08.18: Influence of composite beams on the seismic behaviour of EBF

Abstract

ABSTRACTThe Eccentrically Braced Frames (EBF) represents a structural typology largely used in case of steel structures located in seismic zones due to their possibility to dissipate the seismic input energy through plastic hinges formed in the dissipative “link” element. In case of seismic‐resistant eccentrically braced frames with composite beams, the current design practice suggests avoiding the disposition of shear connectors in the expected plastic areas, thus taking into consideration shear plastic hinges that occur only in the steel beam or link element. The existing experimental results show however that this consideration is not realistic, as the behaviour of full‐composite beam with connectors disposed over the link is closer to the case in which the beam is disconnected over the link element as suggested by the modern seismic norms: the response characteristics (resistance, stiffness and ductility) of composite beams with or without connection over the link length are very in fact close and different from the case of pure steel link element.The paper presents the results of a parametrical numerical study based on experimental results, with the main purpose of investigating the extent of the composite behaviour of EBFs with short links subjected to lateral seismic loads.