Geometry Control Method In Long-Span Hybrid Girder Cable-Stayed Bridges

The rapid development of cable-stayed bridge in our country booms the bridge construction control theory and technology. To guarantee the construction quality and to ensure the structural safety during the construction process for long-span and super long-span cable-stayed bridges, a new construction control method, based on geometry control rules in the whole process, comes into being. This method has made significant progress in both the control concept and the control means, and it has been successfully used in the Sutong Bridge constructing control work. Taking the construction of Edong Yangtze River Bridge for background, this thesis has done some research on the application of geometry control method in long-span hybrid girder cable-stayed bridges. The main works are as follows:(1) The current construction situation of hybrid girder cable-stayed bridge is firstly depicted, and the history on the development of control methods for the construction of cable-stayed bridges is described secondly. Then the rules and the application of geometry control method are introduced on emphasis.(2) Basing on the geometry control rules, the unstressed configuration of key components in cable-stayed bridges is calculated, including the inclined cable, main beam, tower, etc.(3) In accordance with the theory of geometry control, the calculation methods are studied on the unstressed configuration and the installing location of a beam element while in various construction ways, considering that different constructing ways are used in the concrete part and the steel part of a hybrid girder. Then the unstressed constents of a large hybrid girder cable-stayed bridge is computed by means of finite element method, including the manufacturing configuration of the side concrete girder and the middle steel girder, the unstressed cable length, the pier length and the installing location of anchors.(4) Basing on the construction of Edong Yangtze River Bridge, it is analyzed that the effect of geometric nonlinearity and that of concrete shrinkage and creep of the side girder on the unstressed constants of those components. The influence of geometric nonlinearity on the structure during its constructing is studied. Also, the structural change through the operational phase, caused by concrete shrinkage and creep, is carefully considered. Lastly, the geometric nonlinear features of long-span hybrid girder cable-stayed bridges during the construction is probed into, comparing with those of the long-span steel box girder cable-stayed bridges. All these works are to provide a useful reference for the entire process construction control.