Ancestor | Box girder bridge |
---|---|
Related | Precast Segmental Bridge |
Carries | Traffic |
Span range | Long |
Material | Concrete |
Movable | No |
Design effort | High |
Falsework required | Yes |
A segmental bridge is a bridge built in short sections (called segments), i.e., one piece at a time, as opposed to traditional methods that build a bridge in very large sections. The bridge is made of concrete that is either cast-in-place (constructed fully in its final location) or precast concrete (built at another location and then transported to their final location for placement in the full structure). [1]
These bridges are very economical for long spans (more than 100 metres or 330 feet), especially when access to the construction site is restricted. They are also chosen for their aesthetic appeal.
The first cantilevered segmental cast-in-place concrete bridge, built in 1930, was Ponte Emílio Baumgart across Rio do Peixe in the state of Santa Catarina of Brazil. [2] It was followed in 1951 by the prestressed concrete bridge across the Lahn River in Balduinstein, Germany , the first of many cantilevered bridges designed by Ulrich Finsterwalder . [3]
The first prestressed concrete bridge, assembled by several precast elements, was the Pont de Luzancy across the river Marne in France, built according to the design by Eugène Freyssinet and commenced in 1940, but due to the war, completed only in 1946.
The sequence of construction is similar to traditional concrete bridge building, i.e., build the support towers (columns), build the temporary falsework, build the deck, perform finish work. The principal differences are as follows:
A cable-stayed bridge has one or more towers, from which cables support the bridge deck. A distinctive feature are the cables or stays, which run directly from the tower to the deck, normally forming a fan-like pattern or a series of parallel lines. This is in contrast to the modern suspension bridge, where the cables supporting the deck are suspended vertically from the main cable, anchored at both ends of the bridge and running between the towers. The cable-stayed bridge is optimal for spans longer than cantilever bridges and shorter than suspension bridges. This is the range within which cantilever bridges would rapidly grow heavier, and suspension bridge cabling would be more costly.
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, and partially into a vertical load on the arch supports. A viaduct may be made from a series of arches, although other more economical structures are typically used today.
Prestressed concrete is a form of concrete used in construction. It is substantially "prestressed" (compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. It was patented by Eugène Freyssinet in 1928.
A cantilever bridge is a bridge built using structures that project horizontally into space, supported on only one end. 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.
The eastern span replacement of the San Francisco–Oakland Bay Bridge was a construction project to replace a seismically unsound portion of the Bay Bridge with a new self-anchored suspension bridge (SAS) and a pair of viaducts. The bridge is in the U.S. state of California and crosses the San Francisco Bay between Yerba Buena Island and Oakland. The span replacement took place between 2002 and 2013, and is the most expensive public works project in California history, with a final price tag of $6.5 billion, a 2,500% increase from the original estimate of $250 million, which was an initial estimate for a seismic retrofit of the span, not the full span replacement ultimately completed. Originally scheduled to open in 2007, several problems delayed the opening until September 2, 2013. With a width of 258.33 ft (78.74 m), comprising 10 general-purpose lanes, it is the world's widest bridge according to Guinness World Records.
Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary support structures for formwork used to mold concrete in the construction of buildings, bridges, and elevated roadways.
Bangabandhu Bridge, also known as the Jamuna Multi-purpose Bridge is a bridge opened in Bangladesh in June 1998. It connects Bhuapur on the Jamuna River's east bank to Sirajganj on its west bank. It was the 11th longest bridge in the world when constructed in 1998 and at present is the 6th longest bridge in South Asia. The Jamuna River, which it spans, is one of the three major rivers of Bangladesh, and is fifth largest in the world in discharge volume.
An extradosed bridge employs a structure that combines the main elements of both a prestressed box girder bridge and a cable-stayed bridge. The name comes from the word extrados, the exterior or upper curve of an arch, and refers to how the "stay cables" on an extradosed bridge are not considered as such in the design, but are instead treated as external prestressing tendons deviating upward from the deck. In this concept, they remain part of the main bridge superstructure.
The Bandra–Worli Sea Link is a 5.6 km long, 8-lane wide cable-stayed bridge that links Bandra in the Western Suburbs of Mumbai with Worli in South Mumbai. It is the second longest sea bridge after Mumbai Trans Harbour Link, as well as the 5th longest bridge in India after Mumbai Trans Harbour Link, Bhupen Hazarika Setu, Dibang River Bridge and Mahatma Gandhi Setu. It contains pre-stressed concrete-steel viaducts on either side. It was planned as a part of the proposed Western Freeway that would link the Western Suburbs to Nariman Point in Mumbai's main business district, but is now planned to become part of the Coastal Road to Kandivali.
Perai River Bridge is a dual-three lane cable stayed bridge that straddles the Perai River in Seberang Perai, Penang, Malaysia. It is part of the Butterworth Outer Ring Road (BORR).
The Incheon Bridge is a reinforced concrete cable-stayed bridge in South Korea. At its opening in October 2009, it became the second bridge connection between Yeongjong Island and the mainland of Incheon. The Incheon Bridge is South Korea's longest spanning cable-stayed bridge. In comparison, it is the world's sixteenth longest cable-stayed bridge as of January 2019.
Eugene C. Figg was an American structural engineer who made numerous contributions to the field of structural engineering, especially in the design of the cable-stayed bridge and the use of the segmental concrete construction method.
La Vicaria Bridge is a through arch bridge that spans the Segura River, where it meets La Fuensanta Reservoir near Yeste, in the province of Albacete, Spain. It forms part of a future road that will join Yeste with Letur and the neighbouring area to the east. The bridge has 2 vehicle lanes and 2 sidewalks.
The Newton Navarro Bridge, is one of the biggest cable-stayed bridges in Brazil built on a project by the Italian engineer Mario de Miranda. It is located in the city of Natal, the capital of the Brazilian state of Rio Grande do Norte. It connects North Zone and the cities of the north coast to the South Zone and the other regions of the city that cross the Potengi River.
Incremental launch is a method in civil engineering of building a complete bridge deck from one abutment of the bridge only, manufacturing the superstructure of the bridge by sections to the other side. In current applications, the method is highly mechanised and uses pre-stressed concrete.
The Mangfall Bridge is a motorway bridge across the valley of the Mangfall north of Weyarn in Upper Bavaria, Germany, which carries Bundesautobahn 8 between Munich and Rosenheim. The original bridge, designed by German Bestelmeyer, opened in January 1936 as one of the first large bridges in the Reichsautobahn system and was influential in its design. Destroyed at the end of World War II, this bridge was replaced with a temporary structure in 1948; the current bridge consists of a replacement built in 1958–60 to a design by Gerd Lohmer and Ulrich Finsterwalder and a second span for traffic in one direction which was added in the late 1970s when the autobahn was widened to six lanes.
A double tee or double-T beam is a load-bearing structure that resembles two T-beams connected to each other side by side. The strong bond of the flange and the two webs creates a structure that is capable of withstanding high loads while having a long span. The typical sizes of double tees are up to 15 feet (4.6 m) for flange width, up to 5 feet (1.5 m) for web depth, and up to 80 feet (24 m) or more for span length. Double tees are pre-manufactured from prestressed concrete which allows construction time to be shortened.
A launching gantry is a special-purpose mobile gantry crane used in bridge construction, specifically segmental bridges that use precast box girder bridge segments or precast girders in highway and high-speed rail bridge construction projects. The launching gantry is used to lift and support bridge segments or girders as they are placed while being supported by the bridge piers instead of the ground.
The Long Key Bridge, officially known as the Dante B. Fascell Bridge, is a bridge in the Florida Keys connecting Long Key and Conch Key, roughly halfway between Miami and Key West. At a length of nearly two and a half miles, it is the second longest bridge on the Overseas Highway after the Seven Mile Bridge. The current bridge opened in 1982, replacing the parallel Long Key Viaduct, which carried the Overseas Railroad from 1907 to 1935 and was repurposed for highway use shortly after.
The Loddon Bridge disaster was a collapse of falsework during construction of a reinforced concrete deck on the Loddon Bridge of the A329(M) motorway in Berkshire, England, on 24 October 1972. It killed three people and injured ten others. It is thought that a design error led part of the falsework, transitioning between the deck and the supporting towers, to be understrength and it failed by buckling or twisting. The part-poured deck fell into the river below. The collapse was investigated by Her Majesty's Factory Inspectorate and the contractor, Marples Ridgway pleaded guilty to a breach of the construction regulations at a trial in Bracknell, being fined £150.
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