A Constitutive Model to Capture Asymmetric Behavior of Soil Under Dynamic Loading

Seismic response evaluation of the site of interest subjected to a particular bedrock motion is one of the most important problems in earthquake geotechnical engineering. A stress–strain relationship is needed in a complete nonlinear time-domain site response analysis. Mostly used, Massing rule does not incorporate asymmetric behavior of the soil. Researchers had showed that the hysteresis loops become progressively asymmetric with increasing shear strain. Most of the available stress–strain relationships provide greater hysteresis damping for medium to large strains compared to the damping values obtained in dynamic tests. In the present study, a Bouc–Wen class model is proposed to capture the asymmetric behavior of soil at high cyclic shear strain. The model parameters are calibrated against cyclic triaxial experimental results of saturated sand available in literature. The calibrated model could successfully capture the stiffness decay, loss of strength and asymmetric behavior of saturated sand for higher cyclic shear strain.