Xihoumen Bridge

With a span of 1,650m, Xihoumen Bridge is the longest spanning suspension bridge in China and the second longest in the world, after Japan’s Akashi-Kaikyo Bridge.

The bridge was built as part of the Zhoushan Mainland and Islands Link Project, which was launched by Sichuan Road and Bridge Co in 1999.

Located in Zhoushan Islands in China’s Zhejiang province, Xihoumen Bridge is one of five bridges linking the city of Ningbo and the Zhoushan Archipelago, the largest offshore island group in China. The bridge was built by Zhejiang Government at a cost of 2.48bn yuan (about $363m).

Construction work began in 2005 and the main span of the bridge was completed in December 2007. The bridge was completed and opened to traffic on 25 December 2009.

Project

The Zhoushan Mainland and Islands Link Project started in 1999. It includes construction of five bridges to link the Zhoushan Archipelago to the mainland.

Construction of three bridges has already been completed. The two tow bridges were built as part of the second phase.

Xihoumen Bridge is one of the two bridges built in the second phase. The other bridge is the 27km-long Jintang Bridge. Traffic started using the bridge when the main span was completed in December 2007.

The 5.3km-long bridge consists of a 2.6km main bridge and 2.7km side joint sections with a 1,650m central span. The total length of steel box girder is about 2,200m.

The bridge is stayed by 169 pre-formed parallel wire strands (PPWS) and eight back cables weighing 10,758t together. A total of 476 suspenders of different sizes were used.

The suspenders weigh 1,394t in total and include 452 pieces of 60mm each, eight pieces of 80mm each and 16 pieces of 88mm each.

Design

China Communications Construction Company designed Xihoumen Bridge, adopting a long span design. The bridge was designed as a two-span suspension bridge. The main bridge is of steel twin-box girder suspension.

The bridge was designed in accordance with four-lane express highway standards. It has a width of 24.5m and allows vehicles to travel at 80km/h.

The north end of the bridge is connected to Cezi Island and the south end is linked to Jintang Island. Mentou Hill and Shangxiong-ezui were selected as bridge foundation sites to decrease the main span of the bridge over the waterway. Laohu Hill was used as a pylon location.

The north side span is located over the water channel between Cezi Island and Laohu Hill and supported by a stiffening girder. The south side span is on land and supported by piers.

The middle ventilation was adopted for the stiffening girder according to the wind load requirements. A strong transverse connection was provided to ensure the transverse integrity of the stiffening girder.

The transverse connection of the box structure was provided at the hung point and an I-shaped beam was set between two transverse connecting boxes.

The main cables consist of 1,770MPa parallel wires. High-quality steel core wire ropes with a fixed spacing of 18m were used for hangers and 211.3m-high cable pylons were used in the bridge.

The main deck of the bridge is an orthotropic plate with a 14mm-thick top plate and a 10mm-thick bottom plate. It is stiffened with a U-shaped rib.

Contractors and suppliers

The bridge design contract was awarded to China Communications Construction Company. China Highway Planning and Design Institute (HPDI) Consultants was chosen as the design consultant. UK-based Dorman Long Technology (DLT) designed and supplied the deck erection gantries.

Site supervision for the operation and maintenance of the gantries was also provided by DLT. Aerodynamic analysis was conducted by northern European consulting group COWI.

Baosteel Group Corporation supplied 65,000t of steel products including wire rods, steel plates, steel coils, rebars and stranded wire. Shanghai Pujiang Cable Co (SPCC) supplied the main cables for the bridge in 2004. The DP-180 cantilever form-work system was supplied by Zulin Africa.