Research On The Nonlinear Behavior Of Long-Span Cable-Stayed Bridges Considering Overall Construction Process

This thesis focuses on the geometric nonlinear analysis of long-span cable-stayed bridges considering overall construction process. According to the contents the thesis is constituted of two parts: general geometric nonlinear analysis method and geometric nonlinear behavior of long-span cable-stayed bridges.Firstly, the geometric nonlinear fundamental theory and the finite element formulation in Solid Mechanics are introduced. The simplified one-dimensional integral forms of finite element matrix, the explicit expression of the matrix and the computing method of the residual force are discussed. The two methods to determine the initial coordinate of the element generated in different computing stages and the way to resolve the structure status transferring and accumulating between stages involving overall construction process are put forward.Then, according to the characteristics of structure and the features of analysis of cable-stayed bridges, the thesis uses multi-level equivalent concentrated force method or the cooling method of finite element to solve the non-conservative difficulty of the inclined cable during its stressing, and the iterative algorithm to search the appropriate temperature in element cooling method is also proposed. The similitude and difference between erection profile and fabrication profile are clarified. A simple method to compute the fabrication profile based on the beam subsection erecting elevation and the analysis results considering overall construction process is explained in detail. The method is independent of analysis type of linearity or nonlinearity. Also the method to realize the smooth connection between installing element and installed element in computing process considering bridges construction is proposed, the method is consistent with the actual construction procedure and can introduce arbitrary erection profile in the analysis, and it results in no convergence problem in solving nonlinear equations.Based on the nonlinear finite element method theory and various methods proposed here, a computer software LSB2006 (Long-span Structure and Bridge analysis system version 2006) is programmed. LSB2006 uses the mixed language programming technology of C# and .NET FORTRAN and can achieve the geometric nonlinear analysis of long-span cable-stayed bridges or other type bridges considering overall construction process.Finally, the Third Nanjing Yangtze River Bridge and Sutong Yangtze River Highway Bridge are analyzed by LSB2006 considering actual overall construction process. From such aspects as the incremental deformation of constructing and completed structure under loads, the total structure deformation during overall process, the structure internal force, etc., the magnitude and rule of geometric nonlinear influence of long-span cable-stayed bridges are fully researched.