The effects of beam-column connections on behavior of buckling-restrained braced frames

Abstract

Buckling Restrained Braced (BRB) frames have been widely used as an efficient seismic load resisting system in recent years mostly due to their symmetric and stable hysteretic behavior and significant energy dissipation capacity. In this study, to provide a better understanding of the behavior of BRB frames with various beam-column connections, a numerical study using non-linear finite element (FE) analysis is conducted. All models are implemented in the Abaqus software package following an explicit formulation. Initially, the results of the FE model are verified with experimental data. Then, diverse beam-column connections are modeled for the sake of comparison from the shear capacity, energy dissipation and frame hysteresis behavior points of view until appropriate performance is assessed. The considered connections are divided into three different categories: (1) simple beam-column connections including connection by web angle and connection by seat angle; (2) semi-rigid connection including connection by web and seat angles; and (3) rigid beam-column connections by upper-lower beam plates and beam connections with web and flange splices. Results of the non-linear FE analyses show that these types of beam-column connections have little effect on the maximum story drift and shear capacity of BRB frames. However, the connection type has a significant effect on the amount of energy dissipation and hysteresis behavior of BRB frames. Also, changes in length and thickness of the angles in simple and semi-rigid connections and changes in length and thickness of plates in rigid connections have slight effects (less than 4%) on the overall frame behavior.