The Research Of Site Dynamic Effects On Topography

The code for seismic design of buildings proposes that site with the character of extensive, flat, dense, uniform is good for seismic resistance, while an area with irregular spur and isolated high hills is opposite. Sometimes structures have to be built in or around these places. There is no detailed description of unfavorable site conditions for seismic resistance in the code, so much of research attention should be paid on the influence of these unfavorable site.This paper does a research on the influence of site geography under the effect of earthquake, which is based on numerical simulations with the help of Midas GTS and ABAQUS. There are two models of different site conditions in this paper. The analysis results show that:1. The altitude has great influence on amplification effect of PGA. The higher of the site geography is, the stronger amplification effect of PGA is. The model simulates three different type topographies of hill, flat land and valley, and the results show that PGA decreases when the altitude of the topography becomes smaller.2. The site geography shows a vital influence on amplification effect of PGA. The amplification effect of a single isolated hill is larger than that’s of valley,flat land and a couple of mountains.3. The angles of peak and valley are very important for amplification effect of spectral ratio. When the angles change from100°to160°, the spectral ratio increases with the increasing of angles in the peak area. The two parameters show nearly linear correlation, and the coefficient is between-0.0056and-0.0049. The two parameters also have linear correlation in valley areas, but the coefficient changes between0.0051and0.0057.4. Spectral ratio curve and site geography have same change disciplines. When the site altitude raises, the spectral ratio increase. When the site geographies turn to flat land, the spectral ratio remains invariant.5. The correlation relationship between spectral ratio curve and topography curve in stone layer is better than in soil layer.