Research On Key Technologies Of Construction Monitoring Of Long Span Steel Box Girder Single Tower Cable-Stayed Bridge

Based on the construction project of a two-span cable-stayed bridge with single tower and steel box girder,this paper studies some consequential technical issues in the construction and construction monitoring of the cable-stayed bridge.In order to determine the reasonable finished dead state of the total structure,the global mechanical analysis and stability analysis of the cable-stayed bridge were conducted by using the finite element software Midas civil.Furthermore,the internal force and deformation of the main girder,the deflection of the main tower and the variation of the cable force during the construction of cable-stayed bridge are analyzed comprehensively to guide the construction monitoring.Secondly,combined with the special inclined tower structure of the bridge,a reasonable construction scheme of the main tower support was proposed and the finite element model is established to analyze the stress and local stability of the steel pipe support during the construction,in order to ensure the stability and safety of the main tower when the support is removed and the cables are symmetrical tensioning,the pre-tensioning measures of main span side cables should be carried out first.Based on the theory of influence Matrix method,the mathematical model of optimal control of the secondary cable adjustment of cable-stayed Bridge is established,and the solving process of penalty function method is analyzed.Furthermore,the influence matrix theory is used to adjust and optimize the cable force of cable-stayed bridge in the construction stage,and the concept of local cable force adjustment is introduced.According to the different influence matrix of cable force,two different calculation methods of local cable force are introduced,and the accuracy of cable force adjustment under two local cable adjustment methods is compared.Finally,the local model of cable-beam anchorage zone that includes the 10 m standard beam section under the most unfavorable cable force state is established by using ANSYS.The local stress and displacement of the anchorage zone are analyzed comprehensively,and the safety evaluation and reasonable suggestions are made for each component in the anchorage zone.