| The continuous rigid frame arch composite bridge is an innovative bridge type appearing at the beginning of the early 21 st century.Because of its advantages of strong spanning capacity,large overall stiffness of structure,convenient construction,beautiful and lightweight appearance,etc,the composite bridge has been widely concerned and gradually adopted in recent years.The bridge type is a high-order statically indeterminate structure system,and its internal force of the structure is affected by temperature change,shrinkage,creep,foundation displacement,stiffness of each part and construction scheme of beam and arch.In order to ensure the safety of construction process and the quality of completed bridge,sufficient analysis and research should be carried out in practical application.Based on the finite element analysis,the whole construction process of cantilever pouring of the main beam,the steel tube arch in-situ assembling construction scheme and the arching and installation with low bracket construction scheme are simulated and studied in this paper.And through field monitoring of deformation and stress of the main beam,the actual alignment and stress of the main beam are evaluated based on monitoring data.The main contents of this paper are as follows:(1)Simulation analysis of the whole construction process and research on field monitoring of the main beam: Based on Midas civil,the structural response of the main beam during the whole construction process is analyzed,and the pre-camber of each beam section and the formwork erection elevation of the constructed beam sections are calculated.And the actual deformation and stress state of the main beam are measured by field monitoring technology.The research shows that the results of finite element analysis are in good agreement with the reality.The actual elevation of the constructed beam sections is close to the theoretical elevation,and the alignment of the main beam is well controlled.The stress of the main beam is in a safe state,and the stress of the bottom plate is well controlled.When monitoring the stress of the roof,measures such as adding surface strain gauges should be taken to ensure the accuracy of the monitoring data.(2)Simulation study on steel tube arch in-situ assembling construction scheme: Based on Midas civil,the stress,deformation and stability of steel tube arch in-situ assembled bracket and the influence of the bracket on the structure of the main beam are analyzed.The research show that the strength,stiffness and stability of the bracket meet the requirements of the code and design,and the influence of cross-bridge wind load on the lateral stability of the bracket is limited,and the deformation and stress of the main beam meet the requirements of the code,thus verifying the safety of the construction scheme.(3)Simulation study on steel tube arch arching and installation with low bracket construction scheme: Based on ANSYS,the structural state of arch rib in different vector height states and the system transformation process of arch rib in the design arch axis position are simulated and analyzed.The research shows that the middle hinges should be set on the arch roof,and for the sake of safety,it is suggested that 25 meters should be taken as the initial height of the arch rib when the arch rib is arched.Considering the particularity of the arch rib structure,the model tests should be carried out later to check its stability.Secondly,when the arch rib moves forward at a height of 25 meters,the low brackets have a good resistance to the vertical downward deflection of the arch rib.After the arch rib moves forward 0.2 meters,the arch rib is completely separated from the brackets,and in the process of the arch rib moving forward,the connecting member between the arch rib and the mobile trolley has a larger force,which should be paid attention to in the design;at the same time,when the arch rib is closed at the design axis position,attention should be paid to adjusting the displacement of the arch rib. |
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