Research On Seismic Reinforcement Method Of Reinforced Concrete Bridge Pier

Bridge is an important part of the modern transportation system.As the hub of the traffic lifeline,it plays a vital role in evacuation during the earthquake and postearthquake rescue.Reinforced concrete(RC)bridge pier is a vulnerable component in the bridge structure under earthquake.At the same time,bridge pier is the key bearing structure of the bridge,which is important to maintain the seismic performance of the bridge.Once it is damaged,it will lead to the falling of the beam or the overall collapse of the bridge.Therefore,how to improve the seismic performance of RC pier has attracted more and more scholars’ attention.Based on the OpenSees finite element software,this paper analyzed and compared the seismic response of the bridge pier after being reinforced by steel tube,carbon fiber reinforced polymer(CFRP)and external prestressed tendons.At the same time,the influence of three kinds of steel pipe reinforcement methods(full-height reinforcement,tube reinforcement and local reinforcement at the bottom of pier)on the seismic performance of RC pier is discussed,in order to provide reference for the seismic reinforcement and reconstruction of RC pier.The main research contents and conclusions of this article are as follows:(1)The numerical model of RC pier was established by using Open Sees software in which the bond-slip deformation was considered,and the pseudo static test and shaking table test of RC bridge pier were simulated by using this model.The results show that the hysteretic curve calculated by the numerical model is in good agreement with the test curve,and the displacement time history curve obtained by the numerical simulation is in good agreement with the shaking table test results.(2)The numerical models of reinforced concrete bridge piers strengthened by steel tube,external prestressed reinforcement and CFRP sheet are established.Through time history analysis,it is found that the three reinforcement methods can effectively reduce the peak displacement and residual displacement of RC bridge piers.Under the action of remote fault ground motion,the steel tube reinforcement method had the largest reduction in the peak displacement of the pier.Under the action of near fault pulse-type ground motion,The external prestressed tendons reinforcement method had the largest reduction in the peak displacement of the pier.Whether under the action of far-fault ground motion or near-fault pulse ground motion,The external prestressed tendons reinforcement method had the largest reduction in the residual displacement of the pier after the earthquake,and the residual displacement suppression rate can reach more than 60% under different shear span ratios.(3)The RC pier was reinforced with round steel pipes for full-height reinforcement,tube reinforcement,and local reinforcement at the bottom of the pier.The elastoplastic analysis of hysteretic performance showed that the degree of improvement of the bearing capacity and energy consumption capacity of the bridge pier by each reinforcement method in order from large to small is: full height reinforcement,local reinforcement at the bottom of the pier,and casing reinforcement..The results of dynamic time history analysis show that the restraint effect of full height reinforcement on the peak displacement response of pier was always the best.Full-height reinforcement can significantly enhance the bending performance of the pier,local reinforcement can slightly improve the bending performance of the pier,and tube reinforcement has little effect on the bending performance of the pier.