curve to reflect the natural environment and provide complementary contrast to the College’s earlier architecture. Large windows throughout the lecture spaces let in natural light.

Construction of the Kresge College Academic Center began in 2020, and the building opened to students in 2023.

The Kresge College Academic Center is a unique approach to hybrid construction, recognizing opportunities to use materials and systems in less conventional ways to benefit the project. By remaining open to all materials during the early stages of design, MKA and the project team were able to integrate them in ways that play to each material’s inherent strengths and push their limits. Materials might make sense where they are least expected. ■

Alex Wilson, PE, is a Senior Design Engineer at Magnusson Klemencic Associates (MKA).

Fig. 6. The Center’s two-story concrete podium and retaining wall structure is built into the hillside above a ravine, supporting significant unbalanced permanent soil load. (Photo by Jason O’Rear)

Ian McFarlane, PE, SE, is a Senior Principal at MKA.

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Trial by Fire: Structural Engineering Challenges in a Historic Hotel Conversion

Figure 1. In 1847, as attendance grew, the south wing was added to the Visitation Academy. In 1851, an additional expansion was constructed on the east side of the original main building which included a chapel and monastery. In 1860, a large hall was added to the end of the south wing of the building. (Photo by Ron Blunt)

The adaptive reuse project modified a 179-year-old academic building into a boutique hotel in Maryland.

By Chelci E. Dell & Jeffrey D. Viano

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hat is today a Tribute Portfolio Marriott Hotel in Frederick, Maryland, was once an all-girls Roman Catholic school that dates back to the Civil War era.

The Visitation Academy, founded in 1846, originally consisted of a large three-story building and was later expanded through multiple additions. The main building and its additions are constructed primarily of mass brick masonry walls with wood framed floors and large, heavy timber roof trusses. After nearly two centuries of establishment, the Visitation Academy was seeing a decline in enrollment and ultimately decided to close its doors in 2016. A developer purchased the property in 2017 with plans to convert the building into a boutique hotel. Wanting to keep as much of the history of the building as possible while also modernizing the space, the Visitation Hotel became a quintessential adaptive reuse project.

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Adaptive Reuse of Visitation Academy An adaptive reuse project typically involves the renovation of a building or space for a new purpose while keeping the majority of the structural framing and components. Often times, strengthening or other modifications are required to meet the new function and aesthetics of the space as well as updated code requirements.

Originally primarily used for classrooms and sleeping quarters, the majority of the building was subjected to roughly 40 pounds per square foot of live load. Today, some of these same spaces are being used for the hotel lobby, fitness center, egress pathways, and dining areas which have higher loading requirements to meet today’s building code. In several areas, the existing floor joists required strengthening with new laminated veneer lumber (LVL) sisters to meet new loading requirements as well as deflection criteria for occupant comfort. In

Project Team Development/Owner Team: Jim O’Hare & Lance Jaccard Architect: OTJ Architects Structural Engineer: Simpson Gumpertz & Heger General Contractor: Bognet Construction

Fig. 2. The chapel was converted into a bar and restaurant space.

other areas, it was desired to keep more of the historic fabric intact, thus strengthening of the existing floor framing was not an option.

The existing floor framing in these areas could not support the new live loads required to comply with the designated occupancy per the International Building Code. Instead of sistering, the existing floor framing was evaluated for a reduced live load that was determined based on the size of the space and the number of people that were expected to use the space at a given time. This approach is allowed per the International Existing Building Code for alterations and requires placards to be displayed in the area where the live load is limited.

In addition to upgrading the floor framing to meet new loading requirements, the new programming of the space required several new, large openings in the existing load-bearing brick masonry walls.

These openings required wide-flange steel beam lintels to support the weight of the mass masonry wall and floor framing above while also meeting tight deflection criteria.

Several areas of the building also needed upgrades to meet current Americans With Disabilities Act (ADA) requirements. Ramps were constructed throughout the building and three new elevators were added. At two of the elevators, the depth of the elevator pit exceeded the bottom of the existing footing bearing elevation, requiring underpinning of the existing foundations. Additionally, where the elevator

shafts utilized existing masonry walls, several masonry repairs were required to establish a suitable substrate for the elevator rail attachments. The elevator in the east wing of the building also required a pop-up at the roof level to provide enough clearance for the elevator overrun. From a historic standpoint, it was important that the construction of the overrun blend with the original construction since it was on a prominent corner of the building.

A Blazing Halt to Construction Construction began in early 2022 and was targeting completion in late spring of 2023—just in time for wedding season. A couple of months before construction was anticipated to be complete, the schedule was significantly impacted by a fire in the west wing of the building during a severe thunderstorm on the night of April 1, 2023.

The fire damage was localized to one wing of the building and in areas with two distinct structural framing systems. Existing roof framing in the southern portion of the west wing consisted of heavy timber trusses spaced approximately 12 feet apart and spanning roughly 40 feet. The trusses were supported on masonry pilasters within 25 foot-tall mass masonry bearing walls. Wood purlins and rafters spanned between the JULY 2025

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Fig. 3. A fire in 2023 caused severe damage to the building, including these timber roof trusses.

trusses and were topped with wood decking. Existing framing in the northern portion of the west wing consisted of 3x6 wood rafters spaced 24 inches apart supported on masonry bearing walls, and a series of timber posts and beams which also framed an exterior balcony.

The fire caused severe damage to the building. Before repairing the historic building, it was critical to understand the extent of structural damage. When assessing a damaged structure, safety of personnel is of paramount importance. The first step in the assessment included a survey around the exterior perimeter of the building to understand the general locations of damage and identify any potential hazards such as unstable masonry, damaged handrails, and compromised floor and roof areas. Engineers then inspected the interior of the building starting at the lowest levels and working their way up, ensuring they did not step on fire-damaged wood framing that could no longer support weight. The extent of the fire damage presented significant challenges when it came to accessing the attic framing and roof trusses.

Ultimately, the team determined that a custom-built scaffolding system was necessary to facilitate a hands-on inspection of these components.

Hands-on inspection is important to gain an understanding of the remaining cross-sectional properties of fire-damaged wood structural members. When exposed to fire, the outer layer of timbers becomes charred, but this outer char layer can often be scraped away revealing a reduced, but still potentially viable, structural cross-section.

The zone beneath the char layer (i.e., the pyrolysis zone) experiences thermal degradation, affecting the load-carrying capacity of the wood framing. However, wood below the pyrolysis zone retains its strength and a residual cross section of a fire-damaged timber can be analyzed for structural loads. The United States Department of Agriculture’s (USDA) Wood and Timber Condition Assessment Manual and the 2024 Edition of the National Design Specification (NDS) provide guidance to determine section properties of residual cross sections.

After inspection and review, the engineering team determined that the fire damage was too extensive, and the remaining cross-section of the attic and roof framing was not adequate and thus needed repairs.

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Several different options for repairs to the fire-damaged structure were explored. Ultimately, replacing the framing in-kind (particularly the heavy timber trusses) was deemed problematic due to cost and schedule concerns, and the team decided to remove much of the fire-damaged framing and replace it with new metal plate-connected (MPC) wood trusses.

Given the lightweight nature of the new roof trusses, uplift forces due to wind had to be carefully considered. New anchorage details and lateral bracing were designed to counteract potential uplift, ensuring the roof system remained stable under wind loads. Coordination with the architect and contractor was crucial to integrating these structural elements without compromising the historic character of the building.

The significant damage to the roof also put the existing exterior masonry walls at risk of collapse due to compromised bracing. To provide stability, temporary wall bracing was installed that consisted of a combination of diagonal wood and steel members anchored to stable portions of the structure. This temporary support system remained in place until the permanent structural repairs were installed.

The design of temporary bracing was delegated to a specialty shoring engineer and carefully reviewed by the Structural Engineer of Record.

MPC trusses are commonly used for their efficiency and cost-effectiveness, but they are also prone to fabrication and installation flaws.

Typical issues include improper handling and on-site storage of trusses, truss plates installed with wane or wood with other defects, and improperly installed bridging or bracing. Each defect requires careful evaluation and coordination with the MPC truss delegated design to determine whether repairs or replacements are necessary.

Lessons Learned Adaptive reuse projects can often create more challenges than new construction due to constraints of the existing structure and unforeseen conditions.

One of the greatest lessons learned during this project was the importance of confirming existing conditions early on in the design and establishing construction contingencies to account for both cost and schedule impacts for unforeseen conditions. The original structural drawings for the building were not available to the design team; therefore, exploratory openings were made at select locations prior to the start of the design phase to verify the existing framing. However, these openings were limited, and several conditions were made much more apparent once the full demolition of finishes for construction took place. This resulted in several Requests for Information (RFIs) during construction and redesign of several elements based on the existing conditions.

Additionally, since several areas of the building were heavily modified to meet the new function of the space, it was important to understand the load path of the original construction and verify that the new structural framing could follow the same load path or that a new load path would be established to the building foundation. For example, the columns supporting the balcony in the chapel did not have a clear load path down to the building foundation. A new steel beam was installed to transfer the balcony column reaction to two new steel posts and concrete foundations. Another example is a unique framing system was designed for the MPC trusses. Typically, structures framed with MPC trusses consist of closely spaced trusses supported on load-bearing walls or beams.

However, this framing scheme was not consistent with the existing load path in the southern area of roof damage. The new framing plan consisted of 2-ply MPC trusses sistered to the existing timber trusses and supported on the existing masonry pilasters to mimic the load path of the original timber trusses and wood purlins.

back from the original completion date, the Visitation Hotel officially opened for business in December of 2024. The hotel and its acclaimed restaurant by the Voltaggio brothers, who are known for their appearances on Top Chef and Food Network, cement the project as a landmark destination in Frederick. ■

Chelci E. Dell is a Senior Consulting Engineer in the Structural Engineering Division of Simpson Gumpertz & Heger's Washington, DC, office.

Jeffrey D. Viano is a Senior Project Manager in the Structural Engineering Division of Simpson Gumpertz & Heger's Washington, DC, Office.

Importance of Adaptive Reuse Developers can easily purchase a property and demolish the entirety of a building to create something new and more modern. However, as sustainability gains more and more traction in the built environment, projects like the Visitation Hotel will continue to be of great importance. Not only is adaptive reuse often a greener alternative to new construction, the majority of the building, including its historical integrity, was saved.

Epilogue The Visitation Hotel in Frederick, Maryland, is a beautifully reimagined space and serves as a great place to stay, grab a bite to eat, or hold a special event. Although the fire damage and necessary repairs set the construction schedule

Fig. 4. The Visitation Hotel opened in December 2024.

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Exterior View of the 70th Street Garden, Reception Hall, FARL Extension, and overbuild with offices and a new conservation studio.

Photo: Nicholas Venezia

Gilded Age Revival: The Frick Collection Simpson Gumpertz & Heger engineered custom solutions for this historic New York mansion-turned-art-museum to achieve the architectural design intent while encountering a variety of archaic gravity systems from prior structural renovations.

By Lauren Feinstein, PE, David Ribbans, PE, Kevin Poulin, PE, and Filippo Masetti, PE This is Part 1 of a two-part series discussing the renovation of The Frick Collection in New York City.

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Restored West Gallery. Photo: Joseph Coscia Jr.

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ocated on Fifth Avenue on the Upper East Side of Manhattan, The Frick Collection houses the art collection of industrialist Henry Clay Frick and his wife Adelaide Clay Frick in their 1914 Gilded Age mansion. Through several building renovations spanning between 1935 and 2011, the museum expanded its footprint by enlarging existing buildings and constructing new ones. Because of the renovations and the long timeline over which they occurred, The Frick Collection contains an expansive array of archaic structural systems hidden behind its opulent architectural finishes.

The original Beaux-Arts mansion was designed by Carrère and Hastings in 1914 with the intention of opening the residence to the public and sharing the Fricks’ private art collection after their deaths. In 1935, after Adelaide’s death, their daughter Helen hired architect John Russell Pope, who seamlessly doubled the footprint of the mansion to create a museum that included two large galleries with skylights, a new interior garden (the Garden Court), the Music Room, and the nine-story Frick Art Research Library (FARL). During World War II, the museum also constructed a three-story below-grade art storage vault to protect its collection. A later

Project Team Engineer of Record: Simpson Gumpertz & Heger Structural Consultant: Guy Nordenson and Associates Architects of Record: Selldorf Architects and Beyer Blinder Belle Architects & Planners, LLP Construction Manager: Sciame Construction

1977 addition added the single-story Reception Hall, along with the 70th Street Garden. The museum, including the historic exterior gardens, is a National Historic Landmark. In 2011, the Frick enclosed an extant garden portico to create an additional gallery within its footprint.

In 2017, The Frick Collection began a new phase of expansion and renovation that would allow the museum to showcase its expanded collection, modernize back-of-house facilities, and improve energy efficiency. The project included a narrow nine-story horizontal addition and a new bulkhead at the FARL, a three-story vertical addition above the Music

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Room, and a one-story vertical addition above the Reception Hall.

The renovation also included the removal of the art storage vault to allow the construction of a new auditorium, restoration of the second floor of the mansion for conversion to gallery space, replacement of skylights, and the addition of new stairs and elevators to improve visitor circulation. The complicated project was rife with challenges associated with the repair and strengthening of numerous archaic structural systems throughout the historic buildings.

Simpson Gumpertz & Heger (SGH) served as the Engineer of Record to design the renovation and expansion.

Historic Slab Systems As a result of The Frick Collection’s history of construction, SGH encountered structural systems spanning the six decades of previous renovations. The structural floor systems within each building often comprised multiple systems, including draped-mesh cinder concrete slabs, slagblok slabs, formed stone concrete slabs, flat-arch terracotta slabs, terracotta plank slabs, and the obscure “stack-slab” system. The authors analyzed, repaired, and strengthened these floor systems for increased loading and designed unique details for new floor penetrations.

Stack Slabs At the library stack levels of the FARL, the floors are a proprietary system of stack slabs, originally engineered by Snead and Company.

These floors are supported by rows of closely-spaced double-angle steel posts and hangers hidden within the library stacks (Fig. 1). The posts and hangers are supported by steel-framed “strong floors” that support up to three levels of library stacks. The floor systems include 2½ inch x 2½ inch steel double-angles that span between the posts and hangers. These angles are embedded in and support one-way 3½ inch thick concrete floor slabs. The limited capacity of these slabs, limited head-height of the stacks, and the interconnected nature of the system between multiple floors curtailed the options for structural modifications.

At limited locations, the MEP engineer required new mechanical penetrations through the stack slabs. To frame these openings, SGH decided to re-support the slabs by welding 1-inch thick shims to the underside of the horizontal legs of the slab’s support angle. The contractor installed WT steel sections that spanned between the angles and connected to the shims and then shimmed the WTs tight to the underside of the slab only at the perimeter of the opening.

Draped-Mesh Cinder Concrete Floor Slabs Draped-mesh cinder concrete floor slabs, also known as short-span construction or cinder-arch slabs, were common for floor construction

Fig. 2. The draped-mesh cinder concrete below-slab repair is shown in detail.

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Fig. 1. Stack slab construction at the library stacks comprised rows of closely-spaced doubleangle steel posts and hangers.

between the 1920s and the 1950s. The design team encountered this system throughout the Music Room and the FARL. This system comprises wire mesh draped over the top flanges of upset steel floor framing that is encased in a 4-inch thick low-strength cinder-concrete slab topped with a 4-inch lightweight non-structural layer of cinder fill and a 1-inch cement layer. The structural capacity of this system results from the catenary action tension force in the wire mesh.

Empirical formulas for the capacity of these slabs are included in the 1968 New York City Building Code, in which the key variable is a “continuity” factor that accounts for mesh continuity (e.g., at an interior bay) or anchorage (e.g., at an end bay).

Project infrastructure for MEP systems required widespread floor openings. Cutting the wire mesh for the new openings caused a loss of catenary action at the opening and typically resulted in changing the mesh continuity of the adjacent bays (from interior bay to end bay).

Prior to cutting the mesh, SGH specified local removal of the cover

Fig. 3. Shown is the draped-mesh cinder concrete topside repair in detail.

over the steel beams and welding of the wire mesh to the steel beams for anchorage. Then, the team framed the openings with flat steel channels (Fig. 2). The solution did not require removal and replacement of the slab in the bay with the new opening. Instead, additional flat channels in the design shortened the span of the remaining slab that functioned as plain concrete. At midspan of the adjacent bays, flat channels span perpendicular to the direction of the slab to offset the reduction in strength caused by the change in mesh continuity.

During the authors’ field investigation for the project, we extracted samples from steel beams at several locations and found that the steel was not weldable in specific areas, rendering the above-described detail, shown in Figure 2, unfeasible. An alternate solution included removal of the cinder fill at newly-created end bays and replacement with a reinforced lightweight concrete topping slab, placed directly over the existing cinder-concrete slab (Fig. 3). The new topping slab was designed to span from beam-to-beam, and the existing cinder concrete acted as stay-in formwork. Finally, the design team analyzed the existing beams and their connections for the increased load from the new topping slab, but typically these beams and connections did not require strengthening.

Slagblok Slabs The team also encountered slagblok slabs at several locations within the FARL. This slab system is comprised of a two-way grid of reinforced concrete joists below a thin concrete slab spanning to concrete-encased steel girders. The areas between the ribs are infilled with non-structural slagblok, which serve as a stay-in formwork.

When designing support for penetrations in these slabs, the relative size of the penetration with respect to the joists was critical. SGH coordinated with the architect and mechanical engineer to minimize penetrations through multiple joists. Where small penetrations only interrupted one joist, supplemental steel angles were added with the horizontal leg re-supporting the portions of the slabs around the openings and the vertical leg through-bolted to the remaining joists.

At larger penetrations that interrupted multiple joists, new steel framing below the joists framed the openings. Because the existing steel beams extended below the underside of the slab, WTs welded to the bottom flanges functioned as “web extenders” that allowed for connection of new steel framing.

Other locations required infill of existing openings created by previously cut concrete joists. Limited demolition at the existing joists exposed the ends of the cut reinforcing, and the contractor installed couplers to extend the rebar and re-established the continuity of the joists in both directions (Fig. 4).

Flat-Arch Terracotta Slabs In the mansion, the floors comprise structural clay (terracotta) tile flat-arch floor construction, while the roof is hollow clay tile plank construction. Structural hollow clay flat-arch construction consists of three types of hollow clay block shapes that interlock and span between steel framing. The “skew block” is set against the webs of steel beams on one side and a skew plane on the other side forms the arch spring. The skew blocks interlock with an “inter-block,” and a “key” is finally placed in the middle of the span to distribute loads outward toward the beams. The arching action allows the gravity loads to be transferred to the steel via interlocking and thrust loads. Steel tie rods extend through the flat-arch construction and connect between the webs of adjacent steel beams to resist unbalanced thrust loads during construction and at end spans. Non-structural cinder fill is placed atop the structural clay blocks and steel beams to distribute the loads and provide fire protection to the top of the steel beams.

Creating large openings within flat-arch floor systems interrupts the Fig. 4. As seen in this slagblok infill repair detail, couplers extend the rebar and re-establish the continuity of the joists in both directions.

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new fall-arrest system, the existing ridge steel channels were replaced with new HSS sections and the ridge connections to the trusses were reinforced (Fig. 6). The team also analyzed the trusses, purlins, and their riveted connections for the increased loads associated with the new skylights and shade louvers. At the locations where the existing trusses and connections had insufficient capacity, the team designed steel strengthening, while coordinating with the new louver, lighting, and MEP systems.

Riveted Connections Strengthening

Fig. 5. Existing riveted truss and catwalk above Oval Gallery stem from a 1935 expansion.

(Photo Credit: Beyer Blinder Belle Architects & Planners, LLP).

thrust-shear arching action created by the geometry of the blocks in the span. As a result, where the project required new floor openings, it was necessary to demolish the full span of the flat-arch system between beams over the width of the opening. When the clay tile is removed, the existing steel beam at the ends of the opening is subjected to the unbalanced thrust load from the adjacent bays and needs to be analyzed for weak-axis bending. To reinstate the slab around the openings that were not full-span, the team installed steel framing between the existing steel beams, framed the new opening, and placed a new concrete-on-metal-deck slab. The new steel beams serve two purposes: in addition to supporting the new portion of the slab, they also brace the existing beams to resist the unbalanced thrust loads between tie rods.

Historic Steel Systems At the start of the project and under SGH direction, the contractor extracted coupon samples from representative existing steel beams in each of the buildings to perform chemical analysis and laboratory testing to determine the composition, material properties, and weldability requirements for each vintage of steel. The project site contained four different steel compositions, with varying weldability requirements.

Skylight Truss Strengthening The 1935 expansion included the Oval Gallery and the iconic Garden Court, which both featured hip-gabled skylights supported by steel trusses featuring riveted connections (Fig. 5). The museum needed to replace the existing skylight’s glazing to improve the thermal performance and provide enhanced ultra-violet protection for their priceless collection. The facade consultant specified the replacement of the original single-pane glazing with much heavier triple-pane glazing, along with new shade louvers. Additionally, The Frick Collection wanted to add a fall-arrest system at the ridge of the skylights to accommodate cleaning and future facade maintenance.

The original trusses support an access catwalk that allowed up-close access to field measure and document the trusses, purlins, and their connections. The structural system comprises five different truss configurations and, over the East Gallery, a horizontal plan offset of the skylight framing resulting in a “jog” of the ridge elements, atypical framing, and double cantilevered purlins. To support the loads imposed by the 32 STRUCTURE magazine

In the FARL, building setbacks and complicated geometry resulting from stack slabs and strong floors required an indirect column gravity load path, where columns are interrupted by double transfer girders at several floors. The renovation featured increased loads at the roof due to enlargement of a limestone-clad mechanical roof bulkhead for new boilers and cooling towers.

The convoluted load path and increased loads necessitated the evaluation and strengthening of many riveted connections of the double transfer girders. Typically, access to these connections was limited to one side, rendering the strengthening options more challenging. To minimize shoring, SGH developed supplemental connection details that could be installed prior to the increase of loads, while leaving the existing connections in place. For example, at riveted connections to beam webs, the team installed new stiffened beam-seat connections. SGH considered “locked-in” loads at existing riveted connections as well as load sharing with the strengthened portion of the connection and closely coordinated the construction sequence with the contractor.

At one location, the connection consisted of double-girder webs riveted directly to the flanges of the columns and the bottom flanges also supported by riveted seats. Because of historic finishes in the space below, the contractor requested a solution that could be installed from the top side of the slab. SGH designed a welded stub column to extend the existing downward column, which terminated at the top flange of the beam, above the slab level (Figure 7). New “web extender” plates were then connected to the top flange of existing girder webs, which were connected to the new stub column. This detail was concealed within a built-up slab that was part of the original design.

Steelcrete Reinforced Concrete The 1940s Art Vault, which was built at the southeast corner of the property to safely house the collections during the Second World War and remained during the Cold War, was constructed with

Fig. 6. Existing riveted truss and catwalk above East Gallery supplemented by new fall-arrest rail and ridge strengthening.

“Steelcrete” reinforced concrete. The original vault had one-story above-grade and three levels below-grade. After the threat of the Cold War subsided, The Frick Collection demolished the above-grade portion of the Art Vault to make space for the 70th Street Garden, but the below-grade levels remained. The vault was a heavily fortified structure comprising double concrete Fig. 7. The connection strengthening detail at a double-girder to column connection is shown. walls with sand layer between them and two sand-filled floor levels at grade (Figs. 8-9).

The concrete structure included Steelcrete reinforcing above the top of bedrock and conventional reinforcing the public in April 2025. While the collection of historic structural below. Steelcrete was a thick expanded metal sheet reinforcing prod- systems is now concealed by lavish finishes, the holistic strengthuct produced by Consolidated Expanded Metal Companies. Layers ening of the structure allows for improved energy efficiency and of Steelcrete were densely placed 2½ inches on center transverse in unprecedented access to the second floor of the mansion, new special the walls and slabs, creating heavily reinforced concrete sections. exhibition gallery spaces, and the preserved first-floor galleries. ■ The current renovation required the removal of two below-grade levels Part 2 of this series will discuss the design challenges that the authors of the Art Vault, as well as its west and north walls for construction of faced in modifying archaic lateral systems at The Frick Collection. the Stephen A. Schwarzman Auditorium. Due to the removal of the existing intermediate slabs, the team analyzed the Steelcrete-reinforced Lauren Feinstein, PE, is a Senior Consulting Engineer in the New York office of east and south walls for the new 30-foot unbraced wall height (triple Simpson Gumpertz & Heger, Inc. (SGH) focused on restoration and rehabilitation of the original) from the stage level to the garden slab to resist lateral of historic structures and renovation of existing buildings. (Lpfeinstein@sgh.com) earth pressures. During demolition of the vault, SGH also confirmed the as-built construction and splices between the Steelcrete and the David Ribbans, PE, was previously a Consulting Engineer in the New York office conventional reinforced concrete sections to verify that splices had of SGH for the duration of this project and focused on the repair, restoration, and adequate strength to develop reinforcement at the joints. strengthening of existing structures. He now works for K2M Design. (david.ribbans@gmail.com)

Conclusion

Kevin Poulin, PE, is a principal in the New York office of SGH specializing in the restoration and adaptive reuse of existing buildings. (Kcpoulin@sgh.com)

Navigating the challenges of structural strengthening of a myriad of archaic systems, while maintaining the historic architectural fabric intact, requires in-depth knowledge of the systems, extensive literature review, and some ingenuity. The Frick Collection reopened to

Filippo Masetti, PE, is an Associate Principal in the New York office of SGH with extensive experience in assessing, analyzing, repairing, and strengthening existing structures. (Fmasetti@sgh.com)

Fig. 8. Steelcrete is visible at the double-lined walls and floor slabs of the art vault during demolition.

Fig. 9. Construction documents from the 1940s detail a section of the original vault structure.

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Photo Credit: Perkins&Will/James Steinkamp Photography

Mass Timber and the Power of Reuse

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The University of Houston RAD Center combines architectural vision and structural ingenuity to maximize efficiency and sustainability.

By Sarah Evans, PE and Thomas Kostelak, PE

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he University of Houston (UH) Retail, Auxiliary, and Dining (RAD) Center is a testament to sustainability and economy. Far from being at odds, the sustainable use of mass timber over existing columns and foundations minimized structural costs and maximized the building’s program. Located on UH’s main campus in Houston, Texas, the site previously housed a one-story subterranean dining hall prone to flooding. The RAD Center transformed the site into a vibrant hub of campus life, featuring a 41,000-square-foot, two-story building filled with natural light for dining, retail, and office functions. The project showcases the beauty of mass timber through architectural design by Perkins & Will and thoughtful engineering and detailing by structural engineer of record Walter P Moore, in collaboration with Martinez Moore Engineers, who contributed additional engineering and modeling expertise.

Existing columns were reused to support the new RAD Center after demolition of the lid structure.

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Post-installed screw couplers were used to splice new reinforcing to the existing column longitudinal bars.

The Intersection of Sustainability and Economy Walter P Moore recognized a unique opportunity to reduce cost, improve scheduling, and significantly enhance the sustainability of the UH RAD Center by reusing existing columns and foundations. The existing onestory, below-grade building was constructed in the 1970s and featured a heavy concrete joist lid structure weighing nearly 200 pounds per square foot. It was designed to support plaza and landscaping loads exceeding 250 pounds per square foot. By removing the lid and plaza to capitalize on this excess capacity and minimizing the weight of the structural system, the team supported the new building on the existing concrete columns and belled piers.

Although the UH RAD Center was initially conceived as a structural steel building, Walter P Moore proposed and evaluated a slightly lighter mass timber system, which would allow the reuse of the existing columns and foundations without widespread strengthening or replacement.

In total, 66 foundations were reused, with only 11 new foundations required, primarily for areas of the new building that extend beyond the original footprint. The foundation reuse alone resulted in substantial cost

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savings and significantly improved sustainability by reducing embodied carbon by more than 175 metric tons of carbon dioxide equivalent.

Walter P Moore worked closely with Perkins & Will to set a 25-feet x 25-feet column grid, closely matching the existing grid, which ranged from 20 feet, 2 inches to 24 feet, 10 inches. Due to the expansive clay soils prevalent in Houston, UH requires elevated construction at all ground-level slabs, so this was utilized as the transfer structure for the new columns. The ground-level beam and slab system distributed loads in a similar pattern to the original building and was tied into the existing structure by attaching couplers to the column longitudinal bars. The existing basement was sealed off and backfilled with a combination of soil and geofoam in localized areas to prevent overloading the structural elements that would remain.

The RAD Center’s superstructure consists primarily of southern pine mass timber, with glued-laminated (glulam) columns and beams, cross-laminated timber (CLT) floor panels, and steel braced frames. The 25-foot bay width is slightly longer than the optimal span for CLT panels, so intermediate beams were introduced to reduce panel spans to 12 feet, 6 inches. With the favorable structural properties of southern pine and shorter spans, the floors utilized 3-ply CLT panels instead of the typical 5-ply, reducing wood volume to improve both cost and sustainability. Additionally, because the building is classified as Type IIIB construction, it did not require a fire-resistance rating, eliminating the need for additional wood volume to create a char layer. The floor panels were topped with a 2-inch acoustical mat and a 3-inch lightweight concrete topping slab.

One portion of the building, a one-story structure primarily outside the existing building footprint, was constructed in structural steel. This localized change addressed the owner’s concerns regarding maintenance and food safety in the kitchen and allowed for a larger column-free space. Walter P Moore developed details to connect the steel and timber structures, transmitting lateral forces and eliminating the need for a highmaintenance expansion joint.

Walter P Moore’s creative solutions reduced cost, shortened the schedule, and improved sustainability on the RAD Center. The use of mass timber and foundation reuse saved roughly $1 million and contributed to an overall carbon reduction of 650 tons.

A bespoke CLT canopy cantilevers over the main entrance to the RAD Center. (Photo credit: Perkins&Will / James Steinkamp Photography)

Details of the lateral force transfer between the steel and timber portions of the structure.

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Celebrating Mass Timber Structure as Architecture

Exposed MEP systems required careful coordination with the architect and MEP consultant.

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Mass timber is unique in that it often functions both as the structure and as an exposed architectural feature. This dual role offers a unique opportunity for structural engineers to contribute to the architectural vision. At the RAD Center, our team thoughtfully considered aesthetics alongside structural performance and efficiency when selecting member sizes, designing feature elements, and creating details.

Nearly every column, beam, and CLT panel is visually exposed. As a result, member size selection involved additional considerations beyond structural strength and serviceability. These included accommodating exposed MEP systems, managing lighting impacts, and

Walter P Moore maintained consistent beam widths and depths at the atrium to create a uniform perimeter band. (Photo credit: Perkins&Will/James Steinkamp Photography)

ensuring visual consistency. For example, the RAD Center features large openings that create multi-story volumes. Beam widths and depths around these openings were kept consistent to form a uniform perimeter band.

Openings in mass timber must be defined early for shop cutting, which ensures greater precision and cleaner edges than field cuts.

Horizontal penetrations in beams for MEP systems were common due to the absence of ceilings, and the structural team used Technical Notes S560 and V700 from APA—The Engineered Wood Association to assess openings. Because member depths and opening sizes are interdependent, close coordination with MEP consultant, Henderson Engineers, was essential to achieving a visually cohesive effect.

Exposed connections also necessitate careful detailing. Fully concealed timber connections were specified wherever possible, and minimal exposed steel elements were used at locations with higher reactions. For exposed steel braced frames, Cast Connex Universal Pin Connectors provided an aesthetic end connection while conventional connections were used where bracing was concealed.

A major architectural feature of the building is an exterior canopy with an exposed timber soffit that cantilevers more than 13 feet over the main entrance and an additional 10 feet to the side. Working with mass timber subcontractor Timberlyne, the team achieved this dramatic form using custom CLT panels approximately one foot thick and concealed structural steel beams hidden by the soffit and building facade. Throughbolt connections between the steel channels above and the CLT panel were recessed at the bottom and concealed using wood block patches that matched the panel species.

Another structural challenge involved large openings in the floor and roof diaphragms. CLT panels comprised the primary diaphragm, but one area adjacent to the building facade narrowed to approximately nine feet wide, where CLT alone was insufficient. Deepening the structure would have negatively impacted the aesthetic. Instead, Walter P Moore removed the acoustical mat in this location, where it was not needed, and

The team concealed timber connections as much as possible to minimize visible steel.

thickened the concrete topping slab to carry diaphragm forces across this narrow band.

Concealed steel angles, screwed to the CLT and embedded in the concrete with headed stud anchors, transferred forces into and out of the concrete topping slab.

Where Innovation Meets Impact The University of Houston RAD Center project exemplifies the successful integration of architectural vision and structural engineering. By repurposing existing structural elements and leveraging the unique properties of mass timber, the project met its economic and aesthetic goals while significantly enhancing sustainability. The thoughtful engineering and close collaboration among stakeholders resulted in a distinctive structure that enhances the campus and stands as a model for innovative, sustainable construction. ■

Sarah Evans, PE, is a Principal and Design Manager at Walter P Moore, where she focuses on digital delivery of higher education, sports, and commercial projects. Evans was a leader of the UH RAD Center structural team and is a member of the STRUCTURE Magazine Editorial Board.

Thomas Kostelak, PE, is a Senior Engineer at Walter P Moore focused on higher education, healthcare, and commercial projects. Kostelak oversaw the construction administration for the UH RAD Center.

JULY 2025

39

CONNECTIONS Real World Challenges Drive Innovation

By STRUCTURE Magazine Staff

S

TRUCTURE approached representatives of companies

They stressed that when it comes to connections, connecting with

that offer different types of connections for structural

fellow collaborators is key, and beyond product advancements, one

engineering applications to talk about developing

of the biggest trends is developing tools to make it easier to com-

trends in materials, manufacturing, and resources.

municate intention and specification with the rest of the team. ■

What manufacturing trends are you seeing for connection

?

products, and what do they mean for structural engineers?

Jennifer Pazdon, Vice President, USA, Director, UK Division, Cast Connex: Use of cast steel connections has become increasingly popular as designers and construction professionals have identified the benefits to structural performance and bottom line. Demanding project delivery schedules and projects with ambitious structural demands call for reliable connections solutions that can be easily understood from a load path perspective, are straightforward to design, or are pre-engineered.

40 STRUCTURE magazine

Ryan Smith, Vice President, Engineering, and Global Design Engagement, MiTek: As a company that is involved in the design and manufacturing of a variety of connection solutions, we have seen a particular interest in focusing on connections that speed up overall construction time. I believe manufacturers and designers are listening a lot more to the other project constituents. A couple examples from both our Timber Construction and Steel Construction supply chain partners are the MiTek Firewall Hanger and the SidePlate Bolted Moment Connection. Connections like these make it easier to install firewall assemblies and in the case of SidePlate, eliminate the need for expensive and time-consuming field welding.

Fayad Rahman, Research and Development Engineer, Simpson Strong Tie: Moment connections are a common lateral system in structural steel design, offering the advantage of unobstructed sight lines and clear passageways. However, they often come with significant cost and labor demands. Fully welded moment connections require extensive beam preparation, welding, and inspection, while common bolted solutions, such as flange-plated and end-plate moment connections, still involve welded components, leading to installation and fit-up challenges.

Bolted moment connections provide an alternative to the labor and inspection associated with field welding. The bolted connections used in common practice have issues with fit-up and transportation to the site. These connections typically involve welding in the fabrication shop that can lead to warping and cracking. Field-welded connections are often used when there are high connection demands or architects push engineers to use smaller beam sections while developing high capacities.

Rigid moment frames are often used in structural steel lateral systems.

To achieve the required frame rigidity, the beam/column connections are often CJP welded in the field - which is very costly. Bolted alternatives shift most of the welding to shop labor but afford little adjustability (causing or exacerbating fit up issues), and many are proprietary and come with licensing fees. Connection design is often delegated to the performing contractor, allowing them to select and employ the most efficacious solution. Steel fabricators and erectors want a solution that can be easily designed, reduces both shop and field labor, expedites frame installation, is adaptable for field fit up, and is cost effective.

? ?

As construction using mass timber and high strength

steel evolves, how have their

connections evolved? How can

structural engineers adjust their connection designs to

be leveraged with careful consideration of the construction process when developing connection details.

The opportunity to expose mass timber to celebrate the warmth of the material is complimented by connection details that support aesthetic value. The ability to sculp sculptural steel in casting manufacturing can lead to lovely cast steel-timber hybrid connection details. Standardized connectors for cast steel-timber hybrid projects are aligned with the goals of reducing site time and cost.

maximize constructability and

efficiency with this design trend?

Structural connectors

are critical to a structure's ability to withstand

seismic events, high winds, and more. What improve-

ments or innovations have been made to further

elevate their performance in extreme events?

Rahman: Flange-plated connections use plates with predrilled bolt holes shop-welded to the column. Providing the correct plate spacing while accounting for field tolerances and variations in beam depth can be challenging.

End-plate moment connections have predrilled plates welded to the end of the beam instead. Ensuring the beam end is cut square, preventing plate warping during welding, and accounting for variations in column depth are all critical for fit-up.

Tee-stub connections, which predate end-plate moment connections, offer the best of both worlds as both the column and beam side of the connection are bolted. However, they are uncommon in modern steel construction. Fabrication shops are not optimized to produce these relatively small, complex components, whose quality can significantly impact constructability. Detailing conventional double-tees can also be tricky as the connection may interfere with the space required for shear tab connections.

Rahman: The new Strong-Link moment connection (SLMC) is an evolution of the double-tee, designed to address these challenges. It features a notched link flange, which allows larger connections to be installed on shallow beams while leaving adequate space for shear tab connections. These larger connections improve strength, stiffness, and ease of installation beyond what was previously possible. The improved geometry accommodates oversized holes at the column bolts, providing greater tolerance for variations in beam height and accelerating fit-up in the field. The SLMC is factory manufactured to Simpson’s high-quality standards, reducing the labor and cost for the fabricator.

Pazdon: Mass timber construction presents the opportunity to rethink how we design connections with consideration for how projects with this material will be delivered. The advantages of timesaving on site that can come from panelized CLT construction can

STRUCTURE Magazine has a page dedicated to collecting all connections-related articles and webinars together in one spot. Visit www.structuremag.org/connections.

Connections Resources at www.structuremag.org

JULY 2025

41

?

CONNECTIONS In your discussions with structural engineers,

what challenges are they

facing (in terms of connections) that your company is specifically addressing?

Brad Fletcher, Sr. Engineer, Atlas Tube: “Many of the questions relate to HSS connection design. Our most common piece of advice is to think about the connections during design to avoid miscommunication about intent, loads, and other variables that can lead to late changes during the construction phase.

In an effort to demystify these challenges, Atlas Tube launched the HSS Connections Hub. The HSS Connections Hub includes fabrication-friendly, fully code referenced, and reliable HSS connection tools to help engineers think through these things, even if they are delegating the connection design. The education and tools we provide are built to address the challenges that engineers face, from general knowledge of HSS connections to tools such as typical details and connection calculators. Our goal is to simplify and optimize HSS connection design, which can help the team avoid late changes and project delays.

Pazdon: Structural engineers come to us for solutions to geometrically complex and/or architecturally significant connections that would be difficult to design, fabricate and/or install using conventional methods. Delegation of connection design to a casting supplier ensures that structural performance is coordinated with manufacturing processes and delivery schedules are met in the interest of design and construction professionals.

Structural engineers may be well trained in connection design by codified equations, but they may not be as well versed in steel manufacturing methods nor in shop fabrication or field activities. As EOR, their scope of responsibility is extensive, and success relies on working with capable partners to achieve the final built project. With our attention specifically on connection design and manufacture, our scope is comparatively quite limited, but with potential for substantial impact.

Our design process is akin to DFMA in that we develop products that provide value at every stage from design though construction while respecting manufacturing limitations and harnessing manufacturing capabilities to improve upon conventional solutions.

Time is always a challenge. Structural engineers come to us for preengineered solutions that save them time in design, development of design documents, and review of shop drawings.

Smith: When looking especially at timber construction, we have received feedback that many of the typical details being used have not been updated for quite some time. This can be very challenging if the goal is to advance connections to be more efficient and cost effective. Besides working to create more effective hardware, like top 42 STRUCTURE magazine

plate screws, and firewall hangers that make install easier, we are working to support our professional design customers in updating their details. MiTek, an innovator in timber construction, has substantial experience in how design decisions early in the process will affect productivity downstream. We are utilizing this supply chain knowledge and helping educate professional designers on the pros and cons of certain details. This should help professional engineers make good, informed decisions, and therefore I encourage professional engineers to reach out to their local MiTek Design Engagement Consultant to see what support we can provide.

What resources and

?

tools do you recommend to structural engineers

when they are designing

and specifying connections in their projects?

Smith: I recommend that engineers develop a very good network of subcontractors and partners that specialize in connection designs. I encourage engineers to reach out to the field and specialized connection engineers, like those from MiTek’s SidePlate solution, anytime there is an abnormal condition. It is likely that these groups have experienced the condition before and can provide insight.

Rahman: Simpson Strong Tie has developed the SLMC design guide with useful aids for selecting and designing SLMC connections. This resource allows engineers to quickly determine available connection strengths and verify FR compliance. A detailed design example is also provided for reference.

Pazdon: Talk to your fellow engineers who are standing on the other side of the table at tradeshows! Connection product suppliers are generally trained as structural engineers and have spent time working in the same role you are in as a consultant. Now they are focused experts in the type of connections they design and supply with their company, and they are likely to have more exposure to other products and solutions available on the market.

We have developed 2D and 3D CAD assets and Revit families as well as sample specification language to help designers to describe standardized connectors and custom products in their contract documents. For the pre-engineered products we have data sheets or design manuals to provide the specifier with relevant technical information.

“How to Specify” guides available on our website walk the structural engineer through each step of specification. This saves time in design and specification and sets the project up for success in the tender phase and beyond. ■

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CONNECTIONS

Spotlight: Atlas Tube’s HSS Connections Hub™ The HSS Connections Hub offers complimentary access to typical HSS connection details as well as corresponding calculators that perform utilization checks in real-time to help complete designs. Users can download in three formats, including PDF, AutoCAD and Revit. The HSS Connections Hub enables you to design efficient connections, minimize changes, and keep projects on track.

A Direct Path to Efficient HSS Connection Design This invaluable—soon-to-be indispensable—online resource will save design time by eliminating the need for developing and maintaining custom spreadsheets. Fabrication-friendly typical HSS details are an excellent starting point for connection design, while corresponding calculators enable design completion.

Teams can streamline the design process and enhance collaboration directly on HSS Connections Hub. Engineers can quickly create HSS connection calculations based on the

most recent AISC design manual and specific code requirements.

Fabricators will receive connection designs that meet requirements and are fabrication-friendly, eliminating back-and-forth revisions.

Leverage the Benefits of HSS With the HSS Connections Hub •

Access a growing library of HSS connection calculators and fabrication-friendly typical HSS details, each available with a wide range of options.

• Calculators automate and confirm connection designs in real-time based on the AISC Steel Construction Manual, 16th edition.

• Clear and concise indicators show whether the designed connection is efficient and meets specified requirements.

• Full transparency: Review and verify your calculations against specific code references with a simple click.

• Download or share detailed connection drawings, including dimensions, bolt sizes and other relevant information for easy communication with fabricators.

• Request support from Atlas Tube’s engineering experts on your project.

Sign up today and start using the HSS Connections Hub! connectionshub.atlastube.com

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I N T R O D U C I N G AT L A S T U B E ’ S

HSS CONNECTIONS HUB™ Complimentary tools and expert support for engineers, fabricators and detailers looking to better leverage the advantages of HSS. Discover the HSS Connections Hub™ — an online resource that enables more efficient design of fabrication-friendly HSS connections.

• Download typical HSS connection details (PDF, CAD, RVT) • Perform utilization checks in real time with corresponding calculators • Create and share designs with your project team • Eliminate the need for time-consuming spreadsheets Learn more and sample three typical HSS connections.

Create an HSS Connections Hub account to access the full suite of typical HSS details and connection calculators. atlastube.com/hub-scs

JULY 2025

43

CONNECTIONS

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Spotlight: This Bolt Launches Spaceships The TNA® Torque+Angle Fastening System was utilized throughout the build of NASA’s new Mobile Launcher 2. The ML2 ground platform structure will launch spaceships to the Moon and Mars as part of NASA’s Artemis program.

The TNA® Torque+Angle Fastening System is redefining standards in fastener reliability and assembly consistency.

Developed by LeJeune Bolt Company, a name synonymous with quality fastening solutions, this system delivers an advanced, datadriven method for applying the perfect clamp load in critical joints.

Unlike traditional torque-only methods, which are susceptible to variations in friction and material properties, the TNA® Torque+Angle Fastening System combines both torque and angle measurements to ensure optimal bolt stretch and clamping force. By monitoring the angle of rotation after a predetermined snug torque is reached, the system guarantees that each bolt is tensioned to the correct specification—regardless of thread condition or lubrication inconsistencies.

LeJeune’s proprietary TAE Series tools are exclusively designed for the TNA® Torque+Angle Fastening System. Through the use

of Torque for the snug operation and Angle for the Pre-Tensioning operation the TAE tools provide unmatched control and accuracy. This is the simplest and most accurate means to perform the RCSC Approved Combined Method of installation.

TNA® is the only fastening system that delivers both a quantifiable Snug Tight condition—ensuring every bolt in a connection meets a minimum requirements for tension—and the precise required angle for the perfect final pretension. In addition, the TNA® Bolts meet the requirements of ASTM F3148 and are 100% Melt & Manufacture in the U.S. Whether you’re assembling a suspension bridge or a gas turbine, the TNA® Torque+Angle Fastening System from LeJeune Bolt Company ensures each connection is as solid as the reputation behind it. It’s not just about turning bolts—it ’s about turning precision into progress.

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THIS BOLT LAUNCHES SPACESHIPS. IT’S TRUE.

The TNA® Torque+Angle Fastening System was utilized throughout the build of NASA’s new Mobile Launcher 2.

The ML2 ground platform structure will launch spaceships to the Moon and Mars as part of NASA’s Artemis program.

NASA did. Learn more at www.tightenright.com or schedule a webinar here

800.872.2658 | lejeunebolt.com | jcaven@lejeunebolt.com ©2025 LeJeune Bolt Company | All Rights Reserved. | Images used with permission. | TNA® is registered in U.S.A. Patented.

44 STRUCTURE magazine

CONNECTIONS CONNECTIONS guide ASDIP Structural Software

RISA Tech, Inc.

ENERCALC, LLC

Phone: 407-284-9202 Email: support@asdipsoft.com Web: www.asdipsoft.com Product: ASDIP Steel

Phone: 949-951-5815

Phone: 800-424-2252

Email: info@risa.com

Email: info@enercalc.com

Web: risa.com

Web: enercalc.com

Product: RISAConnection

Product: ENERCALC SEL/ ENERCALC 3D

Description: Intuitive software for the design of steel members and connections, such as composite/non-composite beams, steel columns, base plates, anchoring to concrete, shear connections, moment connections, and web openings, per the latest design codes. ASDIP Steel includes modules that substantially simplify the timeconsuming calculations of structural designs.

Description: RISAConnection is at the cutting edge of next-generation connection design software. Featuring full 3D visualization, Shop-drawing –style views, and expandable engineering calculations for all limit states, RISAConnection is an essential tool for engineers who use steel. Its complete integration with RISA-3D and RISAFloor allow one-click connection design for entire structures.

Description: Save hours on steel design with ENERCALC! Beams, columns, 2D frames, bolt group analysis, and more. The simple user interface makes it fast & easy to setup, confirm, & “what-if” designs.

Optimize your steel base plate connections with modules for simplified AISC design procedures as well as FEM-driven stress analysis. Try it free for 30 days!

Available Online

Structural Engineering Resource Guide From STRUCTURE Magazine wwww.structuremag.org

Find your next industry partner for connections, as well as anchors, foundations, concrete, software, wood products, steel, and more.

JULY 2025

45

structural FORUM

Why Structural Firms Should Adopt an Inside-Out AI Strategy

As AI technology reshapes engineering firms, companies need a well-defined AI strategy to stay competitive and foster innovation.

By Dr. Mehdi Nourbakhsh and Dr. Sam Zolfagharian This article is Part 2 of a three-part series on AI for structural engineering presented by the Coalition of American Structural Engineers (CASE), the National Council of Structural Engineers Associations (NCSEA), and the Structural Engineering Institute of the American Society of Civil Engineers. The corresponding webinar, put on by CASE, will be held on July 29.

A

few months ago, at one of the large AEC industry conferences, we met John, the IT director of a mid-sized structural engineering firm. He introduced himself as a “technology scout,” someone who hops from conference to conference in search of the latest AI tools to bring back to his organization.

When we asked him, “What’s your AI strategy?” his eyes lit up. He eagerly pulled out his laptop and walked us through dozens of presentation slides: software demos, vendor links, and proof-of-concept experiments. His enthusiasm was contagious.

But when we asked how his team was responding and how far they were in their adoption journey, his tone shifted. He sighed and said, “It’s hard. Some people are excited. Others resist. There’s a lot of pushback.”

We’ve heard this story many times, especially from engineering firms.

Too Many Tools. Too Little Alignment When we started our careers in structural engineering nearly two decades ago, technology looked very different. Fast forward to today, 46 STRUCTURE magazine

the landscape is flooded with more than 10,000 AI-powered tools and counting. It’s become nearly impossible to separate signal from noise.

The pace of software development has accelerated. Tools are easier to access and more abundant than ever. Amid the noise, the challenge for firms isn’t access to AI. It’s focus.

So the key question becomes: How can structural firms adopt AI in a strategic, sustainable, and scalable way?

Let’s look at two contrasting approaches.

The Outside-In Approach: Popular, But Problematic Many firms default to what we call the outside-in approach. Like John, they look outward, to conferences, webinars, peers, and vendors, for inspiration. They run pilots, test tools, and explore what’s trending. But when asked how these tools align with business strategy or integrate into day-to-day workflows, the answers are often vague.

This approach often results in a long list of disconnected pilots

with no clear throughline. Teams experience tool fatigue. Data becomes siloed. Workflows get fragmented. And instead of excitement, internal resistance grows. Technology leaders find themselves constantly "pushing" adoption, trying to convince busy employees to engage.

While well-intentioned, the outside-in model is reactive. It chases shiny objects rather than strategic business opportunities. It focuses on toolkits but not business transformation.

The Inside-Out Approach: Strategic and Scalable A more effective and resilient model is the inside-out approach.

Here, firms begin by looking inward, identifying operational bottlenecks or opportunities, workflow inefficiencies, and unmet client needs. Only after defining these priorities, leaders and employees explore external AI tools that align with their goals.

This method is grounded, focused, and aligned with their business strategy. And most importantly, it works.

When AI is linked directly to existing pain points, adoption becomes organic. Teams don’t need to be convinced; they pull the solutions in because they see the benefits firsthand: faster site reports, automated compliance checks, optimized designs, streamlined QA/QC, and smarter documentation.

An added benefit? Strategic clarity. In a fast-moving landscape, tools will come and go. But when your AI roadmap is anchored in long-term value drivers, not vendor hype, decision-making becomes simpler and more stable.

As Jeff Bezos once said, “If you want to build a successful, sustainable business, don’t ask what could change in the next ten years. Ask what won’t.”

For structural engineering firms, what won’t change is this: • The need to deliver more reliable, smarter structures.

• Faster project timelines.

• Lower capital and operational costs for clients.

Anchoring your AI investments in these unchanging goals helps future-proof your strategy, no matter how the tools evolve.

Why Governance Matters, Now More Than Ever But strategy alone isn’t enough. Innovation without guardrails is risky, especially in structural engineering, where safety and compliance are non-negotiable.

That’s where governance plays a critical role. Governance is not about adding bureaucracy. It’s about creating safe lanes for fast-moving innovation. A strong governance framework sets clear standards for how AI is evaluated, implemented, and monitored. It minimizes AI risks, ensures data privacy, and reinforces responsible, safe usage.

So, what’s the relationship between governance and strategy?

Executives must find the right balance between governance and strategy. Too loose, and you expose the firm to risk. Too strict, and you kill momentum. We saw this when ChatGPT first emerged.

Some engineering firms quickly banned it over data concerns. But later, when they rolled out enterprise tools like Microsoft Copilot, they faced confusion. Employees weren’t sure what was allowed, and adoption stalled.

The goal is structured flexibility: clear policies that support experimentation, paired with education, transparency, and guidance.

AI Webinar Dates June 24 (recorded): Towards AI Adoption in the Structural Engineering Profession July 29: AI Strategy for Engineering Leaders: What You Need to Know August 26: AI Developments That Will Shape the Practice of Structural Engineering

Visit program.acec.org/2025-joint-summer-series-artificialintelligence to register for this summer AI webinar series.

How to Get Started A practical path forward starts with two parallel task forces: • AI Innovation Task Force: This group identifies opportunities by mapping current bottlenecks, inefficiencies, opportunities, and client pain points.

They explore how AI can solve real problems, not abstract ones. They prioritize high-impact use cases to run as pilots and build internal momentum.

• AI Governance Task Force: This team assesses risks, reviews tool terms and usage policies, and develops clear, lightweight guidelines. Their role is to ensure AI adoption is secure, compliant, and aligned with the firm's values, without stalling innovation.

Crucially, these groups must collaborate. Innovation without oversight is reckless; oversight without innovation leads to stagnation. Together, they create the balance needed for sustainable AI integration. This approach is explained in more detail in the book "Augment It," which outlines how AEC organizations can start their AI journey.

Additionally, firms should: • Audit current workflows and tools.

• Evaluate data readiness.

• Launch basic AI literacy training.

• Establish feedback loops from pilot to scale.

Leading the Way Forward Ultimately, successful AI adoption isn’t just a tech issue. It’s a leadership imperative. In the book “Disrupt It,” we explain how AEC executives can prepare their organizations for the age of AI, treating it not as a tech upgrade but as a transformational initiative that reshapes culture, business models, and operating models.

This calls for senior leaders to go beyond budget approvals. They must set the vision, champion early wins, and foster a culture of curiosity, accountability, and responsible experimentation. They must model the balance between agility and integrity.

Firms that embrace an inside-out AI strategy, supported by balanced governance, will achieve more than short-term efficiency. They’ll build resilience. They’ll deliver smarter designs, stronger performance, and deeper client value.

In an industry that’s traditionally slow to change, that’s not just a competitive edge; it’s a future-proofing strategy. ■ Dr. Mehdi Nourbakhsh is an author, speaker, and CEO of YegaTech, a technology consulting company in the AEC industry specializing in AI strategy, governance, and implementation for AEC companies.

Dr. Sam Zolfagharian is an AI strategist, keynote speaker, and author of Disrupt It: How AEC Executives Can Transform Their Organizations in the Age of AI Disruption. As Co-Founder of YegaTech, she advises CEOs and boards on AI strategy, governance, and innovation.

JULY 2025

47

structural FORUM

Australia Is Becoming Hotter: Climate Change and Its Impact on Long-term Monitoring of Structures

More research is needed to explore how temperature-induced frequency shifts interact with actual structural conditions.

By Parsa Ghannadi and Seyed Sina Kourehli

A

ustralia is experiencing significant climate change, which has led to more extreme weather events, posing challenges to monitoring the structural integrity of critical infrastructure. Structural health monitoring systems are essential for detecting early signs of damage in structures such as bridges, buildings, and dams, ensuring their safety and longevity. However, structural health monitoring methods, which rely on dynamic characteristics like natural frequencies and mode shapes, are susceptible to temperature changes. Climate change introduces a new variable that traditional nondestructive techniques may not adequately address, potentially leading to false alarms and impaired damage detection. Despite the critical role of temperature in influencing structural behavior, limited research has focused on its effects on natural frequencies and how to distinguish temperature-induced shifts from actual damage. Researchers at Australian research institutes are well-positioned to construct a large-scale benchmark structure to collect vibration data under various temperature and damage scenarios, thereby contributing to further studies that are needed to fully understand the nature of temperature changes in long-term monitoring of structures. Such initiatives would enhance the accuracy of structural health monitoring systems, foster international collaborations, and ensure the safety and performance of Australia's aging infrastructure in the face of climate change.

Australia’s Changing Climate at a Glance Since national records began in 1910, Australia has experienced an average increase in temperature of 1.51 ± 0.23 degrees C, with most of this warming happening after 1950. Each decade since then has consistently been warmer than the one before it. Globally, land areas are experiencing a warming trend that outpaces the oceans. This is particularly evident in Australia, where land temperatures increase about 40% faster than the surrounding waters.

The Sun is Earth's primary source of energy. To keep surface temperatures stable over time, the energy that reaches Earth must be offset by an equivalent amount of heat released back into space. Greenhouse gases like CO2 in the atmosphere hinder the release of this heat, contributing to higher temperatures of the Earth's surface, oceans, and atmosphere. Research conducted in Australia and globally, along with The Intergovernmental Panel on Climate Change (IPCC)’s Sixth Assessment Report, shows that Australia's future climate will keep warming, bringing more extremely hot days and fewer extremely cold ones.

Why Is Structural Health Monitoring Important?

Australia’s susceptibility to extreme weather events, such as cyclones, floods, and bushfires, makes structural health monitoring essential for 48 STRUCTURE magazine

surveying structural impacts and ensuring resilience during and after such events.

Additionally, many of Australia’s critical infrastructure assets, including bridges like the Sydney Harbour Bridge, are decades old.

Structural health monitoring ensures these structures remain safe and functional, extending their service life. A group of researchers formed the Australian Network of Structural Health Monitoring (ANSHM) on June 30, 2009, at the inaugural ANSHM Workshop, and the association has developed extensively since then.

Structural health monitoring involves collecting and analyzing data from structures to assess their condition and ensure their safety and performance. The measurements generally are dynamic data like acceleration or static data like strain. Acceleration is measured using sensors known as accelerometers, which enable extraction of dynamic characteristics of the structure, such as natural frequencies and mode shapes. Damage typically changes the natural frequencies and mode shapes. Therefore, tracking changes in natural frequencies and mode shapes can reflect structural damage or degradation. Recent studies have shown that natural frequencies are significantly sensitive to temperature changes. Climate change potentially introduces a new variable beyond the detection capabilities of conventional non-destructive methods, adding another source of uncertainty to structural health monitoring.

What If Climate Change Is Ignored in Longterm Structural Monitoring?

If climate change and its associated effects are not considered in the long-term monitoring of structures, the sensitivity of natural frequencies to temperature changes could lead to significant impairment of the effectiveness of structural health monitoring systems and report of false alarms. In other words, temperature variations can cause significant shifts in the natural frequencies of materials, potentially masking or mimicking damage-related changes in vibration patterns. Therefore, it

is essential to remove the effects of temperature on the natural frequencies for accurate damage detection.

More Studies and Benchmarks Needed Despite the critical role temperature plays in influencing the dynamic behavior of structures, relatively limited research specifically focuses on its effects on natural frequencies. The existing body of research has not fully explored how these temperature-induced frequency shifts interact with actual structural degradation or how they can be effectively distinguished from damage signals in real-world structural health monitoring applications.

Benchmark structures for structural health monitoring are designed to evaluate and compare newly developed algorithms and methodologies. Additionally, less thoroughly understood structural behaviors and complex phenomena, such as temperature changes, can be explored by providing controlled, repeatable, and standardized environments that are challenging to analyze in real-world settings. For example, composite materials, such as fiber-reinforced polymers, exhibit behaviors that are less thoroughly understood compared to traditional materials like steel or concrete. Therefore, Stanford Structures and Composites Laboratory, in collaboration with the Prognostics Center of Excellence at NASA Ames Research Center, tested fatigue aging on carbon fiber reinforced polymer (CFRP) composites. This dataset, available from the NASA Prognostics Data Repository, enables researchers to evaluate the performance of newly developed frameworks for fatigue damage propagation in CFRP composites using experimental measurements and study the composite structures’ behavior under cyclic loads.

Another benchmark structure that focuses on less comprehended subjects in structural health monitoring is the Qatar University Grandstand Simulator. This benchmark structure offers researchers an experimental dataset of different joint damage scenarios and enables them to evaluate their damage detection solutions based on a standard dataset. The Qatar University Grandstand Simulator is distinguished from existing benchmark problems in structural health monitoring by introducing joint damage scenarios instead of elemental ones.

Regarding temperature effect on long-term monitoring of structures, very few benchmark structures incorporate temperature to evaluate their impact on structural response and damage detection. For example, the Z24 Bridge, a well-known benchmark in the structural health monitoring community, was a concrete highway bridge in Switzerland monitored extensively before its demolition. It is one of the most widely used full-scale structures for studying environmental effects, including temperature changes, on vibration measurements. Another benchmark structure to study the significant influence of environmental variability on the modal data, specifically natural frequencies, is the Wooden Bridge.

Wooden Bridge is a laboratory-scale truss structure, and damage scenarios were designed by adding different point masses. In this example, environmental variations have evidently induced frequency shifts significantly larger than those caused by structural damage.

Built in 1983, a long-span, pre-stressed concrete cable-stayed bridge named Tianjin Yonghe opened to traffic at the end of 1987 in China.

The total length of the bridge is 510 meters, with multiple spans, a couple of towers, and several cables. The bridge was closed and repaired between 2005 and 2007 because of several damage patterns detected at the bottom of the mid-span girder and corroded cables. According to the structural health monitoring system implemented at the end of 2007, 14 uniaxial accelerometers were mounted on the bridge deck to continuously measure acceleration. Additionally, an anemoscope to measure the wind speed and a temperature sensor to measure air

temperature were attached. In August 2008, periodic inspections identified multiple damage patterns. Researchers found that wind speed and air temperature had substantial effects on the variability in the bridge’s natural frequencies. For example, Sarmadi et al. conducted an operational modal analysis based on fast Fourier decomposition and identified 24 natural frequencies per day as dynamic features. In contrast to the Z24 Bridge, which is influenced by a single dominant environmental factor, the natural frequencies of the Yonghe Bridge are affected by multiple environmental factors, including temperature and wind speed. The Tianjin Yonghe Bridge is not a standard benchmark, and its measured environmental data (air temperature and wind speed) is not available for research purposes. However, the Tianjin Yonghe Bridge is still one of the few structures that researchers can utilize to study the environmental effects on the acceleration responses.

The I-40 bridge over the Rio Grande in Albuquerque, N.M., is one of the well-known benchmark structures in structural health monitoring.

A group of researchers from New Mexico State University and Los Alamos National Laboratory obtained the modal properties before it was razed in 1993. Los Alamos National Laboratory has published the natural frequencies and mode shapes of the bridge in healthy and several damage scenarios. Additionally, the group used ABAQUS to assemble a full-scale finite element model of the I-40. Acceleration responses of this structure have not been published, which may restrict researchers from thoroughly studying the impact of temperature changes on the accuracy of structural damage detection methods. Analysis of the experimental data indicates that ambient temperature has a significant influence on the changes in natural frequencies. Given that the natural frequencies of the bridge are directly related to its stiffness, it is anticipated that these frequencies would reduce as damage progresses. However, the findings indicate that the frequency magnitudes actually increase at the first two levels of damage. The increase in the magnitude of the natural frequencies is attributed to a decrease in the ambient temperature.

Recommendations and Roadmap Designing and constructing a large-scale benchmark structure and collecting an experimental dataset can be useful to fully understand the effect of temperature change in the long-term monitoring of structures if the following recommendations are met.

• Provide acceleration time series data for undamaged and damaged scenarios under different temperatures.

• Conduct modal analysis based on the acceleration signals and extract natural frequencies and mode shapes as reference values.

• Prepare a full-scale finite element model using ABAQUS, ANYSYS, SAP 2000, OpenSees, or any popular finite element analysis software.

• Prepare a MATLAB-based simplified finite element model to employ in iterative model-based methods like finite element model updating. ■ Full references are included in the online version of the article at STRUCTUREmag.org.

Parsa Ghannadi is an author, researcher, and civil and structural engineer.

He works in the Department of Civil Engineering, Ahar Branch, Islamic Azad University, Ahar, Iran, and a BINDT Affiliate Member.

Seyed Sina Kourehli is an associate professor of the Department of Civil Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran.

JULY 2025

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historic STRUCTURES Merchants' Bridge, St. Louis, Missouri, 1890 19th Century Mississippi River Bridges

By Dr. Frank Griggs, Dist. M. ASCE

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he Eads Bridge (see article in the April 2024 issue of STRUCTURE) opened in 1874 and went into bankruptcy in 1875 when it was purchased by the Terminal Railroad Association (TRRA). As it was the only crossing of the river in the St. Louis area, they controlled the rates they charged the various railroads to cross their bridge. Local merchants, with the hope of decreasing their shipping costs, formed the Merchants Exchange Company in 1886 to build their own bridge with the company being incorporated on May 11, 1886, by the State of Illinois, “for the purpose of constructing a bridge and approaches thereto, over the Mississippi River to the city of St. Louis, Mo., from & suitable point between the north line of St. Clair County, in Illinois, and a point opposite the mouth of the Missouri River in Missouri.” The site is where the competitor bridge to the Eads Bridge was proposed in 1867 by Lucius Boomer and his associates.

Authority for construction of the bridge was granted by an act of Congress, approved February 3, 1887, Chapter 91, “An Act authorizing the construction of a bridge over the Mississippi River at St. Louis.” Section 3 of the act stated, SEC. 3. That if the bridge shall be made with unbroken and continuous spans, it shall have at least two channel spans of not less than five hundred feet clear width each, and one span of three hundred feet clear width of channel way: Provided, That said bridge may have two spans of not less than seven hundred and fifty feet each clear width of channel-way, if thought best, instead of three spans as aforesaid, the said channel-ways to be measured at right angles to the current at any and all stages of water; and said span or spans shall not be of less elevation in any case than fifty feet above highwater mark, as understood at the point of location, to the bottom chords of the bridge, and the piers of said bridge shall be parallel with the current of the river, and there shall not be less than fifty feet at high-water mark from the surface of the water to the bottom chords of said bridge.

SEC. 11. Stated in part, That whereas a principal reason for giving authority to build the bridge herein contemplated is to secure reasonable rates and tolls for corporations and individuals for passing over the same, the Saint Louis Merchants' Bridge Company, or its successors or assigns, shall not agree or consent to the consolidation of this bridge with any other bridge across the Mississippi River, or to the pooling of the earnings of this bridge company with the earnings of any other bridge company on said river.

The Merchant Exchange company chose George Morison as consulting engineer and Elmer Corthell as chief engineer. Morison had built several bridges using Whipple double intersection trusses, gradually changing from wrought iron to steel. They chose a site 2 ½ miles north of the Eads Bridge with lowlands on both sides of the river requiring long trestles and three long span trusses over the shipping 50 STRUCTURE magazine

Site map and rail connections of the St. Louis Merchants’ Bridge.

channel. The river itself was about 1,600 feet wide at the site. The required horizontal clearance set by the enabling Act of Congress was 500 feet with a vertical clearance of 50 feet above high water. They designed their three main spans with a length of 517 feet, 8 inches and a clearance over high water of 52 feet.

They submitted their report on November 2, 1887, with three main double track spans over the shipping channel. The plans for the bridge were approved by the Secretary of War on November 15, 1888.

The spans were described as follows, “At either end of the main bridge there is about 425 feet of deck spans, [three spans with clearances of 125 feet] and on the east side there is trestle which is eventually be filled in with earth as shown on the plan, over the Alton Bee line and Wabash railways there is 175-foot double track spam and one, 40-foot girder span. On the West End of the bridge, beyond a 425 feet of deck approach, there will be an iron viaduct over ferry street about 400 feet long then 600 feet of wooden trestle, then 196 feet deck span with 40-foot girders at each end, over ferry street again and then a trestle until the embankment has reached at a height of 25 feet.

Even though Morison had built 518-feet long Whipple double intersection trusses at Cairo, Illinois, over the Ohio River, they were considered to be the longest that could be built with that truss style.

At the Merchants Exchange Bridge, he decided to go with double

Profile of the Merchants’ Bridge with long approaches

Three main spans of Merchants’ Bridge

intersection steel Pennsylvania Trusses with curved upper chords.

The three main spans are built with 18 panels, each 29 feet, 6 inches.

The trusses were 75 feet high in the center and are set 30 feet apart on centers, making room for two tracks placed 12 feet apart, center to center. A system of diagonal and lateral bracing is carried down the posts so as to leave a clearance of 21 feet over the railroad track, thus bracing the center part of each span for the upper 50 feet of its length. The trestles were built of piles driven 20 to 25 feet into the ground and standing 25 to 45 feet above the ground, all the members of the structure above ground being firmly braced and tied together.

The Union Bridge Company, under Charles Macdonald, built the main spans and the 425-feet flanking deck span trusses as well as the viaduct and bridge over Ferry Street and the bridges over the railways on the east and Angelica St. on the West approach. Anderson & Barr placed the foundations and masonry work. The trestle and earthwork

were shared by several local contractors.

Construction started in February 1889, and the bridge opened to a grand celebration in May 1890. Tolls were not as much as anticipated, and during the financial panic of 1893, the company went bankrupt. Its competitor, the Terminal Railroad Association, took over the company and once again had a monopoly on transit across the river in St. Louis.

The approaches were rebuilt in 2005 and the main trusses in 2022 on the existing, with some modifications, piers. ■ Dr. Frank Griggs, Dist.M. ASCE, specializes in the restoration of historic bridges, having restored many 19th Century cast and wrought iron bridges.

He is now an Independent Consulting Engineer (fgriggsjr@verizon.net).

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JULY 2025

51

SE NEWS

SOM completes new headquarters for WeBank, China’s first digital-only bank S

kidmore, Owings & Merrill (SOM) has completed the new headquarters for WeBank, a Tencent-founded digital-only bank and fintech pioneer, in Shenzhen’s Qianhai Business District.

The 148-meter, 30-story tower has an expressive form defined by staggered floor plates and double-height openings, creating a porous facade that promotes airflow and daylight.

Expansive open-plan offices are designed for comfort and collaboration, with direct access to outdoor terraces and natural light. The large floor plates—exceeding 4,000 square meters—enable flexible team configurations, a key advantage for the dynamic needs of financial and tech companies. Multi-level indoor atria facilitate connectivity across departments, while a suite of leisure- and wellness-focused amenities—including a basketball court, gym, outdoor pool, cafeteria, and auditorium—cultivates a sense of balance and community throughout the day.

The LEED Platinum-certified tower—also targeting China Green Building Label 3 Star certification—incorporates a mix of passive and active environmental strategies tailored to Shenzhen’s subtropical climate. Solarresponsive facades filter glare and reduce heat gain, using overhangs and recessed balconies to cut solar radiation by more than 50 percent, which lowers cooling demands and contributes to a more comfortable indoor

Large floor plates and multi-story, mixed-mode spaces promote interaction and knowledge sharing. (Photo by Dave Burk © SOM)

environment year-round. A network of automated systems manages these responsive features, maintaining optimal indoor conditions with minimal mechanical intervention.

A holistic Indoor Environmental Quality (IEQ) strategy guides the building’s approach to comfort, air quality, and energy efficiency—with natural ventilation serving as a central component. Guided by computational fluid dynamics (CFD) analysis, the ventilation strategy combines operable facades with stack-effect atria that act like vertical fans, drawing fresh air up through the building. A

network of environmental sensors monitors outdoor air quality and temperature, allowing the system to activate natural ventilation only when conditions are optimal. As air moves through the tower, it passes through a series of vegetated terraces planted with native Lingnan species, which help filter pollutants and enrich the indoor microbial environment.

On the rooftop, a landscaped garden provides space for relaxation while capturing rainwater for irrigation and managing stormwater runoff. The roof is also designed to support solar integration. ■

Council on Tall Buildings and Urban Habitat announces Award of Excellence Winners T

he Council on Tall Buildings and Urban Habitat (CTBUH) has announced the winners of its 2025 Award of Excellence competition, spanning 20 countries and more than 20 categories.

In categories such as Best Tall Building, Innovation and Urban Habitat, this year’s winners emphasize reuse, low-carbon materials, equitable housing and integrated infrastructure.

Submitting companies were also asked to share data on the carbon and material usage in their projects—part of the CTBUH 2025 Awards 52 STRUCTURE magazine

Carbon Pilot Program—which attempts to consolidate embodied carbon data from across the globe and serve as a benchmark for sustainable development practices. Several projects introduce hybrid programmatic models, blurring the line between public and private realms and prioritizing circularity from the outset.

Each submission was evaluated by multidisciplinary juries comprising leaders in architecture, engineering, planning, construction and real estate development. The selection criteria prioritized performance—environmental, cultural

and operational—over prestige or aesthetics alone. Awardees will present their work during the CTBUH 2025 International Conference, themed From the Ground Up: Tall Buildings and City-Making, taking place 6–9 October in Toronto, where they’ll vie for “best in category” recognition. Results will be announced during the conference’s award ceremony.

For more information on the CTBUH awards program, including this year’s winners and all prior Award of Excellence winners, visit awards. ctbuh.org. ■

Ribbon cutting held for new pedestrian and golf cart bridge at Road America M

cMahon, a full-service professional engineering, architectural and consulting firm, shared its role in the design and completion of a new pedestrian and golf cart bridge along Road America’s front straight. Replacing a decades-old structure, the new bridge enhances accessibility and functionality while marking another project milestone in the longstanding partnership

between McMahon and Road America, the iconic Elkhart Lake, Wisconsin, motorsports destination.

Designed by McMahon, the new bridge accommodates both pedestrians and golf carts. Unlike its predecessor, which was limited to foot traffic and included stairs, the updated, wider design features ramped approaches, making it accessible

and convenient for all guests.

Beyond its functionality, the new bridge serves as a viewing point where patrons can watch cars roaring out of Turn 14.

A ribbon-cutting ceremony was held, May 27, with team members from Road America and McMahon, along with members of the Sheboygan County Chamber of Commerce. ■

Structural Engineering fellowship awarded to Rebecca Henig to study reef resilience T

he SOM Foundation has announced the winner of the 2025 Structural Engineering Fellowship. Rebecca Henig, a spring 2025 graduate of the University of Southern California with a Bachelor of Science in Civil Engineering, will receive $20,000 to conduct original research related to her proposal, “Reef Resilience: Designing Modular Solutions for Coastal Protection.”

During her fellowship, Henig will scuba dive at seven reef sites worldwide to research and reimagine structural solutions for threatened coral reefs, with a goal of enhancing coastal protection while protecting marine ecosystem vitality.

In 2024–2025, the SOM Foundation is supporting research that addresses the complex relationship between water, people, and the built environment through its annual research topic “Advancing Toward a WaterSecure Future.”

Rebecca Henig graduated in 2025 with a Bachelor of Science in Civil Engineering from the University of Southern California (USC) with an emphasis in Building Science through a cross-disciplinary program between the Viterbi School of Engineering and the School of Architecture. In her time at USC, she held leadership positions in the university’s chapter of EERI-SEAOSC, during which her team placed in the annual international Seismic Design Competition her senior year. Henig also has professional experience in BIM, construction management,

and sea level rise research. Raised in the San Francisco Bay Area, Henig developed an ongoing passion for the ocean, which she continues to explore through scuba diving, surfing, and swimming. As an Advanced Open Water Diver, she has gained a deeper understanding of the human-built environment by observing the complexities of the natural underwater world.

To read Rebecca Henig’s full proposal, “Reef Resilience: Designing Modular Solutions for Coastal Protection,” visit: somfoundation.com/fellow/rebecca-henig. ■

Rebecca Henig will receive $20,000 for original research related to her proposal: "Reef Resilience: Designing Modular Solutions for Coastal Protection.

JULY 2025

53

University of Florida wins 2025 Student Steel Bridge Competition F

or a record-breaking fifth consecutive year, student engineers at the University of Florida were crowned the John M. Parucki National Champions in the 2025 Student Steel Bridge Competition, placing in five categories and taking home $8,000 in scholarships.

This year’s national finals at Iowa State University in Ames, Iowa, brought together 43 qualifying teams from colleges and universities across North America. The American Institute of Steel Construction (AISC) and the American Society of Civil Engineers (ASCE) offer the Student Steel Bridge Competition to give future engineers hands-on steel design knowledge beyond the classroom.

Participants took on the challenge of designing, fabricating, and constructing a scale-model steel bridge that would span a river corridor passing through a wildlife conservation area—with the additional obstacle of constructing around a protected sandbar. Competitors found innovative ways to navigate new rules and challenging assembly

54 STRUCTURE magazine

constraints, including a height restriction to minimize impact on the surrounding landscape and a minimum clearance to ensure the safety of paddlers passing underneath the bridge.

In addition to winning the overall prize, the University of Florida placed first in stiffness and efficiency, placed second in lightness and economy, and came in third for cost estimate. They pulled off a 9:37 assembly time with only two builders on the floor.

Lafayette College came in second overall, winning first place in economy and taking home $6,000 in scholarship funds.

Virginia Tech won third place overall, earning them $4,000 in scholarships. They placed first in aesthetics, second in efficiency, and third in lightness and stiffness.

The SSBC planning committee also announced that University of Texas at El Paso is the official host of the 2026 SSBC National Finals (May 22 and 23 in El Paso, Texas).

The final results of the 2025 competition are as follows: Overall University of Florida Lafayette College Virginia Tech Construction Speed Pennsylvania State University, Harrisburg University of California, Davis University of Alaska, Fairbanks Lightness Universidad Autónoma del Estado de México University of Florida Virginia Tech Aesthetics Virginia Tech Université Laval Universidad Autónoma del Estado de México Stiffness University of Florida University of Wisconsin-Platteville Virginia Tech Cost Estimate Worcester Polytechnic Institute Kennesaw State University University of Florida Economy Lafayette College University of Florida Pennsylvania State University, Harrisburg Efficiency University of Florida Virginia Tech University of Alaska, Fairbanks Team Engagement Award University of California, San Diego Robert E. Shaw Jr. Spirit of the Competition Award Lincoln Memorial University

Open Space Institute and the West Point Cadets unveil Appalachian Trail bridge replacement at Harriman State Park

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ugged long-distance hikers and day-trippers alike will enjoy a new pedestrian trail bridge along the Appalachian Trail at Harriman State Park, thanks to a partnership between the Open Space Institute (OSI), cadets from the United States Military Academy at West Point, the New York State Office of Parks, Recreation, and Historic Preservation (OPRHP), and the Palisades Interstate Park Commission (PIPC).

The 34-foot-long steel bridge was constructed as part of a senior-year capstone project by a team of five Civil Engineering cadets with support from three faculty advisors. Located near where the Appalachian Trail crosses Seven Lakes Drive, the new pedestrian bridge features safety upgrades, including level wood decking over steel girders, decorative handrails, concrete abutments and stone armor to minimize streambank disturbance and erosion. In addition, the bridge is nearly two feet higher than the previous version to accommodate seasonal flooding.

OSI’s collaboration with West Point provides the cadets with invaluable hands-on design and expeditionary construction experience as they pursue their civil engineering degrees and train for their military careers, while creating or replacing infrastructure within New York’s state parks.

Over the past eight years, OSI has contributed more than $125,000 toward cadet-built pedestrian bridges in state parks. The institute’s ongoing connection with West Point has yielded nine trail bridges over eight years. This year’s bridge is the second replacement to be completed at Harriman State Park. Projects have also been accomplished at Schunnemunk State Park, and five bridge replacements were completed along the School Mountain Road section of the Hubbard Perkins Loop Trail at Fahnestock State Park.

A tenth cadet bridge that predates the OSI partnership is located near the residence on Bannerman Island. ■

Frank J. Hatfield Ingenuity Award Kennesaw State University John M. Yadlosky Most Improved Team Award Clemson University Video Award New York University Universidad Nacional Autónoma de México University of British Columbia ■

The 2025 West Point Cadet Bridge ribbon cutting was held May 22 in Harriman State Park, N.Y. (Photo by Bill Amos).

JULY 2025

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IN BRIEF All Weather Insulated Panels welcomes key additions All Weather Insulated Panels (AWIP) announced the addition of three key team members: Mike Schuil as Director of Customer Experience, Chris Snell as Senior Manager of Logistics and Fulfillment and Bo Bently as Quality Service Manager. These strategic roles are integral as AWIP continues to advance its “Customer First” service and support objectives.

AWIP also announced the promotion of Joe Paparella to Vice President of Sales & Marketing. Since joining AWIP as Director of Commercial Sales in 2023, Paparella has been instrumental in advancing strategic growth initiatives, strengthening key account relationships and elevating commercial sales performance.

DeSimone Consulting Engineering appoints Ahmed Mantawy Associate Principal in Miami DeSimone Consulting Engineering announced that Ahmed Mantawy, an expert in complex structural engineering, has joined the firm’s Miami office as an Associate Principal.

Mantawy will leverage his expertise in both new construction and large-scale rehabilitation projects, to deepen DeSimone’s market presence in the South Florida market and beyond.

Call for public input for revising NRMCA 100 - 2023 The National Ready Mixed Concrete Association (NRMCA)

Standard 100 Committee announces the opening of the window for public input towards the revision of the publication in accordance with the American National Standards Institute (ANSI) compliance requirements.

NRMCA 100-2023 is the “Prescriptive Design of Exterior Concrete Walls for One- and Two- Family Dwellings.” It provides an approach to the design of concrete footings, foundation walls, and above-grade walls—both load and non-load bearing.

Originally developed by the Portland Cement Association (PCA), NRMCA now hosts the standard and is mandated to follow periodic review to meet state-of-the-practice industry needs and trends.

The committee is requesting all stakeholders—architects, designers, engineers, developers, the academic community, contractors, building product manufacturers, code officials and individuals—to submit their input and recommendations to be considered for possible integration during the standard’s current review cycle.

The NRMCA 100-2023 standard is available for free download at: my.nrmca.org. Interested parties may send their submissions to standardsdev@nrmca.org.

The deadline for all submissions is August 8 at 11:59 p.m. EST. For further information and questions, contact NRMCA’s Director of Civil/Structural Codes and Standards, Dr. Julian Mills-Beale at jmills-beale@nrmca.org. ■

Work on Scotland’s Forth Road Bridge saves 240 metric tons of CO₂e on Scotland’s Forth Road Bridge

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y reassessing wind-induced demands in a more data-driven and evidence-based way, COWI in the UK & Ireland has delivered an important advancement in structural engineering for BEAR Scotland on behalf of Transport Scotland. This approach avoided the need for extensive strengthening works, resulting in a reduction of 240 metric tons of embodied carbon emissions—the equivalent of driving a typical car 1.2 million km, or around the Earth 30 times.

The Forth Road Bridge’s Critical Elements Program (CEP) was launched in response to a 2015 truss end link failure, with earlier assessments having identified overstresses in key structural members and the need for widespread strengthening of much of the stiffening truss.

Global consulting firm COWI, acting as Independent Checker, combined high-resolution RWDI wind tunnel testing with stateof-the-art GNSS-based monitoring data collected during eight major storms between 2021 and 2023.

56 STRUCTURE magazine

“This project exemplifies the future of infrastructure management—where real-time data and intelligent modeling replace unnecessary construction,” said Andy Sloan, Managing Director, COWI UK & Ireland. “Not only have we ensured the bridge’s safety, we’ve also significantly reduced carbon impact.”

The reassessment revealed that internal forces and modal accelerations were significantly lower than previously assessed, with the structure demonstrating higher net damping at moderate wind speeds, likely due to articulation friction. As a result, the number of overstressed top lateral members dropped from 184 to just eight, and over 120 metric tons of strengthening steelwork will no longer be needed.

Beyond the technical success, the project highlights a powerful message: that intelligent, evidence-based engineering can extend the life of existing infrastructure responsibly and sustainably. As global infrastructure ages, this approach offers a compelling model for others to follow: build nothing, if nothing needs building. ■

SEI Update The SEI Board of Governors Elections are now open

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EI wants YOU to participate in the vote! Cast your ballot and help choose the next leaders on the SEI Board!

In accordance with the SEI Bylaws, this year SEI is conducting elections for one At-Large Governor, and one Young Professional Governor, and the next SEI Board President-elect to the Board of Governors, terms effective October 1. Elections are open until 11:59 pm EST, July 31, 2025. Check your inbox for an email with the link to the ballot! The SEI voting body includes all non-student Institute members who are up-to-date on this year’s membership dues. Contact sei@asce.org for questions.

The slate of nominees for the SEI Board of Governors elections is as follows:

President-elect

John Cleary Ph.D, PE, F.SEI, M.ASCE

Chad Schrand PE, F.SEI, M.ASCE

Eric Williamson Ph.D, PE, F. SEI, F.ASCE

John Duntemann PE, SE, F.SEI

Ishwarya Srikanth Ph.D, PE, M.ASCE

Prateek Srivastava A.M.ASCE

At-large

Young Professional

58 STRUCTURE magazine

News of the Structural Engineering Institute of ASCE Call for members: ASCE/SEI Business Practices Committee

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oin the ASCE/SEI Business Practices Committee, led by Chair Trevor Walker, PE, SE, to help shape how structural engineers thrive in today’s business landscape. Current initiatives include the Futures Fund Continuing Education Series, a Best Practices resource hub, and outreach to grad students and local chapters. Get involved in planning for Structures Congress 2026 and advancing cross-disciplinary leadership. Apply: go.asce.org/sei-committees.

ASCE publications now available

Register now for free e-learning webinar—Entrepreneurship for Civil and Structural Engineers: Tuesday, August 5

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his session is the last of a three-part series, exploring strategies to foster an entrepreneurial mindset and provide guidance for longterm career growth and fulfillment in structural engineering. Don’t miss this chance to enhance your professional toolkit with valuable insights and practical strategies, featuring industry experts, interactive case studies, and Q&A. Free for ASCE members; brought to you by the SEI Business Practice Committee and the SEI Futures Fund. Register: go.asce.org/e-learningwebinar.

Upcoming ASCE Continuing Education Webinars

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tructures Congress 2025 Proceedings: Explore the peer-reviewed proceedings from Structures Congress 2025, held in Phoenix, Arizona, April 9–11.

This collection features 42 papers covering key topics in structural engineering, including blast and impact loading, transportation structures, buildings, codes and standards, forensics, life-cycle assessment, and more.

A valuable resource for practitioners, academics, and researchers.

Learn more and register at mylearning.asce.org/.

Thursday, July 10 and Friday, July 11: Design Construction, Renovation of Masonry Structures Thursday, July 17, and Friday, July 18: Industrial Buildings: Design and Renovation Monday, July 21: Design of Masonry Anchors

Celebrating the 2025 SEI Futures Fund Scholarship recipients headed to ETS 2025

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ongratulations to the recipients of the SEI Futures Fund Scholarship, awarded to support emerging structural engineers attending the Electrical Transmission and Substation Structures Conference, September 14–17 in Dallas! This competitive scholarship provides complimentary registration, travel assistance, and informal mentoring with industry leaders—empowering recipients to expand their professional networks and gain valuable insights into the future of transmission and substation structures.

Are you excited yet for Dallas? Remember that on July 16 early bird rates are closing, so take advantage of the low prices today!

Learn more and apply for the next student/young professional scholarship to Structures Congress April 29-May 1 in Boston at https:// www.structurescongress.org/program/scholarships.

The scholarship recipients are: • Oshan Adhikari, R.Eng, S.M.ASCE, New York University • Juan Camilo Buitrago Hurtado, S.M.ASCE, Universidad de La Sabana, Columbia • Abdullah Braik, Ph.D., A.M.ASCE, Texas A&M University • Aagya Dahal, S.M.ASCE, University of Connecticut

• • • • • • • • • • • • • • • •

Giana Fuller, S.M.ASCE, San Francisco State University Rebecca Giuntoli, A.M.ASC, University of Texas at Austin Syed Mujtaba Haider, PE, S.M.ASCE, Auburn University Samuel Harris, A.M.ASCE, University of Wisconsin-Madison Pooria Mazaheri, S.M.ASCE, Iowa State University Gavin Nelson, A.M.ASCE, Colorado School of Mines Kehinde Omotayo, S.M.ASCE, Tennessee State University Muneer Qudaisat, S.M.ASCE, Iowa State University Ehsan Rajaie, S.M.ASCE, University of Texas at Arlington Jordi Ramos Nunez, A.M.ASCE, Colorado School of Mines Ahmad Rasa, Ph.D., S.M.ASCE, University of Alabama in Huntsville Amir Ali Shahmansouri, S.M.ASCE, Washington State University Nasim Shakouri Mahmoudabadi, S.M.ASCE, University of Memphis Ledia Shehu, S.M.ASCE, University of Alabama in Huntsville Faith Shipapa, S.M.ASCE, West Virginia University Vidhi Rasik Solanki, Ph.D., Aff.M.ASCE, University at Buffalo JULY 2025

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NCSEA News NCSEA Foundation opens 2025 SEA grant submission period

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he NCSEA Foundation is accepting applications for its 2025 SEA Grant Program, an annual initiative that funds innovative and community-driven projects led by Structural Engineers Associations (SEAs) across the country.

The program empowers SEAs to launch forward-thinking initiatives that support the Foundation’s mission to advance innovation, advocacy, and people in the structural engineering profession. From technology upgrades to outreach efforts, member programming, and more, the grants are designed to help SEAs grow their impact locally and nationally.

All SEAs or SEA members are eligible to apply. Proposals must first be submitted to local SEA leadership for review and approval before

being forwarded to the NCSEA Foundation for consideration. There is no application fee.

A subcommittee of the NCSEA Foundation Board of Directors will evaluate proposals based on alignment with the Foundation’s mission.

Political contributions and lobbying reimbursements are not eligible for funding.

The deadline to apply is August 18, 2025.

To learn more about the SEA Grant Program—including full criteria, eligibility details, and past funded projects—and to apply, visit www.ncsea.com/foundation/advocacy/sea-grants.

Questions? Contact foundation@ncsea.com. ■

CFSEI Expo spotlights NCSEA’s role in advancing AI

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John-Michael Wong gives the keynote lecture at the annual expo of the Cold-Formed Steel Engineers Institute last month.

ohn-Michael Wong, Ph.D, SE, a member of the NCSEA Foundation’s AI Taskforce, recently served as keynote speaker at the 2025 CFSEI Expo, drawing widespread attention for his insightful presentation on integrating artificial intelligence into structural engineering.

Wong delivered a clear message: AI isn’t a distant concept—it’s here, it’s powerful, and it’s time to engage with it responsibly. His talk provided real-world examples, practical strategies, and a roadmap to begin leveraging AI safely and effectively. He also highlighted NCSEA’s resources, including sample AI policies and tool evaluation frameworks, and emphasized the importance of engineers maintaining “responsible charge” as they adopt new technologies.

The keynote sparked important conversations, and it positioned NCSEA’s AI Taskforce as a national leader in this fast-moving space. ■

SEAoK Young Members Group fosters cross-disciplinary connections

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he SEAoK Young Members Group (YMG) has been steadily building momentum with a series of events designed to connect young professionals across Kentucky. With a focus on collaboration, education, and community, the group is creating space for interactions among emerging structural engineers, architects, and project partners.

They started the year with a pickleball tournament co-hosted with AIA East Kentucky—a fun way to bring together emerging architects and structural engineers for networking (and some friendly competition).

They also had the rare opportunity to tour the under-construction Heaven Hill Distillery in Louisville, led by the project’s Engineer of Record. The tour highlighted the complex structural challenges involved in building a world-class bourbon facility.

Focused on bridging the communication gap between disciplines, 60 STRUCTURE magazine

SEAoK also brought together young structural engineers with architects, construction managers, and other disciplinary experts to discuss topics they wished they better understood. The event was titled “What the _____ Wishes the Structural Engineer Knew” and resonated with members of all experience levels.

Through events that mix education with approachability, SEAoKYMG is equipping early-career engineers with the skills and relationships they need to thrive in a collaborative profession. ■

News from the National Council of Structural Engineers Associations 2025 SEE Awards feature new categories, expanded eligibility

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CSEA has opened submissions for the 2025 Structural Engineering Excellence (SEE) Awards, its program honoring outstanding achievements in structural engineering.

This year marks a major evolution of the SEE Awards, with a completely reimagined slate of categories that reflects the expanding impact and innovation of the profession.

New for 2025: •

• •

All-new award categories—The entire lineup has been refreshed to better showcase the breadth of structural engineering excellence. New categories include Innovation in Materials, AI in Design, and Sustainable Design, among others.

Expanded eligibility window—Projects completed within the last 10 years are now eligible for submission (previously limited to 3 years).

Small firm discount—Firms with 20 or fewer employees across all office locations are eligible for a $100 discount on the submission fee.

Projects from anywhere in the world are eligible and can be entered in one of 10 categories: • Landmark Structures • Innovation in Materials • Sustainable Design • Performance Design for Resilience • Social Impact • Residential/Single and Multi-Family Homes • Bridge and Transportation • Forensic/Renovation/Retrofit/Rehabilitation • Non-Building Structures • AI in Design The top project will be honored with the Structure of the Year Award.

Entries are due by July 18, 2025. Submissions must include the name of a licensed PE or SE whose practice or activity is primarily in the field of structural engineering. Winners will be honored at the SEE Awards Celebration on October 16, 2025, during the NCSEA Structural Engineering Summit in New York City.

To learn more or submit a project, visit www.ncsea.com/2025seeawards.

Celebrating NCSEA’s advocacy at the ICC code hearings

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ecently in Orlando, members of the NCSEA Code Advisory Committee (Emily Guglielmo, Emily Dunham, Erik Madsen, Julie Furr) proudly represented structural engineers at the International Code Council (ICC) Committee Action Hearings—a pivotal step in shaping the next generation of building codes. This year’s hearings marked a strong showing for NCSEA, not only in terms of presence but also in outcomes.

Our Role in the Process For those unfamiliar, the ICC code development process is a multi-year cycle where proposals are submitted, debated, and voted on—ultimately shaping codes like the International Building Code (IBC) and International Existing Building Code (IEBC). The Committee Action Hearings (CAHs) are the first major public step, where expert testimony, public comment, and committee votes determine whether proposals move forward.

NCSEA plays a Emily Dunham addresses the ICC during a committee action

critical role in this process. Our Code Advisory Committee—which includes subcommittees focused on seismic, wind, general, existing buildings, and special inspection/quality assurance—develops, reviews, and advocates for proposals that advance safety and clarity.

What We Achieved NCSEA submitted more than 20 code change proposals and actively advocated on over 100 others—both in support and in opposition.

The majority received favorable votes to advance to the next stage.

Our proposals were well-received thanks to thoughtful coordination, deep technical knowledge, and the strong relationships we’ve built across the ICC and broader design community.

Why It Matters NCSEA’s involvement ensures that the voices of structural engineers are at the table—not just reacting to change, but driving it. Code development is a long game, and these victories—large and small— help shape safer, more resilient communities for years to come.

Looking Ahead As the code process continues through another round of Committee Action Hearings and Public Comment Hearings and final votes, NCSEA will keep advocating for smart, practical updates to the codes that define our practice. We also encourage members to get involved—whether by joining a subcommittee, offering technical review, or engaging with your local SEA. Thank you to the incredible volunteers and staff who made our participation in Orlando so impactful. Your work elevates the profession and protects the public—and we’re proud to celebrate that here. ■

hearing.

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CASE in Point Congratulations! CASE members and their projects win top honors in Engineering Excellence Awards

Severud Associates Consulting Engineers, PC

KPFF, GRI & PAE

Project: Sphere

Project: Portland International Airport Terminal Core Redevelopment

GRAND AWARD With its 516-foot-diameter and 366-foot height, Las Vegas’ Sphere is the world’s largest spherical structure, enclosing a bowl-shaped theater for 17,600 guests seated beneath a domed roof and suspended media plane. Designed using advanced engineering modeling tools, Sphere was prefabricated in sections to facilitate construction and reduce the need for temporary support. Through sophisticated detailing and carefully controlled tolerances, Sphere’s prefabricated 400-foot dome was delivered within about one inch of ideal geometry. Sustainability was a priority in the design of Sphere, as well as mitigating the unique challenges of a desert climate. Recycled materials were used throughout the structure, while the Exosphere’s design allows for thermal expansion.

GRAND AWARD The Portland International Airport (PDX) Terminal Core Redevelopment Project modernizes and expands one of America’s favorite airports. Between outdated facilities, seismic vulnerabilities, and projections that showed travel demand would soon exceed terminal capacity, PDX needed a solution that would create more space, safer space, and do so while still delivering peerless passenger experience. In the interest of both time and efficiency, the team modernized the existing terminal in phases to minimize disruption, with the new expansion designed to exceed code for seismic resilience. The project features a 400,000-square-foot mass timber roof supported by more than 30 Y-shaped columns equipped with seismic isolators.

CASE to host summer meetings in Philadelphia this August

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tructural engineers from around the country will gather in Philadelphia this August for the Coalition of American Structural Engineers (CASE) Summer Meetings, a two-day event centered on collaboration, education, and innovation.

Set for August 14–15, the meetings will begin on Thursday at the Burns Engineering office in downtown Philadelphia. The morning will be dedicated to the CASE Executive Committee, while the afternoon opens to all attendees for a roundtable discussion and an educational session. A highlight of the day will be an offsite tour of the Aero Aggregates plant, offering a The day concludes with an offsite tour of the Aero Aggregates plant—one of the country’s leading producers of ultra-lightweight foamed glass aggregate. Aero played a key role in the emergency repair solution for the I-95 overpass collapse in 2023, and 62 STRUCTURE magazine

the tour offers a behind-the-scenes look at how sustainable materials are being used in real-world infrastructure recovery.

On Friday, the focus shifts to open committee meetings where members and guests alike are invited to engage in discussions on pressing industry topics. Attendees will have the opportunity to contribute their insights, learn about ongoing CASE initiatives, and connect with peers in a collaborative environment. Meals and refreshments will be provided throughout the day.

While the event is open to all interested participants, space may be limited. CASE encourages early planning to ensure full participation.

The Summer Meetings offer more than a professional gathering— they’re a chance to shape the future of structural engineering in a setting that fosters both innovation and community.

News of the Coalition of American Structural Engineers Explore CASE’s newest refreshed publications

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xplore CASE’s top publications that inspire and inform professionals like you. From cutting-edge research to actionable insights, this year’s bestsellers are not to be missed. Plus, if you’re not a CASE member, don’t forget to use your discount code NCSEASEI2022 at checkout for exclusive savings.

CASE Position Statements and White Papers Beyond the Code: Shrinkage Cracking CASE recognizes that the International Building Code or other governing codes do not address all aspects of structural engineering and design. Often, the most common issues where the owners, or the contractor or the design team are not aligned deal with what is not clearly addressed by the various codes or design guidelines.

This is the second in a series of “Beyond the Code” white papers that will attempt to collate design considerations that need to be discussed with the owners at the beginning of a project to establish a clear Basis-of-Design for the project. By proactively bringing up the design consideration in front of the owners, the Structural Engineer can set up realistic expectations and discuss the cost impact of alternative designs.

This white paper in the “Beyond the Code” series discusses shrinkage cracking in concrete with an explanation of why it occurs, common locations they occur, and strategies to mitigate them becoming a risk in your project.

CASE Position Statements and White Papers: Performance Based Design Performance-Based Design (PBD) is a relatively new and powerful approach to structural engineering born from ongoing efforts

to resolve the differences between the actual observed performance and the expected performance of structures. Previously observed differences between the actual and expected performances of structures, especially because of earthquakes, has led to advances in the understanding of system and material performance by the research and practicing community that at times go beyond the prescriptive requirements often found in the building codes.

With the improvements in the capability of relevant analytical tools and computing technology, structural engineers are increasingly using PBD for new design and for evaluation or retrofit of existing structures to better predict building performance, provide more economical designs, or address when the prescriptive provisions of the building code just do not apply.

CASE Position Statements and White Papers: Teaming Agreements An important aspect of a joint project pursuit between a contractor or design professional and a structural engineer is an agreement covering the activities of the parties prior to contract award. This agreement is commonly referred to as a teaming agreement. Teaming agreements are often associated with design-build projects but can be used on any project pursued jointly by two or more parties. Many organizations familiar to structural engineers provide a standard form teaming agreement. This commentary summarizes the contents and typical clauses of the standard form teaming agreements offered by these four organizations: • American Institute of Architects (AIA): Contract C102-2015 • Engineers Joint Contract Documents Committee (EJCDC): Contracts D-580 and E-580 • Design-Build Institute of America (DBIA): Contract No. 580 • Consensus Docs: Contract Nos. 296 and 498.

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codes and STANDARDS FAQ on SEI Standards What you always wanted to ask.

By Jeannette Torrents, PE, SE

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his quarterly article addresses some of the questions received about structural standards developed by the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE).

Questions from engineers, building officials, and other design professionals are often considered to develop future editions.

These topics and more are discussed on the ASCE Peer-to-Peer Standards Exchange Forum. ASCE/SEI members can ask and answer questions in the forum. Visit https://collaborate.asce.org/standardsexchange/home to learn more and read about other topics.

Positive Attachment of Non-Structural Components Per ASCE/SEI 7-22 Table 13.1-1, Nonstructural Components Exempt from the Requirements of This Chapter, mechanical and electrical components in Seismic Design Category C that are positively attached to the structure and have a component Importance Factor, Ip, equal to 1.0 are exempt from the requirements of Chapter 13, Seismic Design Requirements for Nonstructural Components.

If that nonstructural component is analyzed for stability from overturning and found to be stable under the seismic demand required per Chapter 13 (e.g. Factor of Safety of 1.5 against overturning using ASCE load combinations) and is qualified seismically for the same loading for the structural integrity of the component itself (to prevent life-safety hazard by component failure), is there any commentary or consideration for the positive attachment not to be required based on engineering analysis?

Answer: There are no exceptions to Table 13.1-1. Positive attachment is required for mechanical and electrical components in Seismic Design Category C with an Ip of 1.0; these components are exempt from the other requirements of Chapter 13.

Note that there is no exemption for architectural components in Seismic Design Category C. Per Section 13.4, Nonstructural Component Anchorage and Attachment, non-structural components and their supports shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity.

The only exception to this requirement is for rooftop solar panels that satisfy the provisions of Section 13.6.12, Rooftop Solar Panels.

Seismic Qualification of Architectural, Mechanical, And Electrical Components ASCE/SEI 7-22 Section 13.2.1, Applicable Requirements for Architectural, Mechanical, and Electrical Components, Support, and Attachments, states that the component itself (not just the support and attachment) shall be analyzed or tested. However, C13.6, Mechanical and Electrical Components, implies that at the usual safety level (Ip=1.0), if failure of the mechanical or electrical component itself poses no significant hazard, only supports and attachments need to be 64 STRUCTURE magazine

designed, not the component itself. The Commentary also implies that engineering judgment can be used to determine whether failure of the component is a threat to life.

Can you please confirm that the intent of the standard is to allow engineering judgment (when Ip = 1.0) to determine whether a component itself needs to be analyzed or tested?

Answer: SCE/SEI 7-22 Chapter 13 code and commentary only requires the design of supports and attachments for Ip = 1.0 components, but “supports” can include parts fabricated by the equipment manufacturer, as described in 13.6.4, Component Supports, and C13.6.4. Although not in the code sections, it is established by C13.6 that the design of supports integral to the equipment is required when there is a life safety hazard, typically for overhead or wall mounted components and base mounted components of such height that they could pose a life safety hazard.

Risk Category for Light Poles What Risk Category does ASCE 7-22 require for light poles? Would a 30-foot light pole in a parking lot qualify as Risk Category I? What about a 75-foot pole lighting a Little League field?

Answer: ASCE/SEI 7-22 limits Risk Category I to structures that represent low risk to human life in the event of failure. While a light pole is not an occupied structure, it does represent a risk to the public if it were to fail and therefore should be classified as Risk Category II. ASCE/SEI 72-21 Design of Steel Lighting System Support Pole Structures provides more specific guidance related to lighting fixtures and appurtenances. Per Section 2.3, Classification of Structures, of ASCE/SEI 72-21, all lighting system support structures are classified as Risk Category II, because nearly all light poles have some proximity to occupied areas. As noted in the question, there certainly is a difference in the number of people that could be affected by the failure of a 30-foot parking area pole versus the failure of a 75-foot athletic field lighting pole. The Commentary to ASCE/SEI 72-21 states that the Risk Category may be increased to Risk Category III or higher at the engineer’s discretion. The ASCE 72 Committee is currently reviewing the Risk Category provisions for possible revision in the next edition of the standard. Any feedback or input regarding Risk Category of steel lighting system supports should be directed to Wes Oliphant, Chair of ASCE 72, at woliphant@exoinc.com.

This article’s information is provided for general informational purposes only and is not intended in any fashion to be a substitute for professional consultation. Information provided does not constitute a formal interpretation of the standard. Under no circumstances does ASCE/SEI, its affiliates, officers, directors, employees, or volunteers warrant the completeness, accuracy, or relevancy of any information or advice provided herein or its usefulness for any particular purpose. ASCE/SEI, its affiliates, officers, directors, employees, and volunteers expressly disclaim any and all responsibility for any liability, loss, or damage that you may cause or incur in reliance on any information or advice provided herein If you have a question you want to be considered in a future issue, please send it to sei@asce.org with FAQ in the subject line. Visit asce. org/sei to learn more about ASCE/SEI Standards. ■ Jeannette Torrents, PE, SE, F.SEI, is the Technical Director of the Structural Engineering Institute.

inSIGHTS When Good Engineers Make Bad Business Decisions: A Risk Management Solution Employing client evaluation criteria helps firm owners spot common client selection red flags and avoid costly claims.

By Mark Blankenship, CPCU, AIC, LEED AP

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he swing stage crashed onto the street below on a Saturday afternoon, killing several people. The structural engineer who designed the attachment points hadn't made a single calculation error—but his firm was now facing bankruptcy. How could this happen?

This tragedy, along with another devastating $2 million claim, nearly destroyed a five-partner structural engineering firm where all the partners were superb engineers. The problem wasn't technical incompetence—it was business naivety. One partner's inability to recognize project risks had put the entire firm in jeopardy.

Over my 27 years specializing in architects’ and engineers’ professional liability insurance, I've seen this pattern repeatedly. Technical excellence means nothing if you can't identify which projects are likely to generate losses rather than profits. That's why I developed what I call the Four Cornerstones of Risk Management: 1. Risk identification and client selection.

2. Contract negotiation including integration of subconsultant agreements.

3. Quality assurance and quality control including documentation.

4. Construction contract administration including project closeout.

This article focuses on the first cornerstone—the one that could have saved that engineering firm from catastrophe.

As if one catastrophic claim wasn't enough, the same engineer agreed to design attachment points for a 100-foot aluminum swing stage suspended from a high-rise building during facade restoration. The work plans clearly specified that the stage should be lowered or tied off if winds exceeded 35 mph.

But plans don't control Saturday weather.

High winds struck when no one was monitoring the site. The swing stage detached and crashed to the street below, killing several people and leaving the firm facing another multi-million-dollar lawsuit.

Suddenly, the firm confronted two devastating claims with no engineering errors involved. Their professional liability insurer non-renewed their policy, and without insurance, they would be disqualified from most projects. The five partners—all excellent engineers—faced the prospect of closing their doors.

The frustration was overwhelming. Perfect technical work had been undone by poor project selection.

The $2 Million Favor That Nearly Destroyed Everything

The 100-Point Project Evaluator: How It Works

The trouble began when the firm's largest contractor client asked for what seemed like a simple favor. They were building a sports arena and needed an Illinois engineer to stamp plans for bleachers prepared by an out-of-state designer. Since Illinois separately licenses structural engineers, this was perfectly legal—provided the engineer performed all necessary calculations and documented the work.

Racing against deadline pressure, the engineer stamped first and reviewed later—a fatal sequence.

The design builder had hired different engineers for various components without coordinating between subconsultants. The result was an unstable structure with pinned connections stacked on top of pinned connections.

When repairs exceeded $2 million, the engineer learned a harsh lesson: when you seal plans, you buy all the problems associated with those plans.

Recognizing that client and project selection was the root cause of their problems, the firm developed a systematic approach: the Project Evaluator, which grades prospective clients and projects on a 100-point scale.

When Perfect Engineering Isn't Enough

Contract Assessment (0-20 points) The evaluation begins with contract terms. Contracts including limitation of liability provisions earn the maximum 20 points. Standard contracts reflecting generally accepted care standards with consequential damages waivers (like AIA contracts) receive 10 points. Client-prepared contracts typically unfavorable to design professionals earn just 5 points.

Verbal agreements score zero and are generally avoided.

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Fee Structure (1-15 points) Fee size receives appropriate weighting: small fees earn 1-5 points, medium fees get 6-10 points, and large fees receive 11-15 points. For a medium-sized firm, $200,000 might constitute a large fee threshold.

Profitability Analysis (5-10 points) Projects with 20% profit potential earn maximum points (10). Profits between 10-20% receive 7 points, while margins under 10% get 5 points.

Hourly projects, typically profitable due to their structure, automatically receive 7 points.

Client Classification (5-25 points) This category carries significant weight due to its predictive value: • "A" clients: Bring profitable projects, pay promptly, and receive priority during competing demands.

• "B" clients: Provide good projects but may have less favorable contracts, payment histories, or other risk factors.

• "C" clients: Frequently take over 120 days to pay invoices and typically bring high-risk, low-profitability projects.

• "D" clients: Have proven problematic in past relationships.

First-time clients cannot score above 5 points due to relationship uncertainty—a crucial safeguard the original firm had ignored.

Schedule Considerations (0-20 points) Reasonable schedules allowing adequate time for checking and coordination earn 10 points. Projects with sufficient available staff to execute without overtime pressure receive an additional 10 points—recognizing that rushed work creates unnecessary risks.

Experience Match (0-10 points) Points reflect familiarity with building types and project territories.

Unfamiliar work increases risk and reduces scores accordingly.

Legal Risk Deductions The final step subtracts points for high-risk project types: • Condominiums: -20 points (highest risk category).

• High-rises (15+ stories): -15 points.

• Parking garages, correctional facilities, wastewater treatment plants: -5 points each.

• Single-family residential, hotels/motels, renovations: Variable deductions based on partner judgment.

The 60-Point Threshold Projects scoring 60 or above proceed without partner consultation.

Lower-scoring projects require majority partner approval—crucially, this creates a "pause" rather than an automatic rejection. The system never results in a hard "no," but it forces deliberate consideration of high-risk situations.

Join an NCSEA webinar from the author on this topic on August 7. Register at www.ncsea.com/webinars.

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The Verification Process: Beyond the Numbers Once projects pass initial grading, verification begins: • License verification for prime professionals when working as subconsultants.

• Reference checks with previous clients, focusing on payment history, communication style, and dispute resolution approaches.

• Credit analysis through Dunn & Bradstreet reports to confirm financial stability.

• Web searches for litigation history, news coverage, or reputation issues that might signal problems.

This process has revealed numerous red flags that pure scoring might miss—from companies facing bankruptcy to clients with patterns of suing design professionals.

20 Years of Results Since implementing this systematic approach over two decades ago, the firm has experienced zero significant E&O claims. They now qualify for the lowest available professional liability insurance rates—a dramatic transformation from facing policy non-renewal.

The numbers tell the story: hundreds of projects evaluated, dozens of highrisk situations avoided, and millions in potential claims prevented through systematic risk assessment rather than intuitive decision-making.

More importantly, the five partners can focus on what they do best—excellent engineering—knowing their business decisions are equally sound.

Beyond Technical Excellence The engineering profession attracts individuals who excel at solving complex technical problems. However, business risk assessment requires different skills—ones that aren't taught in engineering school but are equally critical for long-term success.

The Project Evaluator system transforms subjective "gut feelings" into objective, repeatable assessments. It creates firm-wide consistency in decisionmaking and provides clear documentation for difficult conversations with potential clients.

Most importantly, it recognizes that in professional services, the client you don't take can be more valuable than the one you do.

This systematic approach to risk identification and client selection represents just one of the Four Cornerstones of Risk Management. When combined with strong contract negotiation, quality assurance protocols, and construction administration practices, it creates a comprehensive framework for protecting design firms from preventable disasters.

The five partners learned this lesson the hard way. Your firm doesn't have to. ■ WTW hopes you found the general information provided in this publication informative and helpful. The information contained herein is not intended to constitute legal or other professional advice and should not be relied upon in lieu of consultation with your own legal advisors. In the event you would like more information regarding your insurance coverage, please do not hesitate to reach out to us. In North America, WTW offers insurance products through licensed entities, including Willis Towers Watson Northeast, Inc. (in the United States) and Willis Canada Inc. (in Canada).

Mark Blankenship, CPCU, AIC, LEED AP specializes in architects and engineers professional liability insurance. Future articles will explore the remaining Cornerstones of Risk Management.

NEW YORK. NEW KNOWLEDGE. NEW CONNECTIONS. 50+ expert-led education sessions.

6 iconic tours in New York City.

90+ exhibitors in the Exhibit Hall.

And that’s just the beginning.

Hilton Midtown October 14-17, 2025

Get ready for the biggest structural engineering event of the year at the 2025 NCSEA Structural Engineering Summit.

Scan the QR code or visit www.NCSEASummit.com.