Buckling-restrained braced frame (BRBF) is a structural

steel frame Steel frame is a building technique with a " skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The devel ...

that provides lateral resistance to

buckling In structural engineering, buckling is the sudden change in shape ( deformation) of a structural component under load, such as the bowing of a column under compression or the wrinkling of a plate under shear. If a structure is subjected to a ...

, particularly during

seismic activity An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

. The BRBF is typically a special case of a concentrically braced frame. Tests have demonstrated BRBF systems are highly effective for energy dissipation, while being vulnerable to large deformations and story drift.Kiggins S., Uang C.-M. ''Reducing residual drift of buckling-restrained braced frames as a dual system'' (2006) Engineering Structures, 28 (11), pp. 1525–1532. A buckling-restrained brace (BRB) consists of a steel core surrounded by a hollow steel section, coated with a low-friction material, and then grouted with a specialized mortar. The encasing and mortar prohibit the steel core from buckling when in compression, while the coating prevents axial load from being transferred to the encasement, thus preventing strength loss and allowing for better and more symmetric cyclic performance. These elements most commonly brace a bay diagonally or in a chevron pattern. Because maximum tension and compression forces in a BRB are much closer than in a standard brace, there is much less imbalance of force in the chevron configuration resulting in smaller beam sizes than a standard braced frame.

Footnotes

References

*AISC Seismic Design Manual, Second Printing Pg 5–23 *ANSI/AISC 341-05 Section 16 & C16 Structural engineering Structural steel {{Engineering-stub