Research On Key Mechanical Behavior Of Long-span Continuous Beam-arch System In Construction Stage

Concrete-filled steel tubular arch continuous beam-arch composite bridge has become a bridge type with great development potential in China due to its novel structural system and beautiful shape.In view of the insufficiency of domestic research and Analysis on the construction of concrete filled steel tube arch continuous beam-arch composite system bridge,this paper takes Shenmao Bridge as the actual engineering background,uses the finite element software Midas/Civil and Ansys to establish the model,and studies the arch rib stress and suspender tension problems in the construction of the bridge.1.Aiming at the problem of steel web deformation in the process of dumbbell arch rib pouring,this paper firstly analyzed the stress and deformation of dumbbell arch rib steel web high-strength bolt based on classical thin plate bending theory,and established three-dimensional solid arch rib truncation model with finite element theory to analyze the parameters.By changing the parameters of bolt spacing and steel web height,the high-strength steel web bolt was determined.The reasonable arrangement range of high strength bolts is obtained according to the stress performance of bolts.The results show that when the height of steel webs is between 1.2 and 2.4 m,high-strength bolts can be installed at the maximum deflection of steel webs,and the spacing of bolts can be set between 0.5 and 0.85 M.2.Secondly,aiming at the influence of suspender tension on arch rib in construction stage,the whole bridge model is established by Midas/civil.According to the structural characteristics of Shenmao Bridge,four different order suspender tension schemes are put forward,and the suspender tension force is solved by forward analysis method,so that the maximum Suspender Force and the minimum deformation of suspender can be controlled simultaneously.Then,the most reasonable tension sequence is obtained.The results show that the change of deflection and upper and lower edge stress of batch interval tension mode is smaller than that of sequential tension mode.3.Finally,aiming at the influence of suspender tension on continuous beam section in construction stage,Midas/civil full bridge model is used to analyze the influence of suspender tension on key section of continuous beam section,and the influence of suspender tension on the change of prestress tension in construction stage.Finally,it is concluded that the displacement and stress changes at the key section of batch-spaced tension are more uniform and stable than that of batch-symmetrical tension in turn;and the tension of suspender has little effect on the prestress changes of steel bundles at the top,bottom and web.The dumbbell-shaped arch rib webs of concrete filled steel tube reinforced by high-strength bolts have obvious effect in a certain range.In the process of suspender tension,the displacement change and stress change at the key section of arch rib,pre-stressed continuous beam are more uniform and stable.