Crowd–Structure Interaction on Building Floors for Event Use—An Experimental Study

This paper investigates crowd–structure interaction (CSI) on low-frequency floors during concert events. The findings are based on a full-scale experimental study conducted on a floor prototype designed for a specific infrastructure project. Both the structure and the participants were instrumented while performing various rhythmic activities, such as bouncing and jumping. The study emphasizes the necessity of defining load cases based on the music signal, as its frequency and amplitude may have a variable probability of occurrence. Furthermore, human sensitivity to floor vibrations is examined, with specific comfort thresholds identified for different activities. The core contribution of this work lies in quantifying coordination levels for groups of up to 97 jumping individuals, extending the limited existing literature and refining the definition of jumping crowd actions. Additionally, modal characterization of the unoccupied prototype was performed to evaluate the equivalent damping provided by individuals during standing, walking, bouncing, or jumping. The results demonstrate that while the crowd has a significant impact on the system’s equivalent damping, this effect remains highly variable. Finally, the implications of these findings for structural engineering and design practices are discussed.