Research On Structural Mechanical Properties Influenced By Cantilever Construction Deviation By PC Composite Box Girder Bridge With Corrugated Steel Webs

As a new type of steel-concrete composite structure bridge,the PC composite box girder bridge with corrugated steel webs holds the advantages of light weight of superstructure,low longitudinal stiffness of webs,high prestressing efficiency,large span capacity and beautiful bridge shape,showing vigorous development prospects in China.However,limited by the topography,site and construction method,there will be some deviation in cantilever construction of PC composite box girder bridge with corrugated steel webs inevitably.Few studies have been carried out on the influence of construction deviation on the structure of PC composite box girder bridge with corrugated steel webs at home and abroad.Therefore,on the background of a corrugated steel web PC composite box girder bridge,relevant researches and discussions on the influence of construction deviations that may occur during the cantilever construction of the bridge on the mechanical properties of the structure are presented in this paper.The specific researches and work include:(1)Review the development process and research status of PC composite box girder bridge with corrugated steel webs,and summarizes the structural system and mechanical characteristics of PC composite box girder bridge with corrugated steel webs.(2)Through the modeling and analysis of Midas/FEA software,studies of the structural energy influenced by PC composite box girder bridge with corrugated steel webs after the deviation of steel webs assembling angle,the deviation of prestressed reinforcement,the out of control of prestressed reinforcement tensioning and the unbalanced construction load are carried out.The results show that in the maximum cantilever stage,the construction deviation such as the out of control tension of prestressed reinforcement and unbalanced load has a great influence on the deflection of the main beam.The stress of the main beam is deeply effected by the construction deviation such as the angle deviation of steel web assembly and the out of control tension of prestress.The oversize angle deviation of steel web assembly,will even result in the main beam suffering from large tensile stress exceeding the normative threshold.In the stage of completion of the bridge,the construction deviation of out of control tensioning of prestressed reinforcement has a significant impact on the deflection and stress of the main girder.The construction deviation of angle deviation of steel web assembly,deviation of prestressed reinforcement,out of control tensioning of prestressed reinforcement and unbalanced construction load performs few infulence on the shear stress of steel web in the stage of maximum cantilever and completion of the bridge.(3)Analyzes the influence of construction deviation,such as the angle deviation of steel web assembling,the deviation of prestressed reinforcement,the out of control of prestressed reinforcement tensioning and unbalanced construction load,on the structural stability of the bridge in the maximum cantilever stage and the completion stage.The results of stability analysis show that the stability safety factor of the structure in the maximum cantilever stage and the completion stage is greater than 4,which meets the requirements of the code.In the stage of maximum cantilever,the maximum change of prestress tension control stress can reduce the stability safety factor by 7.30%.In the stage of completion,the stability safety factor is reduced by 4.67%.The deviation of steel web assembling angle,the deviation of prestressed reinforcement and unbalanced construction load show little influence on structural stability.(4)Based on the sensitivity analysis of construction deviation,the bridge structural stress and deformation are taken as the control indicators.It is proposed that the construction deviation control limits are conducted by the deviation of steel web assembling angle of 4°,the deviation of prestressed reinforcement tension control stress of 5% and the deviation of beam concrete bulk weight of 10%.Furthermore,the corresponding control countermeasures of construction deviation are put forward.