two-dimensional dynamic analysis of alluvial valleys subjected to vertically propagating incident sh waves

This study presents the formulation of a finite-element numerical method for the analysis of shear wave dispersion out of plane sh. also, it evaluates the seismic behavior of alluvial valleys located in a semi-infinite rigid space. this formulation is implemented in computer codes in time domain. to examine the accuracy of the program, various examples are solved and some numerical considerations in the dynamic analysis of the topographic feature are investigated by parametric studies. the results indicate that the appropriate time step in the finite-element method (fem) is 45/1000 of the predominant period of the incident wave. the appropriate length of the element should be selected for placing at least eight nodes on the smallest wavelength. increasing gaussian points in integrating mass matrices in comparison with stiffness matrices is not effective in the accuracy of results. it was found that the choice of δ > 0.5 in newmark’s integration method reduced the amplitude, but the change in the $$alpha$$ value did not affect the results. the effect of a feature on the ground response is only noticeable if the wavelengths are comparable with the dimensions of the feature.