Vertical braced-frames are the simplest and most effective of the stabilizing options, they are relatively straightforward to analyze, economic to fabricate, and can be erected in a relatively short space of time. Hence, Braced-Frames are without doubt the most popular and efficient stabilizing option and will account for a great majority light commercial and industrial structures.
The Bracing Members are axially loaded, either in tension or compression, depending on how they are configured. A tension member is sometimes referred to as a ‘Tie’ while a compression member may be referred to as a ‘Strut’
The Columns, which are assumed to be continuous, are axially loaded in compression. The beam-to-column connections are Pin-Ended allowing for rotation at the joint.
Braced-frames are essentially vertical trusses and should extend the full-height of the building. The Bracing Pattern may be configured in a variety of ways, but whichever way they are configured, the bracing system should be located so that it can effectively distribute and transmit the lateral forces from the horizontal stabilizing elements or the structure.
Bracing systems may be configured as ‘two-way’ or ‘one-way’ braced. A two-way bracing system is braced in both the -X- and -Y- axes, while a one-way bracing system is braced in one direction (usually the -Y- axis), relying on either a shear-wall or rigid-frame in the other.
A classic example is the ‘Portal-Frame’ which is effectively a rigid moment frame in one direction and a braced frame in the other.
Braced frames may be used successfully with any structure irrespective of height, shape, or form, while the bracing members can be configured to suit almost any load condition. However, with some commercial or residential structures the bracing may be found to impede windows access-ways and be generally unsightly as its often difficult to ‘hide’, but the obvious benefits in terms of construction costs can sometimes outweigh these disadvantages.
Some post-modern structures today have left the bracing system exposed and incorporated it into the overall aesthetic of the building.
