Experimental Study on Fire-Exposed Rectangular Concrete-Filled Steel Tubular (CFST) Columns Subjected to Bi-Axial Force and Bending

Abstract

This paper provides new test data and changing regularity of behavior of rectangular concrete-filled steel tubular columns that have been exposed to high temperature and subsequently are subjected to bi-axial force and bending. Fourteen specimens exposed to constant high temperatures were tested to investigate the residual behavior of them. The investigation emphasized the effect of experimental parameters, such as temperature, slenderness ratio, eccentric angle, height-to-width ratio and confining coefficient, on residual bearing capacity and ductility of members. It is found that the bearing capacity and ductility are mainly influenced by the testing parameters. After being heated to a high temperature lower than 600 °C, the columns still have good carrying capacity. The ductility coefficients of all the specimens in the test are not less than 5.6, which indicates that CFST columns subjected to bi-axial compression and bending have good ductility even after high temperature exposure. The experimental results provide the foundation for assessing, repairing and strengthening the fire-damaged structures.