PRACTICAL METHOD TO EVALUATE RESPONSE SPECTRA OF BEDROCK MOTIONS USING AMPLIFICATION FACTORS FOR SITE CLASSES

Site amplification characteristics are indispensable for evaluating strong ground motions at soecific sites. Theoretical methods, such as 1-D wave propagation analysis, are often employed for this purpose. However, prereauisite structures are not necessarily obtained with ease. In the previous paper, we applied seven site classes in terms of average shear-wave velocity of ground from surface to 30m depth (V30) to site classification sheme. Site amplification factors, Fa for short periods and Fv for longer periods, for seven site classes were derived from strong ground motion records and nonlinear response analysis. In this paper, We proposed a practical method to evaluate response spectra on bedrock using site amplification factors, Fa and FV. The results showed that bedrock motions evaluated by the proposed method aereed with the results using theoretical 1-D analysis.