Evaluation performance for site amplification factors: S-wave impedance vs. V_(S30)

摘要

Simplified regression models to evaluate site amplification are widely adopted for seismic microzonation maps, design specifications, and so forth. In practice, the most popular parameter for controlling the evaluation models is an averaged S-wave velocity of top z m depth, V-Sz, especially V-S30. The S-wave impedance ratio of the uppermost layer to the base layer, I-S1/I-S0, is an alternative evaluation parameter. In this study, we compare the evaluation performance of V-Sz, and I-S1/I(S0 )so for SH wave amplification factors on the basis of numerical experiments on artificially generated soil profiles. Taking the average S-wave velocity, depth z must be selected on the basis of the target period range of the site amplification factors. I-S1/I-S0 is found to perform similarly to V-S10, and it is better than V-S30 for the peak ground acceleration (PGA) and the short-period range (0.1-0.5 s). This implies that I-S1/I-S0 is effective for use in site amplification evaluations because I-S1 only requires a physical parameter on the uppermost surface layer. (C) 2018 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.