Large-scale real-time hybrid simulation involving multiple experimental substructures and adaptive actuator delay compensation

Real-time hybrid simulation provides a viable method to experimentally evaluate the performance of structural systems subjected to earthquakes. The structural system is divided into substructures, where part of the system is modeled by experimental substructures, whereas the remaining part is modeled analytically. The displacements in a real-time hybrid simulation are imposed by servo-hydraulic actuators to the experimental substructures. Actuator delay compensation has been shown by numerous researchers to vitally achieve reliable real-time hybrid simulation results. Several studies have been performed on servo-hydraulic actuator delay compensation involving single experimental substructure with single actuator. Research on real-time hybrid simulation involving multiple experimental substructures, however, is limited. The effect of actuator delay during a real-time hybrid simulation with multiple experimental substructures presents challenges. The restoring forces from experimental substructures may be coupled to two or more degrees of freedom (DOF) of the structural system, and the delay in each actuator must be adequately compensated. This paper first presents a stability analysis of actuator delay for real-time hybrid simulation of a multiple-DOF linear elastic structure to illustrate the effect of coupled DOFs on the stability of the simulation. An adaptive compensation method then proposed for the stable and accurate control of multiple actuators for a real-time hybrid simulation. Real-time hybrid simulation of a two-story four-bay steel moment-resisting frame with large-scale magneto-rheological dampers in passive-on mode subjected to the design basis earthquake is used to experimentally demonstrate the effectiveness of the compensation method in minimizing actuator delay in multiple experimental substructures. Copyright (c) 2011 John Wiley & Sons, Ltd.