Study Of Construction Control Technology For Extradosed Cable-stayed Bridge

With the booming of bridges, lots of new bridge forms have been produced constantly while extradosed cable-stayed bridge is a typical representative. Its mechanical properties lie between continuous girder bridge and cable-stayed bridge, which has been widely built at home and abroad due to its novel structure modeling, rich combination form and good coordination with landscape. In order to ensure the construction safety and meet the expected design target of internal force and alignment in the finished bridge state, it has important practical significance to carry out the construction control of extradosed cable-stayed bridges.This paper takes the Changshan bridge as the engineering background. Firstly, a finite element model based on the beam element is built by finite element software Midas/Civil and the reasonable construction cable force value is calculated by the forward iteration method. On this basis, the stress and deformation of the structure are calculated and analyzed in each construction stage by means of construction process analog simulation. Thus the construction scheme is proved to be reasonable and feasible. The single strand tension force of parallel strand stayed cables are calculated with the theory of stress-free state method to keep the uniformity of strand force and achieve equivalent tension.Secondly, parameter sensitivity analysis is carried out during the construction control process to access the main sensitivity parameters. The cause of error is analyzed and the theory of the least square method is used for parameter identification according to the test results. Then update the calculation model with correctional parameters to simulate the real bridge structure better.Lastly, control methods of internal force and alignment are presented in detail based on construction control program for Changshan bridge. Guide each beam segment construction with formwork erection elevation and cable force. The control results show that the bridge alignment under construction has met the demands, the concrete stress is within safety range and the completion state has met the expected design target.