Study On Calculation Method Of Optimal Stayed-Buckle Cable Force For Reinforced Concrete Arch Bridge With Cantilever Cast Method

At present, the main construction methods of long span RC arch bridge in China are arch centering method, cable-hoisting erection method, precast segmental cantilever method, swing method and Melan method. The cantilever cast method is very appropriate in the site conditions which lack for precast conditions, such as precipitous site conditions with cliffy canyons and torrential rivers, and it can also reduce construction, have good structural integrity, and reduce damage to environment and so on. Because of these advantages of this method, it will get fast development in China. This method has not been applied in all the completed RC arch bridges in China, however, it has been widely utilized to construct RC bridges abroad. During the construction of arch bridge using stayed-buckle cable, the stayed-buckle cable force directly influence the structural stress and geometry under construction and bridge complete stage. So, in order to make sure the stress safety in construction and approach the optimal bridge complete state, the accurate calculation of stayed-buckle cable force is necessary to be researched during the construction control of arch bridge using this method.Based on comprehensive collection of existing research documents at home and abroad, the characters of cantilever cast method is analyzed and the calculation method for optimal stayed-buckle cable force used frequently at present is generalized and compared in this thesis. A calculation method for optimal stayed-buckle cable force based on optimization theory is put forward. In this calculation method, the cable force will be automatically calculated using optimization iteration after set objective function and constrain the state variables and design variables.The Baishagou No.1 Bridge is taken as engineering background and the design optimization of ANSYS is adapted to calculate the optimal stayed-buckle cable force, with the advancing analysis and plane finite element method. The stayed-buckle cable force optimization include two stages: The stayed-buckle cable force optimization during cantilever stage and the stayed-buckle cable force optimization at the largest cantilever stage. The optimization object of the former is minimizing the tensile stress of the arch and the latter is approaching the optimal bridge complete state. The optimization results show that both the structural stress and cable force are limited within safe range during the cantilever cast stages, and the tensile stress of arch is reduced effectively; also the structure in the complete stage approach the optimal state because of the stayed-buckle cable force optimization at the largest cantilever stage before closure.