STUDY ON FIRE RESISTANCE OF CONCRETE FILLED TUBULAR COLUMNS

Abstract

This study aims to evaluate theoretically the fire resistance capacities of concrete filled tubular columns subjected to fire and axial compression. A strength analysis has been made in which all strains found in heated concrete including stress strain, thermal expansion and transient strain are taken into account. Since, among others, transient strain plays a key role on the behavior of heated columns, a new theoretical procedure to treat this strain is postulated and an explicit closed form solution is derived for the ultimate column strength. With comparison between the solutions and test data, it is found that the strength of a heated column is decreased significantly below its full plastic strength due to transient strain, if the column is made of higher strength concrete, is subjected to larger axial force or if it is of a larger cross section. For all the cases, the solutions are found in good agreement with the test results.