Determination of the Parameters Influencing Behavior Factor of Buckling Restrained Braced Reinforced Concrete Frames

The advantages of buckling restrained braces (BRB) attract the researches and engineers attension to use this bracing system. High ductility, high-energy dissipation capacity and symmetric hystresis behavior are the main advantages of this system that is the most effective system to resist the earthquake induced lateral forces. Disadvantages of conventional bracing system such as low ductility, low energy dissipating capacity and local as well as global buckling with unsymmetrical hysteresis performance in tension and compression are the main reason to rehabiliate and or replace this system with the new generation of braces. Buckling restrained brace (BRB) is an energy-dissipating member that inhances the structural stiffness, energy dissipation and ductility.There are few worldwide code of practices provide some recommendations about the bukling-restrained bracedframes where as most of them do not deal with such system. This paper illustrates the good performance of buckling restrained braces used for RC frames. This article determines the behavior factor for RC frames braced with buckling restrained braces. For this puepose RC frames with four, eight, twelve and sixteen stories (each having three and five bays) were considered in this study. All frames designed in accordance with Iranian Standard 2800 and P9-INBC for concrete structures. Analyses for all structural models were carriedout utilizing nonlinear static pushover method.The results indicate that the average value of behavior factor for all models corresponding to the ultimate limit state is around eight.