Lately, there’s been a lot of chatter about bracing elements, so we thought it would be a good idea to get a little more intimate with them—to be better braced against the bracing elements. So let’s start at the beginning.
What Exactly are Bracing Elements? How Do they Work?
In the simplest terms, a bracing element is the portion of a building structure that provides stability for the framing. In other words, bracing elements help stop movement. To paint a visual picture for you, we’ll use the example of the standard base connection in Robertson’s metal structures–the “Pinned Base”.
The best way to understand this type of base is to take a pen and hold one end between your thumb and index finger. Now try to move the pen. No matter how tight you squeeze, it’s pretty easy to move the pen side-to-side and back-and-forth. This is a “Pinned Connection”, and bracing elements help resist the movement they’re apt to make.
The most common bracing element is called rod bracing (or X-bracing). This bracing can be provided by rods, angles, or in heavy structural applications, pipes, and/or tubes. Can’t picture it? Well, next time you look at a building, look for any element that is on a diagonal—and what you see there—that’s called rod bracing. For Robertson buildings, rods are the most commonly used bracing element, but there are plenty of other bracing options available to builders.
For instance, when framed openings, other accessories, or structural loading prevent the use of rod bracing, you can use what we call a “Portal Frame.” A Portal Frame is a frame located in a sidewall bay. The drawback to a Portal Frame is that it has two columns and a rafter that can reduce the amount of available clearance in a bay. So sometimes a framed opening—or another accessory—may require additional clearance, prohibiting the use of a Portal Frame. In that case, you can use what we call a “Fixed Base Bracing Column.”
Fixed Base Bracing Column
Using the pen reference, this compares to holding that pen in your fist. You can feel the added stability. The benefit of this is that you can do away with the Portal Frame rafter and one of the columns. This results in additional clearance in a bay. The Fixed Base Bracing Column collects all of the design forces and drops them into the foundation.
Keep in mind, although Fixed Base Bracing Columns allow for additional clearance in a bay, they do have a downside. Since the foundation for the columns needs to be increased in size and strength to provide the required stability for the building, the cost is going to increase. In big buildings, the dollars multiply quickly with Fixed Base Bracing Columns, but for smaller buildings that have many framed openings, they may be cost effective. Also, they allow a builder to be able to tell their end customer, “Yes, we can do that.” And that’s important.
In all, the better you understand your bracing elements, the better your building process will be. So brace yourself!
If you enjoyed this article and want to learn more, attend one of our training classes where you can learn the basics of metal building assembly, IMP installation, and more. Visit our Training & Certification page for more details about a class near you.