Damping of stay cable with passive-on magnetorheological dampers: a full-scale test

Damping of a full-scale cable with a pair of passive–on magnetorheological (mr) dampers was tested. a cable 215.58 m long with a first mode frequency of 0.658 hz was tensioned horizontally in a cable prefabrication factory. two mr dampers were attached to the cable at an angle to each other, in the plane perpendicular to the cable axis at a position 5 m along the cable from its anchorage point. the applied voltage levels were 0 v, 3 v, 6 v and 9 v, respectively. the cable was excited manually to a certain amplitude level for the first three modes of vertical vibration. the free decay curves of the cable were then recorded. the damping of the cable was calculated from the measured anti-node vibration amplitude. the damping of the free cable was also tested for reference. it was found that the damping of the cable was still low when mr dampers were not strengthened by voltage. however, the damping of the cable increased greatly compared to the free cable case when the mr dampers were voltage-strengthened. the damping of the cable with mr dampers strongly depends on the applied voltage level and the vibration amplitude. there is an optimal damping value when the mr dampers are voltage-strengthened. the dependence of the optimum damping on applied voltage level, vibration amplitude and vibration mode was analyzed further.