Investigation of a vibration mitigation method based on crowd flow control on a footbridge

The vibration mitigation method based on crowd flow control is verified by comparing the numerical and experimental results of its damping performance. The pedestrian characteristics are simulated with the upgraded social force model to include the effects of obstacles on pedestrian commute in a blocking scenario. The coupling system's control equation is established by loading a mass-spring-damping (MSD) model on the structure and the crowd-footbridge vertical interaction is analyzed. In this regard, a large-span interior footbridge in a shopping mall was analyzed, which had been presented in a previous study. The numerical vibration mitigation efficiency of the crowd motion control to different loading conditions is compared to the experimental results of a laboratory footbridge and the percentage of maximum numerical error is 16.7%. The vibration mitigation mechanism is described from the energy perspective. The numerical results were found consistent with the experimental data, and the pedestrian motion data in the simulation environment has enough reliability. It was found that choosing the location of obstacles can effectively help mitigate the vibration of the system. The relationship between the vibration mitigation rates, the number of obstacles, and the pedestrian densities were statistically analyzed to discuss the crowd control system's performance. The analyses demonstrate that the mitigation rate is directly affected by the number of obstacles in a specific crowd density range. It can be concluded that the mitigation performance of the hybrid mitigation method with Layout 1 is significantly more effective than Layout 2 at high pedestrian density.