Steel bridge

The first metallic bridge was constructed from cast iron in England. Known as the Iron Bridge, it was built in 1779 by Abraham Darby III over the River Severn at Coalbrookdale. The bridge has a span of {{convert|30.5|m}} and a total length of {{convert|60|m}}, standing {{convert|30|m}} above the river.{{Harvtxt|Bruyère|1823|p=3–8}}

In France, the first metallic bridge was the Pont des Arts in Paris, constructed in 1803 by Louis-Alexandre de Cessart and Jacques Dillon. The pinnacle of cast iron bridges was reached with the Pont du Carrousel, built in Paris in 1834 by Antoine-Rémy Polonceau.{{Harvtxt|Ciolina|1979a|p=}}

Suspension bridges made of iron began to develop in the United States in 1810.{{Harvtxt|Troyano|2003|p=}} The widespread use of metallic bridges grew with advancements in steel production techniques, coinciding with the expansion of railway networks. This golden age of metallic bridges continued until World War I, despite the emergence of reinforced concrete in France by 1898.{{Harvtxt|Leonhardt|1982|p=}}

The steels used in bridge construction are low-alloy iron-carbon alloys. For aesthetic or safety reasons, other steel types, such as Corten steel or stainless steel, may be used.{{Harvtxt|Lebet|Hirt|2009|p=}}

For safety, steel in bridges is designed to operate well below its yield strength. Material fatigue limits stresses to approximately half the yield strength, around {{convert|120|MPa}} for mild steel and {{convert|180|MPa}} for high-strength steel. Fatigue strength is a critical factor in structural calculations. Other factors, such as temperature, stress corrosion cracking, and performance in saline environments, also influence material selection.{{Harvtxt|Ciolina|1979b|p=}}

Steel profiles used in bridges include:

Common profiles include angle iron, U-shaped beams, and T-beams.{{Harvtxt|Deschamps|1908|p=}}

File:Cornière2.svg|Unequal angle iron

File:Poutrelle.svg|I-beam

File:Fer-en-U.svg|U-shaped beam

Steel assembly methods include bolting, riveting, and welding.

Bolts and rivets secure components through clamping force. Bolts, installed cold, are used for temporary assemblies or in cases where rivets are unsuitable. A bolt consists of a forged head, a threaded shank, and a movable nut screwed onto the threaded portion.

Rivets, installed hot, were historically the primary assembly method in structural steelwork. A rivet has a factory-made head and a shank; the second head is formed by forging the protruding shank while hot, creating a strong clamping force upon cooling.

Welding joins steel by melting and fusing components using coated steel rods (electrodes) that melt under the high temperature of an electric arc. Modern metallic bridges are typically welded, with rivets largely obsolete. Bolts remain in use for emergency bridges, which are assembled rapidly from prefabricated parts.

Metallic beams typically have an I-shaped profile, though U-shaped or box-section profiles are used when height is limited.

{{Main|Plate girder|}}

Solid web beams consist of one or more vertical webs and horizontal flanges (or wings) on either side. These beams can be hot-rolled (I-beams for smaller sizes) or assembled cold from flat plates through welding (welded reconstituted beams, or PRSs) or, historically, riveting with angle irons.

Flanges, with or without angle irons, form the beam’s chords in welded or rolled structures.

File:Poutre-droite-à-âme-pleine.svg|Riveted solid web beam

File:Poutre-droite-en-U.svg|Riveted U-shaped beam

File:Poutre-droite-en-caisson.svg|Riveted box-section beam

File:Poutre-reconstituée-soudée.svg|Welded reconstituted beam

{{Main|Truss bridge|Truss}}

Truss beams, or triangulated beams, consist of chords connected not by a web but by vertical or inclined bars forming a triangulated framework. The arrangement of bars varies depending on the triangulation system used.

Common truss systems include:

File:Poutre-Pratt.svg|Pratt truss

File:Poutre-Town.svg|Town truss

File:Poutre-Town2.svg|Double Town truss

File:Poutre-en-K.svg|K truss

File:Poutre-Warren.svg|Warren truss

File:Poutre-Warren-avec-montants.svg|Warren truss with verticals

File:Poutre-Howe.svg|Howe truss

File:Poutre-Croix-de-Saint-André.svg|Cross of Saint Andrew (Pratt and Howe combination)

File:Poutre-composée.svg|Compound truss

File:Poutre-Vierendeel.svg|Vierendeel truss (non-triangulated)

File:Assemblage-métallique-rivé.jpg

Riveted connections were standard before welding became prevalent. Both straight beam and truss bridges used rivets. A typical truss connection includes vertical and horizontal members made of angle irons and plates riveted together, with inclined members using U-shaped beams. Cover plates, or gussets, are added at joints to enhance rigidity.

File:Viaduc-de-Briare (4).JPG

Modern metallic connections typically involve welding, as seen in solid web beams. A transverse beam, or cross-girder, is welded to a longitudinal beam, or stringer. Vertical stiffeners, often terminating in a gusset, reinforce the assembly.

Depending on the beam structure, these include single box girder bridges (with voussoirs), twin-girder bridges, ribbed bridges, lenticular bridges, and truss bridges.

In a suspension bridge, the beam is called the stiffening girder, typically made of a metallic truss.

File:Pont-suspendu-Indicateurs.svg

Three parameters define a suspension bridge:

• Its span, equal to its length (L) for a single-span bridge without approach spans.
• Its sag (f), the distance between the midpoint of the chord connecting the pylon tops and the midpoint of the suspension cable.
• The height (H) of the stiffening girder, typically between L/80 and L/100.

For small to medium spans, the relationship between span and sag is generally $f\; =\; \backslash frac\{L\}\{9\}${{cite book |last1=Allard |first1=R. |last2=Kienert |first2=G. |title=Notions de Travaux Publics |publisher=Éditions Eyrolles |location=Paris |year=1957 |language=fr |trans-title=Public Works Concepts}}

• Suspension bridge
• Cable-stayed bridge
• Steel
• Structural engineering
• Bridge
• Fatigue (material)
• Welding
• Iron Bridge

{{Reflist}}

• {{cite book |last=Bruyère |first=Louis |title=Études relatives à l'art des constructions, tome 1, Recueil III, Ponts en fer |publisher=Bance aîné |location=Paris |year=1823 |pages=3–8 |url=https://gallica.bnf.fr/ark:/12148/bpt6k108243h/f82.item |language=fr |trans-title=Studies Related to the Art of Construction, Volume 1, Collection III, Iron Bridges}}
• {{cite book |last=Chaix |first=J. |title=Traité des ponts, Deuxième partie, Ponts en charpente, métalliques et suspendus, tome 1 |publisher=Fanchon et Artus |location=Paris |publication-date=1890 |language=fr |trans-title=Treatise on Bridges, Second Part, Timber, Metallic, and Suspension Bridges, Volume 1}}
• {{cite book |last=Chaix |first=J. |title=Traité des ponts, Deuxième partie, Ponts en charpente, métalliques et suspendus, tome 2 |publisher=Fanchon et Artus |year=1891 |location=Paris |language=fr |trans-title=Treatise on Bridges, Second Part, Timber, Metallic, and Suspension Bridges, Volume 2}}
• {{cite book |last=Deschamps |first=Henri |url=https://gallica.bnf.fr/ark:/12148/bpt6k6571438g.texteImage |title=Les principes de la construction des charpentes métalliques et leur application aux ponts à poutres droites, combles, supports et chevalements |publisher=Librairie polytechnique Ch. Béranger |location=Paris and Liège |year=1908 |language=fr |trans-title=Principles of Metallic Framework Construction and Their Application to Straight Beam Bridges, Roofs, Supports, and Frameworks}}
• {{cite book |last=Ciolina |first=François |url=https://openlibrary.org/works/OL6270736W/Construction_me%CC%81tallique |title=Construction métallique, tome 1, Conception des structures |publisher=Éditions Eyrolles |location=Paris |year=1979a |isbn=978-2-212-00676-6 |language=fr |trans-title=Metallic Construction, Volume 1, Structural Design}}
• {{cite book |last=Ciolina |first=François |title=Construction métallique, tome 2, Ouvrages d'art |publisher=Éditions Eyrolles |location=Paris |year=1979b |isbn=978-2-212-00677-3 |language=fr |trans-title=Metallic Construction, Volume 2, Engineering Structures}}
• {{cite book |last=Leonhardt |first=Fritz |url=https://books.google.com/books?id=EPeJoAEACAAJ |title=Brucken Bridges: Asthetik und Gestaltung |publisher=The Architectural Press |location=London |language=de |trans-title=Brucken Bridges: Aesthetics and design |year=1982 |isbn=0-85139-764-6}}
• {{cite book |last=Troyano |first=Leonardo Fernández |url=https://books.google.com/books?id=0u5G8E3uPUAC |title=Bridge Engineering: A Global Perspective |publisher=Thomas Telford |location=London |year=2003 |isbn=978-0-7277-3215-6}}
• {{cite book |last1=Lebet |first1=Manfred A. |last2=Hirt |url=https://search.worldcat.org/title/ponts-en-acier-conception-et-dimensionnement-des-ponts-metalliques-et-mixtes-acier-beton/oclc/495227692 |title=Ponts en acier : conception et dimensionnement des ponts métalliques et mixtes acier-béton |publisher=Presses polytechniques universitaires romandes |location=Lausanne |year=2009 |isbn=978-2-88074-765-7 |language=fr |trans-title=Steel bridges: design and dimensioning of steel and steel-concrete composite bridges}}
• {{cite journal |last=Van Rooden |first=Clementine |date=2013 |title=Ponts historiques en acier |journal=Steeldoc |issue=3+04/2013 |publisher=Centre suisse de la construction métallique SZS |url=http://www.szs.ch/user_content/editor/files/steeldoc_low/steeldoc_03%2004_2013_fr.pdf |language=fr |trans-title=Historic Steel Bridges |archive-url=https://web.archive.org/web/20160411073423/http://www.szs.ch/user_content/editor/files/steeldoc_low/steeldoc_03%2004_2013_fr.pdf |archive-date=April 11, 2016 |access-date=May 7, 2025}}

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Metallic

Category:Structural steel

Category:Steel bridges

Category:Metallurgy