Using CFRP to Achieve Buckling Restrained Behavior in Steel Compression Members

Carbon fiber reinforced polymer (CFRP) composites have been shown to be particularly well suited for external strengthening of reinforced concrete members. The superior mechanical and physical properties of fiber reinforced polymers make them excellent candidates for repair and retrofit of steel structures as well. However, the primary application for CFRP to date has mainly been flexural strengthening. This paper reports on an analytical and experimental study conducted to investigate an innovative technology to improve the buckling behavior of steel members under compression. In this study, rectangular steel bars are sandwiched between thin mortar or PVC blocks and the entire system is then wrapped with CFRP sheets. The requirements to prevent buckling of the steel members are derived from equilibrium conditions and verified with test results. Small scaled tests showed significant improvement in the inelastic axial deformation capacity prior to buckling under compression and an improved load carrying capacity after buckling.