Experimental Research On Simple Seismic Isolation Measures For Masonry Structures In Villages

With the continuous development of isolation technology,it can be flexibly used in all kinds of buildings,but it's high-cost and inconvenient construction make it difficult to popularize and apply in villages or some underdeveloped areas.In view of the above shortcomings,this paper proposes a new simple isolation measure to improve the seismic capacity of masonry buildings in villages,which is composed of simple cross-slot isolation bearing and sand cushion.Simple crossshaped groove isolation bearing has the advantages of high performance,low cost,light weight and easy construction.Sand cushion can simplify the construction of isolation layer,and dissipate seismic energy by sliding friction with frist floor when buildings are subjected to reciprocating seismic action.Through research and analysis,the following conclusions and research results have been achieved:(1)Firstly,the manufacturing process of simple cross-clamped groove isolation bearings is studied,and then the mechanical properties of the bearings are tested.The results show that the bearing has the advantages of simple fabrication process,low cost,light weight,good bearing capacity and horizontal deformation performance,and can meet the application requirements of practical engineering.The test results show that the vertical stiffness of the bearing is 187.8 kN/mm under base level pressure,0.2096 kN/mm under 100% horizontal shear strain,the maximum allowable vertical pressure of the bearing design is 12 MPa,and the shear strain limit value is 250%.(2)Shaking table tests were carried out on a masonry structure model with cross-shaped groove and traditional anchor-bar isolation bearings.By comparing and analyzing the structural response characteristics of non-isolation structure model and two isolation structure models under different earthquake input,the isolation effect of the two kinds of bearings is evaluated comprehensively.The test results show that the two kinds of isolation bearings have good seismic absorption effect,which makes the upper structure of the model in elastic state under different seismic excitations.Among them,under rare and unusual earthquakes,the inter-story displacement of the cross-slot bearing model is reduced by more than 50% compared with that of the non-isolation structure model.(3)Design the typical buildings in villages of Yunnan Province,and build the isolation layer composed of simple cross-shaped isolation bearing and sand cushion.Through the shaking table test,the effectiveness of the combined simple isolation measures is further verified,and the isolation effect is evaluated comprehensively.The test results show that the acceleration response of each layer of this model is obviously reduced.Especially under rare earthquakes,the displacement of this model is reduced more than 60%.(4)Static pushing test.By comparing the results of mechanical properties test,shaking table test and static pushing test,the influence of sand cushion on the stiffness and damping of the whole isolation layer is analyzed.The test results show that the additional equivalent stiffness of sand cushion to model isolation layer is about 0.54 kN/mm,and the additional equivalent damping ratio is about 12.5%.After rare earthquake,the sand cushion loses its friction effect.(5)The combined isolation technology has been put into use in ** Town,** County,Yunnan Province.Through the investigation and study of the structural design and isolation layer construction technology of the pilot project,it can provide guidance and help for the actual construction of residential isolation buildings in villages and towns.However,considering that the sand cushion will be easy to cake and sink after a long time of static,and even lose the frictional effect,the sand cushion is not included in the calculation scope in the structural design of buildings.