Reinforced concrete (RC) columns with insufficient transverse reinforcement and non-seismic reinforcement details are vulnerable to shear failure and loss of axial load carrying capacity. With an aim of developing a macro model to simulate cyclic lateral load-deformation performance, the behavior of non-ductile RC columns is modeled by combining deformation components due to flexure, reinforcement slip and shear. Individual deformation component models developed for monotonic lateral loads serve as envelopes or primary curves for respective cyclic responses.Based on a comparison of their predicted shear and flexural strengths, the columns are classified into five general categories and total monotonic and cyclic response is obtained by combing the three deformation components according to a set of rules specified for each category. The proposed monotonic and cyclic response models are compared with the data from various experimental studies on columns having flexural failure with very limited or no shear effects, flexure and/or shear failure following the flexural yielding, and shear failure prior to flexural yielding. The predicted and experimental response of columns failing primarily in shear and flexure were comparable. Similarly, the hysteretic response of the column with axial load failure was captured reasonably well by forcing the monotonic response envelopes to degrade linearly between the peak strength and the point of axial load failure. Although, the research is focused on modeling the behavior of shear critical columns under seismic loads, the developed model is applicable to all RC columns.
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