Influence of the designer-assumed cyclic hardening parameters on the overstrength of austenitic stainless steel links

Abstract

Dissipative zones in buildings allow for the release of energy when a seismic event occurs. The structural analysis of these zones involves the study of the structure at different levels ranging from mechanical properties of materials, adjacent elements, and the whole system.The materials, elements and structures require ductility and strength. Within this framework, austenitic stainless steel (ASS), as a material subjected to cyclic fatigue, shows significant strain hardening and ductility. These promising features require an in-depth analysis when used for dissipative zones. For instance, structures such as eccentrically braced frames (EBFs), whose dissipative zones are placed in links, need that these links achieve the plastic stage first whereas the adjacent elements remain in the elastic stage.The overstrength within the numerical design of structures deserves particular attention, as do the factors involved in the modelling that can affect its assumption.Particularly, a study of the way of cyclic hardening parameters are used can influence the overstrength ASS was carried out. Three ways were considered: average, single values and the superposition of eight backstresses for kinematic hardening. The last one revealed the most conservative results and a higher influence on the link overstrength.It was found that the designed-assumed cyclic parameters directly influenced the link overstrength. With the designed-assumed that considered several changes to the kinematic hardening, the link overstrength was higher with less energy dissipated. Nonetheless, the link’s ductility and dissipated energy increased when the hardening was regular. The experimental material validation and numerical results of the EBF with ASS links were similar.