Research On Key Technology Of Construction Monitoring Of Long Span CFST Arch Bridge

The concrete-filled steel tube arch bridge has the advantages of high strength,high rigidity,fatigue resistance and impact resistance.It also has excellent construction performances such as economy,convenient construction and fast construction speed.Therefore,it has been widely used in domestic development.In the construction process of CFST arch bridges,the more complicated stage is the hoisting of arch ribs and the concrete pouring in steel pipes.In order to ensure that the bridge line type and internal force meet the design requirements,it is necessary to carry out construction monitoring.Based on the Wuxi River Bridge in Suichang,this paper uses the iterative equation to calculate and analyze the structural line type during the rib erection process,and studies the arch rib concrete pouring sequence.The main contents are as follows:(1)Using the superposition theory to establish the spatial finite element model of the Wuxi River Bridge,and compare and analyze the finite element model and the stress data measured by construction monitoring.The absolute deviation of the maximum deviation between the model data and the measured data is 6.95 MPa.The data size and trend of the two groups are similar: the stress change of the upper rib arch rib is gradually reduced from the arch and the vault to the vicinity of L/8;the stress change of the lower chord arch rib is Gradually from the vault to the arch.(2)Combine the forward analysis method with the backward analysis method,analyze the installation axis and calculate the construction control elevation.The arching axis obtained from the initial calculation is not consistent with the ideal arching axis,so the iterative equation is used for iterative calculation.After 3 iterations calculation,the arching axis is obtained in accordance with the ideal arching axis.Combined with the simulation analysis of the construction stage,the accurate installation axis is obtained and the construction control elevation is calculated to control the construction.The maximum deviation from the actual construction monitoring data is-0.039 m,to the extent permitted by the specification.(3)Simulated symmetrical concrete and asymmetric perfusion schemes for arch rib concrete,and analyzed the optimal perfusion sequence of symmetric perfusion and asymmetric perfusion.Through the comparison of different schemes,the optimal order of the arch rib concrete perfusion recommended for the Wuxi River Bridge in Suichang is: symmetric perfusion,first winding tube,then lower string tube,first outer tube,and then inner tube.