Self-Anchored Suspension Bridge Accurate Calculation and Analysis of Main Cable Alignment in Completed Bridge State

The accurate determination of the main cable alignment in the completed bridge state is the core premise for achieving the design goals and ensuring construction safety of self-anchored suspension bridges. To resolve the contradiction between the insufficient accuracy of traditional parabolic theory and the complexity of the overall calculation of the catenary theory, this paper, based on the engineering background of the Nanchang Hongzhou Bridge (main span 252m), proposes and practices a hybrid algorithm that combines the nodal line method and the segmented catenary theory. The method first uses the nodal line method based on static balance to efficiently solve the initial cable alignment and horizontal component force, which is used as the initial iteration value; then introduces a segmented catenary model that accurately considers the cable self-weight and geometric nonlinearity, and performs nonlinear iterative calculation through the compiled MATLAB program, with the conservation of the unstressed length of the main cable and the balance of the nodal force system as the convergence criteria, ultimately achieving accurate inversion of the completed bridge state. The calculation results show that the main cable alignment obtained by the hybrid algorithm is in good agreement with the design target value, with a maximum coordinate error of only 19mm; at the same time, the precise internal force distribution and unstressed cable length of the main cable in each cable segment are successfully obtained, with the maximum cable force of 64140kN appearing in the section near the main tower. This study verifies that the hybrid algorithm has both efficiency and high accuracy, providing a key theoretical basis and reliable technical support for the refined construction control of the cable system of self-anchored suspension bridges.