Steel Joist Types

Girders or I-Beams

• Girders or so-called "I-beams" got their name from their profile. When viewing a girder from its end, it is the shape of a capital "I" or a capital "H" turned on its side. This clever design maximizes strength. If you imagine a long ribbon of steel, you can imagine that it will bend in its think axis. But if you try to bend it in its wide axis, it's too strong. By capping a long band of steel with perpendicular bands of steel, the girder provides strength for loads exerted in multiple directions. It is the oldest steel building system. Girders are also used for vertical steel members and both exterior and interior wall structures. It is a universal structural members, used wherever there is need for high strength.

Steel Deck

• There is a wide variety of steel decking. Not all decking includes steel joists; some is similar to corrugated roof used as an industrial flooring substrate. But other steel deck systems use relatively short spans of steel in the same way steel studs are used. They are often roll-formed or stamped steel sheets. When laid out in a plane, they form the substrate for a floor.

Web Joists

• Web joists can be made purely of steel or they can be made of a combination of steel and wood where the wood makes up the top and bottom cord and steel makes up the connecting web. Regardless of the cord material, the cords are straight and parallel. A zigzagging line of structural members connects them. This design, unlike an I-beam, cannot withstand great loads in multiple directions. But it is much lighter and very strong along a single axis. So, it is an optimal design for joists.

Custom and Complex Web Joists

• Steel can be used in various forms, unlike natural wood fibers. It can be poured, extruded, roll-formed, machine-fastened or welding into any imaginable configuration. Steel's strength and versatility mixed with engineering concepts like web joists open endless building possibilities. Many common designs are executed in open web steel joists such as: barrel joists, scissor joists and gable joists. But even more possibilities exist such as using three or more cords and creating complex shapes.