Improved equivalent mass-spring model for seismic response analysis of two-dimensional soil strata

This paper presents an improved development of the mass-spring model initially proposed by Okamoto and Tamura for seismic response analysis of two-dimensional soil strata. The new model is based on the mode equivalence method and is constructed as a two-dimensional equivalent multi-degree-of-freedom (MDOF) system. Physical parameters of the model are derived and formulated in terms of modal properties. Dynamic response of the model from inclined SH-waves is obtained and the accuracy and validity are confirmed by comparing with the solution of wave propagation. The improved model is further discussed through a performance comparison with the mass-spring model.