Abstract
A soil has various damping mechanism such as internal viscous damping, hysteretic damping by material nonlinearity and radiation damping in wave motion. The dynamic behavior of a soil layer subjected a strong earthquake motion is in highly strained state under the above damping effects. So as to estimate the vibrational characteristics of highly strained and nonlinearly-behaved soil layers, one layered ground on the elastic base is solved by the equivalent linearization technique by use of complex eigen value analysis. The surface motion and in-ground behavior are clarified by examining the transfer function of the layer on surface response, strain distribution in a layer and corresponding strain-dependent rigidity reduction and hysteretic damping. The effect of the viscous damping, hysteretic properties and base condition on the ground response is discussed. The importance of damping effects and material nonlinearity under strong earthquake are presented.
