Inverted V- bracing (right-hand diagram, also known as chevron bracing) involves the two members meeting at a centre point on the upper horizontal member.īoth systems can significantly reduce the buckling capacity of the compression brace so that it is less than the tension yield capacity of the tension brace. Two diagonal members forming a V-shape extend downwards from the top two corners of a horizontal member and meet at a centre point on the lower horizontal member (left-hand diagram). K- bracing is generally discouraged in seismic regions because of the potential for column failure if the compression brace buckles. This frame has more flexibility for the provision of openings in the facade and results in the least bending in floor beams. K-braces connect to the columns at mid- height. It also results in greater bending in floor beams. However, cross bracing on the outside face of a building can interfere with the positioning and functioning of window openings. As a result, steel cables can also be used for cross- bracing. These only need to be resistant to tension, one brace at a time acting to resist sideways forces, depending on the direction of loading. If a single brace is used, it must be sufficiently resistant to tension and compression.Ĭross- bracing (or X- bracing) uses two diagonal members crossing each other. Trussing, or triangulation, is formed by inserting diagonal structural members into rectangular areas of a structural frame, helping to stabilise the frame. Horizontal bracing is needed at each floor level, however, the floor system itself may provide sufficient resistance. The bracing at each floor (in horizontal planes) provides load paths for the transference of horizontal forces to the planes of vertical bracing.
Framed buildings require at least three planes of vertical bracing to brace both directions in plan and to resist torsion about a vertical axis. The resistance to horizontal forces is provided by two bracing systems called:īracing between column lines (in vertical planes) provides load paths for the transference of horizontal forces to ground level. Buildings adopting high-tech or post- modernist styles have responded to this by expressing bracing as an internal or external design feature. The positioning of braces, however, can be problematic as they can interfere with the design of the façade and the position of openings. The beams and columns that form the frame carry vertical loads, and the bracing system carries the lateral loads. The members in a braced frame are generally made of structural steel, which can work effectively both in tension and compression.
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