Application of modulus degradation model of clays

A degradation model is applied in conjunction with different soil models and stress-strain relations to site response analyses during earthquakes. To evaluate the effects of degradation, computations on two clay deposits subjected to both high and low-level input excitations are conducted. In addition, modulus degradation with or without shear strength reduction is discussed. In terms of surface response, degradation has little effect in the case of low-level excitation. With high-level excitatfons, however, degradation causes lower surface spectral response in the shorter period range, and the difference is on the same order as that from different soil models. Where surface response differs, the use of degradation with strength reduction is less conservative when compared to the use of degradation without strength reduction.