Fire performance of concrete-filled steel tubular columns strengthened by CFRP

With the increasing use of concrete-filled steel tubes (CFST) as structural members, there is a growing need to provide suitable measures for possible strengtheoing or repair of these kinds of structural elements. Fibre reinforced polymer (FRP) jacketing is a recent method and is particularly attractive in which it does not significantly increase the section size, and is relatively easy to install. Thus, it can be used to enhance strength and/or ductility of CFST members. Very little infonnation is available on the perfonnance of FRPstrengthened CFST members under fire conditions. This paper is an attempt to study the fire perfonnance of CFST columns strengthened by FRP. The results of fire endurance tests on FRP-strengthened circular CFST columns are presented. Failure modes of the specimens after exposure to fire, tempemtures in the cross section, axial defonnation and fire resistance of the composite columns are analysed. It is demonstrated that the required fire endurance can be achieved if the strengthened composite columns are appropriately designed.