Real-time hybrid simulations including rocking effects: The case of a frame-structure with unbounded elastomeric isolators

Real-time hybrid simulations (RTHS) have become an attractive alternative for the study of structural systems by conveniently separating an experimental substructure from a numerical component. Due to the technical and economic benefits of applying fiber-reinforced elastomeric isolators (FREIs) in unbounded configuration, the analysis of this device using RTHS is gaining interest among researchers. However, there are aspects associated with the complexity of the unbounded isolators that alter the dynamic behavior of the structure. One of these aspects is the rocking effect, which generally is disregarded when conducting RTHS. This paper addresses the role of rocking effects in the representation of isolated structures through RTHS. The results of different RTHS architectures show that when rocking is not taken into account, the base displacement and interstory drifts can be underestimated by more than 50%. Results from the RTHS are compared to shaking table tests (STTs) of a mock-up structure isolated with unbounded FREIs, with a maximum error less than 8% in peak and root-mean-square values of displacement and force.