Numerical Analysis of Axial Capacity and Ductility of RC Thin- Section Columns with Various Hoops Configurations

This numerical study is done to evaluate the effect of confinement on the axial capacity and ductility of thin section columns using the plastic damage plasticity (CDP) model in Abaqus. Seven specimens of short columns with the size of 100x400x300 mm subjected to uniaxial compression loads were analyzed based on material parameters and modeling technics that were first validated using an experimental specimen. The variation in confinement was made by changes in the configurations of the column hoops giving the variation on the hoops volumetric ratios such as 1,06% (C1), 1,16% (C2), 1,25% (C3),1,34% (C4), 1,69% (C5), 1,25% (C6) and 2,02% (C7). All specimen models have longitudinal rebars of 10D13 (As = 1327 mm2) and hoops Ø5.6 with a yield strength of 437 MPa and 284 MPa, respectively. The compressive concrete strength of 21,5 MPa was considered according to the tested specimen for validation. The validated results show that the finite element analysis can predict well the behaviors of the tested column specimen in terms of stress on concrete, reinforcement, and the crack pattern. The analysis results of the hoops parameters show that increasing the hoops' volumetric ratio can increase the capacity of the concrete core but not the column's ductility. The maximum increase in the column capacity of 87.15% occurs in specimen C4 with the hoops volumetric ratio of 1,34% and the lowest of 58.14% occurs in specimen C3 with the hoops volumetric ratio of 1,25%. The specimen model C7 with the highest hoops volumetric ratio of 2.02% increases the capacity by only 65.27%. The effectiveness of confinement is not only determined by the higher values of the hoops' volumetric ratio but also by the proper configurations of the hoops to obtain effective confining effects on the concrete core.