The Importance of Bracing in Structural Performance

The structural performance of a frame building depends on continuous paths for all loads to be transferred to the ground. In the specific instance of pre-engineered trusses, there are two types of necessary bracing which are sometimes confused: temporary and permanent bracing. Each of these is important to the construction process and ultimately to the structural integrity of the building.
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Temporary or Construction Bracing
This is the proper bracing of the trusses during the erection phase of the structure. Much like walls are braced until the completion of the framing process, when trusses are placed on the plate line, they must be braced to hold them safely and securely in place and to resist environmental influences such as wind gusts during the framing process. Temporary bracing guidelines are available through truss industry documents for truss spans up to 60 ft. For spans over 60 ft. a professional engineer should be consulted for the temporary bracing plan.
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Permanent Bracing
Permanent bracing typically includes continuous lateral bracing (CLB), diagonal bracing, bridging and blocking at the heels and ends of the trusses. This bracing functions to strengthen and stabilize the truss chords and webs which may be particularly long or highly stressed. The required locations of the continuous lateral bracing are typically called out on the shop drawings supplied by the truss engineering company. These lateral braces must be stabilized at regular intervals with diagonal bracing. This extremely important bracing system creates the continuous path through which all loads applied to the roof are transferred, from the truss system into the walls and eventually to the ground.
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Because of the componentized nature of our fast track building process, permanent bracing design is not supplied by the wall panelizer or designer, or by the truss fabricator, because neither party controls the design process of the other component. To bridge this gap in the information process, a number of engineering firms are beginning to provide permanent bracing design based on their review of the wall and truss layouts supplied by separate parties.
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