Control of wind-induced nonlinear oscillations in suspension bridges using a semi-active tuned mass damper

In this article, the along-wind and across-wind response of the suspended cables and the bridge deck response of a suspension bridge subjected to wind loading are studied. The mean wind direction is assumed to be perpendicular to the planes of the suspended cables. It is shown that the suspended cable, if constructed alone, will gallop in the across-wind direction when the mean wind speed exceeds a certain critical wind speed. Similarly the bridge deck, if constructed alone, will gallop when a critical wind speed is exceeded. The construction of a suspension bridge, through coupling the bridge deck with the suspended cables via vertical hangers, increases the critical wind speed at which galloping occurs. However, the increase in the critical wind speed of a suspension bridge over a normal bridge is not sufficient to prevent galloping at moderate wind speeds. This article investigates the use of a passive or semi-active tuned mass damper control mechanism to increase critical wind speed for a flexible suspension bridge without changing the shape or size of the bridge deck cross section.