NONLINEAR SITE RESPONSE ANALYSIS BY COUPLING SCALED BOUNDARY FINITE ELEMENT METHOD AND FINITE ELEMENT METHOD

This paper presented 2D numerical linear and nonlinear site response analyses based on the scaled boundary finite-element method (SBFEM) and compared their results with those of the DEEPSOIL software. In linear time-domain analysis, the seismic boundary traction was applied to lines in the near-field with the same vertical coordinates using seismic time history load. The far-field was modeled utilizing an improved continued-fraction-based high-order transmitting boundary. The constitutive relationship of the boundary was determined utilizing the SBFEM equation in the dynamic stiffness model. It was shown that the results of the SBFEM had a good agreement with those obtained from the DEEPSOIL software. The results of spectral acceleration demonstrated period lengthening. The nonlinear site responses were analyzed using both the DEEPSOIL software and the coupling of SBFEM/FEM. The one-dimensional nonlinear site response was analyzed using the tools in the DEEPSOIL software including the strength correction, pressure-dependent modulus reduction, and the damping ratio curve of sand. In the nonlinear-coupled analysis, the bounded domain was also modeled in OpenSees using a pressure-dependent multi-yield plasticity soil model. The comparison of the results demonstrated the accuracy of the nonlinear analysis using the coupled SBFEM/FEM. The coupling method underestimated spectral acceleration in low periods compared with the DEEPSOIL software. The absolute residual was also obtained less than 0.2.