Looking at Purlin Methods for Steel Buildings
Purlin methods that can be incorporated satisfactorily into pre-fabricated, pre-engineered steel structures are very efficient. You may wish to look at two of the most popular methods in detail.
Hot-rolled steel beams are a purlin technique used in many systems. For industrial applications in the early 20th century, structure roof framework configuration comprised the roof trusses being spanned with hot-rolled channel and I-Beam purlins. Pre-engineered steel structure systems came into general use a number of years after the origination of hot-rolled steel purlins. This approach is still used in pre-engineered steel buildings today, especially in production facilities needing substantial interior support. Compared to less heavier gauged designs, the approval of hot-rolled steel beams is due to their superb load-bearing attributes. This type of structural beam is utilized with spans of more than 30 feet. Hot-rolled purlins are adequate for shoring up weighty overhead building loads within the structural interior. However, this style, although very rugged, can also be pricey.
Braced or unbraced hot-rolled steel purlins are easily adapted for uplift; however, “C” and “Z” cold-formed building framing is not readily customizable to this power. Any wide flanges and channels design will develop the dimensions of hot-rolled pre-engineered roof purlins. Using hot-rolled purlins and adding steel decking enables optimum reinforcement and can span extended distances. Their utilization atop the primary frame rafters could also save money on your project. The particular purlins’ intervals are established by the load-carrying capacity of the steel deck. Implementation of a roof-deck diaphragm or sag rod bracing can modify the stresses relating to the purlins. If sag rods are needed they can be installed up to three inches below the top of the steel. Torsional features can then be lowered.
The use of open-web steel joists is one other purlin setup to look at. Referred to as bar joists, these can span longer distances than cold-formed or hot-rolled purlins. Open web joists are very inexpensive to use in steel building systems that exceed 30 feet in span, as well as in structures requiring wider bays.
A given diaphragm capability is aided by cable or horizontal rod bracing and a standing-seam pre-engineered roof can be easily affixed in pre-fabricated, pre-engineered steel structures using open-web joists. A downside to the employment of bar joists is their inefficiency to withstand heightened turning or twisting stresses because they lack solid webs to uphold shifting of this stress.
In successful setup configurations that have bar joists to reinforce standing-seam steel roofing, there are a couple of dependable approaches. One way is to utilize a steel deck and thin gauge hat channels which run atop the steel deck vertically to its flutes. Another roof design procedure is to introduce tightly spaced cross bridging instead of the steel deck in the configuration. Any cross bridging at the compact spacings provides stability, with the complete unit able to counteract any dynamics that may be introduced.