site classification per IBC for pile foundations

[kozera]

For a pile supported pier structure, when one determines the average properties of the soil in the top 100 feet, per IBC Table 1615.1.1, does this start at the top of the bearing layer for the piles or at the mudline?
thanks for any help

 

[eric1037]

The seismic site class is independant of the depth of the foundation. Seismic loads are both axial and lateral. The movement of the upper soils during a seismic event will induce lateral and downdrag forces on the deep foundation.

Therefore, to answer your question, you start from the ground surface.