Abutment

In engineering, abutment refers to the substructure at the ends of a bridge span or dam whereon the structure's superstructure rests or contacts.[1] Single-span bridges have abutments at each end which provide vertical and lateral support for the bridge, 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.[2] Dam abutments are generally either side of a valley or gorge but may be artificial in order to support arch dams such as Kurobe Dam in Japan.[1][3]

The term may also refer to the structure supporting one side of an arch,[4] or masonry used to resist the lateral forces of a vault.[5] The impost or abacus 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".

Old Town Road SIRT SB stair jeh
Cream-colored concrete abutment gives vertical support to the small red rail bridge, and to the earthen fill of the bridge approach embankment.
Kurobe Dam survey
Kurobe Dam rests on artificial concrete abutments.
DETAIL OF MASONRY ARCH APPROACH SPAN ON THE MANHATTAN SIDE - Washington Bridge, Spanning Harlem River at One-hundred-eighty-first, New York, New York County, NY HAER NY,31-NEYO,162-5
Abutment for a large steel arch bridge
Railway bridge abutment riverbank park yass
Brick abutment supporting disused tramway over the Yass River in Riverbank Park Yass

Use in engineering

An abutment may be used for the following:

  • To transfer loads from a superstructure to its foundation elements
  • To resist and/or transfer self weight, lateral loads (such as the earth pressure) and wind loads
  • To support one end of an approach slab
  • to maintain a balance in between the vertical and horizontal force components of 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

  1. ^ a b "Glossary - "Abutment"". U.S. Bureau of Reclamation. Retrieved 24 January 2015.
  2. ^ Abbett, Robert W. (1957). American Civil Engineering Practice. III. New York: John Wiley & Sons. pp. 26-22&26-32.
  3. ^ "関西電力 黒部川第四発電所 (Kurobe Kansaidenryoku Fourth plant)" (in Japanese). Suiryoku.com. Retrieved 24 January 2015.
  4. ^ Beall, Christine (1987). Masonry Design and Detailing for Architects, Engineers and Builders. McGraw-Hill. p. 449. ISBN 0-07-004223-3.
  5. ^ Pevsner, N. (1970) Cornwall; 2nd ed. Harmondsworth: Penguin; p. 245

External links

Abutment (dentistry)

In dentistry, an abutment is a connecting element. This is used in the context of a fixed bridge (the "abutment teeth" referring to the teeth supporting the bridge), partial removable dentures (the "abutment teeth" referring to the teeth supporting the partial) and in implants (used to attach a crown, bridge, or removable denture to the dental implant fixture). The implant fixture is the screw-like component that is osseointegrated.

Aesepus Bridge

The Aesepus Bridge (Turkish: Güvercin Köprüsü, "Dove Bridge") was a late antique Roman bridge over the Aesepus river (today Gönen Çayı) in the ancient region of Mysia in modern-day Turkey. It is notable for its advanced hollow chamber system which has also been employed in other Roman bridges in the region, such as the Makestos Bridge. In a field examination carried out in the early 20th century, the four main vaults of the bridge were found in ruins, while nearly all piers and the seven minor arches had still remained intact. Today, the two remaining pier stubs in the riverbed are still extant, while the condition of the rest of the structure is difficult to determine.

Ante's law

In dentistry, Ante's law refers to a group of proposals related to crown-to-root ratio put forth by Irwin H. Ante in a thesis paper he wrote in 1926.Ante's law postulated that:

"the total periodontal membrane area of the abutment teeth must equal or exceed that of the teeth to be replaced."Working from this premise, later claims were made that:

"the length of the periodontal membrane attachment of the abutment tooth should be at least one half to two thirds of that of its normal root attachment".Because of these largely unsubstantiated, empirical concepts, many teeth were subsequently excluded from suitability as an abutment for fixed partial dentures and double abutments became a popular means of complying with Ante's law.

Long-term clinical trials failed to provide evidence for Ante's so called "law" and as such, it can be concluded that Ante's law with respect to teeth has been refuted.

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.

The simplest beam bridge could be a log (see log bridge), a wood plank, or a stone slab (see clapper bridge) laid across a stream. Bridges designed for modern infrastructure will usually be constructed of steel or reinforced concrete, or a combination of both. The concrete elements may be reinforced, prestressed or post-tensioned. Such modern bridges include girder, plate girder, and box girder bridges, all types of beam bridges.

Types of construction could include having many beams side by side with a deck across the top of them, to a main beam either side supporting a deck between them. The main beams could be I-beams (also known as H-beams), trusses, or box girders. They could be half-through, or braced across the top to create a through bridge.

Because no moments are transferred, thrust (as from an arch bridge) cannot be accommodated, leading to innovative designs, such as lenticular trusses and bow string arches, which contain the horizontal forces within the superstructure.

Beam bridges are not limited to a single span. Some viaducts such as the Feiyunjiang Bridge in China have multiple simply supported spans supported by piers. This is opposed to viaducts using continuous spans over the piers.

Beam bridges are often only used for relatively short distances because, unlike truss bridges, they have no built in supports. The only supports are provided by piers. The farther apart its supports, the weaker a beam bridge gets. As a result, beam bridges rarely span more than 250 feet (80 m). This does not mean that beam bridges are not used to cross great distances; it only means that a series of beam bridges must be joined together, creating what is known as a continuous span.

Bridge (dentistry)

A bridge is a fixed dental restoration (a fixed dental prosthesis) used to replace one or more missing teeth by joining an artificial tooth definitively to adjacent teeth or dental implants.

Burnsville Lake

Burnsville Lake is both a recreational and flood control reservoir on Little Kanawha River located southeast of Burnsville in Braxton County, West Virginia. Burnsville Lake was authorized by the U.S. Congress in the Flood Control Act of 1938.

Construction of the Burnsville Lake project was begun in the summer of 1972 and the dam was completed in September 1976. The lake project controls the runoff from a drainage area of 165 square miles (427 km²). The dam is a rock-fill embankment dam rising 84.5 feet (25.8 m) above the streambed. Top elevation is 839 feet (256 m) above sea level, and the crest length is 1,400 feet (430 m). A gated spillway is located in the left abutment. The outlet works are located in the spillway section. The minimum pool is maintained at elevation 776 feet (237 m) with a surface area of 550 acres (223 ha). The summer pool is at elevation 789 feet (240 m) and has a surface area of 968 acres (392 ha). The flood control pool is at elevation 825 feet (251 m) with a surface area of 1,900 acres (769 ha).

Many people in Burnsville and surrounding communities opposed the building of the dam since the back waters would flood areas currently occupied and locations of ancestral homes. Cemeteries had to be moved and residents had to relocate. When the dam was built, there was no recreation area for local residents instead residents of Burnsville had to travel to Bulltown.

Chesters Bridge

Chesters Bridge was a Roman bridge over the River North Tyne at Chollerford, Northumberland, England, and adjacent to Chesters Roman fort on Hadrian's Wall. The fort, mentioned in the Notitia Dignitatum, and now identified with the fort found at Chesters, was known as Cilurnum or Cilurvum.

In 2016, public access to Chesters Roman bridge abutments was suspended due to flood damage.

Clair–Fort Kent Bridge

The Clair–Fort Kent Bridge is a steel truss bridge crossing the Saint John River between Clair, New Brunswick in Canada and Fort Kent, Maine in the United States.

The bridge handles approximately 279,490 vehicle crossings per year and forms a border crossing on the International Boundary. It connects with Route 205 in New Brunswick and Route 161 and U.S. Route 1 (US 1) in Maine, also forming the northern terminus of US 1.

Since it is an international bridge, the Canadian portion of the structure is the responsibility of the Province of New Brunswick, while the American portion is operated by the State of Maine. The bridge was built in 1929–30 as a replacement for an existing cable ferry and a cable suspension footbridge. The bridge has three steel through-truss spans of 73.15 m (240.0 ft) each for a total length of 221.93 m (728.1 ft).

In 1995, the first pier from the New Brunswick abutment had major repairs done. In 1997, the steel members under the deck in the first 1.5 spans from the New Brunswick end were sandblasted, and then painted with a primer of inorganic zinc. In the same year, the downstream exterior stringers in these 1.5 spans were replaced. In 1998, the downstream concrete curb in the first 1.5 spans from the New Brunswick end was replaced. In 2000, the New Brunswick end concrete abutment underwent a major restoration.

Commissure

A commissure () is the location at which two objects abut or are joined. The term is used especially in the fields of anatomy and biology.

The most common usage of the term refers to the brain's commissures, of which there are five. Such a commissure is a bundle of commissural fibers as a tract that crosses the midline at its level of origin or entry (as opposed to a decussation of fibers that cross obliquely). The five are the anterior commissure, posterior commissure, corpus callosum, commissure of fornix (hippocampal commissure), and habenular commissure. They consist of fibre tracts that connect the two cerebral hemispheres and span the longitudinal fissure. In the spinal cord there are the anterior white commissure, and the gray commissure.

Commissure also often refers to cardiac anatomy of heart valves. In the heart, a commissure is the area where the valve leaflets abut. When such an abutment is abnormally stiffened or even fused, valvular stenosis results, sometimes requiring commissurotomy.

The term may also refer to the junction of the upper and lower lips (see labial commissure of mouth).

It may refer to the junction of the upper and lower mandibles of a bird's beak, or alternately, to the full-length apposition of the closed mandibles, from the corners of the mouth to the tip of the beak.

It may refer to the upper and lower eyelids.

In female genitalia, the joining points of the two folds of the labia majora create two commissures - the anterior commissure just anterior to the prepuce of the clitoris, and the posterior commissure of the labia majora, directly posterior to the frenulum of the labia minora and anterior to the perineal raphe.In biology, the meeting of the two valves of a brachiopod or clam is a commissure; in botany, the term is used to denote the place where a fern's laterally expanded vein endings come together in a continuous marginal sorus.

Dental implant

A dental implant (also known as an endosseous implant or fixture) is a surgical component that interfaces with the bone of the jaw or skull to support a dental prosthesis such as a crown, bridge, denture, facial prosthesis or to act as an orthodontic anchor. The basis for modern dental implants is a biologic process called osseointegration, in which materials such as titanium form an intimate bond to bone. The implant fixture is first placed so that it is likely to osseointegrate, then a dental prosthetic is added. A variable amount of healing time is required for osseointegration before either the dental prosthetic (a tooth, bridge or denture) is attached to the implant or an abutment is placed which will hold a dental prosthetic.

Success or failure of implants depends on the health of the person receiving the treatment, drugs which affect the chances of osseointegration, and the health of the tissues in the mouth. The amount of stress that will be put on the implant and fixture during normal function is also evaluated. Planning the position and number of implants is key to the long-term health of the prosthetic since biomechanical forces created during chewing can be significant. The position of implants is determined by the position and angle of adjacent teeth, by lab simulations or by using computed tomography with CAD/CAM simulations and surgical guides called stents. The prerequisites for long-term success of osseointegrated dental implants are healthy bone and gingiva. Since both can atrophy after tooth extraction, pre-prosthetic procedures such as sinus lifts or gingival grafts are sometimes required to recreate ideal bone and gingiva.

The final prosthetic can be either fixed, where a person cannot remove the denture or teeth from their mouth, or removable, where they can remove the prosthetic. In each case an abutment is attached to the implant fixture. Where the prosthetic is fixed, the crown, bridge or denture is fixed to the abutment either with lag screws or with dental cement. Where the prosthetic is removable, a corresponding adapter is placed in the prosthetic so that the two pieces can be secured together.

The risks and complications related to implant therapy divide into those that occur during surgery (such as excessive bleeding or nerve injury), those that occur in the first six months (such as infection and failure to osseointegrate) and those that occur long-term (such as peri-implantitis and mechanical failures). In the presence of healthy tissues, a well-integrated implant with appropriate biomechanical loads can have 5-year plus survival rates from 93 to 98 percent and 10 to 15 year lifespans for the prosthetic teeth. Long-term studies show a 16- to 20-year success (implants surviving without complications or revisions) between 52% and 76%, with complications occurring up to 48% of the time.

Douglas Ranges

The Douglas Ranges are a subrange of the Pacific Ranges of the Coast Mountains of the Canadian province of British Columbia, about 70 km (43 mi) east of downtown Vancouver, north of the Fraser River and between the valleys of Stave and Harrison Lakes. They are approximately 4,900 km2 (1,900 sq mi) in area. Their highest peak is Mount Robertson 2,252 m (7,388 ft), at the northwest limit of the range.

The Douglas Ranges among the smallest and lowest of the major named subranges Coast Mountains, but in addition to being smallest and lowest they are also the southernmost part of the Coast Mountains and therefore also of the Pacific Ranges. The only thing more southerly than the Douglas Ranges, other than floodplain, is the unnamed hill-country that is most of Districts of Mission and part of Maple Ridge, from the Alouette River east across the upland to Hatzic Prairie. And in addition to being the most southerly and relatively lower than the rest of the Pacific Ranges, it is also among the wettest and, for being lowland country relative to the rest of its parent ranges, among the ruggedest.

The southern abutment of the Douglas Ranges is over 1,500 m (5,000 ft) above the Fraser River between Dewdney and the Harrison River, which flows along the southeast flank of the range.

East of the Douglas Ranges, across Harrison Lake, are the Lillooet Ranges, while to the west and northwest are the Garibaldi Ranges. Southeast across the Fraser River is the Canadian portion of the Cascade Range.

Hawkesbury River railway bridge

The Hawkesbury River railway bridge is a heritage-listed railway bridge that carries the Main Northern railway line across the Hawkesbury River, connecting just north of the town of Brooklyn, Hornsby Shire on the northern outskirts of Sydney with Cogra Bay, Central Coast Council, both in New South Wales, Australia. The railway bridge was to be the last link in a railway network that linked Adelaide, Melbourne, Sydney and Brisbane and was a major engineering feat at the time. It was added to the New South Wales State Heritage Register on 2 April 1999.

Headstock (rolling stock)

A headstock of a rail vehicle is a transverse structural member located at the extreme end of the vehicle's underframe. The headstock supports the coupling at that end of the vehicle, and may also support buffers, in which case it may also be known as a buffer beam. The headstocks form part of the underframe of a locomotive or a railroad car. The headstocks of locomotives, railcars and cabcars also support headlamps and the hoses for air brakes, vacuum brakes as well as the cables for train control and head end power.

Kürtün Dam

The Kürtün Dam is a concrete-face rock-fill dam on the Harşit River located 5 km (3 mi) east of Kürtün in Gümüşhane Province, Turkey. The development was backed by the Turkish State Hydraulic Works. Construction began in 1986 and the reservoir started to fill in 2002. The dam was completed in 2003 and its underground power station became operational in 2004. The hydroelectric power station, located below and just downstream of the right abutment of the dam, has an installed capacity of 80 MW.

Middle German Chemical Triangle

The Middle German Chemical Triangle (German: Mitteldeutsches Chemiedreieck or locally just Chemiedreieck) is the industrial conurbation around the cities and towns of Halle (Saale), Merseburg and Bitterfeld in the North German state of Saxony-Anhalt and Leipzig and Schkeuditz in the Free State of Saxony. Its name is derived from the dominant industries of the region – the chemical and oil refining industries.

It is often referred to as the Leuna-Buna-Bitterfeld Chemical Triangle (Chemiedreieck Leuna-Buna-Bitterfeld) because these places are the oldest and most important in the region. Buna is not a town, but was the name of the first synthetic rubber (butadiene and natrium) which was produced in the Buna factory at Schkopau. Today Dow Chemical produces synthetic rubber in Schkopau which is marketed under the name of BUNA SB.

At the end of the 1950s the advertising slogan Plaste und Elaste aus Schkopau ("Plastic and Elastomer from Schkopau") was introduced, in order to promote the spectrum of products of the Buna Chemical Works. The slogan was used especially on posters and neon lights. The best known light advert was on a tower on the northern abutment of the Elbe bridge at Vockerode on the transit route from Berlin to Hof (nowadays part of the BAB 9 motorway).

Piermont Bridge

The Piermont Bridge carries New Hampshire Route 25 over the Connecticut River between Piermont, New Hampshire and Bradford, Vermont. It is a Pennsylvania steel through truss bridge, built by the Boston Bridge Works in 1928. The bridge consists of a single span with a clear span of 352' and an overall length of 354'10". The roadbed is 20'7" wide, with a vertical clearance of 14'7". The bridge is approximately 25' above the river. The western (Vermont) abutment is made of split granite quarried from nearby Fairlee Mountain, while the eastern abutment is an early concrete construction built in 1908 by John Storrs for an earlier bridge. The bridge underwent a major renovation in 1993 which included the addition of a sidewalk (under which utilities were laid) and replacement of much of the bridge decking.The bridge was built in the aftermath of major rain and flooding in 1927 along the Connecticut River, which washed away several bridges and caused significant damage in Vermont. The Piermont Bridge was the longest bridge built after this flooding, replacing a c. 1875 two-span Town lattice truss bridge. The center pier of the older bridge was knocked down to the water line and is still visible. The eastern abutment, built in 1908 in a relatively early use of structural concrete, needed to be strengthened to accommodate the increased weight of the new steel bridge. This was accomplished by adding new concrete to the land side of the abutment, preserving the earlier work.The bridge was listed on the National Register of Historic Places in 2001. It is owned by the states of New Hampshire (90%) and Vermont (10%).

Platform switching

In dentistry, platform switching is a method used to preserve alveolar bone levels around dental implants. The concept refers to placing screwed or friction fit restorative abutments of narrower diameter on implants of wider diameter, rather than placing abutments of similar diameters, referred to as platform matching.

Discovered by accident in the late 1980s, the benefits of platform switching have become the focus of implant-related research with increasing frequency. Numerous peer-reviewed articles and recent systematic reviews have revealed that platform switching can be considered a means of preventing initial peri-implant bone loss.

Springer (architecture)

A springer is an architectural term for the lowest voussoir on each side of an arch. Since it is the bottom-most element of the arch, it is where the arch support terminates at the responds. It rests on the impost or pier of the arch, that is, the topmost part of the abutment, from which the arch arises.

Voussoir

A voussoir is a wedge-shaped element, typically a stone, which is used in building an arch or vault.Although each unit in an arch or vault is a voussoir, two units are of distinct functional importance: the keystone and the springer. The keystone is the centre stone or masonry unit at the apex of an arch. The springer is the lowest voussoir on each side, located where the curve of the arch springs from the vertical support or abutment of the wall or pier.The keystone is often decorated or enlarged. An enlarged and sometimes slightly dropped keystone is often found in Mannerist arches of the 16th century, beginning with the works of Giulio Romano, who also began the fashion for using voussoirs above rectangular openings, rather than a lintel (Palazzo Stati Maccarani, Rome, circa 1522).

The word is a mason's term borrowed in Middle English from French verbs connoting a 'turn' (OED). Each wedge-shaped voussoir turns aside the thrust of the mass above, transferring it from stone to stone to the springer's bottom face ('impost'), which is horizontal and passes the thrust on to the supports. Voussoir arches distribute weight efficiently, and take maximum advantage of the compressive strength of stone, as in an arch bridge.

In Visigothic and Moorish architectural traditions, the voussoirs are often in alternating colours, usually red and white. This is sometimes found in Romanesque architecture also.

During the 18th and 19th centuries, British bricklayers became aware that, by thickening the vertical mortar joint between regularly shaped bricks from bottom to top, they could construct an elliptical arch of useful strength over either a standard 'former', or over specially constructed timber falsework (temporary structure to be removed once the construction is complete). The bricks used in such an arch are often referred to as 'voussoirs'.

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