An abutment is the substructure at the ends of a

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

span or dam supporting its

superstructure A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships. Aboard ships and large boats On water craft, the superstruct ...

. Single-span bridges have abutments at each end that provide vertical and lateral support for the span, as well as acting as retaining walls to resist lateral movement of the earthen fill of the bridge approach. Multi-span bridges require piers to support ends of spans unsupported by abutments. Dam abutments are generally the sides of a valley or gorge, but may be artificial in order to support arch dams such as Kurobe Dam in Japan. The

civil engineering Civil engineering is a regulation and licensure in engineering, professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads ...

term may also refer to the structure supporting one side of an

arch An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but stru ...

, or masonry used to resist the lateral forces of a vault.Pevsner, N. (1970) ''Cornwall''; 2nd ed. Harmondsworth: Penguin; p. 245 The impost or

abacus An abacus ( abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Hindu–Arabic numeral system. A ...

of a column in classical architecture may also serve as an abutment to an arch. The word derives from the verb " abut", meaning to "touch by means of a mutual border".

Use

An abutment may be used to transfer loads from a superstructure to its foundation, to resist or transfer self weight, lateral loads (such as the earth pressure) and wind loads, to support one end of an approach slab, or to balance vertical and horizontal forces in an arch bridge.

Types

Types of abutments include: * Gravity abutment, resists horizontal earth pressure with its own dead weight * U abutment, U-shaped gravity abutment * Cantilever abutment, cantilever retaining wall designed for large vertical loads * Full height abutment, cantilever abutment that extends from the underpass grade line to the grade line of the overpass roadway * Stub abutment, short abutments at the top of an embankment or slope, usually supported on piles * Semi-stub abutment, size between full height and stub abutment * Counterfort abutment, similar to counterfort retaining walls * Spill-through abutment, vertical buttresses with open spaces between them * MSE systems, " Reinforced Earth" system: modular units with metallic reinforcement * Pile bent abutment, similar to spill-through abutment

References

External links

Ohio Department of Transportation

Earthen Dam
{{Authority control Bridges Civil engineering Dams Foundations (buildings and structures) Bridge components