Steve Huey, PE
Steve received his Bachelor of Science in Architectural Engineering and his Bachelor of Environmental Design from the University of Kansas. He is a licensed Professional…View Profile
Architectural Space: the final frontier. These are the voyages of Wallace Engineering. Its thirty five-year mission: to explore strange new geometries, to seek out new material uses and new details, (pregnant pause) to boldly go where no engineer has gone before…
Can you see it? Tom Wallace seated commandingly on the bridge of 200 East Mathew Brady Street wearing his lycra Wallace Engineering uniform with the bold periwinkle “swoosh” emblazoned upon his chest and this directive spoken confidently in the background.
Yep, that’s what it’s like.
“Engineering First”; it’s a term I hear tossed around on occasion but I’m not sure I know what it means most of the time, but it definitely sounds bold and exciting. We have been involved in some “engineering firsts”. On the De Young Museum we designed cold-formed copper and extruded bronze wind girts that support the building skin. It had never been done before, we stated that, and we won an award for it. In reality there have probably been many instances on older buildings where bronze elements have provided structural support for architectural elements of a building. I know of at least one 100-year old case where a steel frame was wrapped in copper and bronze and when we opened it up and looked inside, all that was left of the steel framing was a rust colored smudge where the frame had been. In truth, the cast bronze frieze was acting as a circular beam which supported the glass roof structure and did it with no bolts at the joints; just the mechanical interlock between the cast pieces. It was an incredible, but completely accidental bit of engineering and it worked for about 60 years until a tree fell on it and it was taken down and rebuilt with an interior frame made of new stainless steel members.
The design of copper and bronze structural elements of the De Young Museum by contrast were not accidental. It was intentional and it was done within the context of new modern constraints. The constraints of modern building codes; with their seismic and wind resistant requirements, today’s contractual and liability issues and the inevitable review process; which requires that the building meet “Code” while the materials and design theory often times are not directly addressed in “the Code”. It was an engineering technical first if not historical.
Maybe the narrative for a “first” should reflect these realities as well; we aren’t living in a 60’s science fiction TV show after all. “To boldly go with caution and extra review and modeling trial and error (virtual and actual, mind you) and a good deal of research, where no engineer has gone exactly before”. I’ll admit it loses some of it’s heroic aspect and now instead you see the image of a tired worried Tom Wallace sitting at his desk, head in hand wearing a wrinkled dress shirt and Dockers. We are not Lewis and Clark after all and it is not acceptable for us to lose crew members on our expedition towards permit documents and when we run out of budget we can’t shoot our dogs and give them to the bankers to eat.
But still we trudge on.
Here’s the thing, like Captain Kirk and Lewis and Clark we have no idea the obstacles we will run into when starting the journey into “engineering first” territory. Sure we know that these strange new geometries cause torsion and internal warping of the shapes, which do not occur or are negligible in most rectangular structures. We know that reverse curved elements tend to act as much like springs as they do struts when subjects to axial forces but to what extent is highly dependent upon the actual geometry and the effects can reverse with visually subtle changes. We know that temperature changes can set up large forces within a structure if expansion and contraction are not accounted for but in the context of a complex geometry they relieve themselves without impacting the general design, or they may be the controlling design forces.
For visual purposes “the model” can be adjusted and refined in seconds with modern software to change the appearance and everyone in the room can in real time see what the new idea looks like on a “webex” call. Now in minutes, sometimes seconds, everyone on the design team can see what is proposed and we can all comment, “yes, that looks great”. We have Owner buy-in, everyone now agrees this is the direction we are going to move forward with; if the engineer can answer one simple question…”Okay, does that work?”. Everyone is waiting, they did their part, now can we please just get the answer to our one simple question in the timely fashion in which we asked it?
The answer of course is not so simple. See, the ten elements that were moved are part of an interconnected model that includes 2,000 separate elements none of which are regular, planar or square to the world but they all affect the one next to them and next to them and on ad infinitum. So we have to look at not just the ten members that were changed but all 2,000 members to see what subtle and unintended consequences there are to the 99.5 % of the model that was not changed as well as the .5% of the members that were. “Okay, but can you give me a rough ballpark idea of whether or not it will work?”. “Wait let me check my rule of thumb cheat sheet for aluminum structures shaped like a an inverted double helix…”oh damn! The tables only go up to 50 feet and this one is 300 feet tall!”
Okay, so truth be told we don’t have cheat sheets for inverted double helix structures regardless of the height. We have to go through the task of analyzing and checking each of these things from scratch as there are no guidelines, rules of thumb or approximation methods for things other than straight elements in rectilinear frames. It is short sighted of the “Engineering Standards Department” of course to be so myopic in scope. But it is impossible to create an infinitely variable rule of thumb approximation calculator for all possible imaginations of structure. And this is the “first”; it is the original derivation from which all rules of thumb would emanate. But I digress, the “short answer” to the “simple” question is “no”.
The road to an “engineering first” is a winding and treacherous one. It is not a route for the timid or the foolhardy. We take our time and look at the models and the results more than once to see if there is anything we missed and then sometimes we just have to set it aside and come back and look at it after a good nights sleep. Be patient, we haven’t forgotten about this question we just want to be damn sure we give the correct answer. It is the first and probably the last time we (or anyone else) will engineer one of these.
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