Research On Vertical Displacement Of Laminated Rubber Bearing Under Earthquake

As a widely used bearing in the field of isolation,laminated rubber bearing has shown good isolation effect and economic applicability since its appearance,and has been widely used in practical engineering.However,the rubber bearing of high-rise isolation structure may be damaged and overturned in the high intensity area.The vertical ultimate tensile stress of laminated rubber bearing is far less than the vertical ultimate compressive stress,so the bearing shall be avoided as far as possible in the design.If it is unavoidable,the design process will also try to ensure that the tensile stress is less than the bearing limit Tensile stress.The problem of isolation bearing tension has become one of the main obstacles in the application of high-rise building isolation,which limits the promotion of high-rise isolation.For this reason,a large number of different types of tensile devices for isolation bearings have been designed and studied at home and abroad.But at present,the tension device is mostly used as a separate research object,and the influence of bearing deformation on the use effect of the tension device is seldom considered,especially the vertical deformation of the support is almost ignored.The increase of the vertical deformation displacement of the support will reduce the distance between the upper and lower flange plates.If the tension device does not reserve enough working clearance,it may lead to the failure or even damage of the device.In order to study the tensile device more reasonably,the deformation characteristics of the isolation bearing should be studied more thoroughly,and the following problems should be considered:First of all,at present,the research on the deformation characteristics of laminated bearing is mostly static analysis of the bearing under certain vertical load and horizontal thrust,less consideration is given to the influence of the joint action of vertical load and dynamic effect on the deformation characteristics of the bearing,which can not fully reflect the mechanical properties of the bearing in the actual earthquake,so the dynamic analysis of the bearing under the action of seismic wave is It is necessary.Secondly,in a large number of research literature on rubber bearing,rubber isassumed to be incompressible.However,in the process of earthquake,the upper and lower layers of the bearing will produce relative displacement,which will reduce the bearing compression area,and the force transmitted from the upper structure to the upper part of the bearing will also change,and the vertical and horizontal displacement of the bearing will change accordingly.If it is assumed to be an incompressible material,the vertical displacement of the bearing can be ignored,but the vertical displacement of the bearing will affect the effectiveness of the tensile device,which should be considered.In view of the above two problems,the research is carried out,mainly including the following work:(1)The unidirectional horizontal compression shear test and 100% cyclic compression shear test were carried out for laminated rubber bearing(lnr500).During the experiment,the vertical displacement and the lateral displacement of the rubber bearing are monitored,and the relationship curve between the vertical displacement and the lateral displacement is obtained.(2)The mechanical properties of the rubber material and steel used in the bearing were tested,and the mechanical parameters of the material were obtained.According to the experimental data,the ideal elastic-plastic constitutive model is selected for steel and Yeoh constitutive model is selected for rubber.The finite element analysis and Simulation of the bearing are carried out.The simulation results are in good agreement with the experimental data.(3)Then the LNR600 and LNR700 were analyzed by using the material parameters of lnr500,and the simulation data of LNR600 were compared with the test data,the results were in good agreement.Through the simulation data,the change curves of the horizontal and vertical stiffness of LNR500,LNR600,LNR700 and the horizontal displacement of the support are obtained.In order to easily read the values of the horizontal and vertical stiffness in the project,the regression equation is fitted with the relationship curve.(4)The time history analysis of the vertical and horizontal deformation of laminated rubber bearing under the action of earthquake is carried out,and the time history curves of displacement,velocity and acceleration are studied.