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RE: Elevated post-tensioned slab cracks

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Oshin,
 
Now that you state there is water leakage out of a tendon pocket and effloresce you should probably read one of Gail's papers on unbonded PT evaluation - she more than adequately covers issues regarding evaluation for potential corrosion related issue to unbonded PT structures, water leakage and more. This structure may warrant some limited-scope invasive investigation for possible corrosion damage.
 
Just curious, what year was the structure built? Was it heat-sealed strand, or extruded? If you do not know, you should possibly find out.
 
To rely upon catenary action as a justification for ignoring the cracks, you may be on your own there - ACI 318 nor UBC code does not address it. Have you noticed any excessive deflections?
 
Mark Geoghegan
 
Honolulu, HI 
 
 -----Original Message-----
From: Oshin Tosounian [mailto:oshin(--nospam--at)kcematrix.com]
Sent: Thursday, January 09, 2003 1:37 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Elevated post-tensioned slab cracks

Thanks Gail,
 
As I stated in my original post, the cracks are full depth and occur somewhere between column lines (middle strip areas, if you will, just to clarify location), and there has not been any repair work done on them. And, Yes, they are leaking with a lot of efflorescent on the bottom side of the slab. There is one place where water is dripping out of the plugged end of a tendon. We could not trace the source of this one, yet.
 
With regards to the "conventional wisdom", what if the cracks are fully open, essentially no pre-compression? Would you rely on the catenary action of the tendons? Which is another explanation I've heard in the past for ignoring the cracks.
 
Thanks again
 
Oshin Tosounian, S.E.
Los Angeles, CA