Research on the seismic responses of frame construction on sand-gravel cushion

The main purpose of this paper was to study what impact the sand-gravel cushion may make on seismic responses of frame construction on it. This paper uses a reinforced concrete frame construction on the sand-gravel cushion as the analytical model, and two calculating models were made in finite element method for it, one is the reinforced concrete frame construction with sand-gravel cushion under it, the other is the same superstructure but with rigid foundation. The seismic responses of the 2 calculating models were calculated in time history method. By comparing the seismic responses of the reinforced concrete frame structure on sand-gravel cushion and the seismic responses with rigid foundation, it was found that with sand gravel cushion under the constructions, the displacement of the construction at the bottom of the structure increased a little while the displacements of the other floors all decreased, and the acceleration responses of the constructions on sand-gravel cushion all decreased comparing to the construction without sand-gravel cushion. As the results show, the sand-gravel cushion served as a vibrating isolation in a certain extent, that the seismic displacement and acceleration responses of the constructions on it all decreased.