Full-Scale Experimental Study on Vibration Control of Bridge Suspenders Using the Stockbridge Damper

Abstract

The Stockbridge damper (SD) has been used for vibration mitigation of suspender cables subjected to vortex-induced and other types of resonant vibrations. This paper studies its effectiveness and robustness, as well as a simplified design method, by using full-scale suspender experiments. The experiments were conducted on a 36 m prototype suspender cable of a bottom-through arch bridge, and two SDs were designed to control, respectively, the first- and second-mode cable vibrations. The damping effects were tested by placing the damper at different locations, and the robustness of the damper was investigated by varying the cable tension force and hence the cable frequency, to produce deviations from the frequency tuning condition. Furthermore, combined effects of the two SDs were studied. The experimental results are discussed and compared with theoretical results based on complex modal analysis of a taut cable equipped with a linear tuned mass damper. The properties of the SD vibrating with small amplitude were used in the theoretical analysis. The experimental results show that the SD is effective and robust for suspender cable vibration control. The comparison indicates that the analytical analysis generally gives conservative predictions of the damping ratios as long as the damper is installed close to an antinode of the mode shape of the target mode. This suggests that the theoretical analysis can be used for practical design of SDs.