Real time dynamic hybrid testing using force-based substructuring

This paper presents a unified development and implementation of structural testing methods of force based substructuring using shake tables, actuators and computational engines for the seismic simulation of behavior of whole structures. The structures to be simulated are divided into one or more experimental and computational substructures. The interface forces between the experimental and computational substructures are calculated in real time and are imposed by actuators while resulting displacements and velocities are fed back to the computational engine to determine the contribution of the "computational substructures". Earthquake ground motions applied to the physical substructures by shake tables which produce inertial effects - deformations and stresses. In other simplified testing methods ground motion effects are applied directly by actuators simulating inertial effects in pseudo-dynamic fashion, or through effective force techniques. The unique aspect of all the above hybrid system in this development is a force-based substructuring within dynamic testing. Since the shake tables induce inertia forces in the physical substructures, the actuators have to be operated in force control as well. The resulting testing methods are more versatile than currently used seismic testing methods. The substructuring strategy and the numerical integration algorithms associated with the computational substructures are presented along with the implementation of the computational engine. A new dynamic force control strategy developed for this purpose using series elasticity and displacement compensation is presented. An example of a real-time hybrid test implementation, and results from this experiments are also presented.