Study On The Compression Shear Mechanical Properties Of Rubber Bearing And Analysis Of Its Isolation Performance

Earthquake is a kind of sudden and destructive natural disaster,which can destroy a city in an instant and cause extensive casualties.Although the traditional seismic methods can ensure the integrity of the structure and prevent it from collapsing in the earthquake,the components in it have often been deformed or even destroyed.In recent years,with the deepening of research,isolation design has become a new method to replace the traditional seismic design.As a key device in isolation design,rubber bearing has been widely concerned by researchers due to its economy and practicality,and has a huge development prospect.Due to the particularity of rubber bearing structure and the complexity of rubber material performance,the calculation of vertical stiffness of rubber bearing is still not accurate enough,and the distribution of stress and strain under shear is also lack of research.There is often a large error between the theoretical design results and the actual results.In view of the above problems,this paper has carried out the relevant finite element analysis of the rubber bearing.The main research contents and results are as follows:(1)Using ABAQUS finite element analysis software,several groups of rubber bearing models were established,and the influence of various factors such as the diameter of the middle hole and the thickness of the rubber layer on the vertical stiffness of the rubber bearing was studied.The results show that the vertical stiffness of rubber bearing with middle hole is smaller than that of rubber bearing without middle hole under the same condition,and the error between them presents a certain regularity;The vertical stiffness of rubber bearing is highly sensitive to the thickness of rubber layer,and the deformation of rubber layer plays an absolute role in controlling the vertical stiffness.Increasing the thickness of rubber layer will greatly reduce its vertical stiffness;The vertical stiffness of rubber bearing is positively related to the thickness of steel plate layer,but the influence is negligible;Shear modulus has more influence than bulk modulus,but it is suggested to control the vertical stiffness of rubber bearing from two aspects of bearing diameter and rubber layer thickness in the design process.(2)A rubber bearing was subjected to 100% and 300% shear,and the internal stress and strain of the rubber bearing under different shear were studied.The research results show that under 100% horizontal shear,the steel plate layer is in the elastic deformation stage,and most of the rubber is in the compression state.The peak value of the main tensile stress of the rubber is 2.79 MPa,which appears at the lower part of the middle hole of the third layer of rubber,far less than the rubber tensile stress specified in the national standard.The rubber bearing is in good condition.Under300% horizontal shear,all steel plates yield to varying degrees.Compared with 100%horizontal shear,most rubbers change from compression to tension.The main tensile stress of a small part of rubbers exceeds 15 MPa,and the peak value of the main tensile stress is 74.32 MPa.The rubber bearing in this state may have been damaged and needs to be repaired.(3)The horizontal stiffness of rubber bearing can keep stable under 250%horizontal shear;Under 300% horizontal shear,the hysteretic curve of rubber bearing is no longer linear,and the horizontal stiffness is reduced to a certain extent.Under two different shearing conditions,the maximum Mises stress of the steel plate layer appears in the lowest steel plate.In practical engineering,strengthening treatment can be considered for the lowest steel plate.(4)The isolation model and non isolation model of a frame structure are established using SAP2000 software,modal analysis and seismic time history analysis are carried out,the principle of isolation design is verified,and the effect of isolation structure under rare earthquake is analyzed.The analysis results show that the reasonably designed isolation structure can significantly reduce the seismic action,including the top floor acceleration reduction of 63.4% ～ 73.3%,the inter story displacement reduction of 35.5% ～ 46.5%,and the base shear reduction of 51.2% ～64.0%.The isolation effect is similar to reducing the earthquake action by one degree,which can effectively protect the personnel in the structure and reduce the possibility of damage to the structure.Figure [50] Table [17] Reference [81]...