Experimental Study On Seismic Performance Of Precast Piers With Different Connection Methods

Precast piers have the advantages of high efficiency,environmental friendly,and little impact on the surrounding traffic environment.The application of precast piers in rail transit bridges is increasing,and the segment connection methods have important influence on the mechanical behavior of precast piers.A vase pier of rail transit is taken as the research object in this thesis and the seismic performance of precast piers with different connection methods is studied through experiments and numerical simulation.The main work and results of this thesis are as follows:(1)Considering different connection methods of cast-in-place connection,taper sleeve lock connection,grouting sleeve connection and unbonded prestress connection,five 1:3 scale test models of precast piers are designed and manufactured.The quasi-static numerical simulation analysis of the test models are completed,and the test loading scheme is determined.(2)The quasi-static tests of the five precast piers are completed,and the influence of different connection methods on the seismic performance,failure mode,crack development and stiffness of precast piers are analyzed.The results show that: taper sleeve lock connection is basically the same as the cast-in-place connection;the grouting sleeve connection can greatly improve the bearing capacity of piers,but also reduce the ductility.Unbonded prestressed connection can greatly improve the self-recovery ability and initial stiffness of precast piers.(3)The effects of joint position,dead load axial compression ratio,longitudinal reinforcement ratio,arrangement and initial tension of unbonded prestressed tendons on the seismic performance of precast piers are studied.The results show that: the effect of setting joints outside the plastic hinge area of the precast pier on the seismic performance can be ignored;increasing the dead load axial compression ratio can improve the bearing capacity and initial stiffness of the precast pier,while reducing the ductility;increasing longitudinal reinforcement ratio can significantly improve the bearing capacity and energy dissipation capacity of the precast piers;the prestressed tendons should be arranged at the four corners of the cross section of the pier body,and the initial tension of the prestressed tendons has little effect on the seismic performance of the precast pier.