Quasi-static Test Study On Seismic Performance Of Prefabricated Bridge Pier

Bridge assembly construction technology is gradually becoming the main development direction of current bridge engineering.The main advantages of prefabricated assembly members are: fast construction progress,high construction quality,and small environmental impact,etc.So far,the prefabrication technology has been widely used in bridge superstructures,and the application of substructures has been quite popular abroad.However,the research and technical accumulation of prefabricated bridge substructures in China are still very scarce,and there is a lack of relevant theoretical research reserves.Most of the structures using prefabrication technology are applied in non-strong earthquake regions,and there are many strong earthquake regions in western China and even the whole country.This technology has not been widely promoted in strong earthquake regions,which has largely prevented the prefabrication technology from being used in our application.The main obstacle that restricts the application of segment-assembled bridge pier technology in strong earthquake areas is incomplete understanding of its seismic performance.Insufficient research on the seismic performance of joints is the focus and difficulty of current research.Existing experiments in foreign countries have relatively rich seismic performance of the segment-assembled pier columns connected by dry joints and glue joints.At present,there are few pseudo-static experimental studies on the seismic behavior of segment-assembled bridge pier in China,and the theoretical research lags behind the engineering application.It is urgent to carry out research in this area to provide guidance for the seismic design of prefabricated bridge piers.In order to study the failure principle and energy dissipation mechanism of prefabricated pier with different connection structures,it provides a theoretical basis for the seismic design of prefabricated pier.This paper uses a combination of scale model tests and numerical and theoretical analysis to analyze the seismic performance of prefabricated bridge piers with different connection structures.Main work and research are as follows:1、Through literature research,the general connection structure of prefabricated pier is summarized,and the influence of different structures in the design process on various aspects of the seismic performance of the pier is explained.The status of experimental and theoretical research on prefabricated pier at home and abroad is summarized.2、Taking Jiangxi Qiaonancun overpass as a prototype,4 different pier test pieces were designed and manufactured with a 1: 5 scale ratio,including integral cast-in-situ pier,corrugated pipe connection pier,tenon+ corrugated pipe connection pier,and steel sleeve connection pier;A pseudo-static test was performed on it,and the failure process of each test piece was summarized by observing the test phenomena.The results showed that the failure modes of the four pier piers were bending failures,and the damage area of the cast-in-situ pier was large,mainly concentrated.Within a distance of 30 cm from the joint of the pier,the concrete collapsed in the area of the plastic hinge,and the longitudinal tendons buckled to cause damage.The three types of prefabricated bridge piers were mainly damaged at and near the joints.Finally,the joints were too large and the crushing of concrete caused the structure to lose its bearing capacity.3、The seismic indexes of different specimens such as hysteresis curve,ductile deformation,energy dissipation capacity and stiffness are compared in detail.Compared with the integral cast-in-situ pier,the three precast piers have similar seismic performance to the cast-in-situ pier in terms of overall energy consumption,ductility,and stiffness degradation despite the different damage status.4、Under the same level of horizontal load,the piers with the new connection structure of tenon + bellows are slightly better than the other two prefabricated piers in seismic performance such as cracking,overall energy consumption,ductility,and strength and stiffness degradation,indicating that the prefabricated bridge pier of this connection structure has better seismic performance.5、ABAQUS finite element software is used for numerical simulation.The comparison results show that the calculated results agree well with the measured data,which shows that the finite element modeling method used in this paper can reasonably and effectively simulate the mechanical performance of the bridge pier.Based on the results of the finite element analysis,the effects of parameters such as axial compression ratio,longitudinal reinforcement ratio,and cross-sectional shape on the seismic performance of the pier were investigated.It was found that within a certain range,the larger the axial compression ratio,the greater the peak load of the specimen,the greater the power consumption.The stronger the energy,the smaller the residual deformation;the larger the longitudinal reinforcement ratio,the larger the peak load of the specimen,the stronger the energy dissipation capacity,and the larger the residual deformation;the peak load,energy consumption and ductility of the rectangular pier are better than those of the circle Shaped pier.6、Based on the analytical method,the force-displacement curve and the moment-curvature relationship of the cross section of the plastic hinge region under the action of horizontal load and vertical force are theoretically derived.The static test results were compared and the results were found to be similar.Finally,the test data is fitted to obtain the proposed formula for calculating the shear capacity of the joints of prefabricated bridge piers.