Study On Isolation Performance Based On New High Vertical Capacity Isolated Bearing Bridges

With the continuous improvement of the seismic isolation technology and the rapid development of bridge engineering,many long-span bridges have sprung up like bamboo shoots after a spring rain.With the increase of the span of the bridge,a higher requirement is put forward for the vertical bearing capacity of the support on the basis of its stable energy dissipation capacity.However,the widely used high-damping isolation rubber bearings and lead-core isolation rubber bearings at home and abroad are often used to meet the requirements of vertical bearing capacity,which often leads to large support sizes and inconvenient construction and installation.Therefore,based on the new materials,a new type of high vertical capacity isolated bearing with a design compressive stress of up to 35 Mpa was developed to provide more choices for the layout of bridge bearings.This article first introduces the new material and support structures,then determines the support restoring force model,carries out the bearing cyclic shear test,and fits the test data with the bearing restoring force model to obtain pre-yield stiffness,post-yield stiffness,yield force and other data.Then a horizontal friction test is carried out to obtain the sliding coefficient of the bearing.These data provide theoretical support for the bearing parameters in the subsequent Midas model.Then,the Midas model of continuous beam bridges with three different spans of 20 m,30m and 40 m is built.According to the principle that the vertical bearing capacity is equivalent,the three bearings of lead core isolation rubber bearings,high damping isolation rubber bearings and new high vertical capacity isolated bearing are selected.Then select seismic waves and conduct time-history analysis to obtain the model’s internal force,displacement response,bearing hysteresis curve and energy conversion and dissipation ratio for comparative analysis.It is concluded that the new high vertical capacity isolated bearing has good seismic isolation effect.Finally,the continuous beam bridge model under high fortification intensity is established,and the analysis result is compared with the model with relatively low intensity.The results show that,compared with the lead-isolated rubber bearing isolation system,the new high vertical capacity isolated bearing isolation system performs better under low fortification intensity;however,compared with the high-damping isolation rubber bearing isolation system,the new high vertical capacity isolated bearing isolation system performs better under high fortification intensity conditions.