A computational study was conducted to evaluate the extent to which the column panel zone in a gable frame knee joint can develop tension field action when subjected to positive bending (top flange of the rafter is in tension). Past testing was reviewed and used to validate finite element models. The validated finite element modeling approach that utilized shell elements, was then used in a parametric study to evaluate the post-buckling strength of the panel zone beyond the shear buckling strength. In addition, a plastic mechanism model was used to derive an equation for the post-buckling shear strength of the panel zone and the derived equation was validated against the results of the parametric study. The result was a proposed equation for tension field action strength of the panel zone when subjected to positive bending that had an average error of 1% compared to the model results.