Structural design and analysis of long span bridges

The geometric nonlinear effects including initial stresses, large displacements and sags of long cables have to be considered in structural analyses of long-span cable-stayed and suspension bridges. Due to these nonlinearities, theoretical extreme live loads are not able to obtain. It is more practical taking the same extreme loads and positions obtained by linear analysis to perform one round of nonlinear analysis to adjust the results. To define and manage to reach the "ideal state" of a bridge, which can be defined as minimizing the total bending energy under dead loads in girder, is unique to cable-stayed bridges. Taking a recently-built long-span cable stayed bridge in China and an existing suspension bridge in the US as examples, this paper introduces the principles and how they are applied in long-span bridge analyses.