Real-time multi degrees of freedom hybrid fire testing using PI control

Hybrid testing has been successfully developed in earthquake engineering and begins to be applied to fire engineering (Hybrid Fire Testing or HFT) for coupling fire tests and numerical simulations. To this end, several tests have been performed since the 1990’s but were limited to one-degree-of-freedom (DOF) systems.
This paper approaches MDOF tests. It presents fully automated HFT performed on half-scale steel specimens using proportional integral control procedure. Three tests were performed : a one DOF-test, a two-DOF test and a three-DOF test. The tested specimens are steel square hollow sections heated with electrical resistances. The numerical substructure of these tests are modelled with SAFIR® and their behaviour is non-linear. The tests were performed successfully and replicate the numerical predictions to a large extent.