FEM-Based Shape-Finding and Force-Assessment of Suspension Bridges via Completed Loop Adjustment

Abstract

Finding the main cable shape is an essential step in the design and construction of suspension bridges. In this paper, shape-finding and force-assessment of suspension bridges based on loop adjustment are proposed and realized via the finite-element method. Here, loop adjustment refers to the process where the appropriate adjustment coefficient is chosen based on the results of the last modeling and deviations from the design goals to approach the target main cable shape gradually and to satisfy the design requirements. This method adopts a full-bridge model, which provides the comprehensive account of interactions between different components of the suspension bridge, including towers and stiffening girders, as well as the effect of tower compression and splay saddle rotation. Based on the full-bridge model in the completed bridge state, the inverted removal method is used for the calculation of key construction parameters in the free cable state, such as prebias of tower saddles, predeflected angle of splay saddles, and installation position of cable clamps. The proposed method’s feasibility and effectiveness are verified by its application to two particular suspension bridges, namely, the Great Belt Bridge (Denmark) with a main span of 1,624 m and the Jindong Bridge over the Jinsha River (China), with a main span of 730 m. Results of shape-finding and force-assessment both have good accuracy, which are generally consistent with those obtained by other methods.