Sara Nir, a resident, told The Post that shortly before 1 a.m., she noticed loud “knocking” noises that she assumed were caused by construction work. Around 1:14 a.m., she heard a noise that she thought sounded like a wall crashing down, and she left her ground-level apartment to complain to a security guard in the lobby.
She estimated that about a minute later, while she was in the lobby, she heard a very large boom and saw that part of the surface-level parking area — and part of the pool deck — had collapsed into the underground parking garage. She and the two of her children who were home at the time then ran from the building.
Nir’s son called 911 at 1:19 a.m., he said, a time that he said he confirmed by checking the time stamp on his phone. About a minute later, a dispatcher with Miami-Dade County Fire and Rescue called for an engine to respond to an alarm at the building, audio shows...
The experts said that the columns may either have suffered “axial failure,” meaning that they suffered too much stress from compression, or punching shear failure, when a concrete slab fails under pressure at the point that it connects to the column and falls. The column effectively “punches” through the slab. This can cause a succession of collapses as weight accumulates from above, the experts said.
The video footage shows that about seven seconds after the initial collapse, a second section of the building starts to fall…
According to Jack P. Moehle, a professor of structural engineering at the University of California at Berkeley, the first section probably “dragged the remaining portion sideways until its gravity-load carrying capacity was exhausted and it, too, collapsed.”
Experts noted that, unlike the first section, the second section visibly twisted and sloped to one side in the moments before it fell…
https://www.washingtonpost.com/inve...e/2021/building-experts-miami-condo-collapse/
