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Re: need help with slab

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Where are your wall supports? How thick is your slab? What is your
total factored uniform load? I don't understand what your boss' method is.
You say you analyze it as a flat slab without beams. Did you use SAFE to
do this?

On Wed, 29 Nov 2000, Tomas Matta wrote:

> Hello,
> I differ with my boss on the result of a rectangular slab 25x17mts
> (82x58ft) with 70cm (28in) beams on both directions spaced 170cm (67in). 
> Uniform surface load, line suport with no rotational stiffness.  First I
> modeled it in Etabs as a system of T shaped beams.  Then I modeled it in
> SAFE as a slab with T shaped beams.  The max moments in the central beam
> were 78.6 t*m and 78.2 t*m (567 kip*ft).  My boss tells me that those
> results are wrong, that the system should be analyzed as a flat slab.  As a
> flat slab without beams the max moments in the slab are 30.9 t*m/m (223.5
> kip*ft/ft) which multipied by the beam spacing mean that the middle beams
> would get 30.9*1.7 = 52.53 t*m (380 kip*ft).  Are my results overly
> conservative? Or is my boss's idea unsafe? I don't have much experience, so
> any help will be welcome
> thanks in advance
> Tomas Matta