HYBRID CONTROL OF HUMAN-INDUCED VIBRATION

A key objective in the design of any sports stadium is to include the 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 potential drawback of this technique, whereby changes in natural frequencies caused by crowd-structure interaction may detune the TMDs.
This thesis presents a study into the possibility of using Hybrid Tuned Mass Dampers (HTMDs) to augment the vibration serviceability of structures. An appropriate control algorithm is developed. It shows a comparative analysis of vibration mitigation performances that are likely to be attained by utilising the proposed HTMD. Also, 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.
In addition, it shows a comparative experimental investigation of a passive TMD and a prototype HTMD applied on a slab strip structure. The most effective control algorithm to enhance the performance of the HTMD and also deal with the off-tuning problem is investigated. The experimental results verify the developed simulation studies and also demonstrate the effectiveness of employing a HTMD considering both structural response and cost (actuator effort).