Novel Technique for Inhibiting Buckling of Thin-Walled Steel Structures Using Pultruded Glass FRP Sections

The use of composite materials for strengthening the ailing infrastructure has been steadily gaining acceptance and market share. It can even be stated that this strengthening technique has become main stream in some applications such as strengthening concrete structures. The same cannot be said about steel structures; for which research on composite material strengthening is relatively new. Several challenges face strengthening steel structures using composite materials such as the need for high-modulus composites to improve the effectiveness of the strengthening system. This paper explores a new approach for strengthening steel structures by introducing additional stiffness to buckling-prone regions. The proposed technique relies on improving the out-of-plane stiffness of buckling-prone members by bonding pultruded fiber-reinforced polymer (FRP) sections as opposed to the commonly used approach that relies on in-plane FRP contribution. The paper presents results from an experimental investigation where shear-controlled beam specimens were tested to explore the feasibility of the proposed technique. Bar specimens were also tested in tension to compare between in-plane and out-of-plane contributions of FRP to the behavior and strength of thin steel plates. Based on the results, it can be concluded that this strengthening technique has great potential for altering failure modes by delaying the initiation of undesirable local buckling of thin steel plates. Recommendations for future research efforts are made to expand the knowledge base about this unexplored strengthening technique.