Experimental behaviour of high-strength concrete columns in fire

Abstract

Twelve high-strength concrete columns were tested in fire under two heating rates at different load ratio and restraining levels. Imposing axial restraint against column thermal expansion during fire causes additional axial forces to be generated and develops excessive buckling deformations. Therefore, an early failure can take place which may lead to partial failure of the building during fire. This paper reports an integrated parametric experimental study, in which the influence of load level and degree of restraint are investigated together with their interactions. The paper contains main results and conclusions including measured concrete and reinforcement temperatures, axial deformation, temperature failure and additional restraining forces. It is found that, the maximum value of axial deformation is independent of the rate of heating and it is dependent on the load that has been applied during the test. Furthermore, the failure time of columns tested under low heating rate is almost twice the failure time of columns tested under high heating.