Effect of Confining Pressure on Failure Patterns of Square Section Concrete Filled Steel Tube Column

Abstract

This paper aims to develop the performance of the square section of the CFT column using preconfining pressure. The square sections of CFT columns were experimentally investigated for its compressive strength and failure patterns under uni-axial load test. The main parameter investigated was the confining pressure, which various from 0, 2.4, 4.8 and 7.2 MPa corresponding to 0%, 11.4%, 22.9% and 34.3% of concrete strength. The steel tubes grade TIS SM490 with external dimensions of 98 mm, 98 mm and 350 mm were used to confine the core concrete having a compressive strength of 20.98 MPa. The confining pressure was applied by preconfining of the steel jacket. Test results revealed that increasing of confining pressure of 11.4%-34.3% of concrete strength significantly improved the compressive strength of the square section of CFT column by 3.01-19.21%. The main failure mode of the test specimen was due to shear failure in the concretecore which induced outward buckling in steel tube. Moreover, it was also found that changing of confining pressure affected the failure plane angle of CFT column. The minimum failure plane angle occurred at the confining pressure of 11.4% of concrete strength.