Retaining Walls - Lateral Seismic Loads

[moe333]

Does the 2007 CBC state that Lateral Seismic Loads are to be used in the design of retaining walls. I cannot find it anywhere, anyone know what section it is in?

 

[muuddfun]

moe333

The code only says that you have to design for soil lateral loads given in section 1610.1 as given by a soils report, or the table in the code. Then the only place it mentions earthquake loads on the walls specifically is in section 1802.2.7.1 were is says we have to include the earthquake loads in a soils report for structures in Seismic Design Category D,E or F.

The code is kind of screwed up. But all of the local building departments now want siesmic loads on the retaining walls, so what other choice do we end up with but to give them some.

 

[JoshPlumSE]

What do you give them then? Mononabe-Okabe loads? That seems like real overkill for most retaining walls.

What percentage of retaining walls in California have been designed for ANY earthquake loads? Very few.

 

[bridgebuster]

AASHTO (standard Specs) uses M-O for seismic design of retaining walls. It's not too much of an overkill because the SF's for sliding & overturning are reduced.

 

[lsmfse]

My experience is that seismic forces to retaining walls vary by jurisdiction. Some jurisdictions don't require seismic forces unless you have walls over 12'. I agree with muudfuun on the code issue.

 

[msucog]

agree with bridgebuster. also agree with muddfun that ibc is not clear on some things related to walls...however, i do recall that it does call for it (although it is not exactly clearly presented...i have brought this issue to the code council in the past). and i have never seen any codes suggest that structures should be designed for ANY eq loads. i too would like to see more consistency with the implementation of the codes...we almost need to do away with the local to local implementation and defer back to state/regional/national level "blanket" implentation.