A Simplified Calculation Method for Multi-Tower Self-Anchored Suspension Bridges Based on Frame Structure Theory Model

In this paper, a simplified method for the multi-tower self-anchored suspension bridges (SASB) under live load was derived., an analytical model defined as frame structure model was proposed for solving structural behavior of the multi-tower SASB. The bridge consisted of the towers and equivalent spring elements that replacing main cables, hangers and main girders in this equivalent model. The proposed method for the equivalent spring stiffness took into account the compression of the main girder and elastic elongation of the main cable. The horizontal forces of the main cable were computed by using the unstrained length method and equilibrium equations of the tower, then governing equations for the tower and the main girder were derived by using free-body and simply supported beam. The displacements and moment reactions of the tower and the main girder were solved by the proposed method. The finite-element model (FEM) for triple-tower SASB was established to validate the proposed method, and a comparison of the proposed method was good to agree with numerical results, demonstrating that the proposed method can provide accurate estimations for structural behavior under live load.