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[goyallc]

I have modelled a raft using plate mat  in STAAD Pro and got certain values of base pressure.
After increasing the thickness of raft, keeping all other conditions like loads and supports same, the base pressure get modified and the base pressure values are less for higher thickness of raft.

I want to know, whether Safe bearing capacity should be checked against base pressure?

[Yogesh.Pisal]

Dear friend,

In my opinion bearing pressure should not increase. Try to send your STAAD files, so that I will check the reason for same.

You can compare bearing pressure in STAAD against Gross allowable bearing pressure.

Regards,
Yogesh Pisal

[thirumalaichettiar]

Hope that there is a separate program from STADD by name STAAD FOUNDATION is to be used for best results for foundation. Instead of bearing pressure use modulus of subgrade reaction for the support.

T.Rangarajan.

[ankitvaibhava]

[gpsarathyy]

Dear Er. Ankit,

To use SBC in the STAAD file, you can use the following method.
SBC x area of element / allowable settlement (this will give you a spring value KN/m)
which shall be used in the STAAD as spring support.
Here the complication, based on each element size or contributing area we have to modify the spring value whereas if you use subgrade modulus, this is not required. It is taken care by software itself.

This shall be used in the absence of Subgrage modulus only. If subgrade modulus available it is easy and better to go with the subgrade modulus.