World’s tallest skyscraper(s)–CTBUH Chicago

I spent the last part of the week in Chicago attending the Council on Tall Buildings and Urban Habitat’s annual conference–500 skyscraper nerds in one room gets pretty amazing. The speaker list was a who’s who of tower engineers, architects, and developers, and some interesting trends emerged.
CTBUH is, to say the least, a cheerleading group. Higher, larger, faster are the operative words, though there was some critical input by Carol Willis of New York’s Skyscraper Museum. And, this year, it’s a very, very nervous bunch. Several large projects were described in terms of contingency–“when the recession ends” prefaced any number of presentations.
Most interesting was an update on the Nakheel Tower, whose foundations have been under construction in Dubai for a little over a year. Woods Bagot, the architects, described the challenges in building a one-kilometer (that’s about 3,300 feet) tower. If the gravity load of that scale isn’t difficult enough, the main issue at that height seems to be vortex shedding, or disrupting eddies of wind that can lead to harmonic vibrations.
Nakheel is just one of several towers competing to beat out Burj Dubai, which is scheduled to open later this year. Its developer described the final bits of construction–about 12,000 workers are still employed on the site daily–and the 12-month process of bringing the structure on line when it’s complete.
The supertowers, though, will be tough to lease in this economy, and the implosion of Dubai as a financial powerhouse raises real questions about why towers like these really get built. There’s no shortage of land, of course, and there does seem to be an alarming shortage of tenants. One reporter I spoke with over lunch chuckled when I asked him whether Nakheel would get finished in this climate.  There had been rumors that Woods Bagot were going to announce a second kilome-tower for Jeddah, but the first one seems pretty far off.
In all of this Willis’ presentation, along with a brief talk by Mayor Daley and an economist from the Chicago Federal Reserve Bank, raised some good points about skyscrapers as engines of economic, social, and cultural development. The supertalls have always been more about ego, and they are incredibly interesting as challenges and as stories. But the mere fact of urban density that much smaller towers enable–ten to thirty stories, say–seemed to be enough in these presenters’ analyses to kick-start and to support the sort of urban life that energizes the best cities. It remains to be seen what the effect of a Burj Dubai will be. Will it generate more activity? Or will its tenants, work, live, and shop all within the tower itself? Or–more troubling–will the inconveniences of supertall make this nothing more than a technical experiment? Several presenters brought up problems like motion sickness, multiple elevator changes, and pressurization problems, that seem endemic to the whole idea of a kilometer-high tower.  But critics of skyscrapers in the 19th century thought issues like light-headedness and the velocity of elevators were going to doom the skyscraper ‘craze’ then, so who knows?
One highlight for me was the chance to get a behind-the-scenes tour of the John Hancock tower, the building that first convinced me to think about becoming an architect. It was a pioneer of mixed-use, with offices, condominiums, retail, and entertainment all contained within. In among all the talk about elevator sequencing, wind bracing, and massive chillers, the building engineer showed us the lighting system that makes up the Hancock’s “crown.”  Eight-foot fluorescent tubes, like you can buy at Lowe’s, wrapped with colored plastic.  Pretty high-tech…

old chicago skyscraper of the week–the Rookery

The Rookery, La Salle and Adams.  Burnham & Root, 1888The “Rookery” was the result of a complex web of backroom deals and land exchanges.  The City of Chicago had owned the site, which was partly occupied by an abandoned water tank that had been turned into the city’s Library, and an aging, decrepit structure that had served as a temporary city hall since shortly after the great fire.  While many have thought that this old structure was called the “rookery” because it housed as many pigeons as people, the term was also used to describe a den of thieves or con-men, which more than adequately described city hall in the 1880s.

Whatever its origins, the name was stuck on to the new project, funded by a number of local businessmen including Daniel Burnham.  His partner, John Root, took the opportunity to advance a rigorous Romanesque style that combined the heavy masonry arches of H. H. Richardson with a budget-driven sense of order.  Root’s design wrapped a reinforced masonry mass–somewhere between a skeleton and a bearing wall–around a central light court.  While this was a common configuration in Burnham and Root’s work by this time, the court itself featured a stripped-down, skeletal structure that enabled interior offices to access more daylight.  This, and a similar skeletal approach on the lower stories of two rear facades, are often seen as precursors to the larger skeletal frames that the office came to design in the 1890s.

Perhaps as importantly, however, were narrow iron columns inserted into the masonry piers that formed the Rookery’s exterior.  These differed little from the reinforcing installed by Jenney in the Home Insurance Building, a block away and a year earlier, and they enabled Root to widen the building’s exterior windows by reducing the amount of masonry needed to hold the loads of the floors above.  While Sullivan had been experimenting with narrow brick piers by this point, the resulting frame of brick and iron, while nowhere near the narrow proportions that would arrive with steel frames in a few years, nevertheless allowed Root to experiment with the exterior wall as a system of verticals and horizontals, not as a solid mass or plane.  While he had made similar experiments with the Insurance Exchange, the Western Union Building, and the Rialto, all in the same neighborhood (though none of them still extant), the Rookery was his most eloquent statement of this possibility.

If the Rookery represented a tenuous step toward the skyscraper frame and away from the bearing wall, it also fostered a new mode of practice.  Burnham and Root occupied offices on the eleventh floor, and Burnham himself convinced many of the offices’ most trusted collaborators to lease space in the building as well–Illinois Steel, for example, located there.  This gave Burnham and Root a decided advantage when it came to communicating with other members of the design and construction teams they helped assemble, and helped consolidate their near-dominance of the Chicago market.  Burnham and his associates laid out most of the 1893 Fair from this office, and, tragically, well-known Chicago engineer Abraham Gottlieb died on the building’s steps after being fired as the Fair’s chief of construction.  He may well have been on his way to protest his dismissal.

The Rookery has been renovated several times, most notably by Frank Lloyd Wright in the early 1900s.  Wright removed much of Root’s original ornament in the atrium skylight–today we would undoubtedly say he marred the building, but since it was Wright, subsequent renovations have restored his vision, not Root’s.

Fire Day

The Great Chicago Fire of 1871 started on October 8, 1871 and burned until midnight on October 10. The coincidence of a long dry spell, an exhausted and embittered fire department, and stiff winds allowed a small barn fire to spread to its west side neighborhood, and then to jump the Chicago River and begin burning the Loop. Speculative development in timber, cast iron and stone left the city vulnerable, and by the end there was virtually nothing left of downtown or the north side–although timber buildings less than a block upwind of the fire’s origin were left unscathed. Of the two downtown buildings that survived, one of them offered lessons for future construction. The Nixon, still under construction but nearing completion, was built with a new system of heavy plastering around its iron beams and columns and this, along with the fact that the building was empty and thus free of potentially flammable contents, meant that it survived where other structures perished.
Standard histories suggest that the city learned its lesson and immediately began building other fireproof structures. But the reality was that re-construction was so quick that the city did not have time to study or implement any new codes. It would take another fire, in 1874, for Chicago to begin legislating fire-resistant construction.
The rapid re-building did, however, lead to the importation and invention of new fireproofing techniques. New York architect P. B. Wight gave up his practice to come to Chicago, where he began a second career as a fireproofing consultant and entrepreneur, while Chicago builder E. V. Johnson began selling patented terra cotta protection for metal construction.
The site of the O’Leary barn, where the fire began, is now the site of the Chicago Fire Academy on Canal Street just southwest of the Loop–a nice twist.