英语时差:怎样让建筑物在地震中屹立不倒？
In 1989, a massive earthquake rocked San Francisco. About sixteen people were killed and hundreds were injured. Several freeway overpasses toppled, but most of the city’s buildings remained intact. Cut to 2008, when an equally massive earthquake struck China. Hundreds of thousands died when apartments, schools and other buildings collapsed, burying people under tons of rubble. So why did buildings in China topple while those in San Francisco stayed upright? One possible reason is that in many parts of the world, including China, many structures have “partial height” walls, or walls that don’t go all the way up and connect to the ceiling. Partial height walls are cheaper to build, but can also weaken a building’s structure. Civil engineers at Purdue University have found a simple way that could help solve the problem: make partial height walls full height. The researchers built a model three story building containing partial height walls. Then they used hydraulic pistons to push and pull the building in ways that simulated an actual earthquake. Adding walls that went all the way to the ceiling made the building six times stiffer than it was with flimsier walls. It’s not a perfect solution, but the researchers think that this simple fix could help keep more buildings upright during earthquakes, and help save lives.
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