Pedestrian bridges often experience excessive vibration levels due to their low natural frequency. Equipping the bridge with tuned mass dampers (TMDs) is a commonly used solution to address this problem. Guidelines widely used in engineering practice for the vibration serviceability assessment of pedestrian bridges, such as the Sétra guideline, employ a mode-by-mode assessment. This approach is not well suited for bridges with closely spaced modes where the response consists of contributions from multiple modes. In this study, we propose a gradient-based optimization method for designing TMDs for pedestrian bridges with several significant vibration modes, in order to obtain more cost-effective TMD designs. Two cases studies of existing footbridges are presented and benchmarked against the conventional Sétra design method. The results show a significant reduction in total TMD mass.
Uyttebroeck et al. (Wed,) studied this question.