A girder () is a beam used in

construction Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the a ...

. It is the main horizontal support of a structure which supports smaller beams. Girders often have an

I-beam An I-beam is any of various structural members with an - (serif capital letter 'I') or H-shaped cross section (geometry), cross-section. Technical terms for similar items include H-beam, I-profile, universal column (UC), w-beam (for "wide flang ...

cross section composed of two load-bearing ''flanges'' separated by a stabilizing ''web'', but may also have a

box A box (plural: boxes) is a container with rigid sides used for the storage or transportation of its contents. Most boxes have flat, parallel, rectangular sides (typically rectangular prisms). Boxes can be very small (like a matchbox) or v ...

shape, Z shape, or other forms. Girders are commonly used to build bridges. A girt is a vertically aligned girder placed to resist shear loads. Small steel girders are rolled into shape. Larger girders (1 m/3 feet deep or more) are made as plate girders,

welded Welding is a fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melt the parts together and allow them to cool, causing fusion. Common alternative methods include solvent w ...

or bolted together from separate pieces of

steel plate Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high elastic modulus, yield strength, fracture strength and low raw material cost, steel is one of the m ...

. The

Warren Warren most commonly refers to: * Warren (burrow), a network dug by rabbits * Warren (name), a given name and a surname, including lists of persons so named Warren may also refer to: Places Australia * Warren (biogeographic region) * War ...

type girder replaces the solid web with an open latticework

truss A truss is an assembly of ''members'' such as Beam (structure), beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so ...

between the flanges. This arrangement combines strength with economy of materials, minimizing weight and thereby reducing loads and expense. Patented in 1848 by its designers James Warren and Willoughby Theobald Monzani, its structure consists of longitudinal members joined only by angled cross-members, forming alternately inverted

equilateral triangle An equilateral triangle is a triangle in which all three sides have the same length, and all three angles are equal. Because of these properties, the equilateral triangle is a regular polygon, occasionally known as the regular triangle. It is the ...

-shaped spaces along its length, ensuring that no individual

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. A stay is sometimes used as a synonym for ...

, beam, or

tie Tie has two principal meanings: * Tie (draw), a finish to a competition with identical results, particularly sports * Necktie, a long piece of cloth worn around the neck or shoulders Tie or TIE may also refer to: Engineering and technology * T ...

is subject to bending or torsional straining forces, but only to tension or

compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression * Gas compression *Compression ratio, of a ...

. It is an improvement over the Neville truss, which uses a spacing configuration of

isosceles triangle In geometry, an isosceles triangle () is a triangle that has two Edge (geometry), sides of equal length and two angles of equal measure. Sometimes it is specified as having ''exactly'' two sides of equal length, and sometimes as having ''at le ...

Gallery

File:AASHTO Girder.jpg,

Rebar Rebar (short for reinforcement bar or reinforcing bar), known when massed as reinforcing steel or steel reinforcement, is a tension device added to concrete to form ''reinforced concrete'' and reinforced masonry structures to strengthen and aid ...

being placed before casting a

prestressed concrete Prestressed concrete is a form of concrete used in construction. It is substantially prestressed (Compression (physics), compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. Post-t ...

girder File:GirderBridge2.jpg, Bridge built using multiple I-girders File:Third Mandovi bridge (38700203495).jpg,

Box girder A box girder or tubular girder (or box beam) is a girder that forms an enclosed tube with multiple walls, as opposed to an i-beam, - or H-beam. Originally constructed of wrought iron joined by riveting, they are now made of rolled steel, rolled ...

bridge being built by joining prefabricated segments File:Kochi Metro U Girders at Kalamassery.jpg, A

viaduct A viaduct is a specific type of bridge that consists of a series of arches, piers or columns supporting a long elevated railway or road. Typically a viaduct connects two points of roughly equal elevation, allowing direct overpass across a wide ...

being built using U-girders

References

* Song W, Ma Z, Vadivelu J, Burdette E (2014). Transfer Length and Splitting Force Calculation for Pretension Concrete Girders with High-Capacity Strands. Journal of Bridge Engineering. 19(7), DOI 04014026. * Chen X, Wu S, Zhou J (2014). ”Compressive Strength of Concrete Cores with Different Lengths.” Journals Materials and Civil. Engineering, 26(7), DOI 04014027. Structural system Bridge components {{material-stub

Gallery

See also

References