S Foundation Bearing Capacity
Answers
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Hello Steve,
Thank you for posting on Altair's Community Forums. My name is Andrés, and I will be pleased to assist with your request.You can define the soil's allowable bearing capacity for your footing through the Define Soil Profiles menu, by clicking on Define -> Soil Profiles, as shown in the attached screenshot.
The user can assign a value for the Ultimate Bearing Capacity for a Single-Layer profile, as shown in the screenshot, or manually define the Pad's Ultimate Bearing Capacity for each layer of a Multi-Layer Soil profile by unchecking the Auto-Calculate box under the Pad Ultimate Bearing Capacity dropdown menu. By keeping this box checked, S-FOUNDATION will calculate these factors.
Please bear in mind that the Factors of Safety you define for the Bearing Capacity will directly affect the footing pad's soil bearing capacity. These can be adjusted to your needs through the Design Input window under the Geotechnical Factors of Safety dropdown menu, as shown in the screenshot attached to this reply, or by going to the Settings menu -> Design, under the Geotechnical Factors of Safety dropdown menu. If you are curious, there is a bit more information on this topic under the Help System if you search for 'Overburden Pressure'. Please refer to the excerpt attached to this reply.
As for the Design Pads to Soil Bearing design wizard, the Maximum Utilization Factor refers to the maximum allowable code utilization factor, and it is one way of measuring how conservative the user may want their design wizard to be. There is no right or wrong value for this factor, as it depends on the user's needs. Naturally, for a more conservative approach, the user can reduce the Maximum Utilization Factor as much as they see fit.
We hope this information helps clear things up. Do not hesitate to ask any additional questions if necessary. The team is here to help.
Kind regards,
Andrés Chávez Burgos
AEC Solutions Engineer1 -
How is over burden calculated, the model I have indicates the overburden is twice what it really is.
In load cases (say Case A) if I click on substructure load factors self weight and soil does this negate the use for a combination of Case A and self/soil weights.
What setting would I use to ensure there is contact under entire footing.
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Steve Morrison said:
How is over burden calculated, the model I have indicates the overburden is twice what it really is.
In load cases (say Case A) if I click on substructure load factors self weight and soil does this negate the use for a combination of Case A and self/soil weights.
What setting would I use to ensure there is contact under entire footing.
Hello Steve,
Our apologies for the late response, this one slipped through the cracks. To answer your questions, the information related to overburden pressure actually has a dedicated help system topic which you can find if you open the 'Help' Window in S-FOUNDATION, locate the 'Soils' section, and their is a subtopic on 'Overburden Pressure and Soil Bearing Capacity'. This video also touches on the subject:
https://www.youtube.com/watch?v=X0iWqN2tNqQFrom your screenshot it appears that you had some uplift in your soil. This is perhaps due to the presence of lateral loads, or moments on your pedestal? If that is the case, the nonlinear ground springs will deactivate in areas where they are found to be in tension. This is using S-FOUNDATION's flexible analysis option, however if you prefer, you can review the 'Rigid' method, instead.
Regards,
Matthew Sauer
Altair Support
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Altair Employee