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Re: Redistribution of Moments in grid Floor

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I don't recall what your role is here, but if you have ultimate (no pun 
intended) responsibility for approval of the design and it doesn't make 
sense to you then have them neglect redistribution.

Engineering is equal parts art and science. If it isn't reasonable then 
don't go with it.

W. L. Polhemus, Jr. P.E.

4

> On Dec 11, 2013, at 2:36 AM, "Ashraf Manjappara" 
> <ashraf.manjappara(--nospam--at)gmail.com> wrote: 
> Thanks for your response. The ultimate negative moment is 1057kNm
> (779.9kip.ft) and 20% redistribution means 211.4kNm (155.9kip.ft) is
> redistributed. After redistribution, the design moment is reduced to 
> 881kNm (649.7kip.ft). The cracking moment Mcr of the member is 130.6 kNm
> (96.36kip.ft) as per Indian code. The service load moment is 704.6 kNm
> (519.8kip.ft). The Grid floor is covering an area of 14.4mx21.4m (47.2ft 
> x 70.2 ft). Beams are provided at 3.6m (11.8m) spacing. The beam size is
> 350mmx800mm (13.77in x 31.50 in). Slab thickness is 120mm (4.72in). Prima
> facie, I feel member sizes are inadequate.  My major concerns are below.
> 
> 1.      Since it is grid floor, when the support moment is trying to shed
> the moments to the midspan, will the other beams prevent it?. I mean, the
> beam is not able to rotate freely to redistribute the moments.
> 
> 2.      Is there any limit on Ma/Mcr i.e. Mu/cracking moment to avoid
> extensive cracking?.
> 
> Thanks

Truncated 1058 characters in the previous message to save energy.

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