Posted on March 14, 2018 by Heritage
We’ve discussed several key pieces of a metal building: basic components, features and accessories. In keeping with the structure of defining what makes up a metal building, let’s discuss the glue that holds the building together, bracing. There are many different types of bracing, so let’s define what bracing is and explore the different types.
Bracing and bridging are virtually the same thing, so the terminology used depends on the person you are talking to. To minimize confusion, we will use the term bracing for this blog posting.
Bracing is used between structural members of metal buildings. Made up of rods, angles and cables, these components are essential within the plane of the roofing system and wall panels for load transfer. Bracing is a key element in creating a strong foundation to fight seismic, wind, and crane thrusts. It should always be installed to a taut condition removing all slack. Before you make any modifications to the bracing shown on the Construction Drawings, you must have these modifications approved by the manufacturer.
A cable brace, also known as wind bracing (used interchangeably), forms a taut connection in the shape of an “x” between frame structural members and attaches to the main frame or concrete. Metal buildings require cable bracing or x bracing to help transfer wind and seismic loads to the foundation. Cable bracing in metal buildings is critical! It is used in all seismic loads (except for D). Also, note that not all cable bracing can be removed. You may have also seen rods mentioned on your construction drawings, which are generally only used in the seismic D area.
Portal bracing is made up of two columns that attach between the frame liner to the structural frame with a beam connecting them. In the instance that a metal building can’t have cable or wind bracing, the non-panel shear brace will need to have portal bracing. Or, it will need to have a wind column which is a single column that attaches to the column.