Abstract
An evaluation method of horizontal strong motions was examined based on strong-to-weak motion (S/W) spectral ratio at the ground surface. The inverse analysis of S/W spectral ratio is intended to account for the soil nonlinearity (dynamic deformation characteristics) of the target layer, namely, is to determine the shear stiffness (S-wave velocity) and damping factor corresponding to shear strain. Then, the horizontal strong motions are evaluated using the nonlinear ground model obtained by the inverse analysis. In order to confirm the applicability of the evaluation method, we have performed numerical experiments using a simulated ground model, and have further evaluated the horizontal strong motions on the engineering bedrock with S-wave velocity about 500m/s at 300m depth of the Quaternary ground by using the observed S/W spectral ratio. As a result, the estimated strong motions satisfactorily reproduced the observed records on the engineering bedrock and showed high accuracy.
