Design of retaining walls with seismic earth pressure

[KPFFIRVINE]

Good morning guys!

This is kind of related to thread255-277625.
A young engineer in our company is designing a retaining wall in California for DSA, and we have to include lateral earth pressure due to earthquake (AKA seismic increment). He asked me how to input the Fp of the wall in Enercalc, which started this whole second-guessing of what is expected of us...

Basically the questions are:
- Would you consider the seismic increment to be an E or H loads for the load combinations?
- When you design with the earthquake loads, would you add the earth seismic increment to the Fp load of the wall (or a seismic load due to the mass of the wall itself)

Although I have never myself added Fp to the seismic increment, I cannot find a DSA-proof argumentation to justify that we do not need to include Fp (or a seismic load due to the mass of the wall itself)...

Any thoughts?

 

[lsmfse]

Does the DSA require seismic earth pressures for the design of walls less than 12'? If the wall is less than 12', maybe you could assume the soil mass stays where it is and apply Fp. I would discuss this with your Geotech.

 

[FixedEarth]

Try to get this book for your new engineer:

http://www.amazon.com/Basics-Retain...=sr_1_1?s=books&ie=UTF8&qid=1337400638&sr=1-1