Mega-sub control of high-rise buildings

Vibration control of high-rise buildings with application of the mega-sub control method is studied in this research. A building with a mega-sub configuration consists of two major structural components--a mega structure as the main structural frame and several sub structures for residential and/or commercial usage. The author proposed "mega-sub control method" in which the sub structures are designed to serve as vibration control dampers. In this study, the procedure of optimally designing dynamic parameters of a mega-sub controlled building under stochastic wind loads is developed. The fluctuating wind speed is modeled as a non-white random process in both time and space domains. The power-spectral density (PSD) functions of building response are obtained using the random vibration theory. The mean square values (MSVs) of those responses, as functions of the dynamic parameters including the stiffness and damping of they sub structures, are evaluated in the frequency domain by numerically integrating their PSD's. The optimal values of the dynamic parameters are determined so as to minimize the MSV of certain critical building response. The effectiveness of the proposed control method under both wind and seismic loads are evaluated by means of numerical simulation. Feasibility of utilizing base isolation devices and actively-controlled actuators for mega-sub controlled high-rise buildings is also studied.; An example building is used to demonstrate the design procedure, and the numerical simulation of the response quantities is carried out to evaluate the effectiveness of the proposed control method. The results show that the proposed design procedure is suitable to apply to mega-sub buildings with different sub structural configurations, and the proposed control method can significantly reduce the vibration of a high-rise building. Furthermore, the base isolation devices and actively-controlled actuators can be implemented to a mega-sub controlled building in order to effectively improve the building's performance. It is also found that the mega-sub control method is robust in the sense that slight change in the dynamic parameter values affects the building's performance very little.