Seismic Site Classification
Seismic Site Classification
(OP)
With respect to seismic site classification,does it make any difference if your foundations are placed on piles which are driven to bedrock?
Let's say I did a site classification based upon SPT, and found the average N in the first 100 ft to be 25. There is soil for the first 50', and bedrock for the next 50', which the piles are driven into.
Basically, can I get away with classifying the site as Class B (or even A for that matter)?
Is the 10' of soil between the rock surface and bottom of spread footing include the pile?
Let's say I did a site classification based upon SPT, and found the average N in the first 100 ft to be 25. There is soil for the first 50', and bedrock for the next 50', which the piles are driven into.
Basically, can I get away with classifying the site as Class B (or even A for that matter)?
Is the 10' of soil between the rock surface and bottom of spread footing include the pile?





RE: Seismic Site Classification
RE: Seismic Site Classification
Foundation type should not change seismic site classification. Having said that, by using piles, one can ascertain that the fixity to super structure can be achieved. Also superstructure will not be affected by local soil conditions.
Hope this helps.
RE: Seismic Site Classification
With piling driven deep to lower rock below, the lateral energy transfer to the building is not affected at all...the upper soil profile is still moving and driving the building.
Perhaps there's a consideration that the vertical seismic demand (0.2SDS(D)) might be based on the rock, but even then the code doesn't address this.
RE: Seismic Site Classification
RE: Seismic Site Classification
RE: Seismic Site Classification
RE: Seismic Site Classification