Numerical study on the frequency-dependent viscous damping in dynamic response analyses of ground

摘要

The effects of local soil conditions on ground motion are commonly evaluated by performing either frequency or time domain analyses. Time domain analyses usually incorporate in the equations of motion viscous damping which is generally assumed to be of the Rayleigh type, i.e. stiffness- and mass-proportional, or in a simplified form, only stiffness-proportional. These two formulations result in a different dependency of damping from frequency. In order to evaluate the impact of the viscous damping formulations on site response, several linear analyses were conducted for an idealised soil deposit with different computer codes. The results of the analyses show that the use of the simplified Rayleigh damping formulation can significantly underestimate the response, especially for deep deposits and high frequency motion.