Research On The Construction Control Of Cast-in-Situ Large Span Cable-Stayed Bridge With Full Scaffold

Cable-stayed bridge is a complex structure, whose design and construction are highly coupled. Different construction methods not only affect the structure stress in the construction stage, but also play a decisive role on the stress state and geometric alignment of finished bridge. So, the construction control is a key link in the construction of cable-stayed bridge.When the bridge clearance is lower and the river bed is flat, considering the cost and difficulty of construction and other factors, the cast-in-situ with full scaffold may be a suitable construction method. However, this construction method is seldom used in the construction of large-span cable-stayed bridges, which results in practical research significance. Base on a large span concrete cable-stayed bridge, this thesis studied the technical difficulties and solutions when the former construction technology is adopted for it.At first, based on the step-by-step algorithm and least square principle, the minimum bending energy method, stress balance method, influence matrix method and other cable force optimization theories were comprehensively adopted to determine the optimization program for the initial tension of cables. This method was used in the background project of this thesis with satisfactory results.For the construction technology of one-time tensing of cables, there may appear large internal forces in the local position of the main beam, and force redistribution of full scaffold results in strength shortage caused by the main beam deformation. Aiming at these problems, this thesis put forward the solution of two-time tensing method, which is realized by adjusting the construction process and tensioning force reasonably. Taking the background project as an example, by detailed checking of each construction stage, the necessity and rationality of two-time tensing method was confirmed.Finally, taking the background project as an example, the influences of various design parameters on the cable forces, the main beam stress and geometric alignment of finished bridge state were studied. After that, the main contents and methods of the parameter sensitivity analysis and identification of construction control were discussed.