Drilling Holes in Post Tensioned Wall

[comserv]

Anyone have any recommendation on drilling holes through post-tensioned concrete walls for pipe penetrations. What would be the criteria for the maximum sizes and number of holes that can be drilled in the wall as long as the strands are not affected? Any way to reinforce the holes?

 

[dik]

Use a metal locator to make sure you don't hit a strand... also if you can use a small chipping hammer to avoid cutting one.

 

[JAE]

The holes will change the concrete cross section so the following should be considered in addition to dik's post above:

1. Keep the holes away from areas of high shear (i.e. away from the ends of the span. If you cannot keep them away from high shear, check the new shear capacity of the beam with an altered phiVc. (per dik above - avoid cutting stirrups).
2. Keep the holes away from compression zones in flexure - i.e. near the top of the beam at midspan and near the bottom of the beam near the ends of the beam.