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RE: Pt slab, opening

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        Erik,
                “We are doing a remodel where the existing slab on grade is post tensioned and the contractor wants to cut out a 12" to 14" wide strip of  slab running parallel with the tendons, w/out cutting the tendons. They had the slab x-rayed and they know the location of all the tendons. They need to run some plumbing from an existing wall to the new addition.
 
My question is, will this 12" to 14" wide by approx 10ft long opening in an existing pt slab compromise the structural integrity of the slab?
 
This opening will be located next to an existing ftg along the short side of the slab which is a rectangle approx 12' x 31' .”
 
                Some amount of concrete is removed. That increases the prestress on the rest. Is there any reinforcing perpendicular to the prestress? Maybe strength in that direction is unimportant, so the slot is immaterial. Are the loads changing that will make the remaining slab at the slot become a hinge? Is the slot near an end? That could make the remaining slab at the end of the slot crack out. Why was the slab P/T in the first place? Does that condition remain in a way that could cause the building trouble?
        HTH,
        Jim Getaz