Mechanical Characteristics Of Plate Rubber Bearing And Force Performance Analysis Of Bearing/Bridge Pier Series System

Plate rubber bearings have the advantages of simple structure,reliable performance,convenient installation and replacement,and are widely used in small and medium span beam bridges.In the case of horizontal load or displacement of beam,friction slip and shear deformation of plate rubber bearing can reduce the inertia force transmitted to pier,which is helpful to protect the safety of pier.In this paper,the shear deformation law,friction slip energy dissipation law,normal stress and shear stress distribution law of two commonly used sizes of plate rubber bearings in medium and small span bridges are studied.On this basis,the mechanical properties of the series system of bearings and piers are analyzed.The main research work is as follows:The experimental study on shear deformation and friction slip of plate rubber bearings was carried out.The parameters such as the interface connection mode between the support and the contact body,the axial compressive stress and the size of the support are taken into account in the test.The test results show that with the decrease of axial compressive stress,the sliding displacement,void and hysteretic curve area of the support increase significantly,and the total energy dissipation capacity increases significantly,but the effective shear strain of the support is limited.The equivalent shear strain of sand paper bearings on both surfaces can reach 130%~160%.There is no relative sliding between the bearings and the loading body,which improves the performance of the equivalent shear performance.The equivalent shear strain of sand paper bearings on both surfaces decreases obviously,but the sliding displacement is larger.For smaller supports with different geometric sizes,the changes of axial compressive stress and interface connection mode have significant effects on their shear properties..Based on the shear slip test of plate rubber bearings,the mechanical behavior of plate rubber bearings with different interface connection modes was analyzed by usingABAQUS software.The hysteresis curve and equivalent damping ratio of 300 mm *63mm(B1 series)bearings were compared with the numerical simulation results to verify the feasibility of the finite element analysis method.On this basis,the horizontal force-displacement curve,normal stress distribution and shear stress distribution of the support are analyzed.The results show that the order of maximum normal stress from large to small is unbound support > single-side binding support > double-side binding support,which shows that the slip of the support increases its normal stress,and the bearing and contact surface are fixed as far as possible in the design and construction of the support to prevent the stress of the support from exceeding the limit.The shear stress distributes asymmetrically along the width of the cross-section,and the shear stress is about 10% of the normal stress,which is not the main factor of bearing failure.Finite element numerical analysis of series system under horizontal load is carried out.According to the horizontal force balance coordination equation of series system,the calculation formula of series system is deduced.Through XTRACT software,the moment-curvature and horizontal force-displacement of pier are analyzed,and the relationship between pier damage and bearing deformation at different loading stages is deduced based on the calculation formula of mechanical relationship of series system.The finite element analysis proves that the slip of the bearing can reduce the damage of the pier by 5% from the aspects of horizontal force,displacement and plastic compression strain of the pier.In addition,the deformation of pier results in the uneven distribution of bearing stress.