Determination of main cable shape and hanger tensions of a suspension bridge based on the measured live-load deflection of the main beam: An analytical algorithm

Hanger tensions and the main cable shape are key parameters of suspension bridges that must be assessed during their construction and operation phases. An analytical algorithm is proposed for assessing these parameters via the measured deflection of the main beam and tower-top displacements. First, the hanger tension increments caused by the live load are derived based on the known live load and measured deflection of the main beam. Next, the hanger tensions in the initial state are determined according to the conditions for conserving the unstrained length of each main cable segment and the force-deformation coordination of each hanger with and without the live load. Finally, the main cable shape is derived from the hanger tensions in the initial state. In contrast to the conventional method, the proposed analytical approach requires no complex dynamic equations. At the same time, the expression based on static analysis has a simpler form and higher universality and practicality. The proposed approach allows for a faster and more accurate evaluation of the suspension bridge's main cable shape and hanger tensions. The feasibility and effectiveness of the proposed method are verified for an exemplary suspension bridge with a main span of 1080 m.