Vibration Mitigation of Footbridges Considering Human-Structure Interaction and Optimization of MTMD Placement and Properties

Purpose This study investigates the dynamic response of a real footbridge subjected to pedestrian-induced excitation while explicitly accounting for human–structure interaction and evaluates optimized tuned mass damper configurations under non-resonant and resonant walking conditions. Methods The footbridge is represented by a three-dimensional finite element model, and pedestrian–structure interaction is simulated using the previously developed Biodynamic Synchronized Coupled Model (BSCM). Configurations with one, two, and three TMDs are investigated. The previously proposed One-to-One-Based Optimizer (OOBO) is adopted within a two-stage optimization procedure to determine damper locations and mechanical properties, while the dynamic response is obtained through time-domain integration. Results For a mean step frequency of 1.77 Hz, the uncontrolled footbridge remained within the adopted comfort limits. The optimized single TMD reduced maximum displacement, acceleration, and velocity by 8.74%, 36.10%, and 37.98%, respectively. Under resonance, generated by a mean step frequency of 1.96 Hz whose second harmonic coincides with the 3.92 Hz vertical mode, the uncontrolled peak acceleration exceeded the BS 5400 and ONT 83 limits. The optimized single TMD reduced maximum displacement by 43.97%, maximum acceleration by 68.26%, and RMS acceleration by 69.58%. Conclusion Increasing the number of dampers for a fixed total TMD mass does not necessarily improve vibration mitigation. Optimal placement depends on the excitation characteristics and structural mode shapes. The contribution of the present study lies in the integrated application of biodynamic human–structure interaction modeling and optimization of TMD placement and properties to assess passive vibration control under different excitation conditions.