The 2009 convention's over, but before we wrap things up completely, I want to share a tour of Moscone West I was able to snag with Kevin Hart, a local San Francisco architect who worked on the project with Gensler from 1996 to 2003, when it opened.
Convention centers are tricky: they want to be downtown, close to the action of the city, close to hotels, but they also want to be enormous single-level buildings, half a million square feet or more, and far enough from busy streets that loading trucks can easily move in and out. Plus, they're often ugly—controlled access means one main entrance, and yards of blank facade. So what do you do? First, Moscone West is four levels: three convention floors and a basement. Trucks unload underground and a pair of giant freight elevators bring exhibit gear upstairs. Second, the facade is a huge glass curtain wall, putting convention-goers on display for pedestrians on the street, and flooding those inside with natural light—a far cry from the dismal convention halls like the Javits Center.
The curtain wall is awesome in purely structural terms—the whole thing, 112 feet tall in places, hangs completely from the roof, braced by giant, bowed steel beams that let the wall flex more than a foot in all directions during a quake. That's a big deal in San Francisco—it means Moscone West is built not just to survive an earthquake, but to survive one intact, so people can take shelter inside. The flexible curtain wall is part of the quake-proof design, but the real secret is something called a Coupled Girder Moment Resisting Frame. Giant 44-inch steel columns are linked on each story by two girders and a diagonal brace. The horizontal girders are coupled by two small vertical beams in the middle. In a quake, it works like this: if the shaking is subtle, the diagonal beam slides on a teflon pad, taking the energy out of the rest of the frame. If the quake's too strong, the vertical couplings are designed to break, dissipating the force and saving the rest of the building. Invented just for Moscone West, it’s the only system like it in the world.
774,000 square feet, space for 18,000 people, movable walls that can fold into 38 different meeting rooms, 25 stairwells, 28-foot ceilings, spans of up to 200 feet... It's an outrageously huge building, built for serious use—from the heaviest earthquake to the most earth-shakingly boring lecture—but luckily for us conventioneers, and for the whole city of San Francisco, its light-filled lobbies, glass-clad facade, and warm stone walls don't feel nearly that intense.
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