Effective beam width of reinforced-concrete wide beam–column connections

The reinforced-concrete wide-beam floor system is recognised as one of the most efficient beam-and-slab floor systems in buildings. However, potential advantages of the system as a lateral load-resisting structure are often ignored due to a lack of understanding of the seismic behaviour of wide beam–column connections. Design codes prescribe beam width limitations to minimise the shear lag effect on the formation of full-width plastic hinges and achieving the expected capacity. However, owing to insufficient experimental and analytical studies, empirical design formulas for the beam width limitation, with remarkably different results, have been implemented in different design codes. In this paper, parametric studies of the influence of key parameters on the behaviour of wide beam–column connections are conducted based on available test results. An effective beam-width model is analytically developed using the equivalent-frame representation, where the effects of torsion of transverse beams and flexure around the joint core are considered. The validity of the model is verified using flexural strengths of test specimens, covering a wide range of design parameters. Combining the proposed effective beam-width model and the rational analytical approach, a simple and efficient, yet accurate, design formula is presented for determining the beam width limitation of wide beam–column connections.