Abstract:

In this paper, the cable force optimization of cable-stayed bridges with ultra kilometer span is equated as a nonlinear implicit optimization model. Then, by taking the minimum bending strain energy as the optimization object and by determining the nonlinear constraints according to the reasonable finished dead state, the model is solved via the projection gradient method, with all kinds of geometric nonlinearity being fully considered. Moreover, a finite element model of a cable-stayed bridge with the span of 1400 m is established based on ANSYS and is used to establish a mathematical optimization model of cable force. Calculated resuhs show that, after the optimiza- tion, the cable force slightly changes, yet the internal force state under dead load remarkably improves, the bending moment of girder and pylon as well as the deflection of girder significantly decreases, and the deformation of pylon migrates towards the shore side. All these variations contribute favorably to the concrete pylon under longterm loads.

Key words: cable force optimization, projection gradient method, cable-stayed bridge, nonlinear optimization, geometric nonlinearity