Site Consistent Rock Motion

A steady-state transfer function technique is used to obtain a record of hypothetical rock motion beneath soil deposits. This rock motion is designated as site consistent because it is compatible with the dynamic properties of the overlying soil deposits, and a measured or prescribed record of motion at the surface of the soil deposit. The soil deposit is modeled as a lumped-mass shear beam, with constant modal damping. This results in a simple formulation of the transfer function. Two examples are presented. The first example shows the characteristics of the rock motion which might have occurred beneath the El Centro earthquake recording station in 1940. The second example demonstrates the use of the transfer function technique in determining soil-structure interaction effects at a nuclear power station site.