DISCRETE-TIME VARIABLE STRUCTURE CONTROL WITH COMPOSITE REACHING LAW FOR BUILDING STRUCTURES

Time-delay causes unsynchronized application of the control force, which can not only degrade the performances of the control system but also even render the dynamic system unstable. In this study, a new discrete-time variable structure control (DVSC) method involving a composite reaching law, which is one of the active control algorithms, is applied for seismically excited linear structures with time-delay in control. The excessive chattering effect, the major disadvantage of conventional discrete-time variable structure controller, is avoided by introducing the new method. In order to verify the feasibility and robustness of the proposed control method, this paper provides a model on Multiple-Degree-of-Freedom (MDOF) shear building equipped with active brace system (ABS) under seismic excitations. The simulation results prove that our method is quite effective, which not only can reduce the peak-response of the ground motion, but also can avoid the undue chattering effect of the control system so as to ensure the system stable. Since time-delay effect is incorporated in the mathematical model for the structural control system throughout the derivation of the proposed algorithm, the system performance and dynamic stability are guaranteed.