AI summary
Redesigned Hanger System: The original design called for a single set of rods to pass through both walkways, with each walkway supported independently.
The modified design changed this to two separate sets of rods, where the second-floor walkway was suspended from the fourth-floor walkway.
This design placed the entire weight of both walkways on the fourth-floor beams.
Failed Connection Detail: The fourth-floor beam was comprised of two steel box channels welded together, which were not strong enough to handle the increased load. The design lacked proper stiffeners or reinforcing steel plates, causing the nuts to pull through the box beams under the weight.
Failure of Review: The contractor suggested the rod change to ease construction, but the structural engineering firm approved the change without performing calculations or conducting a detailed review.
Neglected Safety Codes: The original design itself was already inadequate by industry standards, with a capacity only roughly 60% of what was required by building codes.
“Failure of Review: The contractor suggested the rod change to ease construction, but the structural engineering firm approved the change without performing calculations or conducting a detailed review.“
Just. Wow. Damn. I’d never have believed professionals on so big a project could be that stupid.