What is Braced Frame Construction?
What is Braced Frame Construction?
Braced frame construction is a form of structural engineering in which the vertical members, or columns, are connected by diagonal braces. The braces absorb horizontal forces and transfer them to the columns, providing stability against lateral movement.
This type of construction was commonly used in buildings throughout history due to its relative ease of construction and cost-effectiveness; while it has been replaced by more sophisticated methods such as reinforced concrete in modern times, braced frame constructions are still used in certain circumstances where strength is not a primary concern.
A braced frame can withstand lateral forces such as wind and earthquakes. This is achieved by adding elements such as shear walls or diagonal steel sections similar to those found in a truss, preventing the frame members from swaying.
What Are The Different Types Of Braced Frame Structures?
Braced frame structures are structural systems composed of columns and beams connected using vertical and horizontal components called braces. These frames come in different styles, including K-braced, X-braced, and V-braced, single-angle bracing, chevron bracing, sway bracing, double-angle bracing, and portal frame structures.
K-braces are the most commonly used system and consist of two or more perpendicular braces joined together, usually at a corner, to form an ‘X’ shape. X-braces feature a series of braces arranged to form an ‘X’ pattern connecting multiple columns at multiple points.
V-brace systems are similar to K-brace but slightly angled outwards instead. Single-angle bracing is generally used in applications requiring a lighter-weight structure than traditional frames.
In contrast, chevron bracing is often preferred when vertical sway needs to be controlled due to its shape, which creates a diagonal force between two columns.
Sway bracing consists of diagonal members connecting consecutive bays from one column to another, often resulting in efficient use of material when helping soften lateral forces acting on the structure.
Double angle bracings are sometimes used for elevation stability, where the additional brace allows for a stiffer connection than single angle braces.
Portal frames combine columns and rafters connected by a rigid node where concentrated loads can be efficiently transferred throughout the entire span yet remain cost-effective.
Why Should The Frame Be Braced?
Bracing a frame is an essential aspect of construction. It helps to strengthen the structure, increase its rigidity, better support any loads placed on it, reduce stress, and provide stability in cases of earthquakes or high winds.
In addition, bracing provides additional strength against deflection of the frame due to increased loads and can also help protect against even small movements caused by vibration. Bracing may also be used when the building structure may be altered due to renovation or expansion work.
Finally, bracing can give a higher degree of accuracy when checking dimensions, such as angles between members and line lengths during installation.
What Are Braced Frames Made Of?
Braced frames are structural systems generally made up of steel, timber, or reinforced concrete designed to resist lateral loads, such as wind and seismic forces. They are usually composed of columns and beams connected by horizontal members called braces.
Braces transfer the lateral loads from the top of the frame to its foundation. Additionally, they provide stiffness and strength to the structure, allowing designers to use lighter materials for other components.
Steel-braced frames typically consist of diagonal compression members placed at each end or corner of a building, while timber-braced frames often incorporate tension ties connecting their horizontal beams.
Reinforced concrete bracing consists mainly of shear walls with large rigid elements that spread out vertical and horizontal forces throughout the building’s mass.
