Controlling Characteristics of Passive Mega-Subcontrolled Frame Subjected to Random Wind Loads

The passive mega-subcontrolled structure proposed recently is a new form of structure associated with the design and construction of supertall buildings. However, a shortcoming still exists in its structural configuration. In this paper, a new configuration of the passive mega-subcontrolled frame is proposed. A more realistic analytical model of this structure subjected to random wind loads is presented, in which the substructures are treated as a multi-degree-of-freedom (MDOF) system and a nonwhite stochastic process in time and space is used. The dynamic equations and the response spectrum expressions, as well as the mean square response expressions, are derived on the basis of complex modal-analysis theory. A practical steel passive mega-subcontrolled frame is investigated; it is designed with reference to the conventional mega-subframe used in the Tokyo City Hall. The influence of the relative mass ratio and the relative stiffness ratio on the controlling effectiveness is investigated; and a proposed relative stiffness region, which is very useful in practical engineering design, is first presented. The corresponding computing results demonstrate that the structural configuration proposed here has extraordinary effectiveness in controlling displacement responses and acceleration responses, and the shortcoming that existed in the previously presented configuration can be overcome effectively.