A New Method for Measuring Cable Tension of Cable-Stayed Bridge-Cable Sag Method

Considering the influence of the cable bending stiffness, the damping device at cable end and the geometric nonlinearity, the relationship between the tension and the sag of the cable of a cable-stayed bridge was analyzed by finite element software ANSYS. Results show that, when the cable tension is larger (the cable sag is smaller), at a certain distance away from the anchorage position and the damping device, a cable segment with suitable length is arbitrarily chosen from the central of the cable, and there is a definite functional relation between its tension and sag. And this relation is almost not affected by the bending stiffness of the cable itself and the supporting conditions at both ends of the cable. Accordingly, a method for determining cable tension by measuring the sag of a segment in the central of stay cable, namely, cable sag method is proposed. Based on the measured inclination angle, chord length and maximum sag of the selected cable segment, the average cable tension of the selected cable segment is calculated with the derived formula. The tension of the whole cable is determined according to the cable tension difference per linear meter and the position of the cable segment. Model test results show that the cable tension error measured by the sag method is less than 2%. © 2018, Editorial Department of China Railway Science. All right reserved.