Document Type : Research Article
Authors
1
M. Sc. Graduated, Department of Civil Engineering, Faculty of Engineering, Qom University of Technology, Qom, Iran.
2
Assistant Professor, Civil Engineering Depatrment, Faculty of Engineering, Qom University of Technology, Qom, Iran
Abstract
Topography and geological characteristics have significant effect on seismic response of structures. Most studies have focused on the amplification caused by a single topography. Limited research has been conducted on adjacent topographies. In this paper, the amplification of homogeneous and non-homogenous hills with semicircular and alternating geometry has been investigated. FLAC2D software is a finite difference program of Itasca software that is used for continuous environments. In order to investigate the effect of the distance between topography, intermittent semicircular hills are located at distances of 0.0, 0.5, 1.0 and 2.0 times the height of the hill. In order to investigate the effect of lateral hill height on the seismic amplification of the studied topography, the height of the side hill is 0.0, 0.0, 1.5, 2.0 and 3.0 times the height of the studied hill. The distance between the hills is half the height of the studied hill. In order to study the geometry of the side hill on the results of the resonance of the studied hill, the side hill is considered in triangular, semicircular and trapezoid geometry. The geometry of the studied hill is semicircular and the height of both hills is equal. Due to the semicircular geometry, ratio of height (h) to half the width of the hill(l), Equal to (h/l=1). The mesh sizes of the models are taken 2× 2 meters. In software modeling, the model boundaries should be considered so large that the waves reflected from the borders are almost dumped and have no effect on the results. The ratio of maximum displacement of the desired point in the model with topography (PGD response) (Peak Ground Displacement) to the maximum displacement of the desired point in the reference model (PGD reference) is expressed as magnification in displacement (UX). The obtained results in this research show that increasing the distance between the hills, decreases the amplification. The results show that increasing the height of the side hill up to 3 times the height of the studied base hill, increases the amplification up to 40%. The results indicate that geometry of the adjacent hill affects the seismic response of the base hill. Reducing the shear wave speed in the non-homogeneous hill reduces the amplification of the base hill compared to the homogeneous hill. For adjacent non-homogeneous hills, resonance increases, so amplification decreases in the homogeneous base hill.
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