Modified Algorithm of Anchor Cable Force in a Suspension Bridge Based on the Cable-beam Composite Structure

Traditional vibrating cable methods usually omit the influence of the bending stiffness of anchor threaded rods when measuring the cable force in suspension bridge tunnel-type anchorage, causing a great deviation in the measurement and calculation of the cable force. The cable tension in the anchorage was calculated using the cable–beam composite structure to improve the accuracy of the main cable force. Based on Hamilton’s principle and the assumption of cable–beam composite structure, a new measuring method was proposed by using the vibrating matrix equation of the cable–beam composite structure. Then, the matrix was solved using Mathematica. With the Qingjiang Suspension Bridge as a case study, the modified precision of the proposed method was verified by comparing its results with those of the conventional method and the finite-element method. Results indicate that using the cable–beam model to calculate the cable force can well describe the relationship among the cable force, the bending stiffness of the threaded rod, and the frequency of the cable. It also reduces the deviation induced by the bending stiffness of the threaded rod, which contributes to obtaining precise results about the actual cable state.