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

Document Type : Research Article


1 M.Sc., Facaulty of Civil and Environmental Engineering, Tarbiat Modares University

2 Professor, Facaulty of Civil and Environmental Engineering, Tarbiat Modares University


The advantages of buckling restrained braces (BRB) attract the researches and engineers attention
to use this bracing system. High ductility, high-energy dissipation capacity and symmetric hysteresis
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 rehabilitate and or replace this system with the new
generation of braces. Buckling restrained brace (BRB) is an energy-dissipating member that enhances
the structural stiffness, energy dissipation and ductility. There are few worldwide code of practices
provide some recommendations about the buckling-restrained braced frames whereas 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 purpose 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 24 structural models were carried
out utilizing nonlinear static push‑over method. The results indicate that the average value of behavior
factor for all models corresponding to the allowable stress design is around eight.


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