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…

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