In a message dated 9/27/2007 2:57:51 PM Pacific Daylight Time, FSRahbar@aol.com writes:
At one of our projects, the contractor needs to core some holes through the structural slab. The slab has both PT cables and regular reinforcing. Cores are from 2" to 4" in diameter and are 16" to 20" apart in both directions. We are not allowing them to cut any of the reinforcing. However, I am trying to give them a guideline as to the distance from the edge of the cores to the edge of the reinforcing. I remember a 1" dimension had been discusses in the past. Is that sufficient? Any thoughts?Thank you,
Farzin S. Rahbar, SE
David C. Weiss Structural Engineer & Associates, Inc.
(818) 227-8040 Ex. 13 Fax: (818) 227-8041
Your biggest worry should be the P.T. strands (besides the rebar). I presume you requested Pacometer readings to establish the location of the strands and rebar. For safety reasons I suggest to use 2" clear between the edge of the cores and and the strands. I am talking about an elevated strcutural slab, but I would use the same precaution for a post tensioned slab on grade.
Antonio S. "Tony" Luisoni
Consulting S.E.
Granada Hills
P.S. Give my regards to Dave