Construction of the Shanghai-Nantong Yangtze River Bridge in China’s Jiangsu province, north of Shanghai, is currently underway. Due for completion in 2019, it is set to be the world’s biggest cable-stayed bridge with a total length of 11,072 m, 1,092-m-long span and 325-m-tall pylons.
The bridge has two levels, including a six-lane highway on the upper level and a four-line railway on the lower. The new traffic link is part of the efforts to create a new economic zone around Shanghai, China’s trade centre and home to some 25 million people. When completed, the bridge will cut the journey time between Shanghai and Nantong from two hours to one.
The south bridge is a cable-stayed structure with steel framework, spanning the main channel of the Yangtze River. The north bridge crosses the Tiansheng Port channel, featuring a rigid steel girder structure and a flexible arch with a main span of 336 m.
In addition to being the world’s biggest cable-stayed bridge, it is also expected to be the longest steel railway bridge in the world. The steel arch weighs 32,400 metric tons, roughly the equivalent of three Eiffel Towers.
The pylons are being constructed in one of the largest and deepest (115 m) cofferdams ever built. The enclosed area is about the same size as 12 basketball courts, and a little more than 147,000 cu m of concrete are needed for one pylon. Developer and contractor of the project is MBEC No.4, No. 2, while the architect is China Railway Major Bridge Engineering Group.
Doka provided its SKE100 plus automatic climbing formwork, used in combination with its Top 50 large-area formwork, to construct the bridge pylons. Some of the major challenges included difficult weather conditions (with wind speeds of up to 72 km/h), climbing in 55 pouring steps without major alterations to the working platforms and progressive re-use of the formwork sheets.
“Height of more than 300 m and poor, foggy weather conditions are the biggest challenge for this jobsite,” said Yuan Bo, principal engineer of China Railway Bridge Bureau.
With the SKE100 plus in operation, adapting to the changing geometry of the pylon legs is easy. Besides meeting the highest safety standards, a single V140 hydraulic unit can climb all 30 automatic climbing units on each pylon foot at once.
Featuring a rated lifting capacity of 10 metric tons per climbing unit, the SKE100 plus is highly suitable for the pylon structure with its high ratio of reinforcing material. This automatic climbing system is combined with the Top 50 large-area formwork to give the concrete its shape.
The Top 50 system is mounted on travelling units on the platforms, and thus forming times are fast and the formwork can be opened and rolled well back for plenty of clearance. A total of 900 sq m of the large- area formwork is being used.