The TMD (Tuned Mass Damper) is an effective structural control device that has been undergoing continuous development since the 1980’s. However, in most situations, its mass has been limited to less than 1% of that of the entire building due to restrictions such as weight limitations and spatial difficulties. As a result, in early studies related to dynamic mass dampers, efforts were focused on how to compensate for the small mass ratio with active control technology. Although performance has been improved by hybrid control technology, devices for controlling structures during major earthquakes have not been put into use for a long while because of the problems of energy supply and stroke control. However, since the 2010’s, there has been rapid development of TMDs that are effective against major earthquakes. Mass ratios of 5% have been successfully realized, and adopted in several actual existing high-rise buildings.
Furthermore, recent studies have examined the utilization of a part of a structure’s weight as a dynamic mass damper. Because a much larger mass ratio can be provided than a conventional TMD, these types of structures can potentially achieve superior seismic control. In addition, the response reductions of a main-system and a sub-system can be made compatible. The authors proposed a stroke control strategy and a practical response evaluation method based on response spectrum in a past study. However, although this strategy is effective in the initial stage of design, we pointed out that several features needed to be developed, such as accuracy of the stroke estimation against earthquake input, how to expand to complicated MDOF systems, and versatility for sub-system parameter fluctuations.
This paper presents a response evaluation methodology for a seismic control structure that includes large-weight sub-systems as dynamic mass damper. The fundamental idea of the methodology is to consider the sub-system’s stroke as amplification caused by the interaction with the main-system from that of the independent sub-system. First, the concept of the proposed response evaluation method based on a 2DOF model is introduced. Then the strategy for expanding the method to a MDOF system, including a system with multiple sub-systems, is presented. After conducting several examinations concerning the influence of the sub-system’s parameter variation based on random vibration theory, practical expressions are derived that describe the relations between variation and response. Finally, the accuracy and validity of the proposed method are discussed through numerical analyses based on earthquake input.
