Buckling-Restrained Brace (BRB), also known as buckling-restrained energy dissipation brace, is a special type of seismic support component.
Composition and Structure
The buckling-restrained brace consists of three parts: the core unit, the restraint unit, and the connection unit. The core unit, typically made of steel, serves as the primary load-bearing component and commonly comes in cross-shaped and linear forms. The restraint unit provides lateral restraint to prevent buckling instability of the core material when compressed, often utilizing steel tube concrete. The connection unit links the core unit and the restraint unit to ensure the stability of the overall structure. Additionally, some non-bonded materials are wrapped around the surface of the core unit to eliminate friction between the core unit and the restraint unit.
Working Principle
During an earthquake, the axial force borne by the buckling-restrained brace is entirely absorbed by the brace’s core material. The core material undergoes buckling energy dissipation under axial tensile and compressive forces, while the surrounding steel tube and the concrete or mortar filled within provide bending constraints to prevent buckling of the core material when compressed. This design allows the buckling-restrained brace to absorb and dissipate a significant amount of seismic energy during an earthquake, reducing the dynamic response of the structure and thereby protecting the main structure from damage.
Characteristics and Advantages
The buckling-restrained brace boasts strong energy dissipation capacity, deformation capacity, a full hysteretic curve, and low residual deformation. Compared to traditional braces, the buckling-restrained brace does not buckle but only yields when compressed, protecting beam and column components from damage through brace yielding energy dissipation. This reduces structural deformation during major earthquakes and facilitates easy replacement after earthquakes due to brace yielding only. Furthermore, the buckling-restrained brace fully exerts its stiffness and strength, with a carrying capacity 3 to 10 times higher than traditional braces.
Application Scope
Buckling-restrained braces have a wide range of applications in buildings, including residential, commercial, industrial, and bridge structures. In residential buildings, they enhance the overall stiffness and energy dissipation capacity of the structure, improving its seismic performance. In commercial and industrial buildings, they support large-span floors and roofs, bearing horizontal and vertical loads during earthquakes. In bridges, they enhance the seismic performance of piers and improve the overall stability of the bridge.
Design and Construction
The design and construction of buckling-restrained braces require consideration of multiple factors, including brace length, cross-sectional dimensions, material strength, restraint methods, etc. Additionally, factors such as the connection mode between the brace and the main structure, the installation location and orientation of the brace must be taken into account. During design and construction, relevant technical standards and specifications, such as the “Technical Standards for Buckling-Restrained Brace Structures” and the “Technical Regulations for Seismic Energy Dissipation and Mitigation in Buildings,” must be followed to ensure the safety and effectiveness of the buckling-restrained braces.
Research and Application Status
Buckling-restrained braces have been extensively researched and applied globally, including in countries like the United States and Japan. In recent years, they have also garnered significant attention in China and have been partially utilized in practical projects, such as the Shanghai Oriental Sports Center, Shanghai World Expo Center, Beijing Yintai Center, and seismic reinforcement and retrofitting of primary and secondary schools.
In summary, as a novel seismic support component, buckling-restrained braces exhibit broad application prospects and significant practical value. Their application in buildings enhances the energy dissipation capacity and seismic performance of structures, safeguarding people’s lives and property. In the future, with the continuous development and advancement of building technology, buckling-restrained braces will gain wider application and promotion.
