Effect of Ground Motion Magnitude and Poisson's Ratio on Site Response Analysis for Clay Soil

Abstract

Studying small sites and analyzing their response are considered important tasks for studying the surface structures’ response and the surrounding soil

deformations, in addition to studying the soil-structure interaction between these structures and the soil beneath and surrounding them. The site response analysis significantly affects practical and theoretical practice for structural and geotechnical engineers. Furthermore, the selection of ground motions influences the analysis results. This paper examines the effect of the ground motion magnitude on site response analysis of clay soil by adopting a three-dimensional soil model with a compliant base, and appropriate boundary conditions. These include quiet and free-field boundaries, and advanced complex nonlinear constitutive models for soil materials. Nonlinear dynamic analysis is adopted; using three real earthquakes with different classifications: major, strong, and moderate. This is used to obtain more reliable results. The effect of Poisson’s ratio on the studied soil is evaluated by changing its value. It can be observed that PGA ratio amplification at the soil surface differs according to the frequency content and amplitude of the applied earthquake. It is important to adopt the nonlinear behavior of the soil, as the octahedral shear strains and settlement values are higher than those of soils with a linear behavior. It is also necessary to emphasize the adoption of the dynamic values of Poisson's ratio and other parameters required to characterize the soil when performing the dynamic site response analysis.