Possible Failure Point Emerges in Miami Building Collapse
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Source: NYTimes via MSN
The investigation into what may be the deadliest accidental building collapse in American history has just begun, but experts who have examined video footage of the disaster outside Miami are focusing on a spot in the lowest part of the condominium complex — possibly in or below the underground parking garage — where an initial failure could have set off a structural avalanche.
Called “progressive collapse,” the gradual spread of failures could have occurred for a variety of reasons, including design flaws or the less robust construction allowed under the building codes of four decades ago, when the complex was built. But that progression could not have occurred without some critical first failure, and close inspections of a grainy surveillance video that emerged in the initial hours after the disaster have given the first hints of where that might have been.
“It does appear to start either at or very near the bottom of the structure,” said Donald O. Dusenberry, a consulting engineer who has investigated many structural collapses. “It’s not like there’s a failure high and it pancaked down.”
Explanations for an initial failure at the bottom of the building could include a problem with the deep, reinforced concrete pilings on which the building sits — perhaps set off by an unknown void or a sinkhole below — which then compromised the lower columns. Or the steel reinforcing the columns in the parking garage or first few floors could have been so corroded that they somehow gave way on their own. Or the building itself could have been poorly designed, built with substandard concrete or steel — or simply with insufficient steel at critical points.
Read more: https://www.msn.com/en-us/news/us/possible-failure-point-emerges-in-miami-building-collapse/ar-AALvJr3?ocid=entnewsntp
Interviews and reviews with a large number of engineers all saying cause can't be determined yet -- and that the issues identified in the 2018 report may or may not be that important to the failure.
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... a design flaw will be to blame. I'm only basing that on some of the pics that I've seen after the collapse, which isn't much.
From your article:
"you certainly can’t rule out a design or construction error that has survived for 40 years."
One other clue that a problem started at the bottom of the building: Immediately before the collapse, one of the residents saw a hole of sorts opening near the pool.
Michael Stratton said his wife, Cassie Stratton, who is missing, was on the phone with him and was looking out through the window of her fourth-floor unit when, she told him, the hole appeared. After that, the call cut off.
Then there's this article about the design:
https://therealdeal.com/miami/2021/06/26/engineer-raised-red-flags-more-than-2-years-before-surfside-condo-collapsed/
Prior to that, there were concrete patching and epoxy injections, which repair cracks, to the concrete slab that supports the pool AND plaza above the garage – but it was “performed less than satisfactorily and needs to be completed again,” according to the report.
So where's a sturdy horizontal beam, like a steel bar, that collapsed near the vertical column in that parking garage pic? All that I see is a broken concrete slab that was reinforced with rebar! The rebar should strengthen it, but it won't support the weight of the slab itself!
