Experimental analysis of structural element connections, made of high strength steel components, monotonic and cyclic loaded

Abstract

Seismic resistant building frames designed as dissipative structures must allow for plastic deformations to develop in specific members, whose behavior has to be predicted by proper design. Members designed to remain predominantly elastic during earthquake, such as columns, are responsible for robustness of the structure and prevention the collapse, being characterized by high strength demands. Consequently a framing solution obtained by combining High Strength Steel - HSS in non-dissipative members (e.g. columns) provided with adequate overstrength, and Mild Carbon Steel – MCS in dissipative members, working as fuses (e.g. beams, links or braces) seems to be logical. The robustness of structures to severe seismic action is ensured by their global performance, in terms of ductility, stiffness and strength, e.g. the "plastic" members of MCS (S235 to S355) will dissipate the seismic energy, while the "elastic" members (HSS - S460 to S690) by higher resistance of material and appropriate size of sections, will have the capacity to carry the supplementary stresses, following the redistribution of forces, after appearance of plastic hinges. Such a structure is termed Dual-Steels Structure. DS concept is extended to connections, too, on the same philosophy related to ductile and brittle components, in order to achieve both ductility and robustness criteria. In fact, when connecting MCS beams to HSS columns it will result a DS beamto-column joint. Starting from the above considerations, a large experimental research program was carried out in order to study the performance of dual-steel configuration for beam-to-column joints under monotonic and cyclic loading.