Study On Flexible Limit Protection Of Isolated Structures

Seismic isolation technology is the most mature technology in seismic control currently,widely used in building and structures such as houses ? bridges and aqueducts.The seismic response of the isolated structure's supper part is very small,but the deformation of isolation layer is large.The structure may collapse as a whole when the horizontal displacement of the isolation bearing reaches the limit deformation.Need to limit the isolation bearing's horizontal displacement.Soft-impact limit protection is expected to achieve good effect.The following aspects of soft-impact limit protection research are discussed in this paper:(1)Design and manufacture of a "mountain" type rubber limit device,And the compression test was carried out.The load-displacement curve of the specimen under the top load is obtained and the maximum reaction force and stiffness that can be produced in the range of deformation are obtained.(2)In this paper,considering material nonlinearities,geometric nonlinearities and contact nonlinearities,nonlinear finite element analysis of "mountain" type rubber protected block under load is carried out by ABAQUS program in order to understand the evolution of deformation in theory computing.(3)Using the SAP2000 software to establish a concrete frame structure with base isolation to simulate the collision between the isolated structure and the "mountain" rubber limit device,and the displacement of the isolation layer,the interlayer displacement angle,the floor acceleration,the interlaminar shear force and the deformation of the limit device are analyzed.The results of the performance test of the "mountain" rubber limit device show that the device has the characteristics of perfectly elasticity,the variable stiffness(small stiffness in early stage and big stiffness in later stage)and certain ability of energy consumption,etc.Meet the requirements of soft collision protection limit device.ABAQUS finite element analysis show that the hyperelastic Mooney-Rivlin constitutive model can better simulate the deformation of therubber material in small deformation(less than 150%).The finite element computing results are agreed well with the actual measured ones,and for the parameters of the "mountain" type limit protective block estimation provides reference.The analysis results of the soft-collision limit protection of the isolated structure show that The disturbance caused by the limiter setting layer is unavoidable when collision between structures and limit device occurs,but it has little effect on the reaction of upper structure.Therefore the limit device is very effective to prevent the collapse of the isolated structure under the large earthquake.