Study On Longitudinal Seismic Performance Of Railway Continuous Girder Bridges Based On Self-Centering Buckling-Restrained Braces

Because the railway continuous girder bridge has a large self-weight,especially the seismic system of one fixed pier in a continuous bridge is easy to be damaged under earthquake,the seismic isolation design is the key to the seismic design of a railway continuous girder bridge in high-intensity earthquake areas.In investigation of seismic damage of actual railway bridges fortified by seismic isolation,it is found that most of the damage of the seismic isolation system under the action of earthquake is due to excessive irreversible displacement of the girder.Although the traditional seismic energy absorption devices can effectively dissipate seismic energy,but the excessive residual deformation of the bridge seismic isolation system after the earthquake will still add difficulties to the repair work of bridges.Therefore,this dissertation proposes a buckling restrained bellows energy dissipation brace based on ring spring selfcentering(referred to as self-centering buckling-restrained brace),which effectively solves the problem of excessive residual deformation of seismic isolation system for bridges.The main work carried out in this dissertation was as follows:(1)On the basis of consulting a large number of relevant literature at home and abroad,the research status of typical seismic damage and seismic isolation technology of continuous girder bridges was reviewed,and the advantages and disadvantages of the existing self-centering buckling-restrained braces were summarized.(2)A buckling-restrained bellows energy dissipation brace based on ring spring self-centering was proposed,the essential configuration and working principle of the device were introduced,the recovery force model that can accurately describe the hysteresis characteristics of braces was studied,and the evaluation indicators of selfcentering ability and energy dissipation capacity of braces were given.(3)The refined finite element model of self-centering buckling-restrained brace was established by ABAQUS software,and the accuracy of the model was verified by existing experiments,on this basis,the hysteresis characteristics of braces under low cycle reciprocating load were studied,and the values of the three main dimensionless design parameters were optimized through parameter analysis,and the design flow chart of the self-centering buckling-restrained brace was given.(4)Based on the equivalent linearization theory,the equivalent linearization methods of each part of the continuous girder bridge and the self-centering bucklingrestrained brace were given,the simplified mechanical model of the continuous girder bridge system was established,and the seismic design method of a continuous girder bridge with self-centering buckling-restrained braces was proposed.(5)Taking a four-span continuous girder bridge in the actual railway project as the background,the software Open Sees was used to establish a finite element model of a continuous girder bridge equipped with self-centering buckling-restrained braces,and the longitudinal damping effect of a continuous girder bridge based on self-centering buckling-restrained braces under two different arrangements of braces was compared and analyzed,and the optimal arrangement method of braces on the railway continuous girder bridge is obtained,by comparing the dynamic time history analysis results with the simplified calculation results of the seismic design method,the reliability of the seismic design method for the continuous girder bridge equipped with self-centering buckling-restrained braces was verified.