9. Employing Hybrid Tuned Mass Damper to Solve Off-Tuning Problems for Controlling Human Induced Vibration in Stadia

A key objective in the design of any sports stadium is to include maximum number of spectators with minimum obstruction in the visual cone. This functional requirement often results in employing one or more cantilevered tiers, which in turn culminates in more slender grandstands often with relatively low natural frequencies and modal damping ratios. These natural frequencies may sometimes fall in the range of frequencies of human movement which can possibly excite the structure in resonance resulting in vibration serviceability issues. One of the available techniques to reduce excessive responses is to use passive vibration control techniques such as Tuned Mass Dampers (TMD). However, the off-tuning problem is a substantial drawback of this technique, whereby changes in natural frequencies caused by crowd-structure interaction may detune the TMDs. This paper presents a study into the possibility of using hybrid (combination of active and passive control) technology to augment the vibration serviceability of sports stadia. It shows a comparative analysis of vibration mitigation performances that are likely to be attained by utilising a passive TMD and the proposed HTMD. An appropriate control scheme is utilised with the proposed HTMD to deal with the off-tuning issues in TMDs caused by crowd loading, and is shown to be effective.