Approximate analysis method for interstorey shear forces in structures with active variable stiffness systems

It has been demonstrated that active variable stiffness (AVS) systems may be effective for response control of building structures subjected to earthquake excitations. Because the performance of structures with AVS systems exhibits strong nonlinearity, the classical dynamic analysis method for linear structures, such as the mode-superposition method, is not applicable to structures with AVS systems. In this paper, an approximate analysis method is proposed for the maximum interstorey shear forces in structures with AVS systems. Firstly, a new equivalent relationship between single-degree-of-freedom (sdof) structures with AVS systems and so-called fictitious linear structures is established. Then, the new equivalent relationship is used to revise the approximate-mode-superposition (AMS) approach for multi-degree-of-freedom (mdof) structures with AVS systems, which was previously suggested by the authors. Subsequently, extensive numerical studies are conducted using the revised AMS approach for building structures equipped with AVS systems and subjected to different types of artificial earthquake excitations. Based on the simulation results, an approximate analysis method is proposed for the maximum interstorey shear forces in structures with AVS systems. The maximum interstorey shear forces in example structures subjected to actual earthquake excitations are obtained using the proposed method, and the results are compared with those obtained using the time-history analysis method. It is shown that the results estimated using the proposed method generally agree well with those obtained using the time-history analysis method.