Study On Key Technology Of Construction Monitoring For Long-span Continuous Girder Bridge

China is currently vigorously expanding its transportation network.The bridge is an important part of the transportation network.Bridge is an important part of transportation network,whether it is urban bridge,highway bridge,or high-speed railway bridge,continuous girder bridge is widely used for its own advantage.During the construction process of the continuous girder bridge using the cantilever construction method,the internal force and the line shape of the structure will change with the construction process.To ensure the smooth construction of the bridge,the linear smoothness and reasonable force after the completion,it is necessary to carry out construction monitoring.Yue Min Avenue cross-railway overpass(48m+80m+48m)is taken as the engineering background in this paper,using the finite element software Midas/Civil to carry out the simulation and analysis of the bridge.Simulates the construction phase to obtain the deflection and stress of each construction phase,and thus the construction process of the bridge is monitored.The main contents and results are as follows:(1)Establish the finite element model of the bridge,simulate the actual construction process,and obtain the theoretical values of deflection and stress at each construction stage,smoothly guiding bridge construction.(2)Sensitivity analysis is performed on the structural parameters.Based on this,the least squares method is used to identify the parameters,the identified model is used to modify the calculation model,and the gray recognition method is used to verify the parameter identification results.(3)Four sequential closure models were established to compare and analyze the stress and deflection values of the structures.At the same time,factors such as construction cost and construction period were taken into consideration.Finally,the closure scheme of the side-crossing is adopted.(4)The influence of internal and external stiffeners on the internal force of the structure was analyzed,and it was found that the built-in stiff skeleton mainly affects the bending moment of the structure.(5)The effect of closing counterweight on continuous girder bridge is analyzed,and the results show that the application of closing counterweight is helpful to reduce the pre-arch degree and improve the resistance to cracking of the upper edge of the main girder.(6)The temperature field test was carried out.The change of temperature,deflection and strain in 24 hours was monitored.The regularity of deflection and stress changing with temperature was obtained and the best closure time was determined.(7)The effect of closure temperature on the longitudinal displacement of Pier supports is studied,and the result shows that the larger the temperature difference,the greater the longitudinal displacement of the bearing.