Structural Steel Shapes: Explaining the Basic Types of Structural Steel Sections

December 16, 2025 | Categorized in: Types

In 1884, the Home Insurance Building in Chicago became the first skyscraper to use steel in its construction. Since then, countless iconic buildings and structures have been built using structural steel, including the Eiffel Tower (Paris), Burj Khalifa (Dubai), Empire State and Chrysler Buildings (New York City), and Willis Tower (Chicago). Because of its popularity, many people are surrounded by structural steel today, but don’t necessarily recognize the wide variety of different shapes and applications it can be used for.

What is structural steel?

Before we discuss the specific types and shapes steel can come in, we have to understand the basics and why there are different shapes. Broadly, structural steel is steel that is used in construction and architecture that usually comes in the form of elongated beams, tubing, or channels. These shapes can be used to support the weight of a structure, in the ground to provide stability, strengthen materials like concrete, and more. Structural steel is usually made from rolled steel (hot-rolled or cold-rolled) because different applications have different requirements.

Benefits of structural steel

One of the biggest benefits of this category of metal is its load-bearing capacity. This is due to most common structural shapes having a high second moment of area and being stiff, which prevents sagging under large weights and forces. In addition to strength, structural steel is typically less costly than other building materials, such as concrete, which often uses steel rebar to reinforce the material. Beyond practicality, structural steel also has a certain aesthetic appeal with its silver color and transparency of frame.

In terms of the modern era, where sustainability is often a topic of discussion, structural steel is the most recycled material on the planet. Incredibly, structural steel can be fully recycled after use, and most steel in use contains an average of around 90% recycled material. Like with other building components, reliability and predictability are highly valued characteristics for not only safety but planning and budgeting as well. Steel again scores highly in this category, making it not only one of the strongest building materials, but also one of the cheapest, best-looking, environmentally friendly, and safest ways to make structures.

Structural steel shapes

Now that we see how varied structural steel’s applications and advantages are, we can start to understand the scale of its flexibility. However, this adaptability is improved even further when we look at how specific shapes can provide additional benefits. Broken down into general categories, structural steel shapes usually come in beams, channels, angles, bars, and tubing (or Hollow Structural Sections). Each of those groupings can be further divided by measurements, minor differences in shape, and use:

Steel Beams

Beams’ primary function is to support heavy loads in construction, such as support trusses or frames in buildings. This strength isn’t limited to one direction either, as beams can resist tension or support weights in various directions and orientations (and can be modified through processing such as cambering).

Learn more about the types of beams here.

Standard I-Beams/S-beams

The most common form of steel beam is the standard I-beam (or S-beam for “standard”), named that way because a cross-section of it resembles an uppercase I. Two flanges, or horizontal pieces, are connected in the middle by a web, the central piece.

Depending on who you ask (or how it’s rotated), they might also be called H-beams, but these are not the same product. I-beams have tapered edges on the flanges and the web is taller than the flanges’ width.

Wide Flange Beams/W-beams

W-beams, on the other hand, are also called wide flange beams (or W-beams). As mentioned above, wide flange beams are shaped like an H, where the web is shorter than its flanges. They also don’t have tapered flanges and are often used in both temporary and long-term structures such as cofferdams, falsework on bridges, and more.

Tee Beams

Lastly, tee beams are essentially half of a beam cut along the web so that the cross-section looks like an uppercase T. They’re used when weight and height might take priority over strength. Because of this, it’s also easier to bend than beams and can be curved to fit specific applications that require arched or rounded support (see our cambering service page for more information).

Steel Channels

Steel channels are structural pieces whose cross-section resembles a C, or an I-beam if the web connects the two flanges at one end rather than in the middle. They’re often used when the web can be mounted on a flat surface to get maximum contact area, and can also be welded together to create a non-standard I-beam.

Channels can be used in conjunction with beams as braces or extra support, or can be used in similar applications to tee beams, where the strength of full beams isn’t necessary. Because of this, channels are versatile and come in several shapes (usually differentiated by the flange slope), such as standard channels or MC channels.

C Channels

While both C and MC channels have similar profiles, C channels (also known as “standard channels”) feature tapered flanges. These structural steel products are typically used in construction and architectural applications, as well as for trailer frames.

MC Channels

MC channels, or “Miscellaneous Channels” (sometimes also called ship channels), have parallel and flat flanges with square corners where they meet the web. This flat surface makes it easier for bolting, so they’re commonly used in agricultural equipment, automotive manufacturing, and similar construction applications as C channels.

Steel Angles

Perhaps the most common form of structural steel, angles are L-shaped pieces of metal (usually at 90° angle) that are used for minor structural support where heavy-duty strength isn’t required. The most common applications for angles include being used as brackets, framing, and for other reinforcements. Because of their size and limited strength, they can also be used outside of construction in things like shelves, bed frames, and tables.

Learn more about steel angles here.

Equal Angles

As the name suggests, equal angles have identical-length legs for uniform strength and symmetry. This results in them being used for building frames, railway tracks, machinery support frames, and other applications where uniform support is needed.

Unequal Angles

On the other hand, unequal angles have legs of different lengths, with a variety of options to choose from. This flexibility can be useful for specific project requirements, such as rack systems, joists, and building frames.

Steel Tubing (HSS)

Structural steel tubing or HSS (Hollow Structural Sections) includes welded steel tubing shapes used for structural applications in construction and architectural support. They can be purchased in round shapes, or made with corners for either square or rectangular shapes (and are different than steel pipes, which only come in round sections). Tubing’s closed nature means that things can be safely enclosed inside it (e.g. wiring) and tend to look more “finished” than other types of structural steel.

Square & Round Tubing

Square and round tubing are symmetrical along both axes, meaning that it has uniform strength in both of these directions. This property makes them good options for columns and can be used as a substitute for a beam if there is a high risk of lateral torsion. This is due to their better resistance to this type of force than I-beams and wide flange beams.

Rectangular Tubing

However, rectangular tubing does not have cross-sectional symmetry along both axes, meaning that its torsional and other types of strength are not equal along these axes. This means that rectangular tubing typically has higher bending strength and stiffness along the longer axis. This makes it ideal for high-load projects like bridges and large spans, as well as for flat surfaces on trailers, truck beds, and industrial equipment.

Learn more about the differences between steel tubing and piping here.

Steel Bars (Merchants)

Steel bars, sometimes called “steel merchants,” are rods designed for structural reinforcement and strength. There are a variety of shapes and sizes to fit different project requirements, from round to flat. In contrast to structural steel shapes like beams that form the main framework, steel bars typically act as the internal support to prevent stretching or failure under tension.

Learn more about the types of steel bars here.

Flats

Flat bars have a thin rectangular cross-section and are best for withstanding static, straight loads applied to the wide surface. In other words, these don’t perform particularly well under torsional (twisting) forces. These characteristics make steel flats good for braces, framing, railings, and grating.

Rounds

Round bars have a circular profile, making them excellent choices for resisting uniform compression forces, as well as rotational and torsional stress. The even distribution of its round shape means that it’s commonly used in automotive axles, supports, and as rebar to strengthen concrete.

Squares

Square bars have a cross-section with four equal sides that are ideal for static, straight loads from any direction. However, the corners can create weak points if forces are applied from multiple directions. Square bars are best for structural projects involving braces, framing, railings, gates, and fences.

Getting structural steel for your projects

Structural steel is vital to construction projects, both large and small. If you need high-quality structural steel products to strengthen your manufacturing or construction projects, Service Steel Warehouse can supply everything you need with our ready-to-ship inventory. We stock one of the largest selections of structural steel shapes, so you don’t have to worry about procurement delays. From beams to tubing, angles, channels, piling, and more, we can ship exactly what you need and process it to fit your application.

Call our team of experts or request a free online quote today.