Shear Displacement Model for Reinforced Concrete Columns

Column shear failures observed during recent earthquakes and experimental data indicate that shear deformations are typically associated with insufficient transverse reinforcement, low aspect ratio and a few other parameters. It was shown that in some relatively tall columns, shear displacements can be as large as displacements due to flexure and longitudinal bar slip at column ends. However, very few researchers attempted to predict the lateral load-shear displacement relationship. In this paper, a piecewise-linear model is proposed to predict the lateral load-shear displacement relationship. Part of the new model is developed using the analysis results from Modified Compression Field Theory (MCFT). The results from the proposed model, which uses simplified equations, are evaluated and compared with the predictions from existing models as well as column test data. The proposed model is fairly simple, and predicts the lateral load-shear displacement relations relatively accurately at critical stages including shear cracking, peak strength, onset of lateral strength degradation, and loss of axial load carrying capacity.