The estimation of the site effects represents a key component in any local seismic hazard analysis. Equivalent-linear is a widely used approach to evaluate these effects on propagated ground motion. It mainly relies on the choice of a complex shear modulus G*. Several existing G* expression that depend on damping β were tested. However, at high damping, either the stiffness is overestimated or the dissipated energy is underestimated. An expression of the complex shear modulus was defined. Despite theoretical results showing that it better represents the layer properties, it was never tested. The objective of this paper is to validate these theoretical results and to prove the capability of the proposed formulation to improve equivalent linear method. Indeed, the formulation was implemented through a MATLAB program. Then, simulations based on the proposed expression as well as the existing ones were conducted and the obtained results were compared. These results show that the differences in the site responses are highly influenced by the values of damping. Indeed, when the maximum deformation exceeds 0.1%, the damping values exceed 10%. This level of damping can overestimate seismic soil response when using the existing expressions.
Keywords: Site effect, Complex shear modulus, Damping, Amplification, Response spectra.