CMMT ASSIGNMENT-I

HANGZHOU BAY BRIDGE

------GROUP-3

The 36km-long Hangzhou Bay Bridge is the longest ocean-crossing bridge in

the world, spanning across the Hangzhou Bay on the East China Sea and crossing the

Qiantang River at the Yangtze River Delta.

The S-shaped Hangzhou Bay Bridge is an important connection in China’s East

Coast Superhighway. Starting in Jiaxing to the north, the bridge ends at Ningbo's

Cixi county in the south.

It shortens the ground transportation distance from Ningbo to Shanghai by

120km and travel time from four hours to two and half hours. It is a six-lane, two-

direction highway with a 100km/h speed limit, and a 100-year, service guaranteed,

cable-stayed design.

The Hangzhou Bay Bridge was the main component of a 5.2km national

highway between the provinces of Heilongjiang in the north and the Hainan in the

south.

Preparatory work started on the bridge as far back as 1994. Construction work

began in June 2003 and was completed in June 2007 and an opening ceremony was

held on 26 June. Several tests and evaluations were conducted for about one year

before official opening. The bridge was opened to the public in May 2008 and carried

about 50,000 vehicles per day in its first year of operation.

INVESTMENT PARTNERS

"Construction of the sea-crossing bridge is an indication of China’s increasing

economic power, and it is expected to boost economic development in the Yangtze

River Delta."

Of the total project cost of CNY11.8bn ($1.42bn), approximately CNY149m ($18m)

was contributed by 17 non-governmental enterprises in the province. Around 35% of

this amount was raised from private companies in Ningbo; 59% was provided as

loans from China’s central and regional banks. The Songcheng Group is the biggest

non-governmental shareholder in the project with its investment accounting for

17.3% of the basic capital. Construction of the sea-crossing bridge is an indication of

China’s increasing economic power, and it is expected to boost economic

development in the Yangtze River Delta, also called the Golden Industrial Triangle.

CONTRACTORS INVOLVED:

China Railway Bridge Bureau Group Co. Ltd. was the main contractor for the

project. The contract for consulting and engineering services was awarded to Hardesty

& Hanover, LLP.

ARCHITECTURE, DESIGN AND STRUCTURE:

The Hangzhou Bay is a gulf in the East China Sea where one of China's natural

wonders, the Qiantang River Tide, creates fast water and large waves. The area is also

a typhoon prone zone. These factors made construction feasibility a major concern for

the project and the plan was only finalised after nine years of consultation and over

120 technical studies with the help of more than 700 experts from throughout the

world

The cable-stayed bridge design was selected for the project as it can withstand

the adverse conditions, multi-directional currents, high waves, and geologic conditions

at the site. The bridge structure has also been designed to seismic criteria and will

retain integrity in earthquake conditions up to seven on the Richter scale.

The 36km length has highway-class road with six, 3.75m lanes, three in each

direction. The overall width of the bridge is 33m. The roadway grade at cross-slope is

2% and a maximum 4% at longitudinal slope.

Designed for 100 years of service life, the bridge has speed limits of 100km/h

for the main spans and 120km/h for land approaches. The bridge has a height of 62m,

enabling fourth and fifth generation container ships to pass through in all conditions.

The total length of cable used in the project is 32.2km

AUXILIARY FACILITIES AND STRUCTURES

At the middle of the bridge, a 10,000m² service island is planned for drivers to

rest and enjoy a full range of services, including hotels, restaurants, petrol stations and

a viewing tower. It is also expected the service island will become a tourist destination

for watching the Qiantang River Tide. The service island will be built entirely on piers

to avoid disrupting the tide. Two public parks are also planned on each side of the

bridge.

The bridge required the installation of traffic safety devices, monitoring

systems, communications equipment, toll plazas, power supply, lighting and

maintenance and office buildings.

METHODS, MATERIALS AND TECHNIQUES INVOLVED:

Controlled Gas Release

Piles Mechanism

Concrete

Bay Mechanism

Girders

Controlled Gas Release :

At concentrated areas small pipes are drilled till the gas pockets and fitted with

pressure valves and gas comes out leaving empty spaces inside.

Piles Mechanism:

A large no. Of 6000 piles are required @depth of 80 metres

Factories are setup near the construction.

Steel sheets of 22mt thick are rolled into a pile of 1.5 mt wide and 90 mt

long and are arc welded twice inner and outer.

These are the longest and strongest piles ever used in China.

To prevent Rusting they used Fusion Bound Epoxy coating.

For the proper alignment of piles they used GPS System where each pile is

given fixed address based on Longitude and Latitude.

Next is the Driving of piles:

Massive Sledge Hammer mounted on a ship served this purpose

It drives a pile at force of 250 tons/m and it takes 2 hours for a pile.

Fig: Piles

Fig: Global Positioning System (GPS)

Fig: Hammer

Concrete:

By the porous nature of concrete, n that salt environment it is difficult for us to rely

totally on the custom concrete.

So, the engineers and material experts tried out numerous technologies and at last

they came out with a solution which is the mixing of SOOT and some Corrosion

inhibitors that reduces the reaction time a lot that occurs between the salt and

concrete.

Girders:

Prefabrication of Giant girders are setup in the site.

For the first time a single cast in mould was adopted.

The girders are 70 m long, 16.5 m wide and 2200 tons of huge weight.

Each girder required 830 m3 of concrete.

These are setup like a table top system.

Fig: Girders

Bay Mechanism:

For a bay bridge to withstand the Typhoons and other natural windward forces there

required a giant spans to support the whole structure.

Also for free movement of cargo i and around the sea the bridge is fixed at a

height of 45m height.

The technique adopted is tested by the Wind Engineers in an artificial

environment and at last they adopted a triangular shaped towers suspended by

the cables all way.

Cable stair Mechanism using 202 m pole A-shaped .

Fig: Bay Mechanism