jojochanchan 發表於 19-8-28 14:58
深圳羅湖區南湖街道一棟6層的居民樓今日（28日）突然傾斜，暫未收到人員傷亡報告。目前周邊居民已被疏散， ...
This past Monday, news came of another bridge collapse in the United States, this time in Chattanooga. The fact that a bridge collapse has to be qualified with the determiner ‘another’ in the richest Country the World has ever know is distressing, even more so considering said bridge was also part of the largest infrastructure project the World has ever know.
Late Monday morning, the side of an overpass on I-75 collapsed, tumbling onto the ramp headed to Chattanooga. This bridge had been built in the 1950’s, and was recently inspected in July 2018. The condition of the bridge was found to be ‘Fair’(1), which sounds more like a weather reportthan something very large that can collapse and kill you.
Fortunately, no one was killed (this time), although one person was seriously injured. And fortunately, this particular failure didn’t appear to be directly related to neglect or structural deficiency.
Engineers were quickly able to determine that the bridge had been previously weakened by an impact from an oversized load. Engineers were able to observe that all connecting steel rebar between the concrete that ultimately failed and the concrete that remained in place had all been laterally deflected (meaning they had been bent or sheared to the side) to the same extent prior to the collapse, and in the same lateral direction(3). The only way this could have happened was is from a lateral impact to that part of the bridge that did not result in its immediate failure. But once the rebar was bent, it was weakened, and it was only a matter of time before it would fail.
This must have been some impact.
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