EFFECT OF CONFINING PRESSURE ON DUCTILITY 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 ductility performance including of ductility factor, energy absorption factor and work index, based on its compressive strength and load-deformation characteristics under uni-axial load test. The main parameter investigated was the confining pressure, which various from 0, 2.4, 4.8 and 7.2MPa 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 showed 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 3.0-19.3%. However, at low confining pressure, the increase of confining pressure slightly increased the compressive strength. Moreover, it was found that the use of preconfining steel jacket for the square section of CFT column does not enhancing its ductility performance unlike the circular section.