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how bad is it?

how bad is it?

how bad is it?

(OP)
I have a RC beam that is integrated in RC slab.
There is a bearing wall on a slab, but not on top of a beam but right next to it.
There is also a hole/opening in a slab for chimney right next to a beam (in a same line as bearing wall).
Im wondering is this something to worry about - how bad is this? What can be done? I cant change geometry/position of chimney or beam. Will a load from a bearing wall be transfered through a beam since its right next to it? Slab is 160 mm thick. Load from a wall is around 40 kN/m (slab shear is not a problem). I wouldnt be concerned if there was no opening but now Im not so sure.



RE: how bad is it?

(OP)
Anyone? I'd really appreciate some opinions/insight. bigears

RE: how bad is it?

Where is the load from the wall going? Check your load path and shears and moments, that will tell you if bad or not.

RE: how bad is it?

Is this an elevated slab or is it sitting on the ground? If it is elevated.....it will be a matter of one-way shear for a lot of that length of slab (especially near that opening) to get it to the beam. (Which is probably where it will run to based on stiffness.)

That is, unless the slab is sitting on that wall on both sides of the opening.

RE: how bad is it?

Not bad at all in my opinion. Mostly one-way shear as others have intimated. In my opinion, the penetration is a feature rather than a problem. You lose a little capacity but gain predictability. Near the opening, your situation will be decidedly one way shear. At the other end of the wall, things will get hung up a bit near the hard spot in a way that resembles two way shear but is pretty difficult to pin down. My approach would be this:

1) Do a one-way shear check using a conservative estimate of the load imposed by the wall and accounting for any eccentricity in that load.

2) Add in an extra safety factor of say 1.25 for good measure.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: how bad is it?

(OP)
Thanks for replies!

English is not my 1st language so correct me if Im wrong - by ONE WAY shear you mean a shear that goes along the line of the beam - red line in picture below.



I made a slab shear control for cross section b/h = 100/16 cm and it got me around 60 kN/m of shear capacity
load form wall is 40 kn/m so it should be alright. But what kinda bothers me is this - doest a bearing wall above a slab transfer loads (self weight + slab above) with compression arch which means that loads (shear forces) at both ends of the wall will actually be greater (concentration of loads). because load of 40 kN/m is pretty idealized - distributed uniformly along the whole lenght of the wall.

RE: how bad is it?

Quote:

load form wall is 40 kn/m so it should be alright. But what kinda bothers me is this - doest a bearing wall above a slab transfer loads 8self weight + slab above) with compression arch which means that loads (shear forces) at both ends of the wall will actually be greater. because load of 40 kN/m is pretty idealized - distribute uniformly acrros the whole lenght of the wall.

I'm not sure I follow what you are saying.....but I think the wall being adjacent to the beam means a lot of the shear will probably run directly into the beam. You can probably run a FEA to be sure.

I'm not 100% sure myself because looking at your bearing wall layout (if I am reading it correctly).....that could mean some 2-way action. But even with that, you could hit some peak shears (at some locations) near to the one-way distribution value.

By the way, are you sure you are considering all the loads here? Seems to me like you'd have more than just the wall load. There would be slab load from the dead + live loads in addition to that.

RE: how bad is it?

That was my point with the two-way shear. The wall will only arch if there's hard spots in the suppport. You've got one of those, to an extent, at the right end. Hence the extra margin of safety. You're unlikely to ever know the exact load distribution with any certainty.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

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