Control of wind oscillations of Rio-Niterói bridge, Brazil

Abstract

Cross-winds of relatively low velocities have been observed over the years to cause large amplitude vortex-induced oscillations of the Rio-Niterói bridge, the world's largest steel twin-box-girder bridge. These oscillations, which were recorded by the automatic long-term monitoring system and by video cameras installed on the bridge, revealed the existence of the lock-in phenomenon and hence the urgent need to attenuate the aeroelastic oscillations. To this end, a novel system of multiple synchronised dynamic attenuators has been installed in the central span of the bridge. A short account is given of how an experimentally calibrated mathematical–numerical model for the aeroelastic behaviour was used to assist in designing feasible mechanical control devices to upgrade the serviceability of this bridge and users' comfort. The conceptual design of the passive control system, together with its main geometric and physical characteristics, are briefly described herein. The efficiency of the control system is demonstrated through comparisons of numerical results obtained for time responses of the original and the controlled structure, and its good performance has been experimentally observed in the actual bridge. Cross-winds of relatively low velocities have been observed over the years to cause large amplitude vortex-induced oscillations of the Rio-Niterói bridge, the world's largest steel twin-box-girder bridge. These oscillations, which were recorded by the automatic long-term monitoring system and by video cameras installed on the bridge, revealed the existence of the lock-in phenomenon and hence the urgent need to attenuate the aeroelastic oscillations. To this end, a novel system of multiple synchronised dynamic attenuators has been installed in the central span of the bridge. A short account is given of how an experimentally calibrated mathematical–numerical model for the aeroelastic behaviour was used to assist in designing feasible mechanical control devices to upgrade the serviceability of this bridge and users' comfort. The conceptual design of the passive control system, together with its main geometric and physical characteristics, are briefly described herein. The efficiency of the control system is demonstrated through comparisons of numerical results obtained for time responses of the original and the controlled structure, and its good performance has been experimentally observed in the actual bridge.