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Opening in One-Way Slab

Opening in One-Way Slab

Opening in One-Way Slab

(OP)
I've been asked by a contractor if it's OK to cut a opening in a one-way spanning slab. Details are on the attachemnt and are as follows:

- 125mm thick, rebar not known
- spanning 3300mm from wall onto steel beam
- opening is 310x260mm at corner

I'm aware of rules governing the positioning and size of openings for 2 way spanning slabs however there seem to be very little on 1 way spanning slabs. My thoughts are rebar will be hit and the slab will lose some of its strength however due to the size and the location adjacent to 2 walls the slab will be OK with needing secondary steelwork or strengthening.

Any thoughts?

RE: Opening in One-Way Slab

It is only 260 (10.5") in the direction that the slab is spanning, run a covermeter over it, the opening hopefully only  cuts 1 bar maximum, it is in a low moment region so hopefully the slab with still have enough capacity in that region.

Is the wall running left to right along the page loadbearing?

RE: Opening in One-Way Slab

I would not hesitate to cut the hole in this location.  A crack could propagate from the corner, but it would be of no consequence.

RE: Opening in One-Way Slab

I would prefer a circular hole for easy of coring, even so I wouldn't hesitate, just make sure they don't over cut too much.

When in doubt, just take the next small step.
 

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