Evaluation of Reinforced Concrete Columns under Biaxial Bending

Modeling by finite element method provides a ground for better perception of the behavior of reinforce columns and it is also useful in prediction of the behavior of these members without the experimental results. The performance improvement depends upon different parameters including the geometry of columns and configuration of reinforcement layers. In this study, slender reinforced columns are modeled under axial and biaxial bending loading with Carbon fiberreinforced polymer (CFRP) with different slender ratios using Abaqus software. The model is validated by the results of Bilchek et al., experiments. In this design, 30 concrete unstrengthened hoop columns with the diameter 100mm and heights 200,400,600,800,1000mm are made and reinforced with bidirectional CFRP composites. In each slenderness, a control sample (unstrengthened) and 5 reinforced specimens with different fiber configurations (hoop, longitudinal, angel and their combination) are tested under axial loading and biaxial bending to the ultimate failure. The results showed that these composites increased strength and ductility of specimens considerably. The results showed that in unstrengthened specimens, by increasing slenderness from 1 to 10, strength and ductility were reduced as 35, 65%, respectively. The results showed that the modeling using experimental data had good consistency. Based on the shortage of experimental data in slender columns at big scale, by performing similar studies, the existing problems can be eliminated.