Behaviour Of FRP Tube Concrete Under Axial Load

A new type of structural columns is being developed for new construction. They are made of concrete-encased fiber-reinforced polymer (FRP) tubes. The concrete-filled FRP tubes are cast in place. The tube acts as a formwork, protective jacket, confinement, and shear and flexural reinforcement. It can also be used to complement or replace conventional steel reinforcement of the column. This paper presents the results of experimental and analytical studies of the performance of concrete columns confined with carbon and glass FRP composite tubes. Concrete-filled FRP tubes are instrumented and tested under uniaxial compressive load. Test variables include the type of fiber, the thickness of the tube, and concrete compressive strength. Results show that external confinement of concrete by FRP tubes can significantly enhance the strength, ductility, and energy absorption capacity of concrete.