The Seismic Performance Study Of The Cross-bridge Of The Pier-Bent Cap-Box Girder System

As an important component of transportation facilities,the continuous box girder bridge is a kind of structural form commonly used in urban elevated and partial cross-river bridges,and its stability and safety under earthquake action play an extremely important role.However,the excessive displacement of the transverse bridge and the failure of the pier are the main forms of seismic damage for continuous bridges in recent years.With the rapid development of seismic concept and technology,the design concept of bridge based on ductility is widely used.However,due to the ductility design,the mechanism of the plastic hinge energy dissipation of the pier is used to cause large residual deformation after the earthquake,which affects the normal use of the pier.A new type of self-resetting pier that can effectively control residual deformation enters the field of view.Based on the above background and the continuous box girder bridge,the theoretical analysis and numerical simulation of the Pier-Bent cap-Box girder system are carried out.The main contents are as follows:(1)The background of seismic research of bridges is briefly introduced.The main seismic damage forms of continuous bridges under earthquake action are analyzed.The importance of continuous bridge transverse bridge and seismic design of bridge piers is emphasized.This paper reviews the evolution of seismic design thinking from the abilitybased seismicism to the performance-based seismic thinking and the history of self-resetting bridge piers.(2)The influence of the inevitable pile-soil effect of the bridge was studied.The models of the Pier-Bent cap-Box girder considering the pile-soil effect and bottom consolidation was established by using Midas software.The response of the structural components of the pier,the bent cap and the box girder to the earthquake under the earthquake was analyzed.The influence of the pile-soil interaction on the seismic performance of the transverse bridge of the system was studied.(3)The influences of the section form of the rectangular pier,concrete strength,longitudinal reinforcement and stirrups on the ductility of the control section of the pier are analyzed systematically.The formula of bending moment-curvature curve based on control section and Pushover analysis method are compared to calculate the error of elastoplastic displacement of double-column rectangular pier.(4)Based on the design concept of ductile seismic resistance,the ductility of the pier is improved by changing the concrete strength of the pier,the longitudinal reinforcement ratio and the volumetric hoop ratio,and the seismic performance of the bridge is improved,and the seismic performance of the transverse bridge is improved.The general relationship between the force of the cover beam and the box girder and the parameters of the pier column is studied.(5)Applying the concept of self-reset to the double-column pier,starting from the basic concept,structural composition and force mechanism of the self-resetting pier,combined with Abaqus finite element software,the double-column self-resetting pier model and the ordinary double-column pier are established.The model analyzes the seismic performance of the pier by comparing the force form,hysteresis curve and skeleton curve of the pier.