STAAD Foundation Punching Shear - Fail. Mat Slab Design

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joseph Lucas Magare — Mon, 06 Dec 2021 11:38:15 GMT

Thanks you,i have some few questions on my post

communities.bentley.com/.../i-need-a-help-on-mat-foundation-design-staad-foundation-advanced-update

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Mon, 06 Dec 2021 11:13:36 GMT

Here is a sample calculation for the area of steel for flexure for a mat per the Eurocode.

communities.bentley.com/.../Area-of-steel-calculation-for-flexure-for-a-mat-designed-in-SFA-to-the-EC2-code.pdf

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joseph Lucas Magare — Mon, 29 Nov 2021 13:41:24 GMT

Continuation for steel calculation by using eurocode,as you did in punching shear

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joseph Lucas Magare — Mon, 29 Nov 2021 13:39:11 GMT

Thank you,iam waiting.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Mon, 29 Nov 2021 13:35:13 GMT

Need some time. Will get back to you.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joseph Lucas Magare — Mon, 29 Nov 2021 07:13:26 GMT

well explained, may i have a continuation of the attached pdf, on how the software calculates the required amount of steel in MAT foundation

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Wed, 25 Aug 2021 15:29:53 GMT

Hello Joselin,

The ACI code requires that if the column transfers any bending moment to the foundation, then the punching stresses in the foundation must be calculated taking into consideration the unbalanced moment (UBM) effect (ACI-318-11 clause No. 11.11.7.2 / ACI-318-14 clause No. 8.4.4). In other words, the total stress will consist of the contribution from the axial compressive force in the column, and the UBM effect.

The UBM effect was implemented in SFA for mat foundations and pilecaps only in version 9.5. In versions before that, the punching stress was calculated solely from the compressive force in the column + weight of pedestal.

You can find this mentioned in the What's New in CONNECT Edition V9.5 section of the SFA documentation.

So, depending on the relative magnitude of the moments and the vertical force, the UBM effect may be a small value, or might have a significant contribution.

So, to answer your question, in version 9.3, the punching stress under columns on the mat will not have the UBM effect. But in version 9.5 and later, that effect is included.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joselin Madueno — Mon, 23 Aug 2021 06:12:31 GMT

Dear Kris,

Can you tell me if the punching shear is wrong in previous versions (9.3 or 9.5 versions) of STAAD Foundation in other codes such as ACI, or this error is limited to the Eurocode check?

Thanks in advanced.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Sun, 25 Jul 2021 10:40:23 GMT

Joselin,

Here is a PDF file that contains the punching shear calculations for column 1 for load case 305.

communities.bentley.com/.../Punching-shear-calculation-for-column-1-for-load-case-305.pdf

Version 9.6.0.62 of the program was released last week and has the correction to the error that was noticed in the earlier versions. Here is a screenshot of the results from this version.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Mon, 19 Jul 2021 17:08:11 GMT

Joselin, apologies for the delay.

The punching results from both versions are wrong. We are releasing a new version by the end of this week which will have the correction for this error. I will provide you with a calculation in the next 1-2 days explaining how SFA calculates the punching shear stress in this upcoming version per the Eurocode.

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Joselin Madueno — Mon, 19 Jul 2021 07:48:36 GMT

Hello Kris, have you taken a look on this?

RE: STAAD Foundation Punching Shear - Fail. Mat Slab Design

Kris Sathia — Thu, 01 Jul 2021 10:20:03 GMT

We are looking into this and will get back to you soon.