Seismic Performance And Design Method Of Segmental Assembling Double-Column Pier Bridges

With the development of urbanization,constructing urban elevated expressway for the diversified urban transport space,and using standardized pre-construction have become a trend.Segmental assembling piers have been more and more widely used in all kinds of bridges,because of its energy conservation,environmental protection,reliable quality,safty and low traffic interference advantages.The existing researches about segmental assembling piers only aimed at failure modes of the component,the real bridges were built mainly in low intensity earthquake zones.With the development of segmental assembly technology to high seismic hazard areas,how to distinguish the seismic performance of the Segmental assembling piers and the whole pouring pier,how to evaluate the seismic performance of the piercing pier viaduct,how to evaluate the effect of the anti-segregation measures,and how to carry out the seismic design And so on,are the urgent need to solve the problems?Therefore,this paper combing the relevant literatures and datas analysis at domestic and abroad,based on the concept of ductility and seismic isolation,used fiber model and nonlinear time history analysis method,the bridge system models with the segmental assembling piers were built up.The ductility of single-pier,the longitudinal and transverse seismic response,the seismic response and the effect of isolated measures were studied,so as to form some suggestions and design methods for seismic design of segmental bridge.The main contents are as follows:(1)Based on the analysis of aseismic theory of segmental assembling piers for the bridge,combined with the basic theory of bridge seismic isolation and the constitutive relationship of materials in-depth analysis,the research method of seismic response of bridge system by using fiber model method to simulate pier structure and nonlinear time history analysis method were determined.Based on the Open Sees fiber model analysis method,the numerical analysis results of the dry joint assembled piers were compared with the existing research results,verify the correctness of the simulation method,which provided for the study on seismic performance and design method of segmented piers.(2)From the perspective of pier components,based on quasi-static test and fiber model numerical method,the ductility characteristics of the single-piers with segmental joints were studied,and similarities and differences of the ductility characteristics of cast-in-site reinforced concrete single-pier structures with the same structure were compared and analyzed.(3)From the perspective of pier components,according to the prestressing force of prestressed segment pier of urban viaducts,comparative studies on the multi-working conditions were carried out through such factors as joint reinforcement ratio,piers ratio,axial compression ratio and so on,and the ductility characteristics of the assembled pier columns of the urban elevated segment were also revealed.(4)From the perspective of the bridge system,based on the concept of seismic isolation,fiber model and nonlinear time-history analysis method,the segment precast pier and cast-in-place pier sections for urban viaduct were contrasted and analyzed under transverse and longitudinal seismic actions.The effects of seismic isolation under different working conditions,the principles of seismic isolation bearing selection and parameters were studied.The influence of different seismic intensity and bridge span on the ductility of the bridge were also analyzed.The adaptive effect of seismic isolation and the principle of setting up seismic isolation in the bridge system with segment were obtained which can provide reference for similar projects.(5)In order to improve the longitudinal and transverse seismic performance of the viaduct system,based on fiber model method and nonlinear time history analysis method,respectively,taking the urban viaduct with segmental assembled piers and precast box girders as the research objects in the horizontal and vertical seismic action,the suitable ductility parameters of segmented pier urban viaduct were discussed.(6)On the basis of the study results about segmental assembling piers,such as single-pier ductility,longitudinal and transverse seismic responses,setting the isolation bearing method,and the appropriate ductility parameters and so on,combined with provisions of the existing codes,the seismic design proposal of the bridge with segmental pier has been formed.Meanwhile,based on the performance of segmental pier structure,the performance design method and design processes of the urban viaduct with segmental piers were established,which can provide reference for engineering applications in high earthquake area.