Post on 15-Apr-2017
Buckling Restrained Braces
BY ▸ R.SIVA NAGARAJU▸ L .TRINATH
Contents
▸ Introduction▸ Types of braces▸ Why use BRBF▸ Components▸ Characteristics▸ Connections▸ Tests ▸ Survey ▸ Advantages▸ Reference structures▸ Conclusion
Introduction • The concept of Buckling
Restrained Braces developed in Japan by NIPPONS STEEL in 1980’s.
• It is designed to allow 1. Cyclic lateral loads on building 2. Earth quake induced loads
• 1. Specially Concentrically Braced (Frame)
• 2. Buckling Restrained Braced (Frame)
TYPES OF BRACES
Specially Concentrically Braced frame
Buckling Restrained Braced frame
Why we use BRBF?
• This structure has high stiffness & high ductility.
• It yields in both compression and tension• (no buckling).• It is a safe guard for building under
lateral loadings coming from earthquake forces.
• This can be moulded by using parameters like storey drift & base shear.
COMPONENTS
• 1. Steel core
• 2. Casing
• 3. Debounding material
Buckling- Restrained Brace:Steel Core+Casing
AA
Section A-A
Steel Core
Debonding material
Casing
Steel jacketMortar
Buckling Restrained Brace
Characteristics
• It prevents the members from buckling.
• It illustrates the envelope of hysteresis curve.
• It acts as a back bone of curve.
Connections
• 1. Welded
• 2. Pinned
• 3. Bolted
Welded connections
Pinned connections
Bolted connections
Literature surveyS. No Title Author Name Journal Published objective
1. Behavior and design of structures with buckling-restrained braces
Kim, J., et al. ELSEVIERVol:26 (2004)
Maximun displacements, story drifts, story shears.
2. Design of buckling-restrained braced frames using nonlinear time history analysis and optimization
Richard, J. B., et al.
ASCEVol: 135 (2009)
Nonlinear time history analysis and optimiztion compared to equivalent lateral forces.
3. Application of buckling-restrained braces in prefabricated reinforced concrete frame
Hongnan, w., et al.
Scientific.netVol: 351 (2013)
Retrofit of BRB to the old prefabricated building.
4. Performance of BRBF and Comparing it with the OCBF
Talebi, E., et al. International Journal of Civil
Design of BRBFs compared with OCBFs under earthquake loads.
TESTS
1. Brace test
2. Sub-assemblage test
Brace test specimen
Uniaxial Loading
Subassemblage test specimen Axial + Rotational Loading
Scale Requirements for Test Specimens
Brace Test Specimen
0.5 [ Pysc ]prototype [ Pysc ]specimen 1.5 [ Pysc ]prototype Subassemblage Test Specimen
[ Pysc ]specimen [ Pysc ]prototype
Advantages
• It is easy to erect.• Mostly used in seismic retro-
fittings.• It is an alternative for Specially
Concentrically Braced Frame.• When compared to SCBF, BRBF is
economical.
University of California dormitory, Berkeley
seismic retrofitting
Fujita Corporation Headquarter: Tokyo
The new five-level, parking structure at John Wayne Airport (SNA) in Tustin
Rio Tinto Stadium,sandy
It minimises the Earth Quake intensity On the structure.
Using BRBF, will be a great step adopted by the Civil Enginners during Earthquake.
Conclusion
THANKS!
Any questions?