Innovative Experimental Assessment of Human-Structure Interaction Effects on Footbridges with Accurate Multi-Axial Dynamic Sensitivity using Real-Time Hybrid Simulation

This study evaluated the dynamic performance of a reference footbridge under human-structure interaction (HSI) effects using Real-Time Hybrid Simulation (RTHS). The footbridge, designed with precise multi-axial dynamic sensitivity, was tested un-der pedestrian gait velocities of 1.20, 1.50, and 1.80 m/s. The RTHS framework in-volved an analytical continuous model of the footbridge as a numerical substructure and real human gait loads as the experimental substructure. Results revealed significant dynamic coupling between pedestrian-induced loads and the structure’s response. Lateral vibrations exhibited a fundamental frequency of around 1.0 Hz, while vertical vibrations peaked near 2.0 Hz. The dynamic synchronization, especially at higher gait velocities, amplified structural vibrations, with lateral loading increasing by up to 300% in the middle span. Vertical loads showed substantial amplification and attenuation, depending on the gait velocity and the footbridge location. Lateral accelerations displayed a dispersion of approximately 15%, while vertical accelerations showed higher variability, with dispersions reaching up to 20%. The RTHS technique demonstrated high fidelity and accuracy, with global errors below 2.95% and delays of less than 2.10 ms across all evaluated directions. These results emphasize the critical im-portance of accounting for HSI effects in the design of pedestrian footbridges, as hu-man-induced vibrations can significantly impact structural serviceability and user comfort. The study offers important insights into optimizing footbridge design to mitigate the risks of excessive vibrations, ensuring both safety and functionality under typical pedestrian loads.