Cable-stayed bridge

A cable-stayed bridge has one or more towers (or pylons), from which cables support the bridge deck.

There are four major classes of cable-stayed bridges: harp, mono, star and fan.

In the harp or parallel design, the cables are nearly parallel so that the height of their attachment to the tower is proportional to the distance from the tower to their mounting on the deck.

In the fan design, the cables all connect to or pass over the top of the towers. The fan design is structurally superior with minimum moment applied to the towers but for practical reasons the modified fan is preferred especially where many cables are necessary. In the modified fan arrangement the cables terminate near to the top of the tower but are spaced from each other sufficiently to allow better termination, improved environmental protection, and good access to individual cables for maintenance.

The cable-stayed bridge is optimal for spans longer than cantilever bridges, and shorter than suspension bridges. This is the range where cantilever bridges would rapidly grow heavier if the span were lengthened, and suspension bridge cabling would not be more economical if the span were shortened.

History

Cable-stayed bridge by the Renaissance polymath Fausto Veranzio, from 1595/1616

Cable-stayed bridges date back to 1595, where designs were found in Machinae Novae, a book by Venetian inventor Fausto Veranzio. Many early suspension bridges were cable-stayed construction, including the 1817 footbridge Dryburgh Abbey Bridge, James Dredge's patented Victoria Bridge, Bath (1836), and the later Albert Bridge (1872) and Brooklyn Bridge (1883). Their designers found that the combination of technologies created a stiffer bridge. John A. Roebling took particular advantage of this to limit deformations due to railway loads in the Niagara Falls Suspension Bridge.

The earliest known surviving example of a true cable-stayed bridge in the United States is E.E. Runyon's largely intact steel or iron bridge with wooden stringers and decking in Bluff Dale, Texas (1890), or his weeks-earlier but ruined Barton Creek Bridge between Huckabay, Texas and Gordon, Texas (1889 or 1890).^[1][2] In the twentieth century, early examples of cable-stayed bridges included A. Gisclard's unusual Cassagnes bridge (1899), in which the horizontal part of the cable forces is balanced by a separate horizontal tie cable, preventing significant compression in the deck, and G. Leinekugel le Coq's bridge at Lézardrieux in Brittany (1924). Eduardo Torroja designed a cable-stayed aqueduct at Tempul in 1926.^[3] Albert Caquot's 1952 concrete-decked cable-stayed bridge over the Donzère-Mondragon canal at Pierrelatte is one of the first of the modern type, but had little influence on later development.^[3] The steel-decked Strömsund Bridge designed by Franz Dischinger (1955) is therefore more often cited as the first modern cable-stayed bridge.

Other key pioneers included Fabrizio de Miranda, Riccardo Morandi and Fritz Leonhardt. Early bridges from this period used very few stay cables, as in the Theodor Heuss Bridge (1958). However, this involves substantial erection costs, and more modern structures tend to use many more cables to ensure greater economy.

Abdoun Bridge, Amman, Jordan

Rio–Antirrio bridge, Patras, Greece

Comparison with suspension bridge

Ada Bridge at dusk in Belgrade (Serbia)

Cable-stayed bridges may appear to be similar to suspension bridges, but in fact they are quite different in principle and in their construction.

In suspension bridges, large main cables (normally 2) hang between the towers (normally 2), and are anchored at each end to the ground. This can be difficult to implement when ground conditions are poor. The main cables, which are free to move on bearings in the towers, bear the load of the bridge deck. Before the deck is installed, the cables are under tension from their own weight. Along the main cables smaller cables or rods connect to the bridge deck, which is lifted in sections. As this is done, the tension in the cables increases, as it does with the live load of traffic crossing the bridge. The tension on the main cables is transferred to the ground at the anchorages and by downwards tug on the towers.

Al-Jisr Al-Mu'allaq, a cable-stayed bridge in Riyadh, Saudi Arabia

• Difference between types of bridges
• 

  Suspension bridge

• 

  Cable-stayed bridge, fan design

• 

  Cable-stayed bridge, harp design

In the cable-stayed bridge, the towers are the primary load-bearing structures which transmit the bridge loads to the ground. A cantilever approach is often used to support the bridge deck near the towers, but lengths further from them are supported by cables running directly to the towers. This has the disadvantage, compared to the suspension bridge, that the cables pull to the sides as opposed to directly up, requiring the bridge deck to be stronger to resist the resulting horizontal compression loads; but has the advantage of not requiring firm anchorages to resist the horizontal pull of the main cables of the suspension bridge. By design all static horizontal forces of the cable-stayed bridge are balanced so that the supporting towers do not tend to tilt or slide, needing only to resist horizontal forces from the live loads.

Key advantages of the cable-stayed form are as follows:

• much greater stiffness than the suspension bridge, so that deformations of the deck under live loads are reduced
• can be constructed by cantilevering out from the tower - the cables act both as temporary and permanent supports to the bridge deck
• for a symmetrical bridge (i.e. spans on either side of the tower are the same), the horizontal forces balance and large ground anchorages are not required

Variations

Side-spar cable-stayed bridge

Puente de la Unidad, joining San Pedro Garza García and Monterrey, a Cantilever spar cable-stayed bridge

Anzac Bridge, Sydney

A side-spar cable-stayed bridge uses a central tower supported on only one side. This design allows the construction of a curved bridge.

Queen Elizabeth II Bridge, Dartford, England

Envigado bridge a cable-stayed bridge in Envigado (Colombia)

Cantilever-spar cable-stayed bridge

Far more radical in its structure, the Puente del Alamillo (1992) uses a single cantilever spar on one side of the span, with cables on one side only to support the bridge deck. Unlike other cable-stayed types, this bridge exerts considerable overturning force upon its foundation and the spar must resist the bending caused by the cables, as the cable forces are not balanced by opposing cables. The spar of this particular bridge forms the gnomon of a large garden sundial. Related bridges by the architect Santiago Calatrava include the Puente de la Mujer (2001), Sundial Bridge (2004) and Chords Bridge (2008).

Multiple-span cable-stayed bridge

Cable-stayed bridges with more than three spans involve significantly more challenging designs than do 2-span or 3-span structures.

In a 2-span or 3-span cable-stayed bridge, the loads from the main spans are normally anchored back near the end abutments by stays in the end spans. For more spans, this is not the case and the bridge structure is less stiff overall. This can create difficulties in both the design of the deck and the pylons. Examples of multiple-span structures in which this is the case include Ting Kau Bridge, where additional 'cross-bracing' stays are used to stabilise the pylons; Millau Viaduct and Mezcala Bridge, where twin-legged towers are used; and General Rafael Urdaneta Bridge, where very stiff multi-legged frame towers were adopted. A similar situation with a suspension bridge is found at both the Great Seto Bridge and San Francisco–Oakland Bay Bridge where additional anchorage piers are required after every set of three suspension spans - this solution can also be adapted for cable-stayed bridges.^[4]

Extradosed bridge

The extradosed bridge is a cable-stayed bridge but with a more substantial bridge deck that, being stiffer and stronger, allows the cables to be omitted close to the tower and for the towers to be lower in proportion to the span. The first extradosed bridges were the Ganter Bridge and Sunniberg Bridge in Switzerland. A new extradosed bridge is also being planned to cross the St. Croix River between Bayport, Minnesota and Houlton, Wisconsin in the Twin Cities.

Cable-stayed cradle-system bridge

A cradle system carries the strands within the stays from bridge deck to bridge deck, as a continuous element, eliminating anchorages in the pylons. Each epoxy-coated steel strand is carried inside the cradle in a one-inch (2.54 cm) steel tube. Each strand acts independently, allowing for removal, inspection and replacement of individual strands. The first two such bridges are the Penobscot Narrows Bridge, completed in 2006, and the Veterans' Glass City Skyway, completed in 2007.^[5]

Related bridge types

Self anchored suspension bridge

A self-anchored suspension bridge has some similarity in principle to the cable-stayed type in that tension forces that prevent the deck from dropping are converted into compression forces vertically in the tower and horizontally along the deck structure. It is also related to the suspension bridge in having arcuate main cables with suspender cables, although the self-anchored type lacks the heavy cable anchorages of the ordinary suspension bridge. Unlike either a cable stayed bridge or a suspension bridge, the self-anchored suspension bridge must be supported by falsework during construction and so it is more expensive to construct.

Notable cable-stayed bridges

See also: List of longest cable-stayed bridge spans and Category:Cable-stayed bridges

• Basarab Overpass in Bucharest (Romania) is the widest cable-stayed bridge in Europe, measuring 44,5 meters in width and accommodating a two way tram station with full platforms, safety areas and two traffic lanes in each direction at its widest point.^[6]
• Brooklyn Bridge, famous as a suspension bridge, also has cable stays.
• Cable Bridge, the second cable-stayed bridge in the United States, crosses the Columbia River and connects Pasco, Washington to Kennewick, Washington.
• Centennial Bridge, a six-lane vehicular bridge that crosses the Panama Canal with a total length of 1.05 km (3,451 ft).
• Clark Bridge, crosses the Mississippi River at Alton, Illinois; subject of the Nova documentary Super Bridge.
• Denver Millennium Bridge, a 130-foot (40 m) long pedestrian bridge which won the Gold Award in 2003 from the New York Association of Consulting Engineers. The bridge is a focal point of the film Imagine That starring Eddie Murphy.

Erasmus Bridge, Erasmusbrug, in Rotterdam, Netherlands

• Erasmus Bridge crosses the Nieuwe Maas in Rotterdam, Netherlands. The southern span of the bridge has an 89-metre-long (292 ft) bascule bridge for ships that cannot pass under the bridge. The bascule bridge is the largest and heaviest in West Europe and has the largest panel of its type in the world.
• Fred Hartman Bridge

A view of the Golden Horn Metro Bridge, with the Galata Tower at the left end of the frame, Istanbul, Turkey

• Golden Horn Metro Bridge, connects the old peninsula of Istanbul with the Galata district and is the first cable-stayed bridge in Turkey.
• Jesús Izcoa Moure Bridge, the first cable-stayed bridge in Puerto Rico and the Caribbean.
• Jiaxing-Shaoxing Sea Bridge, Zhejiang Province, China. The bridge is an eight lane structure that spans 10,100 metres across Hangzhou Bay, connecting Jiaxing and Shaoxing, two cities of Zhejiang province. It was opened on 23 July 2013 and is currently the longest cable-stayed bridge in the world.
• John James Audubon Bridge (Mississippi River): The longest cable-stayed bridge in the Western Hemisphere, crossing the Mississippi River between New Roads, Louisiana and St. Francisville, Louisiana.
• Juscelino Kubitschek bridge, a unique bridge featuring three 60-metre tall asymmetrical steel arches that crisscross diagonally. Decks are suspended by steel cables alternating and interlacing at each side.
• Indiano Bridge, crosses the Arno River in Florence, Italy, 1978, is the first earth-anchored cable-stayed steel bridge in the world with central planes of cables, single inclined masts, vented deck.
• Hale Boggs Memorial Bridge, crosses the Mississippi River in Luling, Louisiana and Destrehan, Louisiana; it was the first cable-stayed bridge in the United States carrying an interstate highway
• Lekki-Ikoyi Link Bridge, the first of its kind in Nigeria completed and opened on May 29, 2013 by Lagos State Governor Babatunde Fashola.
• Leonard P. Zakim Bunker Hill Memorial Bridge, in Boston, Massachusetts was the widest cable-stayed bridge in the world when it was built.^[7]
• Lyne Bridge, crosses the M25 motorway near Chertsey, England, 1979, is one of the few cable-stayed bridges to carry a heavy railway (the Chertsey Branch Line).^[8]
• Millau Viaduct, the bridge with the tallest piers in the world: 341 metres tall (1,118 ft) and roadway 266 metres high (886 ft), spanning the Tarn River in France. With a total length of 2 460 m and seven towers, it also has the longest cable-stayed suspended deck in the world.

Most SNP (Bridge of the Slovak National Uprising) - the world's longest cable-stayed bridge to have one pylon and one cable-stayed plane (Bratislava, Slovakia, 1967-1972).

• Most SNP (Nový most), the world's longest cable-stayed bridge in category with one pylon and with one cable-stayed plane, spanning the Danube in Bratislava, Slovakia.The main span is 303 metres, total length 430.8 metres. The only member of World Federation of Great Towers that is primarily used as a bridge. It houses a flying-saucer restaurant at the top of pylon 85 metres tall.
• Nelson Mandela Bridge, the longest cable bridge in Southern Africa based in Johannesburg, South Africa. The bridge opened in 2003.
• New Railroad Bridge, the first bridge in Europe to use cable-stayed girder system in the railroad industry, connects two banks of the Sava in Belgrade.

Octavio Frias de Oliveira bridge, in São Paulo, Brazil. It is the only bridge in the world that has two curved tracks supported by a single concrete mast.

• Octavio Frias de Oliveira bridge, crosses the Pinheiros River in São Paulo, 2008. It has a 138 metres (453 ft)-high pylon under which two stayed roads cross each other turning 90° to the opposite bank of the river.
• Oresund Bridge, a combined two-track rail and four-lane road bridge with a main span of 490 metres and a total length of 7.85 km, crossing the Öresund between Malmö, Sweden and the Danish Capital Region.
• Pont de Normandie, crosses the Seine in Normandy, France - briefly the world's longest cable-stayed bridge.
• Port Mann Bridge, crosses the Fraser River in British Columbia, Canada. It is currently the second widest bridge in the world at 65 metres (213 ft) carrying 10 lanes of the Trans Canada Highway.
• Queensferry Crossing (formerly the Forth Replacement Crossing) is a road bridge under construction in Scotland. It is being built alongside the existing Forth Road Bridge across the Firth of Forth, and will connect Lothian, at South Queensferry, to Fife, at North Queensferry. The projected completion date is 2016.
• Rande Bridge in Spain near Vigo is the highway cable-stayed bridge with the longest and slenderest span in the world at the time of construction (1973–1977). Three long spans of 148 m + 400 m + 148 m. Pylons in concrete, girder in steel.
• Rio-Antirio bridge, crosses the Gulf of Corinth near Patras, Greece. At a total length of 2 880 m and four towers, it has the second longest cable-stayed suspended deck (2 258 m long) in the world, with only the deck of the Millau Viaduct in southern France being longer at 2,460 m (8,071 ft). However, as the latter is also supported by bearings at the pylons apart from cable stays, the Rio–Antirrio bridge deck might be considered the longest cable-stayed "suspended" deck.
• Russky Bridge, the cable-stayed bridge with the world’s longest span, at 1,104 meters.
• Second Severn Crossing between England and Wales is 3.186 miles (5.127 km) long, consisting of a single central navigation span over the "Shoots" channel and approach viaducts on either side. The Second Severn Crossing Bridge uses Freyssinet cable stays.
• Sidney Lanier Bridge, located in Brunswick, Georgia on U.S. Highway 17 is 7,779 ft (2371 m) long, it is the longest-spanning bridge in the state of Georgia, U.S.
• Skybridge, the world's longest transit-only bridge, spanning the Fraser River between New Westminster and Surrey, BC, Canada.
• Sunshine Skyway Bridge, the world's longest bridge with a cable-stayed main span; carries I-275 across Tampa Bay south of St. Petersburg, Florida, United States. The very similar looking Oresund bridge is slightly shorter but has a longer main span.
• Suramadu Bridge in Indonesia is the longest cable-stayed bridge in Southeast Asia and Indonesia. It connects the city of Surabaya in Java with the island of Madura. Its main span is 818 metres long.
• Surgut Bridge, the longest single-pylon cable-stayed bridge in the world, crossing the Ob River in Siberia.
• Sutong Yangtze River Bridge in eastern China has the second longest cable-stayed bridge span at 1,088 metres (3,570 ft). Completed in 2008, the Sutong Bridge is one of over 40 cable-stayed bridges built over the Yangtze since 1995.
• Tatara Bridge, has the fifth longest span of any cable-stayed bridge at 890 metres (2,920 ft), part of a series of bridges connecting Honshū and Shikoku in Japan.
• Ting Kau Bridge, the world's first major four-span (three towers) cable-stayed bridge, forming part of the road network connecting Hong Kong International Airport to other parts of Hong Kong, China.
• Vasco da Gama Bridge in Lisbon, Portugal is the longest bridge in Europe, with a total length of 17.2 km (10.7 mi), including 0.829 km (0.5 mi) for the main bridge, 11.5 km (7.1 mi) in viaducts, and 4.8 km (3.0 mi) in extension roads.
• Vidyasagar Setu, spans across the Hoogly from Kolkata to Howrah with a total length of 823 metres (2,700 ft). It is the longest cable–stayed bridge in India and one of the longest in Asia
• Zhivopisny Bridge in Moscow, Russia, is the highest cable-stayed bridge in Europe.
• Zárate–Brazo Largo Bridges over the Paraná Guazú and Paraná de las Palmas Rivers in Argentina (1972–1976) are the first two road and railway long-span cable-stayed steel bridges in the world. Spans: 110 m + 330 m + 110 m.
• Langkawi Sky Bridge is a 125-metre (410 ft) curved pedestrian cable-stayed bridge in Malaysia, completed in 2005. It is located 700 metres (2,300 ft) above sea level at the peak of Gunung Mat Chinchang on Pulau Langkawi, an island in the Langkawi archipelago in Kedah.^[9]

References

Further reading

• De Miranda F., et al., (1979), "Basic problems in long span cable stayed bridges", Rep. n. 25, Dipartimento di Strutture - Università di Calabria - Arcavacata (CS) Italy, (242 pagg.) September 1979.
• Gregory, Frank Hutson; Freeman, Ralph Anthony (1987). The Bangkok Cable Stayed Bridge. 3 F Engineering Consultants, Bangkok. ISBN 974-410-097-4. 
• Podolny, Walter; Scalzi, John B. (1986). Construction and design of cable-stayed bridges (2nd ed.). New York: Wiley. ISBN 0471826553. *
• Walther, Rene; et al. (1999). Cable Stayed Bridges (2nd ed.). Thomas Telford. ISBN 0-7277-2773-7. 

External links

Wikimedia Commons has media related to Cable-stayed bridges.

• The Impossible Bridge on YouTube
• North American Cable Stayed Bridge Registry
• Structurae: Cable-stayed Bridges
• Cable-Stayed Bridge
• Cable-stayed bridges on Brantacan
• Bridgemeister: Cable-stayed Bridges
• Cable-Stayed Bridge Basics
• Stay Cable

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