Experimental and Numerical characterization of ultralow-Cycle Fatigue Behavior of Slit Dampers

Slit Damper devices (SDs) have been increasingly studied in last years for they implementation in building constructions to enhance the seismic resistance of structures. SDs are designed as yielding fuses that dissipate energy through large inelastic deformations, while the rest of the structure remains mainly elastic. They are mainly implemented in structural connections at pre-identified locations along the structure and should be able to sustain as much hysteretic cycles as possible before material collapse or fatigue failure in order to prevent local collapses and consequent loss of dissipative capacity. In this paper, finite element (FE) detailed models of single SD devices are presented and analysed under experimental testing-like pseudo-static load protocols by the commercial FE code ABAQUS®. The FE analyses of a variety of SDs in steel which varies each other in shape (hourglass-like shaped) and thickness in order to investigate hysteretic dissipation performances for the preliminary planning of a set of experimental tests. On the basis of the indications provided by the FE analyses, a subsequent experimental campaign is carried out to investigate the low-cycle fatigue damage for the proposed SDs. The SDs was designed for excellent fatigue performance, since the low-cycle fatigue characteristics of the steel SD can be efficiently defined by the Manson-Coffin relationship. These enhanced analyses provided good predictions of the onset of failure in full-scale steel castings across various specimen sizes and loading histories. Finally, it may be said that the newly proposed model can predict well the residual plastic displacements and the remaining life of the damper damaged after an earthquake