Study On Construction Control Of The Continuous Girder-Arch Composite Bridge

The continuous girder-arch composite bridge was a new bridge type which combined the continuous girder and the arch together. With the advantages of large structural stiffness, reasonable mechanical behavior and attractive shape, the continuous girder-arch composite bridge was especially suitable to the long span railway bridge in the area of soft soil and it had strong competitiveness in the span from60to200m. However, the research on the construction control of this composite bridge is relatively few. Therefore, one certain continuous girder-arch composite bridge still under construction was taken as the engineering background, the construction control method of the continuous girder-arch composite bridge constructed by the method of "girder first and arch late" was researched. The main works were listed as follows:(1). The emergence and development of the continuous girder-arch composite bridge was described, and the mechanical behavior and construction method were briefly introduced. The existing research on construction control of the continuous girder-arch composite bridge was mainly focused on.(2). The existing methods solving the reasonable cable tension at the completed and construction stage were studied. After comprehensive comparing, the minimum bending energy method was used to work out the preliminary cable tension at completed stage, and then the influence matrix method was adopted to adjust the cable tension. The initial tension at construction stage was obtained by forward iteration method. Finally, The unknown coefficient of load method of MIDAS/Civil was used to calculate the cable force adjustment at the completed stage.(3). According to the characteristics of the girder construction, the adaptive control method was used in the geometric alignment control of the girder. The feasibility and advantage of applying the Genetic Algorithm to optimize the connection weights and thresholds of BP Neural Network was mainly focused on. Then the Genetic Algorithm-BP Neural Network was used to identify the main parameter affecting the girder geometric alignment. And the deflection of girder was forecasted. So the formwork erection elevation was determined.(4). The influence factors and the set methods of the arch rib camber were analyzed. Based on the background engineering, several set methods of the camber were compared, and a method was chosen to determine the arch rib camber. So the fabrication geometry of the arch rib was determined.