An instantaneous minimum input energy control strategy for isolation systems with covarying stiffness and damping

The seismic isolation stiffness and damping of magnetorheological elastomer (MRE) isolation bearings can adapt instantly to seismic load variations which can provide more intelligent seismic protection for engineering structures. The stiffness and damping change simultaneously following a defined functional relationship. For such systems, an instantaneous minimum input energy (IMIE) control strategy is proposed. This algorithm explicitly establishes the functional relationship between damping and stiffness, converting the optimization problem into a single-variable search for optimal stiffness while automatically determining the corresponding optimal damping. The IMIE strategy operates through total minimization of seismic-induced kinetic energy transmission to the structure and isolation system’s actuation energy consumption during each discrete time interval. A bridge isolation system with MRE isolation bearings is controlled by proposed IMIE algorithm. The control effects under different seismic excitation are compared with passive control, Linear Quadratic Regulation (LQR) control and fuzzy control method. Which reveal that the IMIE algorithm effectively control structural responses under seismic excitation and has unique advantages in reducing the input energy of structural and reducing the displacement of MRE bearings. It provides a new control thought and method for the engineering application of hybrid isolation systems.