A double-arch stone bridge in Japan
|Descendant||Truss arch bridge, moon bridge (masonry)|
|Carries||Pedestrians, vehicles, light rail, heavy rail, water|
|Span range||short, but often set end-to-end to form a large total length|
|Material||masonry, concrete, wrought iron, cast iron, timber, structural steel|
An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. A viaduct (a long bridge) may be made from a series of arches, although other more economical structures are typically used today.
Possibly the oldest existing arch bridge is the Mycenaean Arkadiko Bridge in Greece from about 1300 BC. The stone corbel arch bridge is still used by the local populace.The well-preserved Hellenistic Eleutherna Bridge has a triangular corbel arch. The 4th century BC Rhodes Footbridge rests on an early voussoir arch.
Although true arches were already known by the Etruscans and ancient Greeks, the Romans were – as with the vault and the dome – the first to fully realize the potential of arches for bridge construction. A list of Roman bridges compiled by the engineer Colin O'Connor features 330 Roman stone bridges for traffic, 34 Roman timber bridges and 54 Roman aqueduct bridges, a substantial part still standing and even used to carry vehicles. A more complete survey by the Italian scholar Vittorio Galliazzo found 931 Roman bridges, mostly of stone, in as many as 26 different countries (including former Yugoslavia).
Roman arch bridges were usually semicircular, although a number were segmental arch bridges (such as Alconétar Bridge), a bridge which has a curved arch that is less than a semicircle.The advantages of the segmental arch bridge were that it allowed great amounts of flood water to pass under it, which would prevent the bridge from being swept away during floods and the bridge itself could be more lightweight. Generally, Roman bridges featured wedge-shaped primary arch stones (voussoirs) of the same in size and shape. The Romans built both single spans and lengthy multiple arch aqueducts, such as the Pont du Gard and Segovia Aqueduct. Their bridges featured from an early time onwards flood openings in the piers, e.g. in the Pons Fabricius in Rome (62 BC), one of the world's oldest major bridges still standing.
Roman engineers were the first and until the industrial revolution the only ones to construct bridges with concrete, which they called Opus caementicium. The outside was usually covered with brick or ashlar, as in the Alcántara bridge.
The Romans also introduced segmental arch bridges into bridge construction. The 330 m-long (1,080 ft) Limyra Bridge in southwestern Turkey features 26 segmental arches with an average span-to-rise ratio of 5.3:1, giving the bridge an unusually flat profile unsurpassed for more than a millennium. Trajan's bridge over the Danube featured open-spandrel segmental arches made of wood (standing on 40 m-high (130 ft) concrete piers). This was to be the longest arch bridge for a thousand years both in terms of overall and individual span length, while the longest extant Roman bridge is the 790 m-long (2,590 ft) long Puente Romano at Mérida. The late Roman Karamagara Bridge in Cappadocia may represent the earliest surviving bridge featuring a pointed arch.
In medieval Europe, bridge builders improved on the Roman structures by using narrower piers, thinner arch barrels and higher span to rise ratios on bridges. Gothic pointed arches were also introduced, reducing lateral thrust, and spans increased as with the eccentric Puente del Diablo (1282).
The 14th century in particular saw bridge building reaching new heights. Span lengths of 40 m (130 ft), previously unheard of in the history of masonry arch construction, were now reached in places as diverse as Spain (Puente de San Martín), Italy (Castelvecchio Bridge) and France (Devil's bridge and Pont Grand) and with arch types as different as semi-circular, pointed and segmental arches. The bridge at Trezzo sull'Adda, destroyed in the 15th century, even featured a span length of 72 m (236 ft), not matched until 1796.
Constructions such as the acclaimed Florentine segmental arch bridge Ponte Vecchio (1345) combined sound engineering (span-to-rise ratio of over 5.3 to 1) with aesthetical appeal. The three elegant arches of the Renaissance Ponte Santa Trinita (1569) constitute the oldest elliptic arch bridge worldwide. Such low rising structures required massive abutments, which at the Venetian Rialto bridge and the Fleischbrücke in Nuremberg (span-to-rise ratio 6.4:1) were founded on thousands of wooden piles, partly rammed obliquely into the grounds to counteract more effectively the lateral thrust.
In China, the oldest existing arch bridge is the Zhaozhou Bridge of 605 AD, which combined a very low span-to-rise ratio of 5.2:1, with the use of spandrel arches (buttressed with iron brackets). The Zhaozhou Bridge, with a length of 167 feet (51 m) and span of 123 feet (37 m), is the world's first wholly stone open-spandrel segmental arch bridge, allowing a greater passage for flood waters. Bridges with perforated spandrels can be found worldwide, such as in China (Zhaozhou Bridge, 7th century). Greece (Bridge of Arta, 17th century) and Wales (Cenarth Bridge, 18th century).
In more modern times, stone and brick arches continued to be built by many civil engineers, including Thomas Telford, Isambard Kingdom Brunel and John Rennie. A key pioneer was Jean-Rodolphe Perronet, who used much narrower piers, revised calculation methods and exceptionally low span-to-rise ratios. Different materials, such as cast iron, steel and concrete have been increasingly used in the construction of arch bridges.
Stone, brick and other such materials are strong in compression and somewhat so in shear, but cannot resist much force in tension. As a result, masonry arch bridges are designed to be constantly under compression, so far as is possible. Each arch is constructed over a temporary falsework frame, known as a centring. In the first compression arch bridges, a keystone in the middle of the bridge bore the weight of the rest of the bridge. The more weight that was put onto the bridge, the stronger its structure became. Masonry arch bridges use a quantity of fill material (typically compacted rubble) above the arch in order to increase this dead-weight on the bridge and prevent tension from occurring in the arch ring as loads move across the bridge. Other materials that were used to build this type of bridge were brick and unreinforced concrete. When masonry (cut stone) is used the angles of the faces are cut to minimize shear forces. Where random masonry (uncut and unprepared stones) is used they are mortared together and the mortar is allowed to set before the falsework is removed.
Traditional masonry arches are generally durable, and somewhat resistant to settlement or undermining. However, relative to modern alternatives, such bridges are very heavy, requiring extensive foundations. They are also expensive to build wherever labor costs are high.
The corbel arch bridge is a masonry, or stone, bridge where each successively higher course (layer) cantilevers slightly more than the previous course.The steps of the masonry may be trimmed to make the arch have a rounded shape. The corbel arch does not produce thrust, or outward pressure at the bottom of the arch, and is not considered a true arch. It is more stable than a true arch because it does not have this thrust. The disadvantage is that this type of arch is not suitable for large spans.
In some locations it is necessary to span a wide gap at a relatively high elevation, such as when a canal or water supply must span a valley. Rather than building extremely large arches, or very tall supporting columns (difficult using stone), a series of arched structures are built one atop another, with wider structures at the base. Roman civil engineers developed the design and constructed highly refined structures using only simple materials, equipment, and mathematics. This type is still used in canal viaducts and roadways as it has a pleasing shape, particularly when spanning water, as the reflections of the arches form a visual impression of circles or ellipses.
This type of bridge comprises an arch where the deck is completely above the arch. The area between the arch and the deck is known as the spandrel. If the spandrel is solid, usually the case in a masonry or stone arch bridge, the bridge is called a closed-spandrel deck arch bridge. If the deck is supported by a number of vertical columns rising from the arch, the bridge is known as an open-spandrel deck arch bridge. The Alexander Hamilton Bridge is an example of an open-spandrel arch bridge. Finally, if the arch supports the deck only at the top of the arch, the bridge is called a cathedral arch bridge.
This type of bridge has an arch whose base is at or below the deck, but whose top rises above it, so the deck passes through the arch. The central part of the deck is supported by the arch via suspension cables or tie bars, as with a tied-arch bridge. The ends of the bridge may be supported from below, as with a deck arch bridge. Any part supported from arch below may have spandrels that are closed or open.
The Sydney Harbour Bridge is a through arch bridge which uses a truss type arch.
Also known as a bowstring arch, this type of arch bridge incorporates a tie between two opposite ends of the arch. The tie is usually the deck and is capable of withstanding the horizontal thrust forces which would normally be exerted on the abutments of an arch bridge.
The deck is suspended from the arch. The arch is in compression, in contrast to a suspension bridge where the catenary is in tension. A tied-arch bridge can also be a through arch bridge.
Most modern arch bridges are made from reinforced concrete. This type of bridge is suitable where a temporary centring may be erected to support the forms, reinforcing steel, and uncured concrete. When the concrete is sufficiently set the forms and falseworks are then removed. It is also possible to construct a reinforced concrete arch from precast concrete, where the arch is built in two halves which are then leaned against each other.
Many modern bridges, made of steel or reinforced concrete, often bear some of their load by tension within their structure. This reduces or eliminates the horizontal thrust against the abutments and allows their construction on weaker ground. Structurally and analytically they are not true arches but rather a beam with the shape of an arch. See truss arch bridge for more on this type.
A modern evolution of the arch bridge is the long-span through arch bridge. This has been made possible by the use of light materials that are strong in tension such as steel and prestressed concrete.
"The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch, the vault and the dome."
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it.
Roman bridges, built by ancient Romans, were the first large and lasting bridges built. Roman bridges were built with stone and had the arch as the basic structure. Most utilized concrete as well, which the Romans were the first to use for bridges.
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.
A through arch bridge, also known as a half-through arch bridge or a through-type arch bridge, is a bridge that is made from materials such as steel or reinforced concrete, in which the base of an arch structure is below the deck but the top rises above it. Thus, the deck is within the arch, and cables or beams that are in tension suspend the central part of the deck from the arch.
The Anji Bridge is the world's oldest open-spandrel segmental arch bridge of stone construction. Credited to the design of a craftsman named Li Chun, the bridge was constructed in the years 595-605 during the Sui dynasty (581–618). Located in the southern part of Hebei Province, it is the oldest standing bridge in China.
The Francis Scott Key Bridge, more commonly known as the Key Bridge, is a six-lane reinforced concrete arch bridge conveying U.S. Route 29 (US 29) traffic across the Potomac River between the Rosslyn neighborhood of Arlington County, Virginia, and the Georgetown neighborhood of Washington, D.C. Completed in 1923, it is Washington's oldest surviving road bridge across the Potomac River.
The Alconétar Bridge, also known as Puente de Mantible, was a Roman segmental arch bridge in the Extremadura region, Spain. The ancient structure, which featured flattened arches with a span-to-rise ratio of 4–5:1, is one of the earliest of its kind. Due to its design, it is assumed that the bridge was erected in the early 2nd century AD by the emperors Trajan or Hadrian, possibly under the guidance of Apollodorus of Damascus, the most famous architect of the time.
The Alcántara Bridge is a Roman bridge at Alcántara, in Extremadura, Spain. Alcántara is from the Arabic word al-QanTarah (القنطرة) meaning "the bridge". The stone arch bridge was built over the Tagus River between 104 and 106 AD by an order of the Roman emperor Trajan in 98.
The Ponte San Lorenzo is a Roman segmental arch bridge over the river Bacchiglione in Padua, Italy. Constructed between 47 and 30 BC, it is one of the very earliest segmental arched bridges in the world. It is also notable for the slenderness of its piers, unsurpassed in antiquity.
The Eurymedon Bridge was a late Roman bridge over the river Eurymedon, near Aspendos, in Pamphylia in southern Anatolia. The foundations and other stone blocks (spolia) of the Roman structure were used by the Seljuqs to build a replacement bridge in the 13th century, the Köprüpazar Köprüsü, which stands to this day. This bridge is characterized by a significant displacement along its mid-line, noticeable by looking at its ancient piers.
The Bridge near Limyra is a late Roman bridge in Lycia, in modern south-west Turkey, and one of the oldest segmented arch bridges in the world. Located near the ancient city of Limyra, it is the largest civil engineering structure of antiquity in the region, spanning the Alakır Çayı river over a length of 360 m (1,181.1 ft) on 26 segmental arches. These arches, with a span-to-rise ratio of 5.3:1, give the bridge an unusually flat profile, and were unsurpassed as an architectural achievement until the late Middle Ages. Today, the structure is largely buried by river sediments and surrounded by greenhouses. Despite its unique features, the bridge remains relatively unknown, and only in the 1970s did researchers from the Istanbul branch of the German Archaeological Institute carry out field examinations on the site.
The Macestus Bridge or Bridge of Sultançayır was a Roman segmental arched bridge across the Macestus River at Balıkesir, in the northwestern part of modern-day Turkey. Its flattened arches, slender piers and the hollow chamber system documented the progress made in late antique bridge building. A first cursory investigation of the 234 m long structure was conducted in the early 20th century, but since then its existence has been largely neglected by scholars. Current photos from 2009 show that the bridge has collapsed in the meantime.
The Karamagara Bridge is a Byzantine or late Roman bridge in the ancient region of Cappadocia in eastern Turkey, and possibly the earliest known pointed arch bridge.
The Ponte Altinate is a Roman segmented arch bridge in Padua, Italy. The late Republican bridge once spanned a branch of the Brenta river whose course is today followed by the street Riviera del Ponti Romani. The structure is located at the crossing with Via Altinate and, lying underground, completely obstructed from view by the modern pavement.
The Ponte Molino is a Roman segmental arch bridge across the Bacchiglione in Padua, Italy. The span-to-rise ratio of the Late Republican bridge varies between 3.5–4.5 and 1, the ratio of clear span and pier thickness between 4–6.5 and 1.
The Ponte Corvo, rarely Ponte Corbo, is a Roman segmental arch bridge across the Bacchiglione in Padua, Italy. Dating to the 1st or 2nd century AD, its three remaining arches cross a branch of the river and are today partly buried respectively walled up. The span-to-rise ratio of the bridge varies between 2.8 and 3.4 to 1, the ratio of clear span to pier thickness from 4.9 to 6.9 to 1.
The Ain Diwar Bridge is a ruined masonry arch Roman bridge, 3.5 km northeast of the town of Ain Diwar, Syria. The bridge is within vicinity of the Syria, Iraq and Turkey border region and about 500 m west of the Tigris River of which it used to cross.
The Eleutherna Bridge is an ancient Greek corbel arch bridge near the Cretan town of Eleutherna, Greece.
The Susegana Bridge is one of a series of Roman bridges on the Via Claudia Augusta in Susegana, northern Italy. The small structure is notable for its flattened arch, which classify it as a Roman segmental arch bridge.
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