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Re: Post-tensioned Construction

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In a message dated 3/11/2003 3:51:59 PM Eastern Standard Time, mStuart(--nospam--at) writes:

The problem was discovered when workers doing some repairs on the building noticed weakened tensions among several cables, said Joe Fernandez, assistant chief of the Miami Fire-Rescue Department. On one floor, six of 10 cables investigated failed.

As I’m sure you know, if this is an unbonded system that means that the P/T force has been lost along the entire length of strand, this maybe why they evacuated the entire floor rather than just the area associated with the failure.

Actually, they evacuated the entire building.  According to what I heard (not in the papers),  they were doing balcony repairs on the 12th floor.  There were no signs of distress anywhere in the building.  

I could be wrong (of course),  but this is most likely a flat plate structure with an exposed soffit.  Signs of distress should be pretty obvious.  It was also built at a time when one prevailing thought was that no tension should be allowed in prestressed structures - many of the structures built at this time could (and maybe have) lost alot of tendons without anyone noticing because they are so over-reinforced it doesn't matter.

The public parking garage by the Barnes and Nobles in downtown Evanston, Illinois appears to have lost almost all of its post-tensioning tendons - you can see the broken wires dangling from the slab soffit (it is a button-headed wire system).  There is absolutely no cracking of the concrete however and as far as I know,  nobody is planning on doing a repair.

Gail Kelley