Abstract
AVS30 derived from geomorphological land classifications has been widely used to evaluate amplification factor of subsurface layer and to calculate distribution of ground motion intensity. Natural period of subsurface layer, TG, is also considered important in seismic design of public works such as highway bridges. Seismic design ground motion for highway bridges has been set up based on ground classification determined by TG. This paper presents a procedure for evaluation of TG based on the geomorphological land classification and discusses its validity.
