Experimental Evaluation of an Innovative Buckling-Restrained Fuse for Concentrically Braced Frames under Cyclic Loading

Concentrically braced frames (CBFs) have become prevalent as a lateral load resisting system due to their rigidity, low lateral displacement and ease of implementation over the last three decades. These advantages encourage the increasing utilization of this system in the construction industry. Despite the advantages of CBFs, the lack of ductility and buckling of the bracing element before yielding is the main disadvantage this lateral system. In the last three decades, studies have become focused on the ductility and energy dissipation of the CBFs that were modified in terms of using dampers and fuse segments. The current study aims to presents an innovative Composite Buckling Restrained Fuse (CBRF) to be used as a bracing segment. CBRF with relatively small dimensions is an improvement on Reduced Length Buckling Restrained Brace (RL-BRBs) as a hysteretic damper with different performance in tension and compression. Extra tensile elements in a novel configuration were used to compensate for the limitation of tensile strength that exists in bracing elements containing ordinary fuse segments. Here, some key design parameters of CBRF such as length and cross-sectional area of the core are discussed theoretically. Two specimens were designed and tested under cyclic loads. Moreover, the hysteretic response of the specimens was evaluated to calculate their strength adjustment parameters. The results indicate that the proposed CBRF has a ductile behavior with an average strain of 5% and high energy absorption capacity along with sufficient tensile strength.