How Are Steel Beams Rated?

Compared to wood, structural steel has a wider range of strengths and a higher degree of conformity, which makes them useful in construction projects. Load bearing characteristics are guaranteed by international standards, which means designers can rely on specified dimensions, weight and other properties for their projects.

Applications of Steel Beams

Structural steel is a highly adaptable component for construction also. Steel is easily modified to provide custom fabrication of structural units not available from standard stock. Steel is often the most cost effective solution for small residential projects, large-scale construction such as vehicle bridges and for strengthening the original structure of older buildings under renovation.

Sectional Steel Beams

Steel beams are produced in a wide variety of configurations. In general, there are four standard shapes:

• Beams with a cross-section resembling the letter ‘I’, called I-beams
• Beams with an ‘H’ cross-section, called HP beams
• Channel beams, whose cross-section resembles the letter ‘C’
• Angles, which are L-shaped

Within each of these standard types variations are distinguished by the dimensions of the flange surfaces. I-beams designated by ‘W’ have wide parallel flanges, whereas an American Standard Beam, designated by ‘S,’ has sloping inner flanges.

In addition to the types above, tubular steel in circular or rectangular shapes is used for beams. These are designated as “Hollow Section” with a leading letter indicating the shape:
• C.H.S. – Circular Hollow Section
• S.H.S. – Square Hollow Section
• R.H.S. – Rectangular Hollow Section

Steel Beam Standards

Global regions, such as the EU, Asia and the Americas, have developed different standards regarding steel construction components. All regions regulate structural steel as to its chemical composition, strength, shape and size however.

In North America, structural steel standards developed by the American Society for Testing and Materials, ASTM International, are the norm. Most steel grades have direct equivalents in multiple standards. The EU S235 grade, for instance, is equal to ASTM’s A283C.

Additional standardization of steel construction design is found in the Steel Construction Manual, published by The American Institute of Steel Construction.
I-Beam Specification in the U.S. and Canada

I-beams consist of a vertical section, called the web, plus two orthogonal flanges on top and bottom that are parallel to one another. This configuration is efficient in terms of its load to weight ratio for handling bending and shear loads in the web’s plane. They are not efficient, however, in resisting torsional stresses. For those, hollow section beams are superior.

In both Canada and the U.S., I-beams are specified by the depth and weight of the beam per unit length. The depth is the distance between the outer faces of each flange. The difference in naming between the two countries derives from their different measurement systems, metric versus Imperial.

For example, in Canada a W250X33 wide flange I-beam has a 250 mm depth and weighs 33 kg per meter. The same beam in the U.S. would be designated as W10X22, which translates to a depth of 10 inches and a weight of 22 lbs. per foot.

Improving Steel Beams

The corrosion resistance of structural steel that will be exposed to weather is improved at the time of manufacture or via special chemical coatings before installation. A beam’s thermal resistance is improved with foam coatings that also reduce noise transmission.

If load-carrying or free-span requirements cannot be met by “off-the-shelf” steel beams, plate girders can be fabricated by riveting, bolting or welding separate flanges and a web plate. Some manufacturers produce cellular beams, which have cutouts along the length of the web to optimize load strength and weight ratios.

Our specialized steel division in Stoney Creek has extremely diverse manufacturing capabilities. Contact us to request a quote today on angle iron, reinforcing rod, custom fabricating, beam replacement and more.