Experimental Study On Mechanical Properties Of Friction Sliding Isolation For Bearing Stone Wall

Stone structure is the main structural form of the rural residential buildings in the southeast coastal areas of china.However,due to the stone-is a brittle material and most of them are built with dry-laid method,a large number of stone structures have significant seismic safety hazard.In order to improve the seismic performance of stone structure buildings,the friction properties of granite interface and the friction sliding isolation technique of stone structures are studied in this paper.The low cyclic loading test of 10 groups of double shear specimens was carried out.The friction properties of three kinds of stone interfaces,including machine-cut surface,polished surface and bush-hammered surface,were studied under different vertical compressive stress levels.The hysteretic behavior,friction coefficient and its changing law of different stone interfaces were analyzed.The test results show that:(1)The hysteresis curves of three different stone interfaces are rectangular,basically accord with the Coulomb friction model.(2)The largest static friction coefficients between different stone interfaces are between 0.51-0.61.(3)The dynamic friction coefficients between different stone interfaces are between 0.71 and 1.06.After six times cyclic loading,the dynamic friction coefficients are basically stable and from large to small in turn are machine-cut surface,polished surface and bush-hammered surface.Two kinds of friction sliding isolation techniques that are suitable for stone structures are proposed,including steel-stone friction sliding isolation and double steel friction sliding isolation.The low cyclic loading tests were carried out on double shear specimens,and the feasibility of two kinds of simple friction sliding isolation techniques is studied.The test results show that:(1)The hysteretic curves of steel-stone interface and double steel interface are approximately rectangular,basically accord with the Coulomb friction model.(2)The maximum static friction coefficients of steel-stone interface are between 0.28 and 0.45 under different vertical compressive stress levels.(3)The static friction coefficient of steel-stone interface increases with the increasing of cyclic loading times.(4)The friction coefficient of double steel interface is 0.23 at the beginning of sliding,but the friction coefficient increases with the increasing of cyclic loading times.(5)The friction coefficient of double steel interface lubricated with molybdenum disulfide is between 0.15 and 0.18,and the friction coefficient is stable,which can be used for friction sliding isolation of stone structure.The low cyclic loading test was carried out on a stone wall specimen with double steel friction sliding isolation,in order to study the hysteretic behavior of the wall specimen.The test results show that:(1)The hysteretic model of the wall specimen with double steel friction sliding isolation technique basically accords with the Coulomb friction model under reciprocating loading.(2)The friction coefficient of double steel friction sliding isolation stone wall is between 0.32 and 0.42 under the condition of less cycle times.(3)With the increasing of cyclic loading times,the dynamic friction coefficient has certain degree of increase.