Experimental Research On Seismic Reduced Function Sand Cushion Under Masonry Structure Foundation

Our country is a seismic country where earthquake frequently happens and where seismic area is widely distributed. The great earthquake of XingTai, HaiCheng, TangShan etc. in 1960's and 1970's caused huge calamity to people's lives and properties, which also gave us a miserable lesson. So it has become a serious problem to prevent earthquake and to reduce seismic lost effectively.In traditional anti-seismic design the anti-seismic safety property of structure is ensured by way of raising the function of strength and strain of the structural members. With intensive development of scientific research and experiments all kinds of assumptions and methods of seismic reduction and seismic isolation have been proposed as the times require.In this paper a kind of new method of seismic reduction is presented for multi-layer and low-raise buildings in most towns and countries. The new method draw raw material widely, cost little and handle easily. A certain thickness of sand cushion of a certain size or gradation is paved between the foundation and ground in this new method. When earthquake happens the sand cushion will have plastic shearing strain, reducing the input of high frequency volume, thus consume the earthquake energy form substrate. It is showed in shaking table experiments that there is relevant slippage between foundation and sand cushion, which can prevent the seismic energy from being passed to the above structure and thus reduced the seismic role for the above structure.In this paper, the seismic reduction function of sand cushion under masonry structure foundation and some possible factors that may have effect on its seismic reduction function are tentatively discussed through theoretical computation and shaking table experiments. It provides some foundation for sand cushion's application in civil engineering.