Behavior of Short Reinforced Concrete Columns with Varying Tie Spacing and Concrete Grades Under Compression

The strength and stiffness of a rectangular reinforced concrete (RC) column improves owing to rectangular ties. Concrete presses lateral ties of an RC column under compression when it experiences an axial force. The resistance offered by lateral ties prohibits the expansion of the concrete core. Hairline cracks get propagated along longitudinal steel bars in column corners with the increment in the axial load. Spalling of concrete takes place as soon as the longitudinal bars undergo yielding. The column resists load even after spalling due to confinement by ties. No sooner does the axial load reach its limiting value than buckling of longitudinal bars takes place resulting in opening of the hook of ties. The response of confined concrete is a function of strength and stiffness. The increment in these parameters is due to different parameters of confinement. However, there is no direct correlation of different parameters to assess the mechanical performance of confined concrete, such as the confinement spacing of ties and the compressive strength of concrete. The short columns with dimensions 150x150x300mm are under consideration in this work. The rectangular ties are spaced at 50mm and 75mm. The response of short columns is studied in relation to concrete grade, amount of steel bars provided and equispaced rectangular ties for the evaluation of modulus of elasticity.