I-beam
beam with an I or H-shaped cross-section
An I-beam is any of various structural members with an Ɪ- (serif capital letter 'I') or H-shaped cross-section. Technical terms for similar items include H-beam, I-profile, universal column (UC), w-beam (for wide flange), universal beam (UB), rolled steel joist (RSJ), and double-T (especially in Polish, Bulgarian, Spanish, Italian, and German). I-beams are typically made of structural steel and serve a wide variety of construction uses.
The horizontal elements of the Ɪ are called flanges, and the vertical element is known as the web. The web resists shear forces, while the flanges resist most of the bending moment experienced by the beam. The Euler–Bernoulli beam equation shows that the Ɪ-shaped section is a very efficient form for carrying both bending and shear loads in the plane of the web. On the other hand, the cross-section has a reduced capacity in the transverse direction and is also inefficient in carrying torsion, for which hollow structural sections are often preferred.
History
In 1849, the method of producing an I-beam, as rolled from a single piece of wrought iron, was patented by Alphonse Halbou of Forges de la Providence in Marchienne-au-Pont, Belgium.
Bethlehem Steel, headquartered in Bethlehem, Pennsylvania, was a leading supplier of rolled structural steel of various cross-sections in American bridge and skyscraper work of the mid-20th century. Rolled cross-sections now have been partially displaced in such work by fabricated cross-sections.
Begin with the source’s own compact description: “I-beam” is beam with an I or H-shaped cross-section. The dossier treats that line as a proposition to test through I-beam, beam and H-shaped, not as a finished interpretation.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 26, 2026. The linked authority identifier is Q1780087. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1849.
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This entry incorporates text from “I-beam” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.