Russky Bridge, Russia
One of the longest cable-stayed suspension bridges in the world
Vladivostok town is situated in the Far East of Russia on the coast of the Pacific Ocean, near the border between Russia and North Korea, opposite to Sapporo town in Japan. A great bridge across the Eastern Bosphorus Strait to the Russky Island called Russky Bridge. It was built in preparation for the 2012 Asia-Pacific Economic Cooperation Summit held on Russky Island. The construction project was collaboration between Russian industrial group USK Most and French company Freyssinet and it was completed in an impressive time of 43 months. The bridge was officially opened by the Russian Prime Minister Dmitry Mededev in July 2012.
The Russky Island Bridge is the longest cable-stayed suspension bridge in the world with a total length of 3,100m (10,200 ft). A concrete and steel construction it is 25.5m (97 ft) wide and carries four lanes of traffic on a deck 70m (230 ft) above the water with a 21m width. There are 11 spans in total with the main central one being 1,104m (3,622 ft) in length. The span decks are made of steel-inclined wall box sections, as well as a cast in-place reinforced concrete slab. The bridge's pylon measures at 324m in height.
The two A-shaped anchor pylons are 325m (1,066 ft) tall, the second tallest in the world after those on the Millau Viaduct. The steel stiffening girder of the central navigation span is made of two 6m-long transition panels, as well as 103 panels, each 12m long and 26m wide. The longest and shortest cable stays of the bridge are 579.83m and 135.77m respectively. Viaducts with a total length over 900m provide the approach to the bridge. The bridge crosses the Eastern Bosphorus Strait, linking with the mainland and island, home to around 5,000 inhabitants.
The bridge was designed to cope with the area's extreme climatic conditions of temperature variances of between the -30s and +30s degrees centigrade, storm winds and thick icy layers in winter. It is estimated that the bridge cost in excess of $1 billion.
Design of Russky Island Bridge
Bridge piers M1 on the Nazimov Peninsula and M12 on the Russky Island act as load transfer piers. They handle the load from the stiffening girder of the cable stayed span, which is 1,248m long and made of two panels weighing 23,000t. The cable-stayed system has a total length of over 54km and weighs 3,720t. The cables are composed of 13 to 85 parallel individually corrosion protected strands, which in turn are made up of seven galvanised steel wires enclosed in high-density polyethylene sheathing.
Design of the bridge needed to incorporate the extreme climatic conditions of the area, which is affected by severe conditions, with temperatures varying from -310 to +370. In addition, storm winds flow with a velocity of 36m/s. During winter, 70cm-thick ice layers are also formed.
Construction of the Russky Island road bridge
Construction of the bridge was carried out in extremely challenging conditions. Two production facilities were put into operation, one at each end of the Nazimov Peninsula and Russky Island, which included office buildings, living quarters, canteens, mechanical and woodworking equipment repair workshops, a welding workshop, building laboratories and state-of-the-art concrete mixers.
An existing 4.5km railway line was upgraded and a new 1,340m-long railway track built to ensure that raw materials for the construction are delivered on time. Highly advanced equipment was used in the construction, with unique Kroll tower cranes, of 40t and 20t capacities and telescope ability of up to 340m, used to erect the pylons. The channel span deck was installed using a Russian derrick crane, while the first ten sections of the steel span decks were fitted using a Liebherr Crawler crane.
A manmade islet, constructed from 1.5 million cubic meters of rock and dirt, was used to carry out borehole drilling for the footing of Pylon M6 on the Nazimov Peninsula. The pile footing for the M7 Pylon on Russky Island was built using a temporary steel islet. Around 120 drilled piles of 2m width were put in place to build the footing of each pylon.
Viaduct piers were constructed with heights of 9m to 30m, with Geda express freight passenger elevator, with a load capacity of 2t and lifting speed of 65m per minute, was used for the construction. Around 20,000m³ of concrete mix and 3,000t of steel were used to construct each pylon grillage. Health conditions are monitored using strain gages that are integrated into the grillage body.
The continuous span of the stay cables was constructed using 21,000m³ of pre-stressed cast-in-place reinforced concrete. Various panels of the bridge were delivered to the construction site using barges and then lifted using cranes. The positioning of the barges at the appropriate installation site was carried out using GLONASS, a Russian global navigation satellite system, while the last panel was installed in April 2012, marking the bridge's completion.
French Specialist
Russian legislation demanded a Russian contractor - USK Most got the contract - and a Russian designer - Mostovik - the key component in any cable stayed bridge - the cable stays themselves - were designed and installed by French specialist Freyssinet.
Freyssinet’s world-renowned expertise in long-span cable stayed bridges was unquestionably vital for Russky Island. While only a modest increase in length on Sutong bridge, it is being built in a much more testing environment. Siberian winters are, after all, world-renowned as being particularly harsh and the bridge will have to withstand a marine environment with temperatures as low as -40°C and design wind speeds of 36m/s. By comparison the design wind speed on the 856m span Pont de Normandie was just 15m/s. Freyssinet’s knowledge was therefore seen as key and it carried out design, production and installation of the cable stays and damping system. It also carried out an expert appraisal on behalf of the Russian Ministry of Construction to validate the superstructure design, and brought in world-renowned bridge designer Michel Virlogeux to advise Mostovik on its deck design.Virlogeux’s input was to ensure that the deck had a cross-section in the shape of an inverted aerofoil to give it negative lift and better stability under wind loading. He also advised on optimising the dimensions of the towers. But he is modest about his contribution.
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Construction began in 2007 and the truly momentous moment - the moment Russky Island bridge became the world’s longest cable stayed bridge with a 1,104m span - happened in April when USK Most hoisted the final 12m long deck section 76m from a barge to its final position and welded it into place.
Yet even before that, records had been broken by Freyssinet’s cable team. Long span cable stayed bridges need long cable stays, and the ones on Russky are the longest and heaviest ever; up to 580m long and 65t in weight.
And herein lies the challenge. To keep wind loads down - wind effects on the cables themselves contribute about 55% of wind loadings on long span bridges - Freyssninet has used its patented compact cable stays which can contain around 20% more strands in their sheaths than conventional sheaths of the same diameter. This means the same vertical load can be carried by fewer cables, which in turn reduces the wind loadings.
Reduced wind loads
In fact, wind loads on the structure are reduced by a hefty 25% to 30% as a result. This translates into a massive knock on saving of 35% to 40% on the cost of materials for the pylons and deck.
The longest set of cables was installed earlier this year, but for Freyssinet the build-up started in July 2011 with the positioning of the first pair of 136m long, 4t cables at a height of 186m. From that date operations proceeded with the installation of eight planes of 21 cable stays culminating in March with the installation of the last - and longest - and heaviest - pair of stay cables at a height of 317m. These weighed in at a massive 65t each. Each cable is made up of between 13 and 79 strands of 15.7mm diameter, with each strand comprising seven galvanised steel wires individually covered with a thin film of petroleum wax and encased in a high density polyethylene (HDPE) sheath.
The number of strands in each cable increases as the hanging angle increases - every degree from the vertical decreases the efficiency of the load transfer so the number of strands must be increased to compensate. The longest cables are by definition those that hang the furthest from the vertical and so need the most strands - 79 at Russky.
At its peak Freyssinet had 45 people working on site, with around 300 Russian workers trained by Freyssinet working under the guidance of USK Most to provide the support needed to install the cables.
Shared culture
Since March Freyssinet’s effort has been focused on installing the dampers, used on all long span cable stayed bridges to provide aerodynamic stability. This has been taken to new levels of technical innovation on Russky. Initially the dampers in use will be Freyssinet’s patented but now standard systems - installed where the cables meet the deck. On shorter cables Freyssinet’s Internal Radial Dampers are used. These are located inside the anchorage tubes and provide a smooth outer shape. On the longer cables these aren’t up to the job, and Freyssinet’s Pendular External Dampers are needed. They use piston dampers with a pendular lever system which can move around a rod hinged on fixed support.
They are bulkier looking, and could soon become a thing of the past as Freyssinet has agreed with client the City of Vladivostok to retrofit its newest damper system to the bridge once the hullabaloo of the Apec summit has passed. This will be the first use of its new damping cross tie. It has spent £600,000 developing the patented system and Stubler for one is eager to try it out. Cross ties - often called aiguilles - are nothing new; Freyssinet installed them on the Normandie bridge in France. But aiguilles run across the cable array continuously and are unpopular with bridge architects.
Freyssinet’s system differs in that the cross ties run from just one cable to the next and so are less visually intrusive. It works differently too. The general concept is the same - by effectively strapping pairs of cables together at their mid point, the structure becomes much more robust and resistant to wind loads.
Technical Equipment
About 320 pieces of state-of-the art special equipment were used in construction of the bridge to the Russky Island. Unique 40-ton and 20-ton Kroll tower cranes, which can telescope up to 340 meters, were used for erecting the pylons. Russian-made derrick cranes of up to 400 ton lifting capacity were used for installation of the channel span deck. Liebherr Crawler Crane of the 1,350 ton lifting capacity had been installed within a record short time for lifting the first ten sections of the steel span deck on the Russky Island.
Bridge Piers
The bridge piers, M1 on the Nazimov Peninsula and M12 on the Russky Island, are the heaviest and most complex structures. They are about 35m high. The ‘Number One’ and the ‘Number Twelfth’ are used as the ‘load transfer’ piers. They take up the horizontal load from cable-stayed span stiffening girder.
The builders used self-compacting B35 grade sulfate-resistant Portland cement concrete for erecting bridge pier and pylon grillage. The concrete will protect the footing against corrosive fluids and prevent rebars from getting rusty. Geda express freight-passenger elevator with designed load capacity of up to two tons was used for the construction of bridge piers and pylons. The elevator lifting speed is 65m per minute.
Man-made islets
A man-made islet was rock-filled for Pylon M6 footing borehole drilling on the Nazimov Peninsula. The pile footing for M7 Pylon on the Russky Island was built from the water, using a temporary steel islet. A man-made peninsula was rock-filled after the drilled piles and enclosing sheeting had been completed. This small peninsula is designed for the protection against impacts of vessels of up to 66,000 displacement tonnage, ice drift, and waves. A total of 1.5 million cubic meters of rock and dirt were moved for building the construction sites on the Russky Island and Nazimov Peninsula.
Pile Footing for the Pylon
Drilling and pile concreting operations were conducted from the water at sea for the first time in bridge building in Russia. The water depths in the various areas of operations varied from 14 to 20 meters. 120 drilled piles, each two meters in diameter, have been put in place to build the footing of each pylon. Permanent steel-cased piles under M7 Pylon have been sunk 46 meters deep. The reinforced concrete piles on the Nazimov Peninsula go 77 meters deep.
Grillage for the Pylon
It took about 20,000 cubic meters of concrete mix and about 3,000 tons of steel structures to erect the grillage for each pylon. This was the most labor-consuming and critical operation of the bridge construction project. Strain gages are embedded in the grillage body for monitoring health condition of the giant footing.
Self-Lift Shutters
Custom-made self-lift shutters were used to concrete the pylons. Seven working tiers of a total height of 19 meters allow the preparation of the construction joint, re-inforcing, concreting, concrete cure, and finish to be run simultaneously in three sections that are each 4.5 meters high. The shutters move on their own by hydraulically powered lift modules. The self-lift shutters cut down the cast-in-place reinforced concrete structure erection time by a factor of one and a half. This is a significant time gain given that the total scope of concreting for each pylon is over 20,000 cubic meters.
Reinforced Concrete Girder
The anchor span structures of the stay bridge are located symmetrically with respect to the central span and pylons, and they are each 316-meter long. The continuous span is made of prestressed cast-in-place reinforced concrete, which will take about 21,000 cubic meters of concrete mix to complete.
Plastic ducts were installed in addition to rebars during reinforcement. High-tensile prestressing steel bundles are installed in the ducts. The bundles are tensioned by application of tensioning force of 300 to 370 tons using prestressing jacks after concrete has gained the necessary strength. The workers fill the voids in the ducts with special cement-based mortar after tensioning.
Steel Stiffening Girder
The stiffening girder of the central navigation span of the bridge to the Russky Island is all-metal. It is made as a box that makes up the entire cross-section, with the bottom orthotropic and top orthotropic plates and a system of transverse diaphragms. The steel stiffening girder is composed of 103 panels each 12-meter long and 26-meter wide and two transition panels each 6-meter long. The panels weigh a total of 23,000 tons. The stiffening girder is 1248 meters long.
Panels Preassembling
The panels were preassembled at the production facility on the Nazimov Peninsula and at Nakhodka shipyard. This procedure ruled out additional operations of fitting the heavy tonnage panels during installation, which is important because the work was conducted under strong winds at the elevation of 70 meters above the strait. The time gain has been significant given the fact that over 30 km of first-class welded joints with 100 percent ultrasound flaw detection were completed.
Panels lifting
The panels were delivered to the installation site by barges and then were lifted by crane to the 70 meter elevation. The barge was positioned under the installation unit using GLONASS, a Russian global navigation satellite system.
After the section number 20 has been installed, paired panels that are 24 meters long were delivered for installation to expedite installation of the steel stiffening girder.
Closing Panel Installation
An event that the bridge builders have been preparing for three and a half years took place in the night of April 11-12, 2012. The last panel of the steel stiffening girder was lifted from 'Grigorich' Pontoon. The closing section has tied up together two 546-meter long channel span cantilever sections over the Bosphorus Strait, and the bridge has finally linked the Russky Island to the mainland part of the city.
Stay Cable System
An improved stay cable system with a higher strand density within the jacket is used for the bridge over the Eastern Bosphorus Strait. The stay cable system weighs 3,720 tons with the total length of over 54 kilometers. The stay cables are composed of 13 to 85 parallel individually corrosion-protected strands. Each strand consists of seven galvanized steel wires enclosed in high-density polyethylene sheathing. A compact cable configuration using a smaller-diameter jacket reduces the wind load by 25 to 30 percent. This design cuts down the cost of materials for the pylon, stiffening girder and footings by 35%.
Tricolour over the Eastern Bosphorus
The stay cable jacket is made of two plies: the inner layer is of black high-density polyethylene and the other, thinner layer features the Russian national flag colors. The ornamental jacket also has a helical groove for the protection against vibrations under combined exposure to rain and wind. The comprehensive mechanical protection and quality monitoring throughout fabrication of all stay cable components ensure high strength, durability and corrosion resistance indicators. The stay cable design service life is of at least 100 years.
Central Span Structure
The span structure has an aerodynamic cross section to resist squally wind loads. The deck cross section shape has been determined based on aerodynamic analysis and optimized following the results of experimental wind tunnel testing of the scaled model. Welded field connections are used for longitudinal and transversal joints of the cap sheet of the orthotropic plate and lower ribbed plate. For joints of vertical walls of the blocks, longitudinal ribs, transversal beams and diaphragms, field connections are used provided by means of high-strength bolts.
Prefabricated sections for installation of the deck are supplied by barges to the erection site and hoisted by crane to 76 m elevation within dedicated intervals. Here, the sections will be linked and cable stays will be attached to them.
Cable-Stayed System
The cable stayed system assumes all static and dynamic loads on the bridge deck. Cable stays are provided with maximum possible protection not only against natural disasters, but also against other adverse effects.
The so-called “compact” PSS system has been implemented in the cable-stayed bridge deck; this advanced system differs by denser strands allocation in the sheath. Compact design of cable stays that employ sheaths of smaller diameter makes for wind load reduction by 25-30%. Moreover, the cost of materials for pylons, the stiffening girder and foundations decreases by 35-40%.
PSS cable stays consist of parallel strands of 15.7 mm diameter; every strand consists of 7 galvanized wires. Cable stays incorporate from 13 to 85 strands. The length of the shortest cable stay is 135.771m that of the longest is 579.83 m. The protective sheath of the cable stay is made of high-density polyethylene (HDPE) and has UV resistance to local climate conditions of Vladivostok (temperature range from minus 40°C to plus 40°C) and environmental aggressiveness.
Reference:
http://www.bridgesofdublin.ie/bridge-building/famous-bridges/russky-island-bridge-2012
http://www.roadtraffic-technology.com/projects/russky-island-bridge/
http://www.nce.co.uk/features/structures/bridges-russian-masterpiece/8634173.article
http://rusbridge.net/wp-content/uploads/2010/06/rusmost-book-2012-06.pdf
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