To save buildings from quakes, architects try self-destruction by design
Architects hope to protect buildings by letting them rumble instead of crumble. A new design feature would sacrifice itself during an earthquake without harming anything else.
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The other innovation: vertical cables that run the height of the building. These taut but elastic steel cords realign each floor after a seismic shake. "The system is designed to self-center after an earthquake, while typical buildings are prone to 'story drift,' " where structures settle off-kilter, says Mr. Hamburger.Skip to next paragraph
For example, the California State Automobile Association headquarters remained standing after the 1994 Northridge earthquake. But the 6.7-magnitude tremor caused such a permanent skew that the building was condemned soon after. These vertical cables could immediately correct the drift.
But this three-part system comes with several drawbacks, according to Hamburger – not in its design, but in the realities of modern construction work.
"Their system is something of a Swiss watch," he says. "It takes care; it takes training. Not just anyone can build it." This makes contracting more expensive. Because major earthquakes are still rather rare – and American buildings often change hands relatively quickly – Hamburger says few developers will bother paying to implement such safety features. Exceptions include government agencies, hospitals, universities, and corporate headquarters – institutions that plan to remain in one place for decades.
The other problem could fix itself within four to 10 years. That's how long it is likely to take for Hajjar and Dr. Deierlein's plan to enter American building codes, according to Hamburger, who for 10 years chaired the Building Seismic Safety Council's Provisions Update, the group that writes the earthquake provisions in the International Building Code.
Interested engineers can already use fuses, rocking frames, or vertical cables. (Hajjar says two buildings in Illinois already do.) But getting approval for such designs requires a persistent developer and an open-minded local building authority.
Hajjar and Deierlein are still testing and refining their three-part plan. In 2009, the team put a prototype three-story building through a magnitude-7 tremor at Japan's E-Defense, the largest earthquake simulator in the world. The frames rocked. Steel fuses warped. Vertical cable held strong – exactly as planned.
"We continue to explore new ideas, better configurations, and better materials," says Hajjar. "We're doing this to create a better system not just for owners, but for occupants. Because owners know what they're buying but occupants don't always know that a significant event could cause significant damage to the point where a building can't be repaired or isn't worth being repaired."
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[Editor's note: This piece originally ran in the April 18, 2011 issue of The Christian Science Monitor.]