Civil Engineering Reference
In-Depth Information
innovative steel buildings as the John Hancock Center and the Sears Tower. SOM engineers Hal Iy-
engar, Lawrence Novak, Robert Sinn, and John Zils came up with a concept that convinced Gehry's
design team that the museum could be framed in steel. Again, it was the computer modeling and
software that made such a decision possible.
Underlying steel structure of Bilbao Guggenheim Museum
No two pieces of steel are said to be exactly the same, but there are essentially only three kinds of
members used in Bilbao's structural frame. The typical vertical member is a wide-flanged section,
the kind of steel piece that often forms the vertical or column elements in a warehouse-style super-
store or the exposed structure of an airport such as that of the new terminal at the Ronald Reagan
Washington National Airport. The typical horizontal member in the Bilbao museum is a square
tube, and the typical diagonal is a round pipe. The structure is based on a three-by-three-meter grid,
and at nodes where the three types of members join steel plates allowed them to be fitted together
at the different angles needed to produce the overall shape that Gehry approved. As it did with the
cladding that would be attached to the finished frame, the use of the CATIA software enabled the in-
dividual steel members to be designed and manufactured with relative ease. Although welding was
at first expected to be used to join the six members at a typical node, in the end bolting was decided
upon as quicker and more easily controlled. Since all joint designs were computer generated and all
joint members were computer manufactured, there was little problem with bolt holes not lining up.
Given the elaborately curving shape of the building's facade, the steel frame is remarkably reg-
ular in its design. However, unlike a more conventional building, in which most of the rectangular
spaces framed by vertical and horizontal members are open, with the entire structure being stiffened
against sway by diagonals located only here and there, in Bilbao every one of the rectangular spaces
is bisected by a diagonal pipe. During construction, this gave the smallest part of the incomplete
structure a strength and stiffness that enabled it to be erected without temporary scaffolding, even
where the walls leaned outward, thus turning the constantly curving geometry into a structural as-
set. Indeed, the frame of the Bilbao museum is more like a three-dimensional steel shell than the
rectilinear jungle gym that holds up most conventional steel office buildings. When the steel struc-
ture was completed early in 1996, it was ready to be clad in metal and stone.
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