Fuzzy sliding mode control of sliding-isolated buildings

Based on the theories of sliding mode control and fuzzy control, a new sliding mode control method is presented for application in seismically-excited buildings with a frictional-type sliding-isolation system. The dynamic behavior of buildings equipped with a base-sliding-isolation system is highly nonlinear, and the new sliding mode control method involving fuzzy adaptive reaching law is ideal for such nonlinear systems. The undue chattering effect, which is the major disadvantage of conventional sliding mode controllers, is avoided by introducing the new sliding mode control method. Moreover, here the saturated control law is designed for us to use when the control force exceeds the maximum control force of an actuator. Finally, numerical simulations for an eight-story building model equipped with a frictional-type sliding-isolation system are given. Simulation results show preliminarily that: (1) the sliding mode control method is robust with respect to parametric uncertainties of the structure; (2) the sliding mode control method can keep the chattering effect sufficiently low so as to ensure the system stable; and (3) the hybrid control method is more effective for reducing the building response under strong earthquakes than an active or passive control method used alone.