It was a great thrill yesterday to take part in a Construction History Society of America webinar (credit-free learning!) with David Macaulay, one of my all-time heroes and the author/artist behind many great books that shaped my childhood. Many thanks to Peter Hilger, Melanie Feerst, and the staff at the University of Minnesota for hosting.
My contribution was a quick preview of one emerging theme in the new Chicago book–the “secret history” of SOM’s tube structures. The standard story is fairly well documented–Fazlur Khan is credited with naming the structural type, if not exactly inventing it, and there’s a very clear progression of the idea from the Brunswick and DeWitt-Chestnut buildings of 1961-65 through the world-beating Hancock and Sears Towers a few years later. The basic idea is to think of high rise structures as “super-columns,” pushing all of the structural material to the perimeter of the floor plate so that it gains maximum resisting leverage over wind forces. The analogy I use in class is a paper towel roll. It will take far more axial compressive load in when intact than if you slice it down the side and roll it up into a tighter cylinder, since shortening the resisting moment arm makes it far more vulnerable to buckling.
Brunswick was a cautious step in that direction, but it paired perimeter structure with a traditional shear-core (the green walls in the model above by ace undergrad research assistant Jack Strait). One key to its performance is that the perimeter columns in plane with the shear walls (red in the model) are deeper than their neighbors, reflecting the concentration of loads being transferred from the sail-like exterior walls to the upturned-beam like interior core. Dewitt-Chestnut, on the other hand, was a pure tube structure, with irregularly-placed columns in the center of its floor plate that handled gravity loads only, leaving the perimeter to carry the entire wind load:
I’ve posted elsewhere about I.M.Pei’s proto-tube structures in New York and Chicago–the precursors to Brunswick, according to Bruce Graham. I made that point, and showed how construction improvements led to another set of tube structures that enclosed apartment and condominium buildings throughout Chicago, by the firm of Dubin, Dubin, Black, and Moutoussamy that deserve far more attention than they’ve typically received. But a friendly email from a regular Architecturefarm correspondent this morning points out that I didn’t get to one of Chicago’s biggest–and purest–tube structures, one with a legacy that stems directly from SOM’s work.
Standard Oil was designed by a pair of firms–Edward Durrell Stone from New York and Chicago’s own Perkins + Will. After the Hancock was completed, P+W hired away one of SOM’s lead engineering partners, Al Picardi. At the time of the Hancock, Fazlur Khan was still a relatively junior member of SOM’s office, having joined in 1955. Picardi was more senior and was in fact the lead engineer on Hancock–Khan reported to him. He switched firms, apparently, to lead the engineering of Standard Oil, which from its inception was intended to be colossal, at over two million square feet (far larger, incidentally, than the original masterplan for Illinois Center, which at first included Standard Oil’s site…)
Picardi’s structural system is a clear adaptation of the tube structure to Stone’s heavy-handed massing. The perimeter is composed of hollow, triangular steel columns tied into deep edge girders, while the interior structure is gravity-only columns concentrated in the core. The result is clear span office space and–a Stone trademark–narrow slit windows with starkly vertical proportions.
In addition to the large, clear span floors, the structural advantage to this was a core unconstrained by large shear walls and a lightweight spanning structure. With the building’s stiffness taken up entirely by the exterior, the interior structure could be made of light, open-web steel joists:
Standard Oil’s structure was a successful application of the tube to another tall building–Leslie Robertson engineered a similar pairing of stiff, tightly spaced exterior columns with long span open web joists for New York’s World Trade Center at around the same time, which was further proof-of concept. But the building was an architectural disaster–in addition to being wildly overscaled for the emerging Illinois Center district, Stone’s trademark vertical style struck many as alien to Chicago, where skyscraper facades were known more for their rich interplay of verticals and horizontals. Like many other tube structures, Standard Oil hit the ground with a thud–the need to bring so many tightly spaced columns all the way to the ground proved difficult for nearly every architect, but many got the sense that here, Stone didn’t even try, simply filling in the narrow interstices with glass revolving doors that proved treacherous during downdraft winds.
Stone himself gave the building a luke-warm reaction, remarking only that “it’s good looking” on seeing the project firsthand. The Tribune’s Paul Gapp, on the other hand,was furious. “The Standard Oil Building,” he wrote, “is perhaps the worst thing that has happened to Chicago’s skyline in the last 30 years.” The Prudential’s “headstone by the Lake” was now matched, in Gapp’s view, by Stone’s scale-less, “unbroken verticality.” Its blazing contrast between brilliant white marble and the narrow, dark recesses hid any sense of floor-to-floor rhythm or Picardi’s ingenious structural fabric behind facile elevational stripes. “If you stare at the building from a short distance for more than 15 seconds,” Gapp complained, “it is almost disorienting.”[i]
[i] Paul Gapp, “Ambiguous Statement Snarls Center Debate.” Chicago Tribune, June 30, 1974. 1-e3.