Fast online earthquake simulation of friction-damped systems

Tests on four different layouts of friction damped stiffening systems are reported. They have been subjected to fast online earthquake simulations utilizing the El Centro and Friaul earthquakes. Designed as 'three-stage elements' or at least as one frictional 'module' their intended shear characteristic could be verified. Because such 'stiff-ductile' systems can cause considerable errors during a fast online test that can even destabilize the response, a self-adjusting 'software error-force suppression (SEFS)' was developed and proved to be very effective. Because of its simplicity, adopting SEFS in multi-degree-of-freedom tests seems feasable in future applications. With the behaviour of real-size three-stage elements being verified, work is under way to provide simple design methods and a safety concept for such systems under earthquakes. (orig.)