Study On Mechanical Performance And Key Issues Of Long-span Steel Box Arch Bridge During Integral Lifting And Incremental Launching Construction

Steel box arch bridge is widely used in long-span Bridges because of its advantages such as light weight of steel box arch rib,large torsional rigidity of section,large span capacity and beautiful shape.At the same time,advanced construction techniques are continuously applied to long-span steel box arch bridges.However,in its construction process,due to the lack of mature and perfect new technology and insufficient actual engineering experience,more and more problems will follow.Therefore,in order to ensure the smooth progress of the key stages of bridge construction,and to ensure the quality and safety of bridge construction,it is necessary to conduct research on key technologies and construction control in the construction process.Based on the engineering background of Guohe Bridge in Bozhou City,Anhui Province,this paper analyzes and discusses the key issues in the lifting construction of whole arch ribs and the whole bridge incremental launching construction.(1)The finite element simulation analysis model of the arch rib integral lifting construction stage is established,and the structural stress and deformation performance at the key stage of the lifting construction are analyzed,and the influence of the temporary tie tension and the tensioning sequence on the integral lifting of the arch rib is compared and analyzed.On the basis of structural calculation and parameter analysis,the deformation and stress state of the structure during the construction process are monitored in real time to ensure the safety of the construction and the smooth closing of the arch ribs,and to meet the control requirements of the structure alignment and internal force during the construction process.(2)The norm empirical relationship method,static load test method,and dynamic method are used to study the vertical bearing characteristics of steel pipe piles of the temporary support in water,and the results of the three methods are compared and analyzed.The results show that the steel pipe pile is in a good condition during the jacking process,which can ensure the safety of the superstructure during the jacking construction process.(3)The finite element model of the whole bridge is established to simulate and calculate the incremental launching construction process of the main bridge of Guohe Bridge,and the dynamic changes of stress and deformation of the main component of bridge and the reaction forces of each pier support are analyzed in detail,which provides theoretical data for the incremental launching construction control.The linear shape and internal force of the structure in the process of incremental launching construction are monitored in real time.By comparing and analyzing the monitored values with the theoretical values,the smooth progress of the whole bridge incremental launching construction is ensured.(4)On the basis of the overall analysis of the incremental launching construction,the fine finite element simulation analysis of the local force and local stability of the steel box beam is carried out.According to the similarity theory,a scaled model of steel box girder with a scale of 1:2 is designed and produced,and the mechanical performance and local stability of the model are studied experimentally.Through the comparative analysis and mutual verification between the model test results and the theoretical calculation results,the stress characteristics and local stability of steel box girder in the process of incremental launching are summarized,which provides theoretical support for the incremental launching construction of real bridge.