ABSTRACT
Dynamic analyses to evaluate the response of soil deposits and earth structures to seismic load applications have been finding increased application in geotechnical engineering practices. Seismic response analysis, taking into account the effects of the nonlinear nature of soil deformation, can be made either by the equivalent linear method or the step-by-step integration method. The response analysis to such high-intensity seismic loading often produces shear strains in the soil deposits that are greater than a few percent and are almost on the verge of failure. It has been known that the stress-deformation characteristics of soils vary to a large extent depending upon the magnitude of shear strains to which soils are subjected. The shear modulus and damping ratio determined as functions of shear strain are the key parameters to represent soil properties in this medium strain range. The rule for constructing the unloading and reloading branches of the stress-strain curves as above is referred to as the Masing rule.
