Buro Happold - #2 - Facade Innovation: Performance, Optimization, & Integration

Hello, thanks for having me. I am going to speak about a project I had been involved with over the past few years in collaboration with Snohetta Architects. The project you see before you is the King Abdulaziz Center for World Culture located in Dahran Saudi Arabia and is a gift to the Saudi kingdom from the Saudi Aramco oil company to celebrate its 75th Anniversary.

The project, started in 2007, is a state of the art institution being created to inspire passion for learning, creativity, volunteerism and cross-cultural engagement throughout the Arab community. The center is a result of a initiative

by Saudi Aramco to honor Arab heritage, connecting Saudis to their culture while also attracting other world cultures to the Kingdom through authentic, personal encounters with science, history and culture.

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This presentation will focus on the design of the complex facade which is currently being realized though the collaboration of these players. Snohetta’s Oslo office drove the concept and design. A number of Buro Happold offices were involved, specifically London and New York for the engineering of the façade. And finally, the façade is being fabricated and constructed by Seele who were the successful bidders on the project.

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Saudi Aramco, originally the Saudi Arabian Oil Company, is the state-owned national oil company of Saudi Arabia. It is also known to be the have the world’s largest oil reserves and is the world’s most valuable non-publicly listed company. To put in perspective the wealth of this company, the Project Budget: $400 Million USD is 4.5 days revenue for Saudi Aramco.

The site itself was chosen due to its proximity to Prosperity Well #7, which was the first location where oil was successfully sourced in the region.

Saudi Aramco, originally the Saudi Arabian Oil Company, is the state-owned national oil company of Saudi Arabia. It is also known to be the have the world’s largest oil reserves and is the world’s most valuable non-publicly listed company. The company began in 1933 as a joint ownership between the Saudi government and various amalgamations of American oil companies to what is now known as Aramco (Arabian-American Oil Company) later renamed Saudi Arabian Oil Company.

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The origins of the building form originated around the concept of cultural interdependency in space, time and context, manifesting itself in the form of a series of pebble shapes that are discrete and individually recognizable, but that are organized in a way that every singular form is dependant on the next through the way they are supported.

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All of the building elements are elevated out of the landscape, and are contextually surrounded by a rammed earth ring that defines the boundary of the plaza.

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The program of the complex consists of a large, open assembly area called The Great Hall, A library housing current and historical texts, a Tower which will house offices, flex spaces and a penthouse bar and restaurant, an Auditorium, and the Keystone which houses conference, projection and performance space.

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As a counter point to the surrounding desert landscape and the rammed earth ring that surrounds the site, the building envelop was envisaged at an early stage to be reflective, glossy, skin. This is a rendering of a post competition winning scheme.

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The process of design yielded multiple and often conflicting criteria by the design team as well as the client‌ as often happens‌. The design team focused on delivering a vision and architectural statement, and the client, who was very familiar with building in the region, with their set of more pragmatic criteria.

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So began the lengthy exploration appropriate material types. And as responsible faรงade consultants, we weighed the pros and cons of each of these materials in context of all the criteria previously defined by both Snohetta and the client.

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After settling on and developing a concept utilizing metal mesh until the end of SD stage, the design team changed course and developed a concept of cladding the faรงade with a steel tube veil, arranged in a pattern similar to that seen in a fingerprint.

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A similar technique, it was discovered, was used by Ron Arad in the design of his Thumbprint Chair.

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So the architects began their studies on this idea. Studying both physical and digital models on how this concept could be utilized on these building forms.

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Ultimately resulting in these models which I assume some poor intern spent countless hours on. These models, as you can imagine, were confirmation enough of this design concept. One thing seen here that the design team found important to the building concept, is the creation of these unique “seams� that are a result of offsetting an irregular closed curve over an irregular closed form. Each pebble had its own unique seam and thus unique identity.

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Inspired again by the “veins� seen in the pebble the building forms were imprinted with stripes that defined the location of the windows. It was proposed that the stainless steel tubes in these areas would be flattened to maximize the view out at these locations.

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Early system drawings defined the rules of this patterning technique.

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Ultimately the tubes wrapping the building were classified into three categories. The cylindrical tube which covered the opaque areas were 76.1 mm in diameter and separated by 10mm. The window areas had a flattened or elliptical tube section of 12 mm in height and 73mm gaps, and finally a unique transition tube that transformed from the cylindrical to the elliptical tube forms.

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Together with the architects, we developed the strategy for the entire faรงade assembly. It was conceived that for all but the tower, the primary enclosure would be a faceted/ triangulated skin consisting of metal decking spanning triangulated steel framing. This decking would then be covered with insulation and a fairly mundane membrane skin, as this would not be seen. The inner skin of the tower would be a faceted unitized curtain walling system.

Proud of these primary skins would be a steel substructure penetrating through the primary skin that would support the curved steel tubing.

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Meanwhile the architects asked us to provide assistance in the realization of this concept on all the pebbles. The process they found was extremely time consuming and error prone, and the building forms were constantly changing. At the start we began with the use of CATIA which was known to have the function of repeating the offsetting of a curve on a continuous surface. This however proved to be similarly error prone due to the nature of the input surfaces which were provided by the architects as irrational sub-division surfaces.

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We began trying to figure out how to automate the process error checking and fixing while the software’s inherent offset command was repeating. What you can see here is how errors were detected in each curve by checking the change in curvature between one control point and the next, highlighting a cusp when the change in curvature spikes. However this also yielded errors.

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Ultimately we ended up developing a tool for Rhino using first principles. You can see here that an offset of a straight line is fairly simple.

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But when you offset a curved line, there is a potential of the curve self-intersecting.

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So the tool we created would go through the process of offsetting, but would detect which newly created input points for the new curve were in danger of creating these cusps. These points would be eliminated and a series of individual curves would result. Some heuristics would develop the most accurate vertex and the individual curves would later be joined.

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So what took multiple hours, ultimately took a matter of seconds. Once the centerline curves were created, a number of other algorithms would split and label them multiple times based on input geometry that defined the window locations, export each individual curve as an igs file and record its identifier and start and end point locations in an xml file. This file was then used in another program that automated the generation of the tube geometry in CATIA. As each igs file imported into CATIA as a generic 3D curve element, the xml file was queried and the imported curve was renamed and categorized into its appropriate type set to then be used as the input for its respective tube feature.

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While this process was being undertaken, we were also modeling the tube substructure for each building using the structural models exported from Revit as a background.

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And here you can see the combination of both a series of tubes and the substructure.

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Again, here are some combined models of the various pebbles.

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As we were developing the faรงade design, early prototyping was taking place. The challenge that was recognized early however, was how to bend the tubes.

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Enter this 3D tube bender that was discovered by GIG, the faรงade contractor responsible for the first visual mockup. You can see here the limitless amount of curvature that could be defined.

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And here are some shots of that initial mockup that utilized the faรงade design being developed by the team. This mockup utilized a prefab panalized system, which was preferred by the team due to the quick installation and high quality typically find with factory controlled fabrication.

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Here you can see the substructure that supported the tubes.

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Following this mockup, the team came to the conclusion that this type of system proved difficult to hide the joint between panels or the panels and tubes would not align to a tolerance desired. Additionally it proved difficult to address movements and tolerances at a larger scale as the panel allowed larger movements while the individual tube would only tolerate smaller movements.

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Soon after the project went out for open bid process. Seele, a Germany based façade contractor was successful in winning the bid, primarily because of their unique proposal for fabricating the façade.

Seele’s proposal was chosen because of their idea to have independent tubes attached to a continuous standing seam aluminum surface behind , with no penetrations through the weather line.

This was achieved by fastening the tubes to the standing seams in a manner similar to what you see in the upper right image.

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Duplex stainless steel was chosen for the tubes due to its environmental resistance as well as the need for minimal maintenance which was critical for the hidden, inaccessible components located at the back of tubes, such as the anchors you see here.

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The inner faรงade is a double curved standing seam system. This is the biggest departure from our design concept.

This double curvature is needed because the proposed system requires an inner skin that is an almost perfect offset from the outer skin for tube attachment.

Standing seam trays are installed on site continuously on curved panels on the roof all conditions except the tower where the standing seams are preinstalled on prefabricated single story high panels to allow for the differential slab movement at the stack joint. These joints are sealed on site with insulation membrane and tapes. These panel frames are comprised of a heavy steel frame and are top hung and bottom restrained to the panel below similar to a traditional unitized curtain walling system.

All the glazing is faceted on an aluminum stick system.

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The tubes are 5 meter continuous lengths, pre-curved and selected so that the joints are staggered in elevation.

Each tube length has 3 fixing points.

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Thermal expansion and contraction of the tubes happens in the direction of the tubes through slot holes oriented in the direction of the tube at two fixing points with the third being fixed, as well as through the movement joint between tube sections on the same line.

The male/female movement joints seen here is provided with a ring gasket to prevent water ingress as well as air ingress which could possibly turn this faรงade into an enormous pipe organ. These joints also allow for the removal or replacement of an individual tube by loosening the damaged tube and those on either side of it.

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Movement in the other direction or normal to the faรงade surface is taken through bracket stress. As a result of the stresses, temperatures, and limited access to these brackets, titanium was chosen as the bracket material.

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