Wood+ Towards A Self-Regulating Vernacular

WOOD + TOWARDS A SELF-REGULATING VERNACULAR

IAAC > INSTITUTE FOR ADVANCED ARCHITECTURE

WOOD+ TOWARDS A SELF-REGULATING VERNACULAR

-IN 2019 WOOD+ WAS FEATURED IN THE RESIDENCY PROGRAM AT AUTODESK BUILD SPACE (BOSTON), ON REDSHIFT & AT THE GLOBAL GRAD SHOW IN DUBAI AUTHOR LARS ERIK ELSETH INSTITUTE FOR ADVANCED ARCHITECTURE OF CATALUNYA BARCELONA, SPAIN PRINTING AARHUS SCHOOL OF ARCHITECTURE

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SUPERVISED BY EDOUARD CABAY & RAIMUND KRENMUELLER. MASTER IN ADVANCED ARCHITECTURE. SUBMITTED ON THE 21ST OF SEPTEMBER 2019.

THESIS PRESENTED TO OBTAIN THE QUALIFICATION OF MASTER DEGREE FROM THE INSTITUTE OF ADVANCED ARCHITECTURE OF CATALUNYA

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ABSTRACT During spring and snowmelt, larger waterbodies and ice has a risk of damaging footbridges in rural Nordic environment. While most of these bridges are raised relative to the highest flood datum recorded, they hold a considerably high risk of being damaged if weather averages increases. This urges the need for a responsive structure that can alter its position relative to the rising water levels.

How can one create a flexible, composite-joint, that can augment wood to work in high-impact environments. Each joint is made from a 2x4 member through three-dimensional pocketing operations leaving only a thin strip of wood. By inlaying silicone into the cavity, wood is able to bend with a soft-resistance while keeping its tensile integrity.

Further, this work focuses on the construction of an auxetic moudule of multiple single-axis joints, that can be assembled in series and work as a self-regulating system.

Through rotating the orgin plane for each joint, a horizontal module can translate the forces to a rotated module. This allows the bridge to redirect water flow pressure into lifting forces and regulate its offset to the fluctuating river stream - ultimately allowing the bridge to perform passively throughout the full year without having to be dismounted during winter.

Keywords: adaptable, self-regulating, lowtech, auxetics, flexible wood

**

PREFACE Initially inspired by innovative silicone injected joineries in furniture design (Pelidesign, 2007), the work looks at how to address the connection between wood and silicone once upscaling to larger utilitarian structures. These joints replaces mechanical fixtures such as bolts, nuts and screws with gripping material interface that allows the silicone to hold onto its wooden counterpart.

This brings forward a new scenario for flexible timber structures, and stands critical to the static nature of preceding timber structures situated in challenging, remote environments. It explores a range of assemblies through making. The overall objective for this research is to design a footbridge that can displace itself vertically and avoid collision with ice drifting down the river during snowmelt.

Wood+ also deals with the following sub-objectives: 1 How to make a flexible joint? 2 How to assemble a cell module?

3 How to translate horizontal forces into vertical forces?

4 Where to absorb the necessary forces to facilitate vertical deformation of a full-scale structure?

5 How to layout a system of cells and make them work as one body?

6 How to solve architectural detailing for a moving, shape-changing footbridge?

All experiments are carried out using dimensional lumber as medium to explore connections between wood and silicone on micro, meso and macro level. The work is heavily focused on the making of a linear axis joint, but deals with three-dimensional deformation in a larger structure through re-orienting single joints to new angled planes.

ACKNOWLEDGEMENTS Bottom-Up Catalouge The work explores a variety of hand-made prototypes from wood and silicone. Learning from these assemblies, they are later rationalized and parametrized into variables so that an instance can be produced from the catalogue very quickly. This works with a variety of stocks.

It does however imply a tedious effort that strictly relies on a perfect, unbroken workflow in order to readily generate design instances within a short time frame.

Auxetic Kinetix The overall deployable system is using configurations explored by KinetiX developed at MIT Media Lab. End Case Project At the end this body of work shifts from a material research to an architectural design work, where the system explored - is applied in the making of a footbridge. As consequence it is forced to work in accordance with all the layers of the structure. The intention of this work is to forward an example of how to make use of auxetics in architecture through architecture detailing.

I see this as a crucial effort - particularly in a time where our practice is becoming more and more specialized, That’s why one of the strengths of this thesis is to escape the research phase and provide a thorough design package that uses the prototype as system in order to reach a full scale designed bridge unit.

Concerns The design of this footbridge does not address all structural challenges.

There are numerous variables that have not yet been taken into considerations - that might present new problems and challenges consequently driving the design into new directions. As this research is considered a proof-of-concept I only focus on a few. That’s why I want to take this opportunity to highlight the ones that I haven’t tackled.

On the next page I have made a ‘list of concerns’.

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List of Concerns 1. Structure is made to yield for ice only 2. Design does not consider flashfloods or tropical environments with monsoons.

3. Silicone parts has a high lifetime - any biodegradable alternatives have not been explored in any of the prototypes and could potentially have reduced structural performance.

4. The system works through linear joints and linear actuation - it is a real challenge to fully make sure that the forces of water does not flip or rotate the bridge. This can happen if forces are not entirely perpendicular to the bridge sides and petals. Unpredictable forces could damage the system and prevent the linear-axis deformation to happen. Each joint has low tolerance for rotation and shear forces.

Autodesk Build Space This research project has been supported in part by Autodesk Build Grant, under the IAAC/ Autodesk Build Space Residencies.

-During the summer I have been a resident at Autodesk Build Space in Boston where I have had the chance to accelerate my project in highly advanced facilities with access to simulation-software and industry partners. Hands-on access to machines made it possible to completely reiterate the joint itself using extensive CAM techniques and software directly in tune with the high-end facilities and fabrication space at the Build Space.

During the time I was there - a 1:1 module was created - forming one of the bridge sections. The whole experience was incredibly engaging and forced the project to be re-thought in different software and simulation engines, but as a result - it only strengthening it. The final module is considered an exhibition-piece and therefore its dovetail detailing must be considered as improvisational joinery and suspect to change prior to any structural performance tests. .

Contributors Edouard Cabay & Raimund Krenmueller (supervisors) Soujal -- (For CNC & woodshop help at IAAC), Ricardo Valbuena (tips and tricks on CNC + exceptional fab lab mangement, Ricardo Mayor (Fabrication in general).

Zach at BUILD Space in Boston (For all help with Fusion - from milling strategies and simulation to modelling), Joshua Aigen (Shop supervisor,

CONTENTS 1 Introduction

3 Two-component material system

3.1 Analog joints

3.2 Detailing

3.3 Loading test

3.4 Alternative joints

3.4 Research overview

Reflections

6 Conclusion 7 Conversation 8 Text fragments 9 Thesis details 10 Table of figures 11 Bibliography

New Fabrication Phase

5 Build Space Program

5.1 Build space report

5.2 Joint Fabrication & assembly

5.2.1Joint design

5.2.1.1 Evolved detailing

5.2.1.2 Static stress simulation

5.2.2 Fabrication steps

5.2.2.1 Custom workholders

5.2.2.2 Dovetail design

5.2.3 Cell assembly

Architectural Design + Details

4 The case project

4.1 Site limitations and forces

4.2 Form typologies

4.3 Implementing auxetic system

4.3.1 Rectangular cell assembly

4.3.2 Horizontal to vertical force translation

4.4 Architectural detailing

4.4.1 Kit of parts

4.4.2 Orthographic model views

4.4.3 Seasonal change & ultimate states

4.4.4 Rendered views

Research & Fabrication Exp.

2 The Norwegian context

2.1 Climate, landscape & trekking

2.2 Norwegian building culture

2.3 Smart & adaptable materiality

WOOD+

1 INTRODUCTION

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1 INTRODUCTION Non-material driven design Architecture has historically been limited to static design solutions and is instinctively something we imagine as rigid. Ever since industrialization we have tried to make things more life-like and fluid, through mechanical parts and actuators. Our built environment is stitched together by materials favored by urgency1 (§Contemporary design challenge), readiness and deployability, causing high impact on land and resources. The construction industry has for a time forgotten about materiality and been obsessed with geometry.

Advanced manufacturing has reach a level of sophistication where small turning gears and pins can be downsized and manufactured at the size of a seed2. Highly precise engineered movement favors rigidity and durability. It is a challenge to over-come this and re-favor alternative materials and sciences in the hunt for a more sustaina-ble construction. As cities are growing, the need for a circular, sustainable model in the construction industry could not be rushed more.

Grown structures Recent practices with mass timber have pushed forward a runner-up alternative to other §heavy-duty structures such as steel and concrete.

Timber has long been one of the only grown structures, recently accompanied by an organic brick3 that is grown rather than fired. New sustainable options are more easily accepted when technology doesn’t undermine traditions, but instead makes use of local skillset.

This is arguably why multi-story mass-timber constructions are being erected in the northern regions (Kleppe, 2018).

Performance range Architecture is by default something we imagine as rigid. Therefore, ‘flexibility’ tends to be associated with space organization and configurations. Often resulting in something as moderate as a dynamic coworking space, with moveable furniture units on floor-tracks. This is not the flexibility Wood+ seeks. This work is interested infrastructural components, moreover footbridges in rural environments performing as one flexible timber-body.

1 Ibañez,D. Wood Urbanism 2 M.M.S, Watchmaking: A Machinist’s View 3 BioMason. About Us

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Hypothesis

Can research on wood and soft inlay present a new material system and viable flexible structure?

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2 THE NORWEGIAN CONTEXT BUILDING CULTURE, CLIMATE & FORCES

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2 THE NORWEGIAN CONTEXT 2.1 Climate, landscape & trekking Remote situated structures, such as ยงfootbridges, tends to be product of local vernacular practice. In Scandinavia, these have historically served as important utilitarian devices for access and traverse in rural areas - but does also make appearances in the city due to varied and challenging geography1. Usually the bridge, is a structural exercise, closely in-line with challenges related to typography, service-, snow and ice loads (find ยงexternal forces in glossary).

In Norway, most outback tracks are marked and maintained throughout the year. Bridges and smaller structural components are commonlyfound in the highlands. However, smaller footbridges bridges are disassembled before the winter season, while larger ones tend to be constructed with strong metal fixtures and raised to a level where the flood and ice does not collide with the bridge.

A typical footbridge is raised above water and runs perpendicular to the river stream. Current design practice estimates a safety distance to the water at peak level and builds the bridge accordingly2. This static design approach has a low tolerance for weather conditions pushing beyond normals. As weather conditions becomes more and more irregular, this is an issue that will only continue to increase. In 2018, it was reported (N.N.P.P., (2018)) over a thousand cases where bridges had been damage to some or total extent due to flood. The work is interested in pipeline customization (ยงMass customized timber structures) of elements responding to such extreme forces, and overall, linking this to fabrication of a full-scale timber footbridge3.

There is a particular risk of damage during spring, as the frozen river melts. Ice-blocks and flakes can break off and travel downstream. It is hard to predict the exact water flow during a flood as it can take many paths depending on how the water masses coincidence with the riverbed and other obstacles.

1 DNT, Seasons 2 Aalto et al., Forum Wood 3 Mork et al., Forum Wood

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>> FIG.1. GENERAL STREAM

>> FIG.2. ICE -DAMAGE ON BRIDGE

>> FIG.3. RAISED APPROACH

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>> FIG.4. WATER FLOW PRESSURE

A normal river is likely to reach speeds up to 6 m/s1 during peak season. At this speed water can apply the force of 0.1 MPa per sqm. The figures to the right illustrate the force of water acting on a submerged surface in water. The petal has an area of 0.5 sqm. If you were to place 8 of these along the rivers width - the effect of these submerged surfaces would be as follows; 8 x 0.5 sqm = 4sqm * 0.93 tons = 3.72 tons This means that the force of water travelling downstream during peak season has the potential to move 3.72 tons (that is the weight of two SUV’s). Another way to look at it is to say that a bridge that weighs less than 3.72 tons after service loads apply, can move.

Bridge weight + live load + tolerance < 3.72 tons

1 Yin et al.,Analysis of Water Flow Pressure

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>> FIG.5. W. F. SEQUENCE

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Bridges in rural Norway are suspects to extreme weather conditions.

Any footbridge that does not consider this is likely to be torn apart on the very first encounter with a large waterbody or block of ice.

Supports are therefore to be drilled to bedrock in the least affected areas. Still, the forces of ice pushed by water are so strong that even a steel pole will eventually bend and make way for the ice.

When the ice collides with the bridge, it is likely that the primary structure will deform, and the secondary structure (such as the detailingเบก, timber deck etc.) will be forced out of position or crack. When water freezes, it can also expand and explode the bedrock around the foundations causing the whole structure to move around until it collapses.

Ice and snowmelt do therefore present a considerable treat to most bridges in rural settings in Nordic climate. The effect of these abrasive seasonal forces can typically be seen very easily on the structural members of the bridge. To the right you can see a series of pictures of the selected site for the case study later in the thesis. The steel supports have been bent quite dramatically and the walking-deck is kinked on the middle, hence suffering from decay as it collects a puddle of water every time it rains. >> On the next few pages you will see the site changing across a year, as water levels and climate goes from one extreme to the other.

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>> FIG.6. UNDERSIDE

>> FIG. 7. ENTRY

>> FIG.8. STREAM

>> FIG.9.METAL FIXTURE

>> FIG.10. BENT STEEL

>> FIG.11. OBSTACLE

>> FIG.12. FLOOR BOARDS

>>FIG.13 DECAY

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>> FIG.14. TOP VIEW

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>> FIG.15. DOWNSTREAM

>> FIG.16. TOP

>> FIG.17. DECK DETAILING

>> FIG.18. NEW VS. OLD

>> FIG.19. FOUNDATIONS

>> FIG.20. OVERVIEW

>> FIG.21. UNDERSIDE

>>FIG.22. METAL FIXTURE

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>> FIG.23. SPRING

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>> FIG.24. DOWNSTREAM

>> FIG.25.WATERFLOW 1

>> FIG.26. WATERFLOW 2

>> FIG.27. WATERFLOW 3

>> FIG.28. WATERFLOW 4

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>> FIG.29. SUMMER

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>> FIG.30. DRY RIVERBED

>> FIG.31. ROCK TEXTURES

>> FIG.32. CROSSING

>> FIG.33. DOWNSTREAM

>> FIG.34. STILL WATER

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>> FIG.35. AUTUMN

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>> FIG.36. DOWNSTREAM 1

>> FIG.37. DOWNSTREAM 2

>> FIG.38. CLOSE UP

>> FIG.39. DECLINE

>> FIG.40. WATER FALL

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>> FIG.41. WINTER

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>> FIG.42. FROZEN WATER

>> FIG.43. DOWNSTREAM

>> FIG.44. CABIN

>> FIG.45. CONTEXT

>> FIG.46. CROSSING

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2.2 Norwegian building culture Practice with wood in Norway is common and shapes the surrounding, built environment, largely because it is a very accessible resource and well-known building material 1. The use of wood in domestic architecture, have undergone many iterations and adaptions since the rise of the stave church over one thousand years ago2. However, it seems that wood is still primarily used as a single component system. Sometimes in the format of CLT or glulam, but mostly as a dimensional block performing as a rigid element in construction.

In the last decade Norwegian Public Roads Administration have completed and constructed 300 bridges in timber (CLT & glulam) for infrastructural projects3. Other project of large scale includes the glulam structures (ยงheavy-duty structures) made for the Olympic arenas in 1994, such as Vikingskipet skating oval4. In total, this gives an impression of a great interest and trust in wood as building material. The different projects looks at how to replace steel bridges with, hybrid alternatives such as wood and steel or full-wood bridges only held in place by metal fixtures. It is a great effort that ultimately produces content on how to maintain, service and construct large scale civic infrastructure from local timber and glulam technologies. All of these contributions do however only deal with a rather low-range of flexibility (ยงLow-range flexibility).

Wood is of course a natural, living material, that responds to its environment. Does the living get exhausted? Anything living or moving has a lifetime and what we already know is that pre-detailing and local-situated practice can improve this. Next however, is to think of how advanced construction techniques and manufacturing can further accelerate this design thinking. Have you ever seen two identical pieces of wood?

The unique properties of wood could and should forecast a future of structures that takes full advantage of the unique material properties of wood.

1 Almaas, I.H. 2 Dahlmann, LA. 3 Statens vegvesen 3 Aasheim E.

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â&#x20AC;&#x153;...But despite the unique history of the stave churches and not least Norwegian shipbuilding traditions, the assumed glories of Norwegian timber construction quickly fade when compared with achievements elsewhere.â&#x20AC;?

Almaas, I.H. (2010)

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>> FIG.47. CIVIC BRIDGE

>> Bridge collapses due to unstable and changing ground conditions.

>> FIG.48. FOOTBRIDGE

>> Bridge collapses due collision with ice.

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2.3 Smart materiality Wood is a living material. Have you ever seen two identical pieces of wood? Recent practices in furniture design (§Contemporary furniture design) have experimented with wood parts that are joined together silicone and rubber1. This brings back the question about flexible design in architecture, especially concerning larger loaded structures in timber.

Would it be possible to augment wood through the introduction of a silicone counterpart?

[1] How to make a flexible joint?

Soft-bodied organisms is a term used to group a range of animals that lack a skeleton.2 Their advantage is that they can function without it, while they have developed muscles that can both pull and push. Can such mechanisms be applied to joineries – well enough to withstand or avoid contact with the ephemeral forces of a rural river stream? What is the gripping interface between the two materials?

>> FIG.49. PELIDESIGN CHAIR

1 Cowell, S.K. ‘Fancy a joint?

2 Wikipedia, Soft-Bodied Org.

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>> FIG.50. COMPOSITE JOINT

>> FIG.51. SILICONE JOINERY

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3 TWO-COMPONENT MATERIAL SYSTEM DETAILING, PARAMETRIZING & CATALOUGING

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3 TWO-COMPONENT MATERIAL SYSTEM 3.1 Joint experiments The scalar properties of wood, stresses how a second soft-bodied entity (§Soft-body joints) should interface with it. Although wood is inherently flexible, there lacks an effort in pairing wood with its native characteristics as tree. As tree, it is arguably isotropic (§Isotropic vs. anisotropic) due to its multi directional fibre orientation1 it performs well in forceful environments. Can scale-related techniques bring forward new flexibility in wood and accelerate it as low-impact material in construction?

Prior to any digital assembly, the work carries out a series of analogue joint experiments. All assemblies are made by hand, with a selection of dimensional soft wood (2x4), cut with a dozuki handsaw. The reason for this approach is to develop an understanding for how linear cuts can make cavities for the silicone. Once this is known, similar strategies can be transferred and performed by a 3-axis CNC-machine.

In the beginning the cuts are simple and made in a way that the silicone can only really be held in place by how it adheres to the wood surface.

The next step from there is to address cavities or hook-turns, that could anchor the silicone within the wood and prevent it from being pulled out when being tensioned.

Overall the assemblies you’re about to see varies in size and volume, some are using silicone as method to wrap around the two pieces of wood, others are connected by a tunnel anchoring system. Just by looking at how each of these responded to pressure, the different mechanical properties start to appear. A thin strip of wood, parallel to the grain, has great flexibility. The silicone on the other hand, is easily torn apart by large tensile forces, but can be compressed in all directions hence making it an isotropic material.

1 Green D. W. et al. Mechanical Properties of Wood

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>> FIG.1. FREE HAND

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>> FIG.2. FREE HAND

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>> FIG.3. FREE HAND

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>> FIG.4. FREE HAND

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>> FIG.5. FREE HAND

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>> FIG.6. FREE HAND

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>> FIG.7. FREE HAND

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3.2 Detailing Prior to the research it is necessary to classify the different components: A – the hard/flexible component (wood) B – the soft/elastic component (ex. silicone) The accompanied drawings on the next page represents early digital joints in grasshopper + python, before the joint parameters was standardized. They are considered free-form joints, like the once seen on the previous pages (done manually). In order to fully develop a catalogue of precise joints, it is important that every potential variable is identified as a parameter. In the parameters listed below, only three are varying in this first research, the rest are fixed. The fixed one are piece length, piece width and piece depth (all stock related).

This gives a 3 to 4-dimensional design space. Which is already plenty in the starting phase of this development.

Joint parameters: Piece length – length of stock Piece width – width of stock Piece depth – depth of stock Split parameter – location of joint Bridge gap – distance to span Bridge width – thickness Bridge position – location of bridge (ex. 0.5/1.0 – centered) Micro geometry – interface between materials

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>> FIG.8. INITIAL DIGITAL EXP.

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The purpose of the flexible joint, is to deform in one plane - as a linear element. To be able to measure this performance, a 2x4 piece is held at one side while being loaded at the tip of the material on the other side.

The bridge width and bridge gap are ultimately what determines the flexibility range for each joint, meaning that the thin strip of wood left after subtractive manufacturing is working in tension, and allowing the wood to bend.

All joints are made through three-dimensional pocketing operations.

However, in advance of either cutting or sawing manually, it is important to note the limitations and considerations related to component A, the wood. Node locations should keep a minimum distance from the joint location, as work as rigid objects forcing the wood to crack rather than bend. It also makes more sense to pocket out cavities for the silicone perpendicular to the grain, to allow the fibres to be continuous as much as possible.

This figure below illustrates the structural stresses at work when applying load to the joint.

>> FIG.9. LINEAR JOINT

TENSION STRESSLINES

COMPRESSION STRESSLINES

LOAD

SUPPORT

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Node locations Affected stress lines

>> FIG.10. STRESS LINES

FIBER CONTINOUITY

Pocketing Broken stress lines

>> FIG.11. POCKETING

>> FIG.12. BENDING

49

Node locations Affected stress lines

WOOD+

Wood is strong along its fibre orientation1, see figure 2. on the right .

While silicone can endure a lot of compression. Below are a chart of the different materials tested during the research period. The list includes pine wood and a variety of silcone and/or rubber products2.

Understanding the properties of the different isotropic inlays are critical for further development before entering the fabrication stage.

MICRO

>> FIG.13. MATERIAL OVERVIEW

MATERIAL SPECS Soft elastic materials [B] compared with properties of wood (A) *When Silicone is mixed with an organic material such as starch or coffee (1:1 ratio), it turns biodegradeable.

A B

Type Pine

Category Wood

Material Form as �mber

Tensile Strength (MPa) 40

Compressive Strength (Mpa) 56

Moisture Absopr�on High

Cure Tim None

Elastoil M 4514 PMC 780 WET Dragonskin 30 VytaFlex 40

Silicone Rubber Urethane Rubber Silicone Urethane Rubber

as volume as volume as volume as volume

4.5 6.2 3.4 3.6

0.05 1.20 0.06 0.29

Low High Low Low

10 48 16 16

1 Swedish Wood. Properties of Soft Wood 2 Smooth-On. Products

50

, thus ble).

FLEXIBLE WOOD ASSEMBLIES

>> FIG.14. TENSILE STRESSES

TENSILE STRESSES Wood is strong along its fibre orientation, thus working excellent in tension (hard-flexible).

>> FIG.15. COMPRESSIVE STRESSES

COMPRESSIVE STRESSES A soft material like silicone, is capable of retracting when loads apply (soft-elastic).

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>> FIG.16. CNC-INSTANCE

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3.2 Loading test At this stage joints are linked with their structural performance.

This allows the designer to receive numeric feedback and to pair this with the corresponding parameter-input, along with other information such as machinic time and silicone cast volume. All joints were loaded with 1kg of sand on a mounted fixture at the very front of the piece. Below are some general notes, learning from the feedback given from the structural testing: – Feedback of numeric data (mm precision) to joint parameters.

Once all instances are linked with corresponding performance, one can begin to construct an overall composition working with the range of flexible performances available.

– Furthering the natural behaviour of timber through inlays like silicone (B) (a soft material counteracting upon wood) is improving its ability to withstand applied forces in high-impact environments.

– The use of flexible, potentially isotropic materials, as counterpart is key to negotiate the behaviour of timber when suffering from external forces. This two-way relationship can be seen as a more formal (formal as in form) exploratory research working with not one set of behaviours, but two, in order source new geometries of timber. >> FIG.4. LINEAR DEFORMATION

DEFORMATION DATA EXTRACTION ELEVATION - FRONT VIEW range 0.2 to 3.8 mm

.

1

21

54

22

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>> FIG.17. DEFORMATION 0

>> FIG.18. DEFORMATION 1

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3.3 Alternative Joints A series of â&#x20AC;&#x2DC;otherâ&#x20AC;&#x2122; joints (alternative joints) were also explored along the course of this thesis. These didnâ&#x20AC;&#x2122;t make it to the final assembly, but they are interesting developments nevertheless. The first one is a joint connecting two pieces of wood with a sandwich of veneer strips placed into a thin slot - then glued. It was challenging to get the veneer glued to the wood properly as well as to itself. This joint also explores predrilled holes that enables the silicone to enter deep into the interior of the wood as method to create better anchoring conditions. When testing this joint the veneer would sometimes pull out, before reaching the breaking point. It would be worth investing more time into the lamination of the veneer sandwich and make sure that the glue is applied and remains on the entire surface of the wood (on both sides) when inserting it into the slot.

The second alternative joint is a three-piece node that is connected by 2mm metal plates (could be replaced by a strip of veneer). This was to articulate directional changes within a system of joints. For further editions, it would be key to understand how a joint like this might work better, to allow for a multi-directional compressive, performative structure. For now, however the project relies on linear axis joints to perform an overall three-dimensional deformation.

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>> FIG.19. ALT. JOINT TYPES

T

h o to as

y

ed oft

on

>> FIG.20. VENEER JOINT 11/18

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3.3 Research overview

This is a map that shows the relation between resource to building-element and bld. element to system. It l behaviour of timber looks at how to further the licone, in order to improve of timber natural behaviour d applied forces in high-imthrough inlays like silicone (flexible-joint) and then how to arrange them together as a system; here as a grid.

DEFLECTION NATURAL VS AUGMENTED BLOCK

SRF FROM GOAL GEOMETRY â&#x20AC;&#x2DC;EX. WETLAND BRIDGEâ&#x20AC;&#x2122;

Further, it needs to become a system that can go from MPLE a passive state to an active e composed of many flexistate. It thereby becomes a e to go from a passive state deployable made a response triggeredstructure, by of or flexible parts. This perforas weather live loads. mance is to be tiggered by external water forces.

pable of resisting 50 kgs of

eces together ehaviour with param.

ometry, rationalizing geof parts, and obtainable

SURFACE MATCHING BASED ON X NUMBER OF PIECES

e for live loads > 300 kgs of system cation workflow ure within desired time-

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>> FIG.21. RESEARCH MAP

NATURAL TIMBER BLOCK

AUGMENTED BLOCK (SINGLE/SUBTRACTIVE)

TWO OR MORE PIECE-JOINERIES

ASSEMBLED SURFACE NETWORK

Y

X

15/ 18

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>> FIG.22. JOINT RANGE

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New Ver 62

Goal is to develop a subset of join

FLEXIBLE WOOD ASSEMBLIES

>> FIG.23. END OF FIRST RESEARCH TERM

rnacular

p a structure from nts with varying

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4 THE CASE PROJECT FOOTBRIDGE, DEPLOYABLE SYSTEM & KIT PARTS

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4 THE CASE PROJECT 4.1 Site limitations &forces Understanding the rural ephemeral conditions on site is key to develop a responsive vernacular structure (§new vernacular). Any structure of such kind needs to consider seasonal change, water levels, water speed and size of ice blocks. It needs to determine the architectural use; what is the service loading (live loads), self-weight, surface area, no. of elements - and foremost what is the target deformation that it needs to reach? For the detailing side, this is covered in the previous research part at the element scale (stock size, joint gap, joint positioning, joint width etc.)

At this stage of the e aim is to assemble the research of the flexible joint into a design package that ultimately describes a flexible footbridge (§flexible wood assemblies). To the right is a principle diagram explaining how the form might be articulated. It highlights key functions and aspects for the construction of the bridge typology, such as: Forces + water stream

The speed + riverbed section of local river Moving + non-moving part

One end of bridge needs to be fixed, while the other will have to slide on a rail in order to allow for the necessary elongation during the deformation.

Deformation

Allowing blocks of ice to travel underneath (300mm+ offset).

Materialization + functions (petal zones)

The overall bridge body is made of timber, while there are zones for force absorption named ‘petals’. As these will be submerged in the water they would be of a lightweight composite structure, like carbon fibre.

Cross-section depth

The bridge gets thinner towards the middle, where the maximum deformation is. The bridge is spanning between two points and gets more rigid closer to the ends.

66

FLEXIBLE WOOD ASSEMBLIES

>> FIG.1. PRINCIPLE DIAGRAM

SLIDING END

FIXED END

FREE SPAN APPROX. 4500MM

STRUCTURAL WEAKNESS POINT MAX BENDING

+ OFFSET BOTTOM LINE OF STRUCTURE BLOCK OF ICE PASSING THROUGH

PETAL AREA

PETAL AREA

FLOOD DATUM + 1400 MM

RIVERBED MID-POINT (WATER SPEED) MIN

MAX

MIN

Bridge piers, existing

Bridge and sliding rails is to be supported with pillars down to bedrock, possibly attached to existing infrastructure.

4.2 Form typologies These keys points where then considered when generating the surface model for the bridge. This was done with an evolutionary solver, that was able to address pre-determined conditions about overall surface area, petal size and ice-passage allowance. The final design is not a direct product of the most suitable solution, but rather and interpretation of the findings. The next page shows a field of solved geometries.

Coloured instances are the best fit within their cluster.

67

WOOD+

68

FLEXIBLE WOOD ASSEMBLIES

>> FIG.2. BRIDGE TYPOLOGY STUDY

69

WOOD+

4.3 Implementing auxetic system In order to reach the necessary target deformation, the footbridge implements a mechanical system that allows the flexible elements to work together as one body rather than a series of individual joints. This system is known to be able to facilitate three dimensional displacement, through the use of auxetic principles, developed at MIT (Kinetix, 2018). This system was also used in a furniture project (A.U.X.E Chair, ).

4.4.1 Rectangular cell unit Each cell is assembled by four linear axis joints and can be compressed, causing its neighbouring cell to deform as well. This enables fast production and assembly of a global geometry. Each joint is moment-fixed to the next at both ends, forming a strong connection (ยงrigid body) that ensures stiffness and force transfer between the cells.

4.4.2 Horizontal to vertical force translation Although the joint in this system are linear, meaning they can only deform in one plane. This can be manipulated by rotating the element along its central, longitudinal axis. If a joint is rotated 45 degrees, now the bending will happen in that plane. The bridge is therefore laid out in such a way that horizontal modules collects horizontal force at the sides, while the modules towards the centre of the bridge are gradually being rotated to be able to deform vertically and make way for the ice. This way the structure becomes a kinetic structure much like those seen in nature that can adapt itself to and conform to its environment or to deviate from it1. Although the system of parts is made entirely from timber and silicone, it can still exhibit mechancial characteristics.

1 Schleicher, S. Bio-inspired Compliant Mechanisms

70

FLEXIBLE WOOD ASSEMBLIES

15°

>> FIG.3. AUXETIC LAYOUT

0°

S1

0°

>> FIG.4. LINEAR VS .CELL

UNDER WATER

UNDER WATER

71

WOOD+

AXIAL DISPLACEMENT ISOMETRIC SKELETON

0°

15°

VE STATE

30°

25°

15°

0°

S1

0°

72

1:50

FLEXIBLE WOOD ASSEMBLIES

>> FIG.5. AUXETIC STRUCTURE

T

0

+2600

+2550 +2500 +2450 +2400 +2350 +2300

F3

+2250 +2200 +2150

73

+2600

WOOD+

4.5.2 P etal design In order for the horizontal module to deform, it needs to pick up the forces from the water pressure. It is therefore necessary to introduce a secondary piece of equipment that can extend into the water and absorb these forces. A petal, much like an oar blade is therefore mounted on the side of the bridge (upstream), with a rotational pivot-point at the center of the joint. This is then repeated on the next module on the opposite side. Now you have two petals in the water that stresses the linear axis joints to deform horizontally. These two petals need to be braced 4-ways to keep the module from rotating (avoiding shear forces).

More petals can be installed along the long sides of the bridge. However, it is important to note that the force of water might be so strong that it could be necessary to develop an adjustable sliding mechanism for the petal itself, so that it does not sit too deep in the water during a flood.

>> FIG.6. COMPRESSION

PULLED

UNDER WATER

CABLE

74

FLEXIBLE WOOD ASSEMBLIES

>> FIG.7. 4-WAY BRACED

>> FIG.8. PETALS.

75

WOOD+

4.5 Architectural detailing 4.5.1 Kit of parts

76

FLEXIBLE WOOD ASSEMBLIES

>> FIG.9. KIT OF PARTS

77

WOOD+

4.5.2 Orthographic model views These next drawings showcases the bridge through different stages, anticipating the movement throughout the seasons. On the right the bridge is drawn into its environment at its ultimate state during spring, displacing itself above blocks of ice with a 350mm clearance.

The vector field is showing the turbulent nature of the water, primarily going down stream. but sometimes taking new directions when colliding with obstacles in the river.

78

+2550

FLEXIBLE WOOD ASSEMBLIES

+2500 +2450

>> FIG.10. ULTIMATE STATE +2400

+2350 +2300

F3

+2250 +2200 +2150 +2100 +2050 +2000

+1950

P2

+1800

+1700 +1650 +1600 +1550 +1500 450 +1900

+1750

+1850

+350 +1750

+1750

+2300

+2250 +2200 +2100 +2150

+200

L2

+1900

+2100

+2050

L3

F1

+1800

+1800

1

+1900

+1850

+1850

+1800

P3

+1750

79

F2

1.5 m/s

WOOD+

>> FIG.11. AERIAL OVERVIEW S.1 - RAMP

PROJECT

RAMP

2500 MM

WOOD + Ã&#x2026;SERAL, VEST AGDER, NORWAY

ISSUE

footbridge plan

LEGEND

COMMENT. 1 2 3 4 S.2 - PETALS

5

DRAWN

11/6/2019

BLOCK OF ICE - PASSING

S.3 - MID SECTION

10800 MM

FREE SPAN

APERTURE 80% : FL. LEVEL 1350

BLOCK OF ICE - PASSING

350 MM

SLIDING RAIL

4500 MM

DIST. TRAVELLED

80

REV.

FLEXIBLE WOOD ASSEMBLIES

>> FIG.12. FOOTBRIDGE SYSTEM PROJECT

WOOD + ÅSERAL, VEST AGDER, NORWAY

CONTRACTION DIAGRAM STRUCTURE

CROSS SECTION

ISSUE

1:50

isometric overview

S1 - STRUCTURAL FLOOR COMPOSED OF 2 DECKS X 68 JOINTS S2 - SLIDING END, ALLOWS FOR GLOBAL SHAPE TO CONTRACT WHEN LIFTED S3 - RAMP, ENTRY FROM ROAD SIDE PETALS

LEGEND

P1 - LEFT PETAL, UPSTREAM P2 - RIGHT PETAL, UPSTREAM P3 - PULL OUT, LEFT PETAL, UPSTREAM

PULLED

COMMENT.

REV.

1

LANDSCAPE

2

L1 - RIVERBED L2 - RIVER ISLAND L3 - ICE BLOCK

3 4 5

FORCES DRAWN

F1 - RIVERSTREAM DIRECTION F1 - WATER SPEED F3 - LIVE LOAD, PEDESTRIAN + SELFWEIGHT

11/6/2019 UNDER WATER

x

data

CABLE

JAN

DEC

1200 mm

AXIAL DISPLACEMENT

805 mm

ISOMETRIC SKELETON

1:50 SITUATION PLAN

0°

JAN

15° FEB

ACTIVE STATE

MAR

30°

APR

25°

MAY

15°

JUN

0°

S1

0°

JUL

S3 AUG +2600

+2550

SEP

+2500 +2450 +2400

OCT

+2350 +2600

+2300

NOV

F3

+2250 +2200

DEC

+2150 +2100 +250 +300 +350 +400 +450

+2050 +2000

+1950

+500

+550

P2

+600 +650 +700

+1800

+750 +800 +850 +900 +950

+400 +350 +300 +250 +200 +150 +100 +50

+1000 +1050

+1100

+1700 +1650 +1600 +1550 +1500 +1450 +1400 +1900 +1350 +1300 +1250 +1200 +1150

+1750

+1850

+350 +1750

+1750

+2300

+450

+2250 +2200 +2100

+2000

+2150

+200

+1950

L2

+1900

+2100

+1850

+2050

L3

+2450 +2400

+2350

+2250 +2300

+2200

+2150

+2050 +2100

+2000

+1950

+1850

+1800

F1

+1800

+1750 +1800

P1 +2450

+1900

S2

+1850

+1850

L1 +1800

P3

+1750

F2

1.5 m/s

81

1:5000

WOOD+

>> FIG.13. CROSS SECTIONS PROJECT

WOOD + ÅSERAL, VEST AGDER, NORWAY

SECTIONS

ISSUE

short sections

1:20

S.1 - RAMP

LEGEND

COMMENT. 1 2

1450

3 4

BALLUSTRADE HEAD

5

DRAWN

11/6/2019

1100

1400

HANDRAIL 65X45 MM

TIMBER DECKING 120X19

STATIC JOINT

SLIDING RAIL

SUPPORTS ALUMINIUM PROFILE Ø 45 MM

S.2 - PETALS

1450 BALLUSTRADE HEAD

1200

1400

HANDRAIL 65X45 MM

TIMBER DECKING 90X5

FLEXIBLE JOINT, AXIS 0°

DIMENSIONAL TIMBER 150X90 SILICONE (CASTED) 150X20MM

300

FLEXIBLE JOINT, AXIS 0°

PETAL BLADE 50X1000

WATER FLOW 30-40 M3/SEC DURING SEASON PEAK

300

4-SIDED BRACED FRAME CABLES Ø>5MM

S.3 - MID SECTION

900 BALLUSTRADE HEAD

1200

1400

HANDRAIL 65X45 MM

TIMBER DECKING 90X5 FLEXIBLE JOINT, AXIS 45° DIMENSIONAL TIMBER 150X90 SILICONE (CASTED) 150X20MM

750

FLEXIBLE JOINT, AXIS 45°

WATER FLOW 30-40 M3/SEC DURING SEASON PEAK

82

REV.

FLEXIBLE WOOD ASSEMBLIES

>> FIG.14. SEASONS + SHAPE CHANGE PROJECT

WOOD + ÅSERAL, VEST AGDER, NORWAY

ISSUE

stream flow rate WATER LEVELS LEGEND

COMMENT. 1 2

SPRING FLOOD

3 4 5

DRAWN

11/6/2019

1400 mm

AUTUMN FLOOD

10 YEAR FLOOD

AVERAGE YEAR

805 mm 50 YEAR FLOOD

JAN

FEB

MAR

APR

MAY

JUN

JUL

BRIDGE CURVATURE SCALE

1:200

YEARS 25

20

15

10

5

0

83

AUG

SEP

OCT

NOV

DEC

REV.

4.3 Rendered Views

WOOD+

84

FLEXIBLE WOOD ASSEMBLIES

>> FIG.15. AERIAL VIEW

85

WOOD+

86

FLEXIBLE WOOD ASSEMBLIES

>> FIG.16. PERSPECTIVE

87

WOOD+

88

FLEXIBLE WOOD ASSEMBLIES

>> FIG.17. UNDERSIDE

89

WOOD+

5 BUILD SPACE PROGRAM FABRICATION, SIMULATION & RESULTS

90

FLEXIBLE WOOD ASSEMBLIES

91

WOOD+

5.1 Build space report Intro to report Wood+ was part of the residence program at Autodesk in Boston this summer in order to accelerate the development of the project in a state-of-the-art facilities. The aim of this stay was to continue the development of the flexible joint and to make a 1:1 prototype of the structural cell unit that forms the primary framework for the footbridge. Since the beginning of June, I have made several changes to the linear-axis joint and found a way to simulate its response behaviour during applied pressure.

Goals To continue to explore joint design & to make a 1:1 rectangular unit cell.

Progress: Timeline of tasks and completed work

July 11th to July 20th - Introduction to studio spaces & general safety training - Woodshop: Introduction: Sanders, Bandsaw, Chop-Saw - Woodshop: Intermediate: Jointer & Planers - Woodshop: Advanced: Shopbot Training - Laser cutting: Training - 3D printing: Training - Fusion 360: Milling strategies - Fusion 360: Simulation - Fusion 360: Representation - Robotics: Safety Protocol & Introduction

July 20th to August 5th - Rhino + Gh: Articulating Joineries: Extending Length of Wood Strip - Rhino + Gh: Articulating Joineries: Working w/ Silicone Volume - Rhino + Gh: Articulating Joineries: Rounding & Smoothing Cavity Envelope - Rhino + Gh: Exploring Micro Geometry & Anchoring - Fusion 360: Creating Machining Program: 3D: Adaptive Pocketing: “Inside_Cavity-01.shp” - Fusion 360: Creating Machining Program: 3D: Adaptive Pocketing: “Outside_Cavity-01.shp” - Shopbot: Creating Improvisational Rig w/ Scrap Material (Pine Wood) - Woodshop: Stock: Pine Wood: Moisture Avg. Level: 9 % - Shopbot: Running “Inside_Cavity-01.shp”: 24 min (w/ ¼’’ flat end mill) - Shopbot: Running “Outside_Cavity-01.shp”: 16 min (w/ ¼’’ flat end mill) - Fusion 360: Changing Machining Programs from Adaptive to Pocketing - Fusion 360: Changing Feeds & Speeds in Machine Program - Shopbot: Running “Inside_Cavity-03.shp”: 18 min (w/ ¼’’ flat end mill) - Shopbot: Running “Outside_Cavity-03.shp”: 10 min (w/ ¼’’ flat end mill)- Laser cutting: Assisting Pos. Rig

92

FLEXIBLE WOOD ASSEMBLIES

July 5th to August 13th - Rhino + Gh: Measuring Silicone Quantity - Ordering Silicone: Smooth-On: Dragon Skin 30: 1 Gallon - Composite Lab: General Training - Rhino + Gh: Joinery Revision: Shorter Stock: 2 ft - Rhino + Gh: Custom Workholders - Laser cutting: Custom Workholders: Test (with ¼’ soft-wood) - Shopbot: Custom Workholders: 10 Nested Items - Fusion 360: Simulating Joint Instance - Shopbot: Installing Custom Workholders- Shopbot: Re-running “Outside_Cavity-03.shp” - Rhino + Gh: Articulating Joineries: Tolerance changes - Fusion 360: Creating Machine Program: St. Offsets + H. Roughing: “Inside_Cavity-04.shp” - Fusion 360: Creating Machine Program: St. Offsets + H. Roughing: “Outside_Cavity-04.shp” - Shopbot: Running “Inside_Cavity-04.shp”: - Shopbot: Running “Outside_Cavity-04.shp” - Fusion 360: Changing Feeds & Speeds in Machine Program

July 14th to August 21th - Ordering Wood: Sterritt Lumber: Douglas Fir (2x4x8 KD Premium) - Woodshop: Stock: Douglas Fir: Moisture Avg. Level: 5 % - Stock Handling: Plainer + Jointer: Flattening & Parallel Finishing - Shopbot: Re-running “Inside_Cavity-04.shp”: - Shopbot: Re-running “Outside_Cavity-04.shp” - Rhino + Gh: Articulating Joineries: Dovetail Connection: Triangular - Rhino + Gh: Articulating Joineries: Dovetail Connection: Widths + Lengths - Fusion 360: Representational Documents - Fusion 360: Creating Machining Program: 3D: Pocketing: “Female_Dovetail-01.shp” - Fusion 360: Creating Machining Program: 3D: Pocketing: “Male-Dovetail-01.shp” - Shopbot: Running “Female_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Shopbot: Running “Male_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Shopbot: Repositioning Piece + Re-Installing C. Workholders - Shopbot: Running “Female_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Shopbot: Running “Male_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Fusion 360: Removing Stock to Leave Feature + Drill Corner Holes Last - Shopbot: Re-Running “Female_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Shopbot: Re-Running “Male_Dovetail-01.shp”: 5 min (w/ ¼’’ flat end mill) - Shopbot: Running Program Sequence: “Inside_Cavity-04.shp”, “Outside_Cavity-04.shp”, “Female_Dovetail-01.shp”, “Male_Dovetail-01.shp”.

- Post-Finishing: Joints: Sanding Edges + Cleaning - Post-Finishing: Preparing for Casting: Sealing Edges w. Blue Tac - Post-Finishing: Creating Casting Rig - Composite Lab: Casting Into Cavity: Cure Time: 16 hrs - Composite Lab: Revealing Cast & Removing Rig - Composite Lab: Trimming Edges w. Knife - Composite Lab: Cleaning Faces - Studio Space: Assembling Module - Studio Space: Documentation

93

WOOD+

Summary During the time I was there - a 1:1 module was created - forming a structural layer for a typical bridge segment. The whole experience was incredibly engaging and forced the project to be re-thought and drawn in different software and simulation engines, but as a result - it only strengthening it.

The final module is considered as an exhibition-piece and proof of concept model. Therefore, its end-dovetail detailing is suspect to change prior to any structural performance tests. The training at Autodesk was very resourceful, and provided an in-depth run-through of the labs, exploring all inventory and tools needed in order to make the most of the residency.

Future objectives The next steps for Wood+ would be to create the full bridge segment, meaning two-unit cells + detailing (handrailing, deck, structural floor frames, balustrades). This would enquire a similar workflow, but with additional tolerance tests and stock handling prior to running the final milling files. It would also be necessary to do a total stress-analysis of the module under pressure once assembled. This would indicate which areas of the module that needs further design development.

Problems encountered During the residency I experienced quite a few tolerance issues. I found that this was often related to the stock either moving while milling or varying stock sizes. In the end this was handled by processing the wood through the jointer and planer prior to the milling, as well as creating custom workholders to keep the piece in-place while milling.

94

FLEXIBLE WOOD ASSEMBLIES

>> FIG.1. WORK PROGRESS

95

WOOD+

96

FLEXIBLE WOOD ASSEMBLIES

>> FIG.2. JOINT CLOSE-UP

97

WOOD+

98

FLEXIBLE WOOD ASSEMBLIES

>> FIG.3. JOINT ITERATIONS

99

WOOD+

100

FLEXIBLE WOOD ASSEMBLIES

>> FIG.4. CASTED MODULE

101

WOOD+

5.2 Join fabrication & assembly On fabrication Wood+ was part of the residence program at Autodesk in Boston this summer in order to accelerate the development of the project in a state-of-the-art facilities. The aim of this stay was to continue the development of the flexible joint and to make a 1:1 prototype of the structural cell unit that forms the primary framework for the footbridge. Since the beginning of June, I have made several changes to the linear-axis joint and found a way to simulate its response behaviour during applied pressure.

5.2.1 Joint design

5.2.1.1 Evolved detailing (>> to the right)

5.2.1.2 Static stress simulation Using Fusion 360s simulation engine to analyse total stress in the composite joint under linear static loading. The details around the corners are tearing on the silicone-cast when bending.

102

FLEXIBLE WOOD ASSEMBLIES

>> FIG.5. WITHOUT SILICONE

>> FIG.6. WITH SILICONE

103

WOOD+

The joint design at Autodesk BUILD Space in Boston aimed to detail a longer, strip of wood. This introduces a larger cavity within the joint, hence why a series of new anchors are carved from the interior. This creates better gripping of the silicone and rotational-stiffness. The geometry is rounded and gradually transitioning in thickness to prevent cracks when bending.

The joint design at Autodesk BUILD Space in Boston aimed to detail a longer, strip of wood. This introduces a larger cavity within the joint, hence why a series of new anchors are carved from the interior. This creates better gripping of the silicone and rotational stiffness. The geometry is rounded and gradually transitioning in thickness to prevent cracks when bending.

5.2.2 Fabrication steps

5.2.2.1 Custom workholders During the residency, there was need to develop custom workholders that could hold the 2x4â&#x20AC;&#x2122;s still while milling. The piece is adjustable and rotates around a central fixture. It can also be locked when placing two screws into it. Since the diameter changes, it can press itself towards the wood that it is holding. This turned out to be very effective and quick. A 2x4 piece could be removed or placed securely within seconds.

5.2.2.2 Dovetail design

The end detailing for the joints were made as dovetail joints, with a triangular male- and female part. However, the alignment of the pieces on the CNC bed turned out to be slightly off, making it very hard to achieve a press-fit tolerance. This was later discovered and improved by adding the workholders and changing the positioning on the CNC bed. Another issue was that the milling software would by default leave a certain amount of stock (â&#x20AC;&#x2DC;stock to leaveâ&#x20AC;&#x2122;) This meant that edges were rounded instead of sharp edges. In the end the pieces came together with a tolerance of .125mm.

104

FLEXIBLE WOOD ASSEMBLIES

>> FIG.7. TEST PIECES

>> FIG.8. CLOSE-UP

105

WOOD+

>> FIG.9. CELL + SILICONE

5.2.3 Cell Assembly

>> FIG.1O. CELL UNIT

106

FLEXIBLE WOOD ASSEMBLIES

>> FIG.11. SEGMENT ASSEMBLY

107

WOOD+

6 CONCLUSION

108

FLEXIBLE WOOD ASSEMBLIES

6 CONCLUSION Wood+ articulates a footbridge using an auxetic system of composite joints capable of redirecting forces from horizontal to vertical directions.

It furthers the standard 2x4 profile into a linear axis bending element through 3D dimensional pocketing operations. The design takes advantage of wood’s inherent tensile strength along its grain, while introducing new compressive properties through the isotropic silicone inlay.

Four linear-pieces forms one structural rectangular cell-unit of the full assembled bridge. Each joint can reach a bend-angle of 20 degrees.

Advantages with flexible cell-structure • Avoids collision with ice • Allows for full actuation of timber structure in remote locations • No battery, heavy metal gear or communication dependence • Linear, long profiles for fast assembly • No need for removal during seasons • Replaceable pre-cast silicone parts • Lightweight structure Technology Auxetics, Flexible Composite Joint Problem Addressed It applies auxetic principles in a utilitarian structure in remote context. with full architectural detailing. It is a flexible low-tech design. Moreover, it presents a responsive footbridge that is able to yield to water forces that present a considerable damage in Nordic climate. It shows that a structure composed of natural soft-body elements can exhibit mechanical properties and serve as a remote self-regulating system. This enables the bridge to be an active utilitarian structure without any rigid metallic connectors or parts.

Performance The system is relying on the absorption of water pressure through submerged petals. The risk is that these petals can pick-up forces above what is needed, and consequently force the joints to crack. This is a tolerance issue which can be tackled through stoppers or further detailing of the petal itself. The overall performance is controlled by these var.: (1) Joint detailing (2) Rigid bodies, (3) Rotation planes, (4) Petals

109

WOOD+

7 A CONVERSATION ON WOODWORKING AND SOFTWARE WITH IVAN MARCHUK

110

FLEXIBLE WOOD ASSEMBLIES

111

WOOD+

7 A CONVERSATION Ivan: Hi Lars, can I ask you a couple of questions regarding your thesis experience?

Lars: Hi Ivan, sure! What do you want to know?

Ivan: I’m in the process of choosing my thesis topic right now. One of my options is on multi-objective optimization of timber structures. What is your experience working with wood, does the school facilitate the necessary tools for working with timber?

Lars: First of all, this sounds like a very interesting topic. Second, I think woodworking is something which is achievable and worthwhile tackling. One of the main considerations working with wood is to know how to get it down to straight cut, flat pieces - as lumber comes in all kinds of different lengths and thicknesses. At Autodesk I was using a jointer and planer to handle stocks of dimensional timber in order to be able to lay the pieces flat down on the CNC bed.

However, there are other ways to approach this too. One way is to run a machinic operation using the horizontal roughing program to remove the top layer (first 2mm) of the wood. This would require you to at least do it on one side of the stock, but ideally both. If you’re using sheets of wood on the other hand, like plywood, then this won’t be necessary. For milling strategies, you should look into Fusion 360. It allows you to quickly create jobs and store them on the cloud, while providing a very visual and user-friendly interface that runs smoothly.

Ivan: Is there regular access on the robots, for digital fabrication?

Lars: For the robots, you have to push to get access and prove that you’re using it for the appropriate reasons. Sometimes you may find that it will take you half the time to execute a certain task using a combination of laser cutting and 3D printing. I would recommend getting hands-on early to learn about the different challenges related to robotic fabrication. Then you can go back and develop a specific workflow for your project. If you start this way, staff will likely be able to guide you more easily and it will be a less bumpy road!

112

FLEXIBLE WOOD ASSEMBLIES

Ivan: Thanks. Finally, how applicable is timber in architecture nowadays? Are construction companies interested in applying new concepts and is there a demand for advanced timber strategies in construction?

Lars: If youâ&#x20AC;&#x2122;re dealing with something like glulam then it is very likely that your work will be understood and recognized by the industry, as this is a common format and known building technology. There are more and more offices willing to take upon challenges with wood as primary structural element â&#x20AC;&#x201C; particularly in the northern regions with rooted forestry traditions. The Vancouver based firm HiLo Lab (Zipper Wood, 2019) are looking at how to transform conventional framing lumber into parametrized, flexible scissor joinery for custom use in construction.

113

WOOD+

8 TEXT FRAGMENTS EXPLANATORY TEXT FRAGMENTS

114

FLEXIBLE WOOD ASSEMBLIES

115

WOOD+

7 TEXT FRAGMENTS §EXTERNAL FORCES Referring to extreme weather causing damage on structures in Nordic climate (flood, snow, ice). Also understood as an applied force decreasing structural health over time. When a bridge is suffering from heavy impact its elements either fall out of position, crack or deform.

Rural communities are prone to deal with these conditions on a seasonal basis – where land damages can extend into a chain of events tearing on existing infrastructure. Although periodic, it is difficult to predict exactly how natural forces will play out. §FOOTBRIDGE Remote situated structures, such as footbridges, tends to be product of local vernacular practice. In Scandinavia, these have historically served as important utilitarian devices for access and traverse in rural areas, but does also make appearances in the city due to varied and challenging geography. Their complexity is established by the significance of land at a certain extreme, often resulting in a static solution most ideal for only a specific point in time. §SOFT-BODY JOINTS A strategy to work with joint behavior in high-impact environments.

Like a knee-joint, it is defined by two or more surfaces buffered by a flexible membrane. Joint will have to prove its ability to absorb shock and low-rate damage within a defined domain. This work acknowledges similar approaches found in large bridge constructions. However, there is a novelty in scale – introducing different criteria explored in the making of hand cut joinery. In the beginning stages, silicone will be placeholder, primarily due to its robustness and approachability, combined with the shielding-effect it has on its neighbouring parts. §FLEXIBLE WOOD ASSEMBLIES Advancements in wood related sciences have led to the breeding of competitive structures used in multi-scale applications. While engineered wood is inevitably a product composed of many, it seems to be reinstated as a singular element in construction. For example, CLT is strengthened timber, enabling a whole new spectrum of positions it couldn’t otherwise obtain. As a building- block, however, it is not performing any different than a piece of lumber. What will happen when wood only defines one part of the block – can block logic become agent for new arrays of form in timber industry?

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§NEW VERNACULAR This research explores flexible timber structures that yield more fluidly when confronted with external environmental forces such as ice, water, snow etc. Can this performance be achieved through a soft-body joint and provide alternative solutions to current rural practices in Norway, particularly concerned with footbridges. The project features a flexible element combining wood and silicone. It does not hide the fact that it is a heterogeneous product of the two, it rather becomes a new form-language. §TIMBER AS HEAVY-DUTY STRUCTURE Advancements in wood related sciences like cross-laminated timber (CLT) technologies have led to competitive structures enabling benchmark projects such as the world’s highest standing timber framed building at 49 meters in Bergen, Norway. Key reflections from this project highlights a longer development phase embedded in material sciences and emphasizes on wood as future building material and as replacer of steel and concrete structures. §MASS CUSTOMIZED TIMBER STRUCTURES Recent work done on free-form glulam structures quantifies the complexity of wood as input for fabrication steps in order to obtain desired geometries. Until now, this workflow has not yet been integrated with contemporary practice. There seems to be a strong effort in accelerating glulam technologies for use in multi-scale applications as the previous demand for linear application demand have faded. §DEPLOYABLE STRUCTURE A type of system that can utilize all its members to achieve a target deformation as one global, unified body. This type of system benefits from interlocked, rigid components that can transfer the loading of one part to the next one in the line. It can achieve movement through material elasticity. Rather than hinges, connectors or bolts. §RIGID BODIES Reffering to tight connections between two parts, consequently acting as one component. The benefits of such connection is sucsessful force translation. A rigid body can only work when there very high stiffness, so that two fixed components does not move relative to each other.

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§CONTEMPORARY FURNITURE DESIGN Experimental furniture design explores wood-modules held together by heat-shrunk plastic bottles. This novel research offers ways of appropriating wood to work with other materials, previously perceived as non-structural, hence giving rise to stable, scale-specific assemblies.

‘Plastic Nature’ is another furniture series injecting silicone into wood, as strategy to geometry based interlocking systems as opposed to connector reliant joints (working with bolts, screws etc.). Silicone as structural binder and infill, introduces new flexibility and use in furniture (Pelidesign, 2007). §LOW-RANGE FLEXIBILITY Utilizing timber as a dynamic element have proven to be a challenging matter. To some extent this has been limited to the conception of wood as a fragile and soft material. In 1990, The Norwegian Public Road Administration put forward an initiative to extend the use of timber in civil architecture, resulting in a total of 300 bridges and pioneer projects (Trefokus, 2007). Some of them were set to be composite bridges of steel and timber. In which case glulam and CLTs members were deployed as main structure, fixed by metal connections to concrete decking. While proposed as a lightweight alternative to steel with good dynamic behavior during loading, when compared with a rope suspension bridge the flexibility spectrum is considerably small. Bridges of large scales are of course due to follow strict regulations. However, in high-rise constructions you can feel the building sway in the wind. This is not desirable and therefore kept as low as possible, but this provides a good example of a flexible structure in architecture today. §CONTEMPORARY DESIGN CHALLENGE Today’s architectural practice is challenged by new technologies and population growth. Our cities have become place and process for complex scenarios of contemporary urbanization (Ibañez, 2018). This facilitates densely intertwined urban fabric, stitched together by materials favored by urgency, readiness and deployability, causing high impact on land and resources. As cities are growing, the need for a circular sustainable model in construction industry could not be rushed more. §ISOTROPIC VS. ANISOTROPIC There are two classifications concerning mechanical behavior in materials. When a material is equally strong in all its direction, it is uniform and therefore also isotropic. The opposite are anisotropic materials, which holds specific charactersitics for different directions within the material.

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OTHER TOPICS INCLUDES: +BIO-DEGRADEABLE SILICONE +PETALS + MECHANICAL EQUIPMENT +JAPANESE HANDSAW +COMPOSITES +ROTATIONAL STIFFNESS + BREAKS +MAXIMUM LOADING CAPACITY +UNAVOIDABLE FIXTURES +FLEXIBILITY RANGE & LOADING +MACHINE TIME PR JOINT +FEEDS & SPEEDS +JOINTERS & PLANERS +MILLING TOOL +SHAPE MEMORY ALLOY +BRIDGE MONITORING +SILICONE SLEEVES & POROUS NEGATIVE MOLDS +TETRAHEDONS + SILICONE POROSITY +COMPOSITES + RUBBER LATEX +THERMOCHROMIC SILICONE

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9 THESIS DETAILS A SHORT OVERVIEW

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9 THESIS DETAILS TOPIC

On flexible construction and footbridge design RESEARCH ISSUE

Flexible structures without heavy-mechanical parts AIM

Highlighting composite structure as flexible timber system STATEMENT

A self-regulating structure made from dimensional timber and silicone.

TERRITORY

Infrastructure

> Rural Infrastructure > Bridge > Footbridge

> Self-Regulating Footbridge (Flexible) NICHE

Upscaling novel furniture design with wood + silicone to work as structural system for rural footbridges.

HYPOTHESIS

Can new flexible wood structures emerge from a two-component material system?

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7 TABLE OF FIGURES CHAPTER 2 - THE NORWEGIAN CONTEXT FIG.1. - L.Elseth (2019). GENERAL STREAM FIG.2. - L.Elseth (2019). ICE-DAMAGE ON BRIDGE FIG.3. - L.Elseth (2019). RAISED APPROACH FIG.4. - L.Elseth (2019). WATER FLOW PRESSURE FIG.5. - L.Elseth (2019). WATER FLOW SEQUENCE FIG.6. - L.Elseth (2019). UNDERSIDE FIG.7.- L.Elseth (2019). ENTRY FIG.8. - L.Elseth (2019). STREAM FIG.9. - L.Elseth (2019). METAL FIXTURE FIG.10. - L.Elseth (2019). BENT STEEL FIG.11.- L.Elseth (2019). OBSTACLE FIG.12. - L.Elseth (2019). FLOOR BOARDS FIG.13. - L.Elseth (2019). DECAY FIG.14. - L.Elseth (2019). TOP VIEW FIG.15. - L.Elseth (2019). DOWNSTREAM FIG.16. - L.Elseth (2019). TOP FIG.17. - L.Elseth (2019). DECK DETAILING FIG.18. - L.Elseth (2019). NEW VS. OLD FIG.19. - L.Elseth (2019). FOUNDATIONS FIG.20. - L.Elseth (2019). OVERVIEW FIG.21. - L.Elseth (2019). UNDERSIDE FIG.22. - L.Elseth (2019). METAL FIXTURE FIG.23. - L.Elseth (2019). SPRING FIG.24. - L.Elseth (2019). DOWNSTREAM FIG.25. - L.Elseth (2019). WATERFLOW 1 FIG.26. - L.Elseth (2019). WATERFLOW 2 FIG.27. - L.Elseth (2019). WATERFLOW 3 FIG.28. - L.Elseth (2019). WATERFLOW 4 FIG.29. - L.Elseth (2019). SUMMER FIG.30. - L.Elseth (2019). DRY RIVERBED

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FIG.31. - L.Elseth (2019). ROCK TEXTURES FIG.32. - L.Elseth (2019). CROSSING FIG.33. - L.Elseth (2019). DOWNSTREAM FIG.34. - L.Elseth (2019). STILL WATER FIG.35. - L.Elseth (2019). AUTUMN FIG.36. - L.Elseth (2019). DOWNSTREAM 1 FIG.37. - L.Elseth (2019). DOWNSTREAM 2 FIG.38. - L.Elseth (2019). CLOSE UP FIG.39. - L.Elseth (2019). DECLINE FIG.40. - L.Elseth (2019). WATER FALL FIG.41. - L.Elseth (2019). WINTER FIG.42. - L.Elseth (2019). FROZEN WATER FIG.43. - L.Elseth (2019). DOWNSTREAM FIG.44. - L.Elseth (2019). CABIN FIG.45. - L.Elseth (2019). CONTEXT FIG.46. - L.Elseth (2019). CROSSING FIG.47. - STATENS VEGVESEN (2017). CIVIC BRIDGE FIG.48. - BODÃ&#x2DC;. NORTHERN NORWAY (2016). FOOTBRIDGE FIG.49. - PELIDESIGN (2006). PELIDESIGN CHAIR FIG.50. - COWELL, S.K. (2010). COMPOSITE JOINT FIG.51. - COWELL, S.K. (2010) SILICONE JOINERY 3 TWO-COMPONENT MATERIAL SYSTEM FIG.1. - L.Elseth (2019). FREE HAND 1 FIG.2. - L.Elseth (2019). FREE HAND 2 FIG.3. - L.Elseth (2019). FREE HAND 3 FIG.4. - L.Elseth (2019). FREE HAND 4 FIG.5. - L.Elseth (2019). FREE HAND 5 FIG.6. - L.Elseth (2019). FREE HAND 6 FIG.7. - L.Elseth (2019). FREE HAND 7 FIG.8. - L.Elseth (2019). INITIAL DIGITAL EXPLORATIONS FIG.9. - L.Elseth (2019). LINEAR JOINT FIG.10. - L.Elseth (2019). STRESS LINES

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FIG.12. - L.Elseth (2019). BENDING FIG.13. - L.Elseth (2019). MATERIAL OVERVIEW FIG.14. - L.Elseth (2019). TENSILE STRESSES FIG.15. - L.Elseth (2019). COMPRESSIVE STRESSES FIG.16. - L.Elseth (2019). CNC-INSTANCE FIG.17. - L.Elseth (2019). DEFORMATION 0 FIG.18. - L.Elseth (2019). DEFORMATION 1 FIG.19. - L.Elseth (2019). ALTERNATIVE JOINT TYPES FIG.20. - L.Elseth (2019). VENEER JOINT FIG.21. - L.Elseth (2019). RESEARCH MAP FIG.22. - L.Elseth (2019). JOINT RANGE FIG.23. - L.Elseth (2019). END OF FIRST RESEARCH TERM CHAPTER 4 - THE CASE PROJECT FIG.1. - L.Elseth (2019). PRINCIPLE DIAGRAM FIG.2. - L.Elseth (2019). BRIDGE TYPOLOGY STUDY FIG.3. - L.Elseth (2019). AUXETIC LAYOUT FIG.4. - L.Elseth (2019). LINEAR VS. CELL FIG.5. - L.Elseth (2019). AUXETIC STRUCTURE FIG.6. - L.Elseth (2019). COMPRESSION FIG.7. - L.Elseth (2019). 4-WAY BRACED FIG.8. - L.Elseth (2019). PETALS FIG.9. - L.Elseth (2019). KIT OF PARTS FIG.10. - L.Elseth (2019). ULTIMATE STATE FIG.11. - L.Elseth (2019). AERIAL OVERVIEW FIG.12. - L.Elseth (2019). FOOTBRIDGE SYSTEM FIG.13. - L.Elseth (2019). CROSS SECTIONS FIG.14. - L.Elseth (2019). SEAONS + SHAPE CHANGE FIG.15. - L.Elseth (2019). AERIAL VIEW FIG.16. - L.Elseth (2019). PERSPECTIVE FIG.17. - L.Elseth (2019). UNDERSIDE

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CHAPTER 5 - BUILD SPACE PROGRAM FIG.1. - L.Elseth (2019). WORK PROGRESS FIG.2. - L.Elseth (2019). JOINT CLOSE-UP FIG.3. - L.Elseth (2019). JOINT ITERATIONS FIG.4. - L.Elseth (2019). CASTED MODULE FIG.5. - L.Elseth (2019). CELL + SILICONE FIG.6. - L.Elseth (2019). CELL UNIT FIG.7. - L.Elseth (2019). SEGMENT ASSEMBLY FIG.8. - L.Elseth (2019). WITHOUT SILICONE FIG.9. - L.Elseth (2019). WITH SILICONE FIG.10. - L.Elseth (2019). CAM SOFTWARE FIG.11. - L.Elseth (2019). WORKHOLDERS FIG.12. - L.Elseth (2019). TEST PIECES

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8 BIBLIOGRAPHY CHAPTER 1 - INTRODUCTION 1. Modern Machine Shop (2017). Watchmaking: A Machinist’s View https://www.mmsonline.com/articles/watchmaking-a-machinists-view [Accessed 13 August 2019].

2. Ibañez,D. (2018). Wood Urbanism: From the Molecular to the Territorial.

Boston, Harvard GSD 3. BioMason (2019). About Us, https://biomason.com/about-us/ [Accessed 24 August 2019].

4. Kleppe, O. (2018). Treet, BOB. https://bob.no/treet/treet-info-in-english [Accessed 16 November 2018].

CHAPTER 2 - THE NORWEGIAN CONTEXT 1. DNT; or The Norwegian Trekking Association (2019). Seasons, https://english.dnt.no/seasons/.

2. N.N.P.P (2018). Norwegian Natural Perils Pool, https://www.naturskade.no/statistikk/ [Accessed 13 August 2019].

3. Mork J., Luczkowski et al. (2017). Forum Wood Building Nordic: A parametric toolkit for advanced timber structures, NTNU Faculty of Architecture and Design 4. Aalto P., Wullum O. (2017). Forum Wood Building Nordic: Parametric product development for wood-based SMEs: Residential Stair Example, NTNU Faculty of Architecture and Design 5. Wang Y., Zou Y., Xu L., Lou Z. (2015). Analysis of Water Flow Pressure on Bridge Piers considering the Impact Effect. Fig. 5 [Accessed 29 August 2019].

3. Almaas, I.H. (2010). Norwegian Architecture?. §17 (Nature… and wood), http://www.architecturenorway.no/questions/identity/almaas-norwegian-arch/.

4. Dahlmann, LA. (2016). ‘Wooden buildings one thousand years old’ https://norwaynorge.com/norway-wooden-buildings-one-thousand-years-old [Accessed 14 August 2018].

7. Trekfous (2007). Fokus på tre: Broer i tre. [online] Trefokus.no http://www.trefokus.no/resources/filer/fokus-pa-tre/12-Broer-i-tre.pdf [Accessed 16 Nov. 2018].

8. Aasheim E. (1993). Glulam Trusses for Olympic Arenas, Norway. Structural Engineering International 3.2 p 86-87.

9. Statens Vegvesen (2016). Impregnering Sjekk Av Majorplassen. https://www.vegvesen.no/Europaveg/Damasen/Nyhetsarkiv/impregnering-sjekk-avmajorplassen-bru [Accessed 01 Sep 2019] 10. Apok., Wikipedia (2019). Soft-bodied Organism. https://en.wikipedia.org/wiki/Soft-bodied_organism [Accessed 01 Sep. 2019] 11. Cowell, S.K. (2010). ‘Fancy a joint?: Innovative joinery in new furniture design’https:// www.architonic.com/en/story/simon-keane-cowell-fancy-a-joint-innovativejoinery-innew-furniture-design/7000508. [Accessed 14 August 2018].

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CHAPTER 3 - MULTI MATERIAL SYSTEM 1. David W. Green, Jerrold E. Winandy (1999). Mechanical Properties of Wood, Treesearch - USDA Forest Service 2. Swedish Wood (2018). About Wood: Properties of Soft Wood, https://www.swedishwood. com/about_wood/choosing-wood/from-log-to-plank/properties-of-softwood/ [Accessed 13 August 2019].

3. Smooth-On (2018). Products: Dragon Skin 30 https://www.smooth-on.com/products/dragon-skin-30/ [Accessed 14 August 2018].

CHAPTER 4 - THE CASE PROJECT 1. Ou J., Ma Z., et al. (2018). Computers & Graphics: KinetiX - designing auxetic-inspired deformable material structures, p 72 – 81 2. Schleicher, S. (2016). Bio-inspired Compliant Mechanisms for Architectural Design.

Universität Stuttgart Forschungsberichte 3. Li, T., Hu. X. (2018). Exploiting negative Poisson’s ratio to design 3D-printed composites with enhanced mechanical properties, University of Cambridge CHAPTER 7 - A CONVERSATION 1. Hilo Lab (2019). Zipper Wood, School of Architecture + Landscape Architecture, UBC. http://blogs.ubc.ca/hilolab/zippered-wood/ [Accessed 13 August 2019].

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