Bond stress-slip prediction under pullout and dowel action in reinforced concrete joints

When analyzing reinforced concrete (RC) framed structures under monotonic loading-for example, progressive collapse and pushover analysis-besides flexural deformation, the so-called "fixed end" rotations induced by longitudinal bar slips at the beamcolumn ends connected to the joints can be significant and may result in additional vertical deformations not accounted for in the conventional analysis. Hence, it is important to quantify the deformations arising from the fixed end rotations. In this paper, shortcomings of existing bond stress-slip models are discussed in terms of application limitation and prediction accuracy. A new analytical model based on the bond stress integration along the bar stress propagation length is proposed to predict the bar-slip behavior in RC beam-column joints under monotonic loading. The phenomena of combined axial pullout and transverse dowel action at the joints are considered. The proposed model is validated with experimental studies from published literature and is shown to be simple, yet reliable.