Jafar NAJAFIZADEH - PhD Candidate of Geotechnical Engineering Research Center, IIEES, Tehran, Iran
Peyman AMINPOUR - Graduate Student of Geotechnical Engineering Research Center, IIEES, Tehran, Iran
Mohsen KAMALIAN - Associate Professor of Geotechnical Engineering Research Center, IIEES, Tehran, Iran
Mohammad Kazem JAFARI - Professor of Geotechnical Engineering Research Center, IIEES, Tehran, Iran

This paper is concerned with the problem of soil amplification and seismic site effects due to the local topographical and geotechnical characteristics. It focuses on 2D triangular alluvial valleys subjected to vertically propagating incident SV waves. The medium is assumed to have a linear elastic constitutive behaviour. All calculations are executed in time-domain using the spectral finite element method. Clear perspectives of the amplification patterns of the valley are presented by investigation of the frequency-domain responses. It is shown that the amplification pattern of the valley and its frequency characteristics depend strongly on its shape ratio. The maximum amplification ratio along the ground surface occurs at the center of the valley. A simple formula has been proposed for making initial estimation of the natural period of the valley in site effect microzonation studies. The natural frequency of the triangular alluvial valley decreases as the shape ratio of the valley decreases.

Triangular Alluvial Valleys, Amplification, Site Effects, Topography Effect, Spectral Finite Element, Wave Propagation