Nonlinear displacement-based response prediction of reinforced concrete columns

In this study, the application of two nonlinear finite element method (FEM) procedures and a simplified axial-shear-flexure interaction approach are examined for displacement-based analysis of four reinforced concrete columns, previously tested. The two alternative finite element methods are described based on differing crack modeling approaches: smeared rotating cracks, implemented by the VecTor2 program, and smeared fixed cracks, implemented by the UC-win/WCOMD program. The Axial-Shear-Flexure Interaction approach, a method also based on smeared rotating cracks, is simplified, discussed and compared with the FEM analyses. Experimental and analytical results are compared for pre- and post-peak responses up to axial collapse of the columns. Both FEM methods resulted in satisfactory pre-peak predictions. Adequate post-peak simulations, until near complete loss of capacity, were achievable by the rotating crack method (VecTor2), especially for those columns exhibiting a shear-critical response. The simplified Axial-Shear-Flexure Interaction approach provided response envelope curves for the specimens comparable with the cyclic results obtained by the two FEM approaches.