The construction of Dong Hai Bridge forms part of the comprehensive development of Yangshan Deepwater Port, which is intended to become the Shanghai International Shipping Centre. Shanghai Tongsheng Investment Group, co-funded by the Shanghai Port Authority and Shanghai State Assets Management Company, is responsible for the overall construction of this prestigious development.

The bridge consists of a 2.4km-long upper approach at Luchaogang Port; a 24.6km main bridge which crosses the sea of Hangzhou Bay/ Dong Hai, and 4.5km of bridge connecting the Xiaoyangshan Islands, making a total length of approximately 31.5km. Construction work started in August 2002 and is expected to be completed by the end of 2005. Many major bridge contractors in China are taking part in the construction of various parts of this bridge (see below).

Consultant Halcrow has been involved in the project since its preliminary design bidding phase, and is working for the client, advising on almost every technical aspect of the project – covering design, construction, operation and maintenance of the bridge. Specific tasks include detailed design review, structure modelling and loading analysis, corrosion protection methods and so on.

The bridge is being built over very rough seas, and the workable time for offshore construction is estimated at no more than 180 days per year. This means that the construction schedule for the project will be very tight, although Halcrow says that the construction plan is achievable. The overall cost of the project is estimated at around US$845 million.

Shanghai Urban Construction Design & Research Institute is working as sub-consultant to Halcrow on the project, carrying out a review of the detailed design of one of the continuous girder bridges.

The East Sea Bridge is divided into several main parts, each of which consists of several different bridge types and spans due to cost considerations. Except for two cable-stayed bridges, which will have composite bridge girders, all other spans are reinforced concrete and precast concrete structures. The structures that cross over the sea have spans ranging from 44.5m up to 420m spans for the cable-stayed bridges. The continuous girder bridge has a total width of 31.5m while the cable-stayed bridge is 33m wide. The water depth of the sea ranges from 10m to 20m.

Ground conditions consist of marine mud/soft clay, clay and clayey sand, and the bridge is designed to be supported on piled foundations. These are 1.2m-diameter PHC piles, 1.5m-diameter steel piles and 2.5m-diameter and 3m-diameter bored piles.

The most difficult challenges for the design and construction of this project are the wave and current loads, the live loading that is predicted from the heavy container truck traffic, the ship impact load, wind load and seismic load. The structure also has to cope with this loading for a design life of 100 years. What’s more, the bridge crosses a very rough sea which has a tidal range of more than 5m, a current of more than 2m/s and wave height of more than 6m.

Both numerical model analysis and laboratory physical models have been carried out. Extensive laboratory physical model tests include wind tunnel tests, wave and current model tests, ship collision model test and parapet truck collision tests have been carried out to determine the design criteria and parameters.

Piles are being driven by a heavyweight diesel hammer, while pile cap shells, most of the piers and bridge girders are being fabricated elsewhere in order to keep the in situ concreting to the minimum. This will ensure that the concrete quality is of the highest possible standard, and will reduce construction time required over the sea. A heavy-lift vessel is being built that will be used to lift entire spans of 70m concrete box girders weighing up to 2000t.

Most of the concrete and steel bridge elements will be fabricated on shore or at a fabrication site on the islands and will be installed as entire spans by heavy lifting equipment.

Norwegian specialist NRS has been appointed by Shanghai Tunnelling Engineering Corporation to undertake the design and supply of two Movable Scaffolding Systems for the construction of 50m deck spans for the approach structures of the bridge. NRS is responsible for supplying two sets of underslung Movable Scaffolding Systems for the construction of cast in situ concrete bridge spans. The scope of work includes the design, the steel fabrication, and the supply of ancillary equipment for the MSS. NRS will also provide engineering know-how, technical support and advice on the construction of such bridge.

Several design challenges due to site constraints have to be overcome in the design of the MSS. These include high impact loads on the MSS due to adverse weather anticipated while working over the sea, special considerations to ensure efficient transfer and installation of MSS support brackets, and a purpose-built internal formwork system for the curved section of the bridge.

The project is currently under construction, with the bridge superstructure construction due to start next month (September).

Contractors:

Contracts I and II (bridges on land and over shallow water with spans of up to 60m)

Shanghai Urban Construction (Group) Corporation

Contract III (including all 70m spans)

Major Bridge Engineering Bureau

Contracts IV and VII (including all auxiliary navigation channels, and a cable-stayed bridge with main span 332m)

China Road & Bridge Construction (Group) International Company

Contract V (including a cable-stayed bridge of 420m main span over the main navigation channel)

Shanghai Construction (Group) General Company

Contract VI (all marine works of piling and pile-caps for all non-navigation spans)

China Harbour Engineering Company Group

Contract VIII (a several kilometre-long embankment built by reclamation on more than 15m-deep soft seabed)

Consortium led by Gezhouba Group

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