Multi-mode vibration control of mega-sub-controlled modular high-rise buildings with non-uniform inter-module connections

To facilitate the application of modular construction techniques in high-rise structures, a novel mega-sub-controlled modular high-rise building, termed mega modularized substructure system, has recently been proposed by the authors, consisting of a mega frame and a modularized substructure. By appropriately tuning the inter-module connection properties, the secondary structure can function like tuned mass dampers (TMDs) to mitigate the primary structural response. In the previous work, the inter-module connection properties were assumed uniform across different floors to control the fundamental modal response of the primary structure. However, higher vibration modes may contribute significantly to the seismic response for such high-rise buildings, while the uniform inter-module connection properties are ineffective in controlling the multi-modal response of the primary structure. To address this challenge, this study extends the authors’ previous work by proposing a non-uniform tuning strategy for the inter-module connection properties along the height for multi-mode vibration control. To examine the effectiveness of the proposed method, an analytical model is developed, followed by the formulation of the governing equations of motion. Two types of design strategies, i.e., the single- and multi-objective optimization methods, are introduced to determine the connection properties. The frequency-domain performance of the optimized models is comprehensively analyzed, and the time-domain behaviour is further investigated with consideration of the nonlinear responses of the primary structure. Results indicate that, compared to uniform connections, single-objective optimized non-uniform connections enhance the multi-mode control performance on the primary structural response but amplify the secondary structural responses. In contrast, the multi-objective optimization method achieves a favourable balance in controlling both the primary and secondary structural responses, improving the applicability of the proposed structural system.