An active control system for reducing crowd induced vibrations in a grandstand

The occupancy of structures by crowds often causes vibrations that in turn generate discomfort and, in some occasions, can cause damage to the structure. Football stadia are one type of structures that are especially vulnerable to such excitation and more so when they are used for other events such as concerts. As an experimental platform for investigating human-structure interaction, a grandstand was designed and built with dynamic parameters similar to the south grandstand of the Olympic Football Stadium in Cali Colombia. In the work described in this paper, an electro-magnetic actuator with a 13.2 kg active mass was used with an active control scheme to reduce human-induced vibrations in the grandstand. The structure and controller were modeled, identified and then validated experimentally. Performance of the control system was analyzed through simulations and then verified experimentally as a group of people, with a total mass of up to 232 kg, jumped on the grandstand. The control system reduced the structural response of the grandstand up to 50% of that without the control system.