Behaviour of steel reduced beam web (RBW) connections with sinusoidal voids

The 1994 Northridge earthquake caused widespread damage to moment-resisting frames.Various brittle fractures were found in beam-to-column welded moment connections. So farnumerous efforts have been made to find a better connection configuration to improve the behaviour of the post-Northridge moment connections. The improvements are mainly basedon the connection reinforcement or the weakening of the beam section. These methods are intended to force the plastic hinge to form away from the column face and consequently increasing the connection ductility. In this study these goals are achieved by creating asinusoidal void in the beam web. Finite element study was used to investigate the behaviour of connection with such openings. The depth and length of the void are designed as such to cause the shear yielding of the beam web along the beam span and to keep the connection in elastic region. A parametric study was done to realize the effects of length and depth of such openings on the behaviour of connection. Analytical results showed that the presence ofsinusoidal void moved the plastic hinge into the beam length and caused an increase in the connection ductility. Normalized moment-rotation curves of various void sizes are presented and their strength and ductility are compared. It seems that in the existing buildings this beam end modification is more economical than the reduced beam section (RBS) connections where the break of concrete slab is needed for top beam flange. In addition in this method the mechanical equipments could pass through the openings

Keywords:

Ductility , Plastic hinges , Post-Northridge connection , reduced beam web , Strength