Construction Simulation And The Girder Monitoring Analysis Of Continuous Beam-arch Composite Bridge For High Speed Railway

The continuous beam-arch composite bridge has the common advantages of beam bridge and arch bridge.It has large structural rigidity and strong spanning capacity and was widely used in the construction of high-speed railways.As a multiple statically indeterminate structure,the continuous beam-arch combination bridge must undergo multiple system transformations during the construction process.The structure is subjected to complex forces and its deformation and stress are difficult to control.At the same time,the construction accuracy of high-speed railway bridge is higher than that of ordinary bridges.Therefore,it’s necessary to simulate and analyze the construction process of high-speed railway continuous beam-arch composite bridge and carry out construction monitoring work to ensure that it meets the design requirements after completion.This paper takes Zheng Wan High Speed Railway Bridge which crosses the South to North Water Diversion Channel as the background engineering.The main girder was constructed by cantilever casting method and the asymmetrical construction of the mid-span section of the mid-span section is one of the difficulties in construction of the bridge.The arch ribs were constructed using a vertical swivel method.According to the actual construction process,the main beam and arch ribs of the bridge were subjected to construction simulation analysis.The construction monitoring of the bridge main beam was carried out on this basis.The main research contents are as follows:(1)Simulation analysis of the main girder construction of high speed railway continuous beam-arch combined super bridge.Use the finite element software MIDAS/Civil to establish the main girder spatial model of the bridge.According to the design of the bridge construction organization,the construction stage was divided and the cantilever construction process of the main beam was simulated to discussthe deformation and stress variation of the main beam during the construction process.The influence of parameters such as unbalancedconstruction,prestressed steel beam and concrete weight on the construction of main beam was analyzed to determine the most unfavorable construction parameters.(2)Simulation analysis of the arch rib construction of high speed railway continuous beam-arch combined super bridge.Use MIDAS/Civil to establish the bridge arch rib space model.The construction process of vertical rotating body of arch ribs were simulated and the variation law of the lifting cable force,arch rib stress and deformation during the vertical rotation of arch ribs was analyzed to determine the most unfavorable state of the arch ribs during vertical rotation.The joint section function of MIDAS/Civil was used to simulate the arch ribbed concrete injection process,and the effect of concrete curing time on the arch rib during the injection process was analyzed.The space model of the tower used in the vertical rotation construction was established to analysis the influence on the maximum horizontal component of displacement and maximum stress of the tower,and the cable force of the balance cable and the maximum control displacement at the top of the tower during the vertical rotation of the arch rib were determined.Stability analysis of arch ribs and towers during vertical rib rotation was conducted..(3)Construction monitoring and analysis of the main girder of high speed railway continuous beam-arch combined super bridge.The adaptive monitoring method was used to carry out the construction monitoring of the girder of the beam-arch composite bridge.The construction monitoring program was formulated.The elevation of the main beam was calculated and the measured strain was corrected according to the influencing factors during the stress test.The measured values of the main beam alignment and stress were compared and analyzed with theoretical value.The state of the main beam construction process was monitored real-timely.