Bespoke Footbridge for Studying Pedestrian–Structure Interaction with Vertical Vibration

Progress in quantifying and codifying pedestrian–structure interaction with a vertical structural vibration and the effects on both human beings and structures has been slow, primarily owing to a lack of experimental facilities that can simulate a wide range of vibration conditions. To accelerate the progress of pedestrian–structure interaction research, a new experimental facility (the UNIOVI footbridge) has been developed at the University of Oviedo, Gijón, Spain, and is presented in this paper. The UNIOVI footbridge is a unique laboratory structure, whose fundamental vertical vibration mode can be finely tuned in the frequency range between 1.6 and 9.3 Hz by altering its mass or stiffness. The clear separation of the first vibration mode from higher vibration modes and a low damping ratio make the structure ideal for interaction studies. The paper describes unique features of the facility and provides analytical expressions for modeling its dynamics. Time-domain procedures based on free decay response data are proposed to identify the dynamic parameters of both the structure and the human body in stationary postures. The use of the facility was successfully demonstrated by identifying body dynamics for six test subjects in three passive postures: one standing posture and two instantaneous postures extracted from the walking gait. The next task is to employ the facility in studying walking, for which the facility was primarily designed.