EFFECTS OF HIGH-STRENGTH STEEL BARS ON SHORT CONCRETE COLUMNS UNDER AXIAL LOAD

Abstract

The study involved the effect of high-strength longitudinal steel bars in normal-strength concrete columns. It aims to investigate the axial behavior of reinforced concrete columns due to the use of high-strength steel bars as longitudinal reinforcement. The experimental tests included five-column specimens under axial compressive loading. The longitudinal steel bars used were 13 mm in diameter with average yield strengths of 442.30 and 553.01 MPa. The stirrups used were 10 mm in diameter with average yield strengths of 436.06 and 522 MPa. The tests were carried out under axial compressive loading. The results showed that the capacity of the column specimen with high-strength longitudinal reinforcement (fy 550 MPa) was increased compared to the column with normal-strength longitudinal steel bars (fy 420 MPa). Column specimens with higher-strength longitudinal and transverse reinforcements indicated an increase in compressive strength. It can be concluded that the use of high-strength longitudinal steel bars does not significantly increase the capacity of reinforced concrete columns. Based on the deformations of the specimens under the conditions of peak stress and 0.85 peak stress (post-peak condition), the strain of the column specimen with normal-strength longitudinal and transverse reinforcements is greater than the other column specimens. The number of longitudinal reinforcements used could increase the deformability (ductility) of the concrete column. The stress-strain relationships of all test column specimens show ductile failure modes. It was found that the post-peak stress-strain relationships did not decrease considerably in all column specimens.