Hi,

I am writing this email regarding seismic load case combination method in Caesar-II for static stress analysis.
My client is asking to follow the seismic load combination method as shown in the attached file.
My query is in which case this kind of load combination method is applicable? I am working for an onshore plant only.
In general we never used to combine U1, U2 & U3 in one case.
The attached file shows that it is provided by Intergraph, but there is a seismic load case in which U1, U2 & U3 are combined in one case itself.
So, please let me know, normally in which kind of projects or conditions this type of load combinations will be used.
Also, Please let me know the basis of combining U1, U2 & U3 in a single load case. Is there any document or code which specifies that U1, U2 & U3 are to be combined in one case?
What is D1 & D3?

Thanks for your kind consideration.

With Best Regards,
Ravibabu. M
Piping Stress Engineer.

You seem to imply that Intergraph recommends the SRSS combination of the three orthogonal (static) inertial loads. That is not true.
The presentation from which this slide was lifted was describing the many different ways that you can combine results.
This SRSS combination might be appropriate for your project but the method you use should come from your Engineering Design Specification. If you are the owner, you should specify what you want. There are several.

Dear Dave,

I am not implying that Intergraph recommends the SRSS combination of the three orthogonal (static) inertial loads.

I am just sharing what my client is showing to me as a reference to build the load case and I am just requesting normally for which kind of projects this type of loading combinations will be used.

If you have this presentation, please share it with me.

Thank you,
Regards,
Ravi