|Dr. N. Subramanian
Joined: 21 Feb 2008
Location: Gaithersburg, MD, U.S.A.
|Posted: Tue Jan 03, 2012 7:30 pm Post subject: The World's Top 10 Longest Cable-Stayed Bridges
The World's Top 10 Longest Cable-Stayed Bridges
Overview by Aileen Cho; Slide Show by Scott Lewis
Map by Justin Reynolds/ENR Art Dept.
Nine of the ten longest cable-stayed bridges are in Asia.
The 1,104-meter-long main span of the Russky Island cable-stayed bridge will set a new length record when that Bosporus Strait crossing opens next year. Only two other cable-stayed-bridge main spans have surpassed the 1,000-m mark. But thanks to evolving technologies, materials and advanced methods of measuring external factors, all this could change, say bridge engineers.
For our first global edition of 2012, ENR has compiled a list of the top 10 longest bridges that use cable stays for structural support. Check out the slide show at left to see the list or continue reading below.
Traditionally, very long-span bridges tend to go the suspension route, because cable-stayed bridges are limited by the stiffness of their superstructure, says Joe Tse, manager of long-span bridges for Parsons Brinckerhoff, New York City.
“There is a point [at which] the current high-strength cables will exhibit some non-linear behavior. The weight creates a sag in the cable,” Tse says. “Once you get closer to 3,000 meters, typically you go for suspension bridges. But suspension bridges need fairly good ground conditions and fairly massive anchorages. In very poor soil conditions and with cost issues for concrete, then we might look at cable-stayed bridges.”
Advances in various materials may someday enable cable-stayed bridges to surpass 1,100-m-long main-span lengths. These materials include composites and lighter types of steel for the superstructure, says Craig Finley, founder of Finley Engineering Group, Tallahassee, Fla. Evolving software is improving measurements of wind impacts, which also will allow for longer cable-stayed spans, Finley adds.
Further, evolving concrete mixes are enabling longer-span bridges. “Cable forces are part of a closed force system permitting lighter elements as the compression forces are balanced within the deck,” says Jamey Barbas, global director of strategic projects for Hardesty and Hanover, New York City.
“The higher-strength concrete mixes allow designers to take full advantage of the compressive nature of the cable-stay system. Improved concrete mixes also yield benefits for composite designs by [using] steel-box superstructures for longer-span weight reduction.”
Construction methods and equipment also have advanced to meet design demands, Barbas says. “Climbing forms and larger cranes are enabling taller towers and longer spans to be constructed. The forms are reducing costs and provide for the more complex pylon shapes that are required to deal with the some of the large forces more effectively,” Barbas says.
Linda Figg, president and CEO of Figg Engineering Group, Tallahassee, points to the Penobscot Narrows Bridge as an example of new materials being tested: Three of its cables have fiber-reinforced polymer strands (ENR 7/10/06 p. 26).
The bridge, with a 354-m-long main span, also features the firm’s patented cable-cradle system, which allows for cables to be any size. “With bigger cables, longer spans can be achieved, and installation uses lighter equipment and less labor,” Figg says.
The cable-cradle system also allowed for the Veteran’s Glass City Skyway Bridge in Maumee, Ohio, to have enormous cables, with the largest comprising 156 strands, Figg adds.
Wind is another obstacle to very long cable-stayed bridges. A long, slender superstructure coupled with decreasing efficiency in the cables can make a bridge act much like a sail. “The aerodynamics begin to work against you,” says Tse.
Mitigating methods range from fins and fenders to streamlining the bridge's cross section, which makes the towers rounder to deflect wind, to dampers. “A lot of dampers are located on the deck level, but once you get into really long spans, you need to put dampers on the towers also,” notes Tse.
Two Basic Shapes
There are two basic types of cable-stay arrangements: the fan and the harp. The top 10 longest bridges feature modified fan configurations rather than harp configurations because the latter renders the cable stays parallel. That increases compression in the superstructure, says Tse.
“The fan arrangement was used on the early cable-stay bridges, taking the basic design from the existing suspension-bridge methodology,” notes Barbas. “The main cables of a suspension bridge rest over the tower tops in cable saddles. Similarly, the original fan arrangements for cable-stay bridges passed over the pylon tops. This arrangement was adequate for the earlier, moderate-size cable-stay bridges [in which] the diameter and number of stays were small.”
But as main-span lengths increased, the loads increased and the modified fan arrangement developed, Barbas adds. “In the modified fan arrangement, the cable stays are spaced out over the top portion of the pylon so as to have more room to be individually anchored near the pylon top.
The cable stays for the harp arrangement are anchored in equal spaces over much of the height of the pylon,” she says. “It gives a pleasant aesthetic appearance but is not as structurally efficient as the fan arrangements, since the pylon has greater bending moment on it when the loading is not symmetric.”
Adding intermediate piers to the back spans stiffens the tower behavior, improving its ability to deflect wind, Tse says. The Russky Island bridge, which will have a record-breaking 320.9-m-tall tower and one cable stay reaching 580 m long, includes such piers.
“It’s not inconceivable that cable-stayed bridge spans can someday reach 2,000 meters,” says Tse. “I would say the economics of it is going to be the key.”
1. The Sutong Bridge arcs across a 6-kilometer-wide stretch of the mighty Yangtze River 50 miles upstream from Shanghai. Measuring 8.2 km overall, its main span is the current world record-holder for a cable-stayed bridge. By providing direct road access from Shanghai, it is helping Nantong, a major port and textile production center, play a greater role in the Yangtze River Delta economic zone. The site presented several challenges. The river is tidal there, with waves as high as 3.5 meters. The Yangtze is alluvial, with high erosion and deposition rates. The soil at the site of the main pylons is made up of layers of silty sands and silty clays that extend to bedrock 240 meters below the river bottom. The foundation for each pylon consists of 131 drilled shafts, 2.5 to 2.8 m in dia, extending 114 to 117 m deep and covering an area of 113 m x 48 m. The conceptual scour design for the main piers was performed by COWI A/S (Denmark), and the detail design was done by Jiangsu Provincial Communication, Planning and Design Institute. AECOM provided comprehensive services to the main contractor, China Harbour Engineering Co., in the construction phase of the bridge. The services included development of construction methodology, erection analysis, deck lifting methods and procedures, wind tunnel testing, and vibration mitigation measures. The bridge was completed in 2008 at a cost of $1.7 billion. Rising 306 m, its towers are taller than all other bridges except for France’s Millau Viaduct.
Image Courtesy ANR2008
By linking Nantong on the Yangtze's north bank more closely to Shanghai, the Sutong Bridge is boosting the region's economic vitality.
Image Courtesy of Alex Needham
2. STONECUTTERS BRIDGE: Length of main span: 1,018 meters; Owner: Hong Kong Highways Dept. Stonecutters Bridge vaults across Rambler Channel at the entrance to Hong Kong Harbor, linking Chek Lap Kok Airport on Lantau Island with the New Territories. An international design competition was won by a scheme submitted by a group made up of Dissing+Weitling (Denmark) together with Halcrow Group (Britain), Flint & Neill Partnership (Britain) and the Shanghai Municipal Engineering Design Institute. A group led by Arup with COWI A/S as main subconsultant carried out the design development of the concept design as well as the detailed design that followed. COWI was responsible for the design of the towers, steel superstructure and stay cables. The contractor was the Maeda-Hitachi-Yokogawa-Hsin Chong Joint Venture. It was the first major bridge with a twin-box-girder superstructure. Its distinctive circular towers were jump-formed and are topped by steel sections from which the cables emerge in a modified fan pattern. A major challenge was the problematic ground below the west tower. To avoid clefts and voids, the team reconfigured and spread out the bored piles, resulting in a nine-month delay. The bridge was completed in 2009.
Image Courtesy Baycrest
3. EDONG BRIDGE: Length of main span: 926 meters; Owner: Hubei Edong Changjiang Expressway Bridge Co. Ltd. Spanning the Yangtze River at the port of Huangshi, a city of 1.1 million people in Hubei Province, the Edong Bridge is 6.2 km in length. It was designed by the Hubei Communications Planning Design Institute and CCC Highway Consultants Co. Ltd. It was built by two contractors: CCCC Second Highway Engineering Co. Ltd. and CCCC Second Harbor Engineering Co. Ltd., two subsidiaries of China Communications Construction Co. Ltd. The bridge was completed in 2010.
Image Courtesy of DAIV
4. TATARA BRIDGE: Length of main span: 890 meters; Owner and design firm: Honshu-Shikoku Bridge Authority. The longest cable-stayed bridge in the world when it was completed in 1999, Tatara is part of Nishiseto Expressway, a 59- km link across the Inland Sea of Japan that encompasses nine bridges and connects Japan’s main island, Honshu, with Shikoku. It is a steel-box-girder cable-stayed bridge, with a semi-fan cable-stay arrangement. The 222-m-tall towers are inverted Y-shaped steel structures, with slits in the upper towers for aesthetics as well as aerodynamics. The foundation contractor was a five-company group headed by Hazama Corp. and including Fujita Corp., Okumura Corp., JDC Corp., and Saeki Kensetsu Kogyo Co. Ltd. The superstructure work was handled by two teams: The north end was built by a consortium headed by Mitsubishi Heavy Industries Ltd., with Kawada Industries Inc., Miyaji Iron Works Co. Ltd., Hitachi Zosen Corp. and Komai Tekko Inc. The south end was handled by a team headed by Ishikawajima-Harima Heavy Industries Co. Ltd. and including Yokogawa Bridge Corp., JFE Holdings Inc., The Takigami Steel Construction Co. Ltd. and Matsuo Bridge Corp. Ltd. (ENR 5/3/99 p. 42)
Image Courtesy Simcat
5. PONT DE NORMANDIE: Length of main span: 856 meters; Owner: Haute-Normandy Regional Council. The Pont de Normandie spans the River Seine in northern France and was the world’s longest cable-stayed span when it was completed in 1995. The choice of a cable-stayed design rather than a suspension bridge was based on light traffic loads and a lack of good natural ground support for huge anchorages. It was designed by noted bridge engineer Michel Virlogeux, who worked for Service d’Etudes Techniques des Routes et Autoroutes (SETRA), the engineering arm of the French highway administration. Bilfinger & Berger (Germany) served as the foundation subcontractor, while G.I.E. Pont de Normandie, a joint venture of Bouygues SA (France) and Campenon Bernard SA (France), was the concrete contractor. The main steelwork contractor was Monberg & Thorsen AS, Denmark (ENR 9/19/94 p.76).
Image Courtesy of Marco Farina
6. JINGYUE BRIDGE: Length of main span: 816 meters; Owner: Hubei Jingyue Changjiang Expressway Bridge Construction Project Headquarters. The first bridge across the Yangtze River in Hunan Province in central China, the Jingyue Bridge connects the city of Yueyang in Hunan with Hubei Province on the north bank. Its towers resemble upstretched arms. Opened in 2010, the bridge stretches 5.4 km across a channel of the Yangtze leading to Dongting Lake, the second-largest lake in China. It was designed by the Hubei Communications Planning Design Institute and the China Highway Engineering Consulting Group Co. Ltd. It was built by two contractors: CCCC Second Highway Engineering Co. Ltd. and the Hunan Road and Bridge Construction Group Corp.
7. INCHEON BRIDGE: Length of main span: 800 meters; Owner: Incheon Bridge Co. Ltd. (a joint venture of AMEC and the Incheon City government holds a 30-year concession). Incheon Bridge stretches 12.3 km across the Yellow Sea, connecting Yeongjong Island and Incheon City. Incheon City, located 30 miles west of Seoul and populated by 2.8 million residents, is becoming a center for international trade and will host the Asian Games in 2014. Completed in 2009, the bridge is a vital link that carries the expressway between Incheon International Airport, Korea’s busiest air hub, and Songdo, a potent new urban center within Incheon City. When the bridge is completed in 2016, Songdo, currently home to 22,000 residents, will encompass 35 million sq ft of residential space, 40 million sq ft of office space, 10 million sq ft of retail and five million sq ft of hotel space. The bridge’s design-build contract was awarded to the Samsung Joint Venture, led by Samsung Engineering and Construction and including six Korean partners: Daelim, Daewoo, Hanjin, Hanwha, Kumho and GS. Buckland & Taylor Ltd. (Canada) was responsible for developing the conceptual design. For detailed design, Samsung hired Chodai Co. Ltd., Seo Yeong, and Hyundai Engineering and Construction.
Image Courtesy Jinho Jung
8. SHANGHAI YANGTZE RIVER BRIDGE: Length of main span: 730 meters; Owner: Shanghai Yangtze River Tunnel and Bridge Development Co. Ltd. With a population of 700,000, Chongming Island is a large, 1,041-sq-km alluvial island at the mouth of the Yangtze River, facing Shanghai. To connect it to Shanghai, authorities built the Shanghai Yangtze River Bridge-Tunnel, a 25.5-km-long structure consisting of an 8.9-km-long tunnel from Pudong on the south bank to Changxing Island, a smaller intervening island, and a 16.6-km bridge from Changxing to Chongming. The bridge carries three lanes of traffic in each direction, with room on both flanks reserved for a future metro line. It was designed by the Shanghai Municipal Engineering Design Institute Group Co. Ltd. It was built by two contractors: CCCC Second Harbor Engineering Co. Ltd. and the Shanghai Urban Construction Group Corp. The cost for the entire bridge-tunnel was $1.84 billion, and it opened in 2009. Chongming Island, still primarily agricultural, is the future site of Dongtan, an eco-city master-planned by Arup.
Image Courtesy YHBEST1
9. MINPU BRIDGE: Length of main span: 708 meters; Owner: the People's Republic of China.The double-decker Minpu Bridge is a workhorse, carrying an eight-lane highway on its upper deck and a six-lane local road below. The 3.6-km span over the Huangpu River links downtown Shanghai with Pudong Airport. It was completed in 2009 to meet the traffic needs generated by the 2010 World Expo. Its distinctive H-shaped towers are 210 m tall. It was designed by the Shanghai Municipal Engineering Design Institute, the Shanghai Urban Construction College, and the Shanghai Urban Construction Design Institute, with assistance from Holger S. Svensson. It was built by the Shanghai Huangpujiang Bridge Engineering Construction Co.
Image Courtesy Jucember
10. THIRD NANJING YANGTZE BRIDGE: Length of main span: 648 meters; Owner: the People's Rupublic of China. The Third Nanjing Yangtze Bridge is an important element of the Shanghai-Chengdu Expressway, a vital east-west traffic artery. Including approaches, it is 15.6 km long. Its graceful clothes-pin-shaped piers are 215 m tall. China's Highway Planning and Design Institute, part of the Ministry of Communications, led the design team. The contractor was Nanjing No. 3 Yangtze River Bridge Co. Ltd., a consortium headed up China Railway Shanhaiguan Bridge Co. and including the Hunan Road & Bridge Co., China Harbour Engineering & Construction No. 2 Bureau and China Railway BaoQiao. It was built at a cost of $362 million and opened in 2005. It was financed by a joint venture of Chinese public-sector and corporate entities, including Bright Oceans Corp., a conglomerate with interests in the telecommunications, transportation and energy sectors.
Image Courtesy J. Ye