Reasonable completed state evaluation for hybrid cable-stayed suspension bridges: An analytical algorithm

Abstract

Hybrid cable-stayed suspension bridges have broad application prospects due to their superior spanning ability, excellent overall stiffness, and economical efficiency, which outperform other long-span bridges. An analytical approach is proposed to determine the reasonable completed bridge state of hybrid cable-stayed suspension bridges in the paper. The specific steps are as follows: Firstly, the vertical supports offered by some stay cables and hangers in the main span to the main beam are estimated by assuming a continuous beam on multi-point rigid supports. For regions where both stay cables and hangers are used, the ratio of hanger force to the vertical force in the stay cable is assigned manually. Next, according to the assumption that the horizontal component force exerted by the main cables on both sides of the bridge tower and each pair of stay cables on the bridge tower are equal, the configuration and the internal force of the main cables and the stay cables are determined using the multi-segment catenary theory. The vertical forces exerted by the main and stay cables on the towers are summed up to estimate the axial force and strain acting at each position of the tower. In the side spans, the difference between the vertical support reaction in the continuous beam on multi-point rigid supports and the vertical force in the stay cable is used to calculate the weight of ballast of the main beam. The weight of ballast is apportioned as a uniformly distributed load acting on no more than three segments. The horizontal forces exerted by the stay cables on the main beam are summed up to estimate the axial force and strain acting at each position of the main beam. Finally, the analytical data of the full bridge are obtained as inputs of the finite element model. These data include the node coordinates and internal forces of the main cables, stay cables, towers, and the main beam. The calculation results obtained by the analytical method can be used for the preliminary design of hybrid cable-stayed suspension bridges. The proposed analytical algorithm can quickly solve the reasonable completed bridge state without complex adjustment of cable forces. It has the benefits of simplicity, high accuracy, and a clearly defined physical meaning. Finally, we verify the reasonability and effectiveness of the proposed analytical method in an asymmetric hybrid cable-stayed suspension bridge with a main span of 1400 m.