Seismic fatigue behavior of in-plane deformational metallic energy dissipating devices

The metallic energy dissipating devices (MEDDs) have been developed to mitigate structural damage in the manner that they mainly dissipate seismic input energy rather than typical structural components. Of MEDDs, in-plane deformational metallic energy dissipating devices (IPMDs) are widely used to seismic force-resisting systems (SFRSs) in moderate and low-seismicity regions which are expected to relatively small seismic deformation demands since they effectively dissipate seismic energy throughout the yielding at small displacements obtained from relatively high initial lateral stiffness. However, IPMDs could be fractured due to their small deformation capacities and low-resistance to low-cycle fatigue failures. Even if potential problems of IPMDs exist, a current seismic code requires only a few tests of five-full-reversal cycles with a displacement amplitude expected at a very rare strong earthquake and does not provide specific requirements that can remove concern about such fatigue failures under strong earthquake. In this reason, the low-cycle fatigue behavior of IPMDs installed in SFRSs needs to be discussed in depth. To address this, this study performs nonlinear dynamic analyses of prototype SFRSs employing MEDDs and investigates fatigue damage states of MEDDs based on the strain-based approach. The analytic results show that the more rigorous requirements are required to ensure the target collapse probability under the maximum considered earthquakes (MCEs) and, in turn, to guarantee the seismic performance of structures employing MEDDs with preventing their low-cycle fatigue failures.