Girder bridge

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Girder bridge
Two different girder bridges. The top is a plate girder bridge, while the bottom is a concrete girder bridge.
Ancestor Beam bridge
Related Trestle, truss bridge, moon bridge
Descendant Box girder bridge, Plate girder bridge
Carries Pedestrians, automobiles, trucks, light rail, heavy rail
Span rangeShort, Medium
Material Iron, wood, concrete
Design effortlow
Falsework requiredNo

A girder bridge is a bridge that uses girders as the means of supporting its deck. [1] The two most common types of modern steel girder bridges are plate and box.[ citation needed ]


The term "girder" is often used interchangeably with "beam" in reference to bridge design. [2] [3] [4] [5] However, some authors define beam bridges slightly differently from girder bridges. [6]

A girder may be made of concrete or steel. Many shorter bridges, especially in rural areas where they may be exposed to water overtopping and corrosion, utilize concrete box girder . The term "girder" is typically used to refer to a steel beam. In a beam or girder bridge, the beams themselves are the primary support for the deck, and are responsible for transferring the load down to the foundation. Material type, shape, and weight all affect how much weight a beam can hold. Due to the properties of the second moment of area, the height of a girder is the most significant factor to affect its load capacity. Longer spans, more traffic, or wider spacing of the beams will all directly result in a deeper beam. In truss and arch-style bridges, the girders are still the main support for the deck, but the load is transferred through the truss or arch to the foundation. These designs allow bridges to span larger distances without requiring the depth of the beam to increase beyond what is practical. However, with the inclusion of a truss or arch the bridge is no longer a true girder bridge.


Girder bridges have existed for millennia in a variety of forms depending on resources available. The oldest types of bridges are the beam, arch and swing bridges, and they are still built today. These types of bridges have been built by human beings since ancient times, with the initial design being much simpler than what we enjoy today. As technology advanced the methods were improved and were based on the utilization and manipulation of rock, stone, mortar and other materials that would serve to be stronger and longer.

In ancient Rome, the techniques for building bridges included the driving of wooden poles to serve as the bridge columns and then filling the column space with various construction materials. The bridges constructed by Romans were at the time basic but very dependable and strong while serving a very important purpose in social life.

As the Industrial Revolution came and went, new materials with improved physical properties were utilized; and wrought iron was replaced with steel due to steel's greater strength and larger application potential.


All bridges consist of two main parts: the substructure, and the superstructure. The superstructure is everything from the bearing pads, up - it is what supports the loads and is the most visible part of the bridge. The substructure is the foundation, transfers loads from the superstructure to the ground. Both must work together to create a strong, long-lasting bridge.

The superstructure consists of several parts:

A concrete girder bridge pier during construction prior to installation of the bridge deck and parapets, consisting of multiple angled pylons for support (bottom), a horizontal concrete cap (center), and girders (top) with temporary wood bracing Poinciana Parkway RCMB bridge construction 4.jpg
A concrete girder bridge pier during construction prior to installation of the bridge deck and parapets, consisting of multiple angled pylons for support (bottom), a horizontal concrete cap (center), and girders (top) with temporary wood bracing

The substructure is made of multiple parts as well:

Types of girders

The stubs at the eastern end of the Dunn Memorial Bridge give a good cross section of girder bridge construction Dunn Memorial Bridge Supports.jpg
The stubs at the eastern end of the Dunn Memorial Bridge give a good cross section of girder bridge construction

See also

Related Research Articles

Cantilever bridge

A cantilever bridge is a bridge built using cantilevers, structures that project horizontally into space, supported on only one end. For small footbridges, the cantilevers may be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from structural steel, or box girders built from prestressed concrete. The steel truss cantilever bridge was a major engineering breakthrough when first put into practice, as it can span distances of over 1,500 feet (460 m), and can be more easily constructed at difficult crossings by virtue of using little or no falsework.

Beam bridge

Beam bridges, also known as stringer bridges, are the simplest structural forms for bridge spans supported by an abutment or pier at each end. No moments are transferred throughout the support, hence their structural type is known as simply supported.

Plate girder bridge Type of bridge

A plate girder bridge is a bridge supported by two or more plate girders.


Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary support structures for formwork used to mold concrete in the construction of buildings, bridges, and elevated roadways.


A girder is a support beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing flanges separated by a stabilizing web, but may also have a box shape, Z shape, or other forms. A girder is commonly used to build bridges.

Orthotropic deck

An orthotropic bridge or orthotropic deck is typically one whose fabricated deck consists of a structural steel deck plate stiffened either longitudinally with ribs or transversely, or in both directions. This allows the fabricated deck both to directly bear vehicular loads and to contribute to the bridge structure's overall load-bearing behaviour. The orthotropic deck may be integral with or supported on a grid of deck framing members, such as transverse floor beams and longitudinal girders. All these various choices for the stiffening elements, e.g., ribs, floor beams and main girders, can be interchanged, resulting in a great variety of orthotropic panels.

Svinesund Bridge

The Svinesund Bridge is a through arch bridge crossing Iddefjord at Svinesund, and joining Sweden and Norway. Svinesund is a sound separating the Swedish municipality of Strömstad from the Norwegian municipality of Halden, and thus it is the border between Norway and Sweden in this region. The bridge is the westernmost border crossing between the two countries and carries the European route E6 which is a major traffic route in the area, connecting Oslo and the rest of Norway with Gothenburg, Malmö, Copenhagen and the rest of Europe.

M5 (Cape Town)

The M5 is an expressway in Cape Town, South Africa. It connects the northern suburbs (Milnerton) to Muizenberg in the south, and crosses both the N1 and the N2. For part of its length, from the N1 interchange to Plumstead, it is a limited-access freeway (motorway).

Tied-arch bridge

A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends, rather than by the ground or the bridge foundations. This strengthened chord may be the deck structure itself or consist of separate, deck-independent tie-rods.

Box girder

A box or tubular girder is a girder that forms an enclosed tube with multiple walls, as opposed to an I- or H-beam. Originally constructed of riveted wrought iron, they are now made of rolled or welded steel, aluminium extrusions or prestressed concrete.

Hares Hill Road Bridge

The Hares Hill Road Bridge is a single-span, wrought iron, bowstring-shaped lattice girder bridge. It was built in 1869 by Moseley Iron Bridge and Roof Company and is the only known surviving example of this kind. The bridge spans French Creek, a Pennsylvania Scenic River.

La Vicaria Arch Bridge

La Vicaria Bridge is a through arch bridge that spans the Segura River, where it meets La Fuensanta Reservoir near Yeste, in the province of Albacete, Spain. It forms part of a future road that will join Yeste with Letur and the neighbouring area to the east. The bridge has 2 vehicle lanes and 2 sidewalks.

Locke Avenue Bridge

Locke Avenue Bridge is located on Locke Avenue, a two-lane rural route located at the northwest corner of Swedesboro in Gloucester County, New Jersey. This roadway runs generally north-south, connecting Auburn Road with U.S. Route 322. The posted speed limit on Locke Avenue is 40 miles per hour (60 km/h).

Deck (bridge)

A deck is the surface of a bridge. A structural element of its superstructure, it may be constructed of concrete, steel, open grating, or wood. Sometimes the deck is covered a railroad bed and track, asphalt concrete, or other form of pavement for ease of vehicle crossing. A concrete deck may be an integral part of the bridge structure or it may be supported with I-beams or steel girders.

Hadley Parabolic Bridge

The Hadley Parabolic Bridge, often referred to locally as the Hadley Bow Bridge, carries Corinth Road across the Sacandaga River in Hadley, New York, United States. It is an iron bridge dating from the late 19th century.

Godavari Arch Bridge Bridge in India

The Godavari Arch Bridge is a bowstring-girder bridge that spans the Godavari River in Rajahmundry, India. It is the latest of the three bridges that span the Godavari river at Rajahmundry. The Havelock Bridge being the earliest, was built in 1897, and having served its full utility, was decommissioned in 1997. The second bridge known as the Godavari Bridge is a truss bridge and is Asia's second longest railroad bridge.

Adomi Bridge

The Adomi Bridge is a latticed steel arch suspension bridge crossing the Volta River at Atimpoku in Ghana in West Africa. It is the first permanent bridge to span the Volta River, which drains south into the Gulf of Guinea, and is Ghana's longest suspension bridge. It provides the main road passage, just south of the Akosombo Dam, between the Eastern Region and the Volta Region of Ghana. It was opened in 1957 by Kwame Nkrumah, Ghana's first president. The iconic crescent-shaped arch bridge is featured in Ghanaian stamps and currency.

Balloon flange girder

A balloon flange girder or (colloquially) balloon topper is a form of vertical I-beam wrought iron plate girder, where the top flange, instead of being a simple flat plate, is extended into a hollow tube. When a girder is subjected to a positive bending moment the top flange acts in compression making a flat plate flange more susceptible to local buckling than the balloon flange is.

Rigid-frame bridge Type of bridge

A Rigid-frame bridge is a bridge in which the superstructure and substructure are rigidly connected to act as a continuous unit. Typically, the structure is cast monolithically, making the structure continuous from deck to foundation. The connections between members are rigid connections which transfer bending moment, axial forces, and shear forces. A bridge design consisting of a rigid frame can provide significant structural benefits, but can also be difficult to design and/or construct.

Fisher Covered Railroad Bridge United States historic place

The Fisher Covered Railroad Bridge is a covered bridge in Wolcott, Vermont. Built in 1908, it originally carried the St. Johnsbury and Lamoille County Railroad line over the Lamoille River. Now closed, it was the last covered bridge in Vermont to carry railroad traffic, and is a rare surviving example in the state of a double Town lattice truss. It was listed on the National Register of Historic Places in 1974.


  1. "Girder Bridge" (PDF). Argentina: National Institute of Industrial Technology (INTI). Archived from the original (PDF) on 8 September 2013. Retrieved 26 October 2012.
  2. Design Technology. "Beam Bridges".
  3. Nova . "Bridge the Gap", section "Beam Bridge".
  4. Robert Lamb and Michael Morrissey. "How Bridges Work".
  5. Ohio Department of Transportation. "Bridge Terms Definitions" Archived 2015-01-25 at the Wayback Machine
  6. Leonardo Fernandez Troyano. "Bridge Engineering: A Global Perspective". 2003.
  7. "American Wide Flange Beams - W Beam".