Mitigation of vortex-induced vibrations in long-span bridges

Span lengths of bridges are ever increasing, leading them to be more slender. It is well known that the slender structures are more vulnerable to wind-induced forces and vibrations. Some bridges have shown significant wind-induced vibrations, which were not anticipated during conceptualization and design phase. In order to improve the aerodynamic performance of a bridge after the construction, two approaches are commonly used. The first approach is to retrofit the cross-section of the bridge to be aerodynamically more favorable. The second approach is to add tuned mass dampers to dissipate the energy. In this paper, we propose a method to obtain an optimal solution when both approaches are used simultaneously. Multi-objective optimization technique is employed to select the most significant solution form the set of possible solutions. The owner of the bridge may select the best solution based on the preferred performance and cost criteria.