Stability in Hybrid Fire Testing

Hybrid testing is an appealing technique to observe the behavior of an element in an experimental test while taking into account the interaction with the rest of the structure which is modelled numerically. Being widely used in the seismic field, this technique has been recently proposed in the fire field. The purpose of this paper is to demonstrate that the loading control process may be unstable during the hybrid testing when using the methodology applied in former tests presented in the literature. The stability in the latter method depends on the stiffness ratio between the two substructures. For the purpose of discussion, a one degree-of-freedom elastic system is studied. To overcome the stability issues, a new method is presented, independent on the stiffness ratio. Finally, the hybrid testing of a 2D beam being part of a moment resisting frame is analyzed in a virtual environment (both parts being modeled numerically) using the “first generation method” and the new proposed method.