Modeling of different bracing configurations in multi-storey concentrically braced frames using a fiber-beam based approach

This study presents a modeling approach for concentrically braced frames to be used in multi-storey buildings. The model for an inelastic beam-column brace consists of two inelastic force-based beam-column elements, each of which having five integration points and a discretized fiber section. The hysteretic response of such elements can be derived by integration of uniaxial stress-strain relations. To capture the effects of gusset end restraint, in addition to the two inelastic beam-column elements, this study uses an additional inelastic force-based beam-column element of length 2 t (where t is the thickness of the gusset plate) at each end of the brace. This study presents the correlation of the axial force-axial displacement and the axial force-lateral displacement responses obtained from the brace model with the available experimental results. Based on the comparison of numerical hysteretic responses with the experimental results, it can be concluded that the brace model which includes two additional force-based beam-column elements at the ends of the brace can capture the hysteretic responses of axial force-axial displacement and axial force-lateral displacement more accurately. Finally, this study sets the limits of slenderness and the width-to-thickness ratio in which inelastic beam-column brace model can predict the hysteretic responses of a brace member with adequately accuracy. (C) 2014 Elsevier Ltd. All rights reserved.