Metal beams, sometimes called rolled steel joists (RSJ), provide structure, strength, and rigidity in buildings and structures, but different applications and static loads require different types of beams. Knowing which beam to choose is critical to the integrity and safety of the finished building.
Two common beam types are I-beams and wide flange, or W-beams. These two configurations are similar in shape (i.e., both have cross-sections that resemble a capital letter I or H), and both consist of a long, flat central member called the web, which is centered on a flange on each long side. The width of the web and flanges is variable, as is the thickness and shape, or taper, of the flanges. These differences in design affect how they are used. Here we’ll take a closer look at I-beams and W-beams, and compare how their differences make them suitable for different applications.
Understanding I-Beams
I-beams are widely used for framing buildings in both vertical and horizontal directions, as studs or joists. They are commonly made from structural steel, though 6061 aluminum can also be used for some applications.
These beams typically have flanges that are tapered, with a thicker portion on the end that attaches to the web and a thinner portion at the outer edge. As a result, the flanges are not quite parallel to each other and not quite perpendicular to the web.
Generally, I-beams work best for lower-weight applications compared to W-beams. I-beams are generally suitable for supporting spans from 30 to 100 ft, and are generally available in lengths up to 60 ft. Some common applications include:
- Bridges
- Hospitals
- Parking garages
- Skyscrapers
Understanding W-Beams
W-beams, or wide flange beams, often have a much wider web or flanges than I-beams. Their flanges are also a uniform thickness and not tapered. As a result, the flanges are parallel to each other and perpendicular to the web. Like I-beams, W-beams come in a variety of widths and thicknesses of webs and flanges. While W-beams can be used for spans up to 300 ft., though they are generally manufactured in 70-ft. lengths to limit waste.
The wider web and flanges allow these beams to support more weight, and they are often used in large-scale structures and equipment, including:
- Bridges
- Large buildings
- Trailers, flatbed hauling vehicles, and material handling equipment
I-Beams vs. W-Beams: A Comparison
Both of these beams are widely used in construction and heavy equipment projects because their design carries heavy loads reliably. Generally speaking, I-beams are lighter weight and may be easier to transport, handle, and move; however, they have a lower overall span and support capacity. Here’s a breakdown of how these two types of beams compare.
Shape and Design
Both I-beams and W-beams have the same basic design; however, I-beams tend to have a web that is wider than the flanges, and the flanges are tapered. W-Beams often have wider flanges and may have a wider web as well. W-beam flanges are not tapered.
Weight
Steel W-beams generally weigh more than I-beams because they use wider flanges and, sometimes, are longer. Depending on the application, I-beams can be made from aluminum instead of steel, making them even lighter.
Span
I-beams generally support loads across shorter spans than W-beams. Depending on their dimensions and configuration, I-beams can be used for spans of 30-100 ft., where W-beams are more flexible and can be used for spans up to 300 ft.
Strength
W-beams tend to have higher overall strength because of their web-to-flange ratio, thickness, and welded construction. As a result, they can support heavier loads across longer spans without reinforcement. In contrast, I-beams can carry heavier loads compared to their smaller size, and may be able to resist buckling better than W-beams.
Bend Resistance
Because of their wide flanges, W-beams tend to have higher resistance to bending forces than I-beams. Flange width is the major factor in the ability to resist bending.
Learn More With Delta Steel
Choosing the right beams for every construction application is critical to the stability, longevity, and safety of the completed structure. At Delta Steel, we’re committed to delivering high-quality steel beams for a range of industry applications, and we maintain locations and distribution centers across the US to accomplish it.
Contact us to learn more about our I-beam and W-beam selection, or request a quote to get your project started.