Bracing members include flats, angles, channels, I section, and hollow sections. Bracing arrangements may involve the bracing members working in tension alone, or in both tension and compression. In most cases, the bracing member is attached by bolting to a gusset plate, which is itself welded to the beam, to the column, or more commonly welded to the beam and its end connection.
Bracing systems are usually analyzed assuming that all forces intersect on member centerlines. However, realizing this assumption in the connection details may result in a connection with a very large gusset plate, especially if the bracing is shallow or steep. It is often more convenient to arrange the member intersections to make a more compact joint and check locally for the effects of eccentricities which are introduced.
Bracing connections are generally made with non-preloaded bolts in clearance holes. In theory, at least, this allows some movement in the connection, but in practice, this is ignored in orthodox construction. In some cases, it may be that movement on reversal is unacceptable – preloaded connections should be used in these circumstances.
The general design process is:
- Identify the load path through the connection.
- Arrange the connection to ensure that the design intent of the members is realized, e.g. the beam connections remain nominally pinned.
- Include the effects of any significant eccentricity.
- Check the components in the connection.