Wake-induced vibration of a suspender cable in the rear of a bridge tower

Abstract

For a long-span suspension bridge, the suspender cables in the rear of tower often incur violent vibrations, owing to the wake effect of the upstream tower. In this study, an experimental investigation on the dynamic response of a suspender cable model was conducted, and an analytic model for the wake-induced vibration (WIV) of a suspender cable was proposed. The Xihoumen Bridge was selected as a prototype, and a scale-ratio of 1:10 was adopted for wind tunnel tests. The combined mass damping m∗ζ in the present experiment was 17, and the Reynolds number corresponding to the tower column width was 2.0–5.2×105. The WIV of suspender cables at different relative positions to the bridge tower was successfully reproduced in the wind tunnel tests. The suspender cable model was found to vibrate in an elliptical trajectory, and the dominant vibration frequency was equal to the natural frequency. The WIV response of the suspender cable could be divided into two main parts: a resonance response peak and a cumulative response with increasing wind velocity; these were considered as the effects of the vortex impulse and wake stiffness, respectively. An aerodynamic force model was then proposed, considering the unsteady effect of the tower wake. In addition, a differential equation for the suspender cable WIV was established and numerically validated. The results from experiments and numerical simulations were observed to be consistent in the resonance range and amplitude–velocity curve trends.