Quote:
Originally Posted by rowan
According to the Wikipedia page, even the original design of the walkway was not up to code... but what was built was even weaker., barely able to support itself with zero pedestrian load. This wasn't just a case of excessive loading or lockstep causing resonance, it was flawed from the start.
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Actually, that's not true either. It collapsed because the contractor building it wanted to change the bolted connections from shear to tension. This was marked up on the shop drawings and the engineers overlooked the importance of the connection and approved the changes.
What this did was make each one of those connections approximately 1/20th or so of the capacity and it failed as a result.
Picture a horizontal bolt 3/4" thick and pull down on one end and up on the other (shear force). Very large load to make it fail like that.
Turn bolt vertical and hang a truck from the nut. The threads will simply strip and fail the connection.
That's what happened at hyatt. The walkway was being supported by the threads of a bolt.