Optimization on Axis of Arch-Shaped Pylon for High-Speed Railway Cable-Stayed Bridge

In order to resolve the pylon layout difficulty for high speed railway cable-stayed bridges when the bridges span existing traffic lines, rivers and so on with small angles, the arch-shaped pylon was adopted and the optimization on axis of arch-shaped pylon was analyzed based on the fixed point iteration method and finite element analysis. Firstly, nonlinear equations for arch pylon optimization are established by analyzing the force balance of arch-shaped pylon based on that the height and span of the arch tower are determined and the initial axis is drawn up. Secondly, the non-linear equations are solved by the fixed point iteration method, and the approximate solution of the reasonable arch-shaped pylon axis is obtained, in which the cable-stayed cable force is calculated by the finite element method. Finally, taking the arch-shaped pylon cable-stayed bridge of Guangzhou–Shanwei High-Speed Railway spanning Shenzhen–Shantou Expressway as the engineering background, the approximate solutions of reasonable arch-shaped pylon axes are obtained under three typical load conditions, i.e., dead load, dead load combined with single-track train vertical static live load, and dead load combined with double-track train vertical static live load. The results show that under the three different load conditions, using the optimized arch-shaped pylon axes can reduce bending moments of arch-shaped pylons by 89.8% to 94.8%, compared with using the initial arch-shaped pylon axis; under the main force or both the main force and additional force, bending moments of optimized arch-shaped pylons are reduced by 64.6% to 92.2%, stresses of arch-shaped pylons are reduced from −172.6–−179.5 MPa to −74.0 – −6.2 MPa, and positive and negative deflections of optimized arch-shaped pylons with fitting axis are reduced by 51.0% and 33.8% respectively.