Implementation of MR Dampers to Dongting Lake Bridge for Cable Vibration Mitigation

摘要

This paper outlines a research/implementation project on using semi-active magneto-rheological (MR) dampers for cable vibration mitigation in the Dongting Lake Bridge. The newly built Dongting Lake Bridge is a three-tower cable-stayed bridge with two main spans of 310 m each, and two side spans of 130 m each. Since its open to traffic in the end of 2000, the bridge has experienced severe wind-rain-induced cable vibration several times. Currently, full implementation of MR dampers to totally about 200 stay cables in the bridge for wind-rain-induced vibration control is in progress. Working towards this objective, a series of in-situ vibration experiments have been carried out for several typical cables to understand actual damping performance of the cables before and after using MR dampers, to determine the best damper setup, and most importantly, to demonstrate to the bridge owner the control effectiveness of this unprecedented damping technique. This paper reports four stages of the field vibration experiments in the bridge site: (ⅰ) modal test of undamped cables, (ⅱ) forced vibration test of an MR-damped cable in open-loop control mode, (ⅲ) field measurements of damped and undamped cables under wind-rain-excited conditions, and (ⅳ) comparative test of the cable-damper system under different damper setups. Some issues concerning the full implementation and real-time control testing are also addressed.