Study On Self-centering Performance Of Unbonded Prestressed Reinforced Concrete Pier Under Vehicle Impact

Unbonded prestressed reinforced concrete bridge pier(UBPS pier for short)can self center after vehicle impact,which is a type of bridge pier used to improve the anti vehicle impact ability.However,there are few related researches.In order to explore the self reset performance of the UBPS bridge pier under the impact of vehicles,through the comparative analysis of the numerical simulation analysis of the scaled structure and the real bridge structure,this paper preliminarily obtains the determination method of the ultimate load of UBPS,the dynamic response and the characteristics of energy consumption,and through the analysis of the dynamic response process,the evaluation method of the self reset performance of the bridge pier and the different structural forms and the prestressed design parameters of the UBPS bridge are obtained The influence of self restoring performance of pier.The main contents and achievements are as follows.1)In this paper,the dynamic behavior of UBPS piers under the impact load of rigid body is studied.Through the analysis of quasi-static load and impact load of the segment model at the bottom of the pier,the judgment mode of the impact shear strength and the ultimate design load of the pier is obtained,and the dynamic response,energy consumption characteristics and self resetting performance of the pier are analyzed.The results show that in the dynamic response process of the pier,the rigid swing rotation displacement is the main part,and the self resetting performance is better;the area at the bottom of the pier can be divided into two load action stages,and the load reaching the second stage can be taken as the ultimate design load of the pier;the self resetting performance can be evaluated by energy consumption ratio,residual displacement and self resetting coefficient.2)Taking the UBPS reduced scale pier as the object,the research on the applicable environment and the self reset performance of the UBPS pier under different loads is carried out.Taking the impact strength,impact location and structural axial pressure as the research parameters,through the cross comparison of different parameters,the influence of different load parameters on the dynamic response of the pier is obtained,and the reasons for the influence of different external load parameters on the self resetting performance of the pier are explained.The results show that UBPS has good self resetting performance under various impact loads,and the axial compression ratio of the upper part of the pier shaft should not be too large.3)Taking the actual viaduct pier as the research object,the influence of different structure and prestress parameters on the self reset performance and impact resistance of UBPs pier under vehicle impact is studied.Through the truck single pier impact model,the difference between vehicle load and rigid impact load and the self resetting performance of single pier are analyzed;through the truck frame pier model,the influence of frame pier on the impact resistance and self resetting performance of UBPs pier is obtained.Through the comparison of different prestress axial pressure and initial tension stress,the better recommendation of prestress design parameters is obtained.The results show that the frame pier has good displacement control effect and self reset performance,and the appropriate small axial compression ratio and the small initial tensile stress of steel tendon are more favorable for the unbonded prestressed reinforced concrete pier under the impact load of vehicles.