Seismic Acceleration Coefficients for Segmental Retaining Walls

[NewcastleEngineer]

Reviewing the ASCE7 documents and IBC 2000, it appears that these codes are extremely vague when it comes to selecting seismic design parameters for segmental retaining walls. The codes typicallys refer the designer to the spectral acceleration coefficients or say it is up to a geotechnical investigation. However, I don't believe spectral acceleration coefficients are applicable to segmental retaining walls or free standing retaiing walls (not assciated with a building foundation wall) and typically geotechnical reports do not address seismic earth pressures. How should one interpret the codes for seismic design of segmental retaining walls? The state of practice seems to be to use the peak ground accelerations at either 10% probability of exceedence in 50 yrs or 10% exceedence in 250 years. Based on the codes, what acceleration coefficients should be using in retaining wall design? Any input would be appreciated.

 

[ishvaaag]

All that Spain's standing code NCSR-02 on earthquake design has to say about walls is

3.9. MUROS DE CONTENCIÓN.
Los empujes sobre muros se calcularán con un valor del coeficiente sísmico horizontal igual a la aceleración sísmica de cálculo.

That is use the peak ground acceleration of the ground, a enlarged by some factors in the code to become "that of calculation". Say 0.04g at the ground becomes 0.067g for some important building in weak soil etc or so.

Thinking that at some moments in the shakeout the retained soil is brought violently against the walls in general (and against segmental ones as well) this doesn't look unreasonable, and I bet that proper instrumentation should show transient push far bigger than that.

 

[ishvaaag]

I meant, bigger than the push given when that acceleration is applied to only the active wedge.