Enhancing Local Buckling Behavior of SHS Braces Using GFRP and CFRP Wrap

Abstract

During earthquakes, diagonal members of concentrically braced frames are meant to dissipate hysteretic energy through their postbuckling performance. However, crack formation at the location of plastic hinges obstructs the brace operation. This paper proposes the use of fiber-reinforced polymer (FRP)—both glass fiber–reinforced polymer (GFRP) and carbon fiber–reinforced polymer (CFRP)—to improve the behavior of square hollow section (SHS) braces, and this retrofitting strategy is selected in a way to mitigate the local buckling which plays a key role in the failure of braces. The effectiveness of the proposed approach is validated using an experimental program, and the strengthening specimens are tested under axial compressive loading. The influence of parameters—including the slenderness ratio, the number of FRP layers, and the FRP length—is evaluated. Results indicate that the externally overwrapped FRP fabrics in the transverse direction are highly capable of postponing the local buckling, and the strengthening does not noticeably increase the axial strength of braces. Furthermore, a numerical model using ABAQUS software is developed to extend the experimental results for further studies after verification.