Generating Seismic Loads

Question

Hello. Why do we have to generate seismic loads first and then the other loads after seismic loads? How can I find the seismic weight of the structure so that I can generate the seismic loads similar to floor loads instead of copying my DL and LL under seismic definitions as per IS 13920:2016. I have seen a lot of youtube videos where LL and DL are defined initially and then seismic defitions are created. After that the DL and LL are copy pasted under seismic definition using Staad Editor. It would be of great help if somebody can explain the logic behind this. Thanks in advance.

Sye · Accepted Answer

Seismic loads( equivalent static load) if defined, would have to be physically located as the first load cases in the input editor ahead of any other loads like DL or LL. There is no engineering justification behind it. It is more of a software requirement so that the data can be read properly. So you can always define DL and LL first and then use these to define the seismic weights. There is no harm if your DL is Load 1 and LL is Load 2 and your seismic load is load 100. However you need to later use the editor to move the Load 100 ahead of your load cases 1 and 2.

Sye · Answer

You can always directly define the seismic weight. Once you go to Seismic Definitions and choose a building code, you will get options to define various types of weights including floor weight. 
 Seismic load generation as per any of the codes follow the same process. You can find videos on the Bentley learnserver at 
 https://learn.bentley.com/app/Public/ViewLearningPathDetails?lpId=111709&aftkn=b915ab62-1043-49d8-b4cc-2957a74cea6a

Generating Seismic Loads

Top Replies