In Situ Deformation Behavior Monitoring and Analysis of the Short Suspenders of a Full-Scale Long-Span Suspension Bridge

As the main load-bearing and force-transmitting component of a suspension bridge, the service state of the suspenders directly affects the safety of the whole structure. Significantly affected by multiple factors such as the sudden change in stiffness in the anchor head area, special boundary conditions, and the relative motion between the cable and the girder, the dynamic behavior of short suspenders is extremely complex. Most existing studies mainly focus on refined numerical simulations and wire tests, which are difficult to accurately reflect the complex spatial dynamic behavior of short suspenders under real-service conditions. To address this issue, novel computer vision (CV)-based in situ experiments of the short suspenders of a full-scale suspension bridge, with a main span of 1,418 m, are systematically carried out. Specifically, the CV-based noncontact monitoring system is established for monitoring the relative displacement between the cable and the girder, which can reveal the spatial dynamic behavior of short suspenders. Subsequently, numerical simulation results by integrating the measured displacement data and numerical simulation results, the distribution and variation characteristics of the local bending stress of short suspenders were obtained. The results showed that the longitudinal and transverse relative displacements of the cable-girder were in the ranges of −6 to 6 mm and −10 to 15 mm, respectively. The maximum local bending stresses of the short suspenders obtained from the measurement and simulation were distributed within 60°–150° and 240°–330°. Random traffic loads play a dominant role in the local bending stress of short suspenders in the longitudinal bridge direction. The distribution of cracked anchor heads and broken wires of short suspenders on-site indicates that the random traffic flow load is the main influencing factor for the dynamic behavior of short suspenders during the long-term operation of the suspension bridge.