Study of Buckling Restrained Braces

Abstract

In steel structures, concentric braced frames are commonly used to withstand lateral force due to wind and earthquake. However conventional lateral resisting system can provide sufficient strength and stiffness for designed based earthquake but brace shows non hysteretic behavior in tension and compression. Due to buckling of brace typical frame exhibits sudden strength degradation when loaded in compression. To overcome this deficiency concept of Buckling Restrained Brace (BRB) has been introduced.

Present study aims to understand behavior of buckling restrained brace and its implementation in building for performance enhancement. In this study 3, 6 and 10 story steel frame structure is modelled and analyzed using ETABS software. Design of building is carried out as per IS 456:2000, IS 1893 Part I (2016) and IBC 2012 (IV), SEAOC, STRUCTURAL AND SEISMIC DESIGN MANUAL. Response of building analyzed using Linear Static Analysis procedure and Nonlinear Time History Analysis procedure. A comparative study of Moment Resisting Frame and Buckling Restrained Braced Frame (BRBF) with different geometry is also carried out to understand the advantage of Buckling Restrained Brace. From the above study it was found that buckling restrained brace proved to be good in terms of reduce story displacement, increase energy dissipation, increase stiffness and reduce inter story drift. The length of buckling restrained brace steel core also have a significant effect on energy dissipation of the member. Also a comparative study was done to understand the optimized length of BRB steel core as per Coffin-Manson relationship and analyse the result in terms of energy dissipation and story displacement.