The New Madrid Seismic Zone (NMSZ) is one of the most seismically susceptible areas in United States. Deep alluvial soil deposit of the Mississippi Embayment overlies the NMSZ, which remains a major uncertainty for site response analysis. based on the experiment data, a simple constitutive soil model is developed to take into account the influence of the effective confining pressure on the shear modulus degradation and the viscous damping development in soil, and also the shear strain and the plasticity index. This model is implemented into a two-dimensional finite element code in the time domain. the Rayleigh viscous damping scheme is applied in each finite element according to its shear strain level where the two significant modes of vibration are selected for damping matrix calculation. the new model is calibrated through the recorded motion at Treasure Island during Loma Prieta Earthquake (1989). Results show that this model could provide a reliable outcome with simple input parameters. the soil model is also implemented in a site response analysis in a Missouri bridge site near the NMSZ. the results are compared with those obtained from a SHAKE analysis. based on these comparisons, the importance of the influence of the confining pressure on the seismic site response is evident.


Civil, Architectural and Environmental Engineering

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Article - Conference proceedings

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Publication Date

01 Jan 2003