One way shear in slab
One way shear in slab
(OP)
Hi guys.
I am doing one-way slabs and hope you can clean up my doubts about the one way shear in slab.
As they are one-way slabs I treat them as wide beams.
Normally it works fine but this time after carrying out the calculations the slabs fail in shear because of there are some huge point loads near the support.
So my question is how do you guys deal with it? I mean, Normally we don't arrange fitments in slab, so it seems that increasing the thickness of the slab is the only way now if I don't change the structure system?
Thanks
I am doing one-way slabs and hope you can clean up my doubts about the one way shear in slab.
As they are one-way slabs I treat them as wide beams.
Normally it works fine but this time after carrying out the calculations the slabs fail in shear because of there are some huge point loads near the support.
So my question is how do you guys deal with it? I mean, Normally we don't arrange fitments in slab, so it seems that increasing the thickness of the slab is the only way now if I don't change the structure system?
Thanks






RE: One way shear in slab
Dik
RE: One way shear in slab
You will likely have to thicken the slab to make it work without shear reinforcement. However, if the forces are much higher, you might have to treat this thickened slab as a beam and provide shear reinforcement as necessary.
RE: One way shear in slab
thanks, Dik
RE: One way shear in slab
BS8110...and AS3600 has a similar effective width calculation.
RE: One way shear in slab
thanks... Dik
RE: One way shear in slab
- to my knowledge, the attached PPT presentation is the state of the art on this. I have the corresponding ACI paper from 2013. It's great but there really isn't anything that you'd need from the paper that isn't also in the PPT.
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: One way shear in slab
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: One way shear in slab
I see no ppt.
I already had the linked ACI paper, but thanks for the reminder; well worth a re-read.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: One way shear in slab
By wide beams I meant dividing one-way slab into strips with effective widths.
The client doesn't want to increase the slab thickness.
What I don't quite understand is can we use this effective width to calculate the shear capacity for slabs subjecting to point loads?
And what does one-way shear reinforcement in slabs look like if the shear reinforcement is required? I have seen the shear studs being used in slabs for punching shear but never seen beam-type shear reinforcement in slabs.
RE: One way shear in slab
Dik
RE: One way shear in slab
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: One way shear in slab
I believe that we've already answered this question for you above. A particular effective width may work but an arbitrary effective width probably won't. You've mentioned that you're treating the slab as a bunch of one way beams but you haven't told us anything about how you've subdivided your slab into those beams. It matters.
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: One way shear in slab
RE: One way shear in slab
I did that above WillisV.
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: One way shear in slab
The paper indicates that Regan's method (blue line, also mine) actually most closely matches test results (normalized as green line). It's actually pretty astonishing how closely it mirrors test results. This method was developed in London in the early '80s and incorporates both one-way and two-way action. Or more correctly, it recognizes that concentrated loads are inherently a two-way problem but doesn't treat all sides equal like one would in a standard two-way problem. I've used it many times for point loads close to supports. It's a longer process than taking just an effective width, but doesn't take too long. If you throw it in a quick spreadsheet so values are easy to manipulate, it's not really any longer of a process than ACI.
RE: One way shear in slab
in English and Dutch (I believe).
Dik
RE: One way shear in slab
Dik