Intersections of interest.
So my father is fascinated with structures. It comes from his general fascination with the world and his professional focus (for 21 years!) on the world of commercial construction.
I had a neat time with him at Burning Man. I sent him out on a mission to check out the Belgian Waffle and figure out how it was built. At the time, I had felt like he had been a bit standoffish, reminding me of the wicked son in the passover parables: “What is this thing of yours and how do these traditions relate to you?”
So he came back and blew my mind.
“So how was it?”
He starts: “It was really very Burning Man because… ”
At this point, I start smiling, ’cause I know he’s hooked. Here he is, telling me what Burning Man is. The sense of ownership and presumption was rich! I loved it.
He continues: “… it’s like jazz.”
Now I’m really listening.
“Oh? Do tell,” I say.
“Well,” he say, “they started with a central structure, a tripod and some vague idea of what they wanted. But once that was up, they just got like 70 guys on lifts with nail guns and whole bunch of wood and jammed. If something didn’t work, they might back it out and try again. It’s an improvisation on wood.”
He pauses, then: “It’s gonna be really beautiful when it burns.”
So the other day he sends me a link to this article: Painful Precision Allows Frank Gehry to Twist the Glass Envelope
Three years ago, standing on a cladding factory floor watching robots lift a 10 x 5-ft window pane, Frank Gehry was surprised to see the glass sag under its own weight. It was a pivotal moment, for it led to a suggestion that freed the famed architect to sculpt his first all-glass curtain wall, full of his signature sweeps but lacking budget creep. The novel twist on the 10-story headquarters for Interactive Corp., near the Hudson River in Manhattan, is that crews purposely cold-bent each of the 1,437 flat-glass cladding panels with their “bare” hands as they installed them. It had never been done before.
The 195,000-sq-ft building’s wavy form evokes ship sails. The cold-bending of the glass, instead of prohibitively pricey factory heat-bending, “was really the trick to give us the shape,” says Craig Webb, Gehry’s design partner. “The breakthrough was to actually think of doing it on purpose,” says Webb. Warped panels are normally a “no-no” in the curtain wall sector, he adds.
My dad was so intrigued by some specifics in the article:
Work called for exact placement of 1,600 steel embeds for the glass panel brackets. If the brackets were not set to 1/100 in., site-bending would go awry. “Bracket layout was the most time-consuming activity,” says De Gobbi.
To minimize error, Turner departed from custom and established direct communication between Sorbara and Permasteelisa, which set the embed locations. In addition, Turner required Sorbara to have a licensed surveyor checking work before concrete was cast, instead of after. Turner also had its own surveyor double-checking Sorbara’s.
Because of the building’s form, the slab edge was a segmented radius, with a 10-lb embed every 4 ft. Using a global positioning system-based 3D transit, surveyors first located every insert in theoretical space. “Then we connected the dots” to create the slab edge, says Kell.
So 1/100 in. is an unheard of tolerance. He wanted to make sure that was right. He emails ENR who emails the contractor in question. His question:
This is an order of magnitude tighter than normal construction tolerances? Is it possible that it was to 1/10″ (i.e., 0.01′ or 1/100 of a foot)?
The answer he got:
First of all tolerances that the building SKIN must satisfy (typically 1/8″ max variation from plumb and angles) are much smaller then tolerances of the building STRUCTURE (typically +/- 1″ in every direction).
On a conventional curtain wall project the tridimensional adjustment of the bracket is simpler to accomplish as small variations will not change the geometry of the building (if a panel is sets higher it will just close the joint between panels but it will not change the angle and remains “vertical”). On tilted and curved surfaces, any variation will change the angle thus the geometry will change greatly.
For this reason the tridimensional setting of the anchor brackets (not the embeds in the concrete) at the Interactive project was done (aiming to) at zero tolerances. You can be very accurate with the Total Station on the space coordinates and the tolerances are the ones from the instrument. As far as the curtain wall panels, to address manufacturing and installation tolerances, the system was design to absorb about 1/10″ to 1/8″
He writes back:
Most architects do not understand cumulative tolerance (suppliers and subs do) and so this interests me. Under certain circumstances on certain structures, temperature variations can cause problems where precise measurements are required. The issues here are the elasticity of the structure and possibly the instrument’s response to temperature variation. I ask you: 1) is the Total Station less subject to this than conventional instruments; 2) given your constraints was temperature an issue (or is it simply that there was enough tolerance in the system as a whole that if you went for zero tolerance on bracket placement then any temperature and other variations were absorbed within the panel tolerances)?
So in other news, I’ve met some special, Paula Goldman. I’ll leave the details unpublished, but in trying to (successfully) distract me at work today, she sends a link to her friend Guy’s blog. His first post: gehry building cracked.
I guess my dad was onto something.
NOTE: the original but lost comments by Guy point out that was not a stress fracture, but probably due to an impact of some sort.