NON LINEAR FINITE ELEMENT ANALYSIS FOR NORMAL AND HIGH STRENGTH CONCRETE COLUMNS CONFINED BY RECTANGULAR TIES

This paper presents a nonlinear finite element analysis of normal and high strength reinforced concrete columns confined with rectangular ties under axial compressive loading. The paper presents a nonlinear finite element analysis for nineteen normal strength concrete rectangular columns with different concrete dimensions, different concrete strength and confinement characteristics. These specimens were tested by the author and a set of another twenty high strength concrete square columns were tested by other researchers. ANSYS 15 Finite Element Software was used in this study. Concrete was modeled with eight nodes SOLID 65 element that can be translated either in the x, y and z axis directions. Longitudinal and transverse reinforcement were modeled as discrete element using 3D-link 180 element type. The nonlinear requirements for each material were implemented in the modeling. The results indicated that the axial force – axial strain relationship obtained from the analytical model using ANSYS are closely matched with the experimental data. The comparison shows that the ANSYS is capable of modeling and predicting the actual nonlinear behavior of confined normal and high-strength concrete columns under concentric loading. The maximum applied load and the maximum strain have also been confirmed to be satisfactory. Depending on this agreement between the experimental and analytical results, a parametric numerical study can be done by ANSYS 15 to clarify and evaluate the effect of confinement variables on the strength of normal and high strength reinforced concrete columns confined with rectangular ties under axial compressive loading.