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For the first time, a cable-stayed bridge is set to break the magic 1000 m span barrier. The six-lane Sutong Bridge in China’s Jiangsu Province also sets a new benchmark with its two A-shaped pylons, whose height of 306 metres is also unprecedented. All in all, a great challenge for contractors CHEC Construction and for formwork manufacturer Doka, which is supplying the necessary climbing technology..
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China Harbour Engineering Group (CHEC) have been acquiring a great deal of very positive experience with Doka climbing-formwork systems in recent months – on the 210 m high pylons for the Run-Yang Bridge, for instance, or on the 162 m high pylons of the Yang-Luo Bridge. On these, as on any other Doka climbing project, speed, high-level safety and immaculate surface quality are features that can be relied on from all Doka climbing systems.
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The world-record span of 1088 m requires A-shaped pylons of 306 m in height. And the speed with which work is progressing on the A-shaped legs of the pylons is just as record-breaking as their height. Both legs are rising towards the point where they will meet by two typical 4.50 m sections every week. The driving force behind this swift yet safe growth is the 36 Doka automatic climbers SKE 100 at either end of the bridge. These have the job of executing as many as 68 casting sections on each pylon, on schedule and in top quality.
Other SKE automatic climbers are at work on the bridge piers. These make for an efficient, crane-independent construction workflow. Being anchored to the structure at all times, and with their working platforms enclosed on all sides, they also offer a high level of safety. The largely automated climbing operation runs with the aid of powerful hydraulic units and can be carried out independently of the prevailing weather conditions. The whole operating sequence still runs smoothly even in wind speeds as high as 70 km/h. Incidentally, the structure is being erected in a region that is regularly hit by typhoons, so has been designed to withstand the very highest wind loads.
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The site report from Doka field staff Roger Zhang, Mike Lee and Michael Mäntler lists a number of interesting extra details: “The world’s tallest tower crane is being used for the building work. The concrete needed is pumped up into the formwork by powerful pumps. It is supplied directly from an in-situ concrete plant set up on the pylon island. The specification calls for first-class concrete surfaces, which Doka is consistently assuring with the Top 50 elements in use here. The project is attracting a great deal of attention in the Chinese media, and many foreign visitors come to view the site, such as Gérald Tremblay, Mayor of Montreal in Canada (with which Shanghai is twinned) in April 06.”
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Asked about the main arguments in favour of Doka SKE technology, Roger Zhang, Sales Manager of Doka Shanghai, mentions safety and efficiency, and a number of other important criteria besides: “CHEC were absolutely definite that they wanted to see a repeat of the positive results they had had with SKE automatic climbers on the Run-Yang Bridge on this project as well. Then there is the height of the pylons, which necessitates the greatest possible safety precautions. However, what ultimately decided the issue was the outstanding technical concept behind the SKE technology. The various platforms run from the ground all the way up to the top of the pylon in one piece, with only very minor modification. Without wanting to mention any other systems by name: Carrying out extensive modifications at heights of 50 metres and more is difficult, and – above all – dangerous.”
The new bridge will take traffic across the 6 km wide Changjiang River from the end of 2008, cutting journey times by 55 minutes. To date, it has only been possible to cross the river by ferry. The Changjiang River is a busy waterway, hence the bridge’s generous shipping clearance profile of at least 891 m x 62 m. The 8146 m long bridge construction will be part of the national motorway network linking the two giant cities of Shanghai and Suzhou.
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| The 36 Doka automatic climbers SKE 100 make for swift construction progress on each tower, with a high standard of safety. |
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| The Doka automatic climbers SKE 100 permit a 3-day cycle on the typical sections of the pylon. The formwork adapts to an upward-tapering cross-section here. |
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| The 306 m tall pylons of the Sutong Bridge are being constructed in 68 casting sections using Doka automatic climbing formwork. |
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