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May 22, 2019

This U.S. building code could topple California towers when the ‘Big One’ hits

 

 

As reported in the National Post, I suppose my seismic anxiety should peak when I go to California. After all, the Golden State is famous for deadly earthquakes. But I felt strangely reassured when I stepped off the plane in San Francisco. Sure, California may get more big quakes than the rest of us, but the state has also done more than the rest to prepare for the Big One. And yet on this particular trip it was a seismic problem, not a solution, that prompted my visit. I’d come to find out more about a flaw that could be critical in some steel frame skyscrapers.

But walking through the airport to catch the BART train, I quickly forgot the problem I’d come to investigate because so many obvious earthquake preparations were staring me right in the face. Thick concrete columns and sturdy steel bracing seemed to be everywhere, in an airport engineered to not only withstand a major earthquake, but to remain operational after one.

I got off the train at Civic Center station and went for a stroll. Up on Market Street I felt an unexpected rumbling, but before I could even think of earthquakes a stately old streetcar rolled by on its way towards the Bay. I craned my neck to see the city’s medley of buildings: soaring glass towers, squat concrete warehouses, and solid brick low-rises. I worry about old brick buildings in Victoria, where I live, and Vancouver because so many could collapse in strong shaking. But brick is less of a concern in San Francisco because the City introduced mandatory seismic retrofits of unreinforced masonry buildings in the 1990s. The collapse risk is now significantly lower in San Francisco and many other parts of the state.

A 2016 U.S. study identified California as the only state with specific seismic policies for brick buildings, hospitals, and schools, and called it “the most active state in dealing with earthquake hazards.” Shortly before that, the government of British Columbia had hired the former director of the California Governor’s Office of Emergency Services to assess B.C.’s earthquake preparations. Henry Renteria found “the lack of significant seismic activity near highly populated areas has resulted in widespread apathy. This has meant that earthquake preparedness has not received the day-to-day attention that other pressing needs have received.” Canadians may be tempted to think Americans need to be better prepared because they get more earthquakes than we do. But the geological record is clear that the west coast of Canada has produced bigger quakes than California, and it will again.

If emergency planners in this country look at California’s seismic preparations with envy, their American counterparts are starting to look with worry at something they may have overlooked for a long time: steel skyscrapers built between the 1960s and 1990s. I continued along Market Street, on my way to one of those skyscrapers, to interview one of America’s leading structural engineers about this problem. Ronald Hamburger has worked on skyscrapers for decades, and is still active professionally. Actually, I was surprised he agreed to meet me because when I requested an interview Hamburger had recently been hired to stop the 58-storey Millennium Tower condominium building from sinking further on one side. The “Leaning Tower of Lawsuits” — as 60 Minutes dubbed the opulent condominium — had sunk 17 inches at ground level, and was leaning 14 inches to the northwest on top. The tilting tower unsettled many in a city waiting for the next big earthquake. But Hamburger had just devised a plan to install more than 50 piles under the sidewalk beside the building to stabilize it.

Keep reading in the National Post

 


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