Abstract:Aiming at the problems of complex spatial cable plane forces and difficult cable force optimization in double-arch pylon cable-stayed bridges, taking a double-arch pylon cable-stayed bridge as an example, a cable force optimization method based on the influence matrix is proposed. A finite element model is established using MIDAS Civil to extract the influence matrix. In MATLAB, the optimal cable forces are determined using quadratic programming with the objective of minimizing bending energy, while incorporating constraints on cable forces and displacements. The results show that except for a slight decrease in the cable forces of cables S1 and S2 at the pylon base of the side span and cables N7 and N8 near the pivot point of the main span, the cable forces of the remaining cables all increase by approximately 25%. The maximum negative bending moment of the girder decreases from -235×103 kN·m to -192×103 kN·m (a reduction of 18%), with a reduction exceeding 20% in sections with large bending moments. The bending moments in the main and secondary arched pylons increase by 10% and 20%, respectively. However, the stress in the pylon bodies is far lower than the specified value, and the bearing capacity has a significant surplus. Therefore, the load-bearing potential of the arch pylon can be fully utilized to take the cable force to the allowable upper limit, thereby significantly reducing the adverse effects of the negative bending moment of the girder. The research conclusion can provide a reference for the design of such special-shaped arch pylon cable-stayed bridges.
