Control of hysteretic base-isolated structures: an adaptive backstepping approach

A hybrid seismic control system for building structures is considered, which combines a class of passive nonlinear base isolator with an active control system. The objective of the active control component applied to the structural base is to keep the base displacement relative to the ground, the interstory drift and the absolute acceleration within a reasonable range according to the design of the base isolator. We use the adaptive backstepping approach for the control design. The base isolator device exhibits a hysteretic nonlinear behavior which is described analytically by the Bouc-Wen model. The control problem is formulated representing the system dynamics in two alternative coordinates: absolute (with respect to an inertial frame) and relative to the ground. A comparison between both strategies is presented by means of numerical simulations.