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Raft Foundation with Beams in CSI Safe Software
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Anirudh4569
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PostPosted: Tue Jun 15, 2021 6:41 am    Post subject: Raft Foundation with Beams in CSI Safe Software Reply with quote

Hi all,
I have modelled raft foundation with beams in CSI Safe software. But the beam is not taking any moments from the slab and it doesn't act like a monolithic structure. Can any one please help in this issue. In the safe website itself confirmed that we can model the foundation mat with beams. But the beam is not taking care of any moment and shear force in the slab.so please help & Respond.

Thank you all,
Anirudh
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vikram.jeet
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PostPosted: Tue Jun 15, 2021 7:03 am    Post subject: Reply with quote

Dear Er

From primitive view point only,


If raft slabs and beams are modelled , the beam needs to be broken at points of slab meshing , as I can say on basis of staad modelling.

If slab is modelled and beam element is introduced with just end points with single entity, it will not take loading from slab.
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Anirudh4569
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PostPosted: Tue Jun 15, 2021 7:50 am    Post subject: Raft foundation with beams in CSI Safe software Reply with quote

Sir in safe the slab automatically meshes while analysing it. So we need not mesh like in staad. And the beam I have modelled with a single attachment but the forces not taking by the beam in safe software.
Thanks for your response

vikram.jeet wrote:
Dear Er

From primitive view point only,


If raft slabs and beams are modelled , the beam needs to be broken at points of slab meshing , as I can say on basis of staad modelling.

If slab is modelled and beam element is introduced with just end points with single entity, it will not take loading from slab.
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pvgraju
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PostPosted: Thu Jun 17, 2021 3:31 am    Post subject: Raft Foundation with Beams in CSI Safe Software Reply with quote

Dear Sir,

I think beams and slabs are bending as one unit. Increasing beam width and depth makes it more stiff than slab and beam may take bending moment, shear forces.

Regards,

P.V.Gavarraju.
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Anirudh4569
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PostPosted: Thu Jun 17, 2021 5:54 pm    Post subject: Re: Raft Foundation with Beams in CSI Safe Software Reply with quote

Sir But the bending profile itself is not matching definitely by increasing the beam width and depth it may take more moment and shear force but it should match with our manual calculations for the basepressure.
pvgraju wrote:
Dear Sir,

I think beams and slabs are bending as one unit. Increasing beam width and depth makes it more stiff than slab and beam may take bending moment, shear forces.

Regards,

P.V.Gavarraju.
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vikram.jeet
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PostPosted: Fri Jun 18, 2021 5:13 am    Post subject: Reply with quote

Pl see support input.

It seems that supports points are holding the slab/beams.
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Anirudh4569
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PostPosted: Fri Jun 18, 2021 6:41 pm    Post subject: Reply with quote

I have assigned the soil support (subgrade modulus) to the slab element in the safe.
vikram.jeet wrote:
Pl see support input.

It seems that supports points are holding the slab/beams.
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pvgraju
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PostPosted: Sat Jun 19, 2021 1:27 am    Post subject: Raft foundation with beams in csi safe software Reply with quote

Dear sir,

Refer Beams on Elastic Foundation by Hetneyi or any other reference.

Regards

P.V.Gavarraju
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vikram.jeet
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PostPosted: Sun Jun 20, 2021 3:47 am    Post subject: Reply with quote

Dear Er
If analysis is carried considering foundation input as base pressure instead of springs, may please see the output , probably it may match nearer to yr manual calcs.

Also in case of springs, pl check the value of modulus of subgrade reaction entered .  If value is that of rock , then also , I feel , the rock springs in vicinity of rcc columns share and beams do not reflect.

Just a generic view
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Anirudh4569
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PostPosted: Fri Jun 25, 2021 12:15 pm    Post subject: Reply with quote

Dear sir,
I have monolithically modelled raft foundation with beams in safe. The supports i have applied as soil supports with subgrade modulus.
vikram.jeet wrote:
Dear Er
If analysis is carried considering foundation input as base pressure instead of springs, may please see the output , probably it may match nearer to yr manual calcs.

Also in case of springs, pl check the value of modulus of subgrade reaction entered .  If value is that of rock , then also , I feel , the rock springs in vicinity of rcc columns share and beams do not reflect.

Just a generic view
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