STUDY ON SHEAR PERFORMANCE OF COMMON PLATE RUBBER BEARING IN AGED SITUATION

As an important supporting member, the ordinary plate rubber bearing is widely used in highway reinforced concrete girder bridges in China. The aging mechanical properties of rubber bearings affect the performance and safety of structures locally or entirely. Considering different parameters of aging rubber material, axial compressive stress and bearing geometry configuration, the shear performance of aging rubber bearing in different stress stages is studied. The shear performance tests of 6 ordinary plate rubber supports are designed and carried out, and the shear strain-stress curves, shear modulus, horizontal displacement-force relationship and shear stiffness are obtained. The finite element numerical simulation method is used to analyze the shear performance of the aging bearings, and then the finite element analysis results are compared with the test results. The results show that the effect of rubber aging on shear performance of the bearing is small when the equivalent aging age of rubber is less than 20 years; however, when the equivalent aging age of rubber is greater than 50, the shear modulus and shear stiffness increase, while the shear deformation ability decreases. The influence of rubber aging on macroscopic shear stiffness of the bearing is significantly greater than that on shear modulus. In addition, the simulated shear stress-shear strain curve, horizontal displacement-horizontal force curve and aging shear stiffness are consistent with the test results, and the difference between the simulation results and the test results decreases gradually with the increase of shear deformation. When the shear deformation reaches 100%, the simulated shear stiffness of the bearing is different from the test results by 20.4%, and different from the theoretical calculation results by 21.2%. The environmental conditions, vehicle load and accidental load may accelerate the aging speed of rubber bearing in actual bridges, and the aging effect should be taken into account in the calculation of shear performance.