evaluation of ground motion amplification across empty valleys subjected to inclined sv waves using boundary element method

Many recorded earthquakes in last recent decades have shown that the damage distribution and seismic response of an area depends on source characteristics, pathway of seismic waves and also on local conditions of the site; these conditions can change the amplitude of displacement and frequency properties of ground movement. local site effects include geotechnical and topographical effects. unfortunately, most modern seismic codes consider geotechnical effects, and those who consider topographical effects, focus on simple geometries but other parameters such as wave characteristics are not taken into account; the main reason is lack of quantitative amplification predicting methods and practical information in topography constructions.2d seismic site effects in empty valleys are evaluated in present study. numerical analysis is carried out by hybrid software. hybrid is a nonlinear, two phase, code for solving 2d problems of propagation of the waves; this software combines f.e.m in near field and b.e.m in far field. empty valleys are modeled, with different shapes including rectangle, triangle and trapezoid and with depth ratios equal to 1, 0.8, 0.6, 0.4 and 0.2. oblique sv waves of ricker type are considered as seismic solicitation and its angle of incidence varies from -90º to 90º every 10º. it is shown that the incidence angle is able to change the maximum amplification and critical incidence angle of a half-space is changed by topography.