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A cantilever bridge is a bridge built using structures that project horizontally into space, supported on only one end (called cantilevers).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.
However, continuous truss bridges do not experience the tipping forces that a cantilever bridge must resist because the main span of a continuous truss bridge is supported at both ends. The result of collapse of a continuous truss bridge (the Francis Scott Key Bridge). It is possible to convert a series of simple truss spans into a continuous ...
Most trusses have the lower chord under tension and the upper chord under compression. In a cantilever truss the situation is reversed, at least over a portion of the span. The typical cantilever truss bridge is a "balanced cantilever", which enables the construction to proceed outward from a central vertical spar in each direction.
A cantilever spar cable-stayed bridge is a modern variation of the cable-stayed bridge. This design has been pioneered by the structural engineer Santiago Calatrava in 1992 with the Puente del Alamillo in Seville, Spain.
In cantilever bridges, the cantilevers are usually built as pairs, with each cantilever used to support one end of a central section. The Forth Bridge in Scotland is an example of a cantilever truss bridge. A cantilever in a traditionally timber framed building is called a jetty or forebay.
A self-anchored suspension bridge is a suspension bridge type in which the main cables attach to the ends of the deck, rather than directly to the ground or via large anchorages. [1] The design is well-suited for construction atop elevated piers, or in areas of unstable soils where anchorages would be difficult to construct.
The narrow section at mid-span gives the bridge profile a slight arch shape making this design particularly useful when large headroom is required. The profile also makes the bridge more architecturally pleasing than a beam bridge. Rigid-frame design may be the most efficient bridge type for spans between 35 and 80 feet (11 and 24 m). [5]
A swing bridge (or swing span bridge) is a movable bridge that can be rotated horizontally around a vertical axis. It has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then pivot horizontally as shown in the animated illustration to the right.