Girder in the context of Orthotropic deck

A lattice girder is a truss girder where the load is carried by a web of latticed metal.

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

The term "girder" is often used interchangeably with "beam" in reference to bridge design. However, some authors define beam bridges slightly differently from girder bridges.

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

A box girder bridge, or box section bridge, is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section. Box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. Although the box girder bridge is normally a form of beam bridge, box girders may also be used on cable-stayed and other bridges.

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

Compared to an Ɪ-beam, the advantage of a box girder is that it better resists torsion. Having multiple vertical webs, it can also carry more load than an Ɪ-beam of equal height (although it will use more material than a taller Ɪ-beam of equivalent capacity).

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 by 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 (T-beam or double tee structure) or it may be supported with I-beams or steel girders.

When a bridge deck is installed in a through truss, it is sometimes called a floor system. A suspended bridge deck will be suspended from the main structural elements on a suspension or arch bridge. On some bridges, such as a tied-arch or a cable-stayed, the deck is a primary structural element, carrying tension or compression to support the span.