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Re: FEA slab analysis

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Mark
There are few software's which directly transfer slab (distributed) loads to the beam based on tributary area.
 
If you wants to take advantage of slab bending stiffness, modeling becomes more tedious. Your each slab needs to be divided in no of elements. You have to add more no of nodes in beam element and model smaller elements of slabs. You will get maximum effect of slab based on no of nodes in beam spans. This analysis will alter results slightly.
 
Regarding assumptions, generally beam and columns are considered as part of frame to resist moments/shear/axial forces. Slabs are designed for plate bending and effect of variational deflections of supporting beams is neglected in slab design.
 
 
Shriniwas Mahamuni
Ascent Consulting Engineers
Consulting Structural Engineers
----- Original Message -----
Sent: 09/mm/2004 12:09 PM
Subject: FEA slab analysis

Hello group.
 
I have a question regarding FEA of concrete frame structures: when you do a model of a frame, you basically analyze the moments/shear/axial in the beams and columns. The way you model your structure is to either transfer the tributary area load onto the beams (according to the design code you're using) or
you create a plate element onto which you assign an area load and the software does the same thing for you as in part 1.
 
In either case, as far as i understand, the bending stiffness of the slab is neglected. Even when you model your frame with a plate for the slab, the software just connects the slab to the joints. The slab is not connected to the beams at every point.
So how does that alter the results? Are there any assumptions that are made during this process (by neglecting the slab effect)?
(i'm not referring to earthquake loading where the slab behaves like a diaphragm, but rather in DL/LL bending)
 
 
Thanks.