Investigation of behavior of fiber added concrete filled short steel composite columns

In this thesis, the behavior of carbon steel (CS), stainless steel (SS) and aluminum (AL) short composite columns formed by filling, plain and / or fiber reinforced concrete having the same length / diameter ratio with square cross-section were investigated. For this purpose, columns with 2 mm, 3 mm, 4 mm wall thickness, 250 mm length and 100 mm x 100 mm square cross sections were prepared. The columns are filled with plain and fiber reinforced concrete with a compressive strength of 30 and 70 MPa. The two ends hooked steel fiber and polyamide (Nylon) synthetic fibers were selected as fiber packages. As a fiber additive, single steel and hybrid (steel + synthetic) fibers were selected. The fibers were added to the concrete in 0.5% and 1.5% by volume. All prepared column samples were tested under axial load. Various comparisons were made with the results obtained in the experiments and the behaviors of columns such as buckling modes, ductility, axial load bearing and toughness capacity were investigated. In addition, parameters such as concrete admixture rate (CCR), ductility index (DI) and strength increase index (SI) are defined to better explain the behavior of the columns under axial load. As a result, it is seen that filling the columns with concrete the local buckling of all columns are limited and provides a significant increase in the ductility, axial load bearing and toughness capacities. The use of the fibers did not significantly change the axial load-bearing capacities of the columns, but the CS and SS columns caused significant increases in the energy absorption capacity after ductility and peak load.