Pedestrian-induced dynamic response of structures considering uncertain characterization of human-structure interaction

Vibration serviceability under pedestrian loading is increasingly critical in the design of lightweight footbridges and floors. In the vertical direction, human-structure interaction often has a beneficial effect, introducing additional damping into the system. A common modeling approach represents pedestrians as single-degree-of-freedom (SDOF) oscillators; however, their dynamic properties are subject to significant uncertainty. This study investigates how uncertainty in pedestrian dynamic characteristics propagates into the dynamic properties of the coupled structure-pedestrian system and the structural response. An interval-based model is adopted to represent uncertainty in pedestrian parameters. The structure is modeled as a continuous dynamic system, while pedestrians are treated as stationary SDOF oscillators with mass, natural frequency and damping ratio described as interval variables. Focusing on a single vibration mode, an analytical interval Frequency Response Function (FRF) of the coupled system is considered. The pedestrian-induced load is modeled as a stationary random process using an equivalent spectral approach, enabling closed-form expressions for the interval power spectral density and spectral moments of the response. As a first step, the propagation of uncertainties in pedestrian properties on the FRF of the coupled human-structure system is studied. Then, two case studies—a footbridge and a floor—are presented to demonstrate the impact of uncertainty on vibration serviceability assessment. The results highlight the importance of accounting for the uncertainty in pedestrian dynamic properties when evaluating comfort and performance in lightweight structures.