First,the equivalent relationship between single-degree-of-freedom structures with active variable stiffness (AVS) systems and special linear structures is established,and the equivalent additional stiffness ratio and the equivalent additional damping ratio are determined.Then,an approximate mode decomposition (AMD) method is proposed for multi-degree-of-freedom (MDOF) structures with AVS systems.The accuracy of the method is discussed and improved using revising parameters.Simulation results indicate that the AMD method is effective in estimating the maximum relative displacements and the maximum interstory drifts of MDOF structures with AVS systems.The study provides a foundation for the seismic design method of structures with AVS systems.
