The Golden Gate Bridge revealed

Golden Gate Bridge view

View from bottom 

The Golden Gate Bridge is consider as a wonder of modern world it extend more than 1.5 miles in length.The structure links the U.S. city of San Francisco, on the northern tip of the San Francisco Peninsula, to Marin County, bridging both U.S. Route 101 and California State Route 1 across the strait.

The bridge is the international symbol which represents the city of San Francisco in the world. 

The bridge was built to reduce the time taken by the ferries to cross the channel and to connect the two part of the cities. The construction  begins at 5 January 1933 and lasted till April 19,1937 finally on may 27 the same year the bridge opened,  and it has been functioning since that day. 

Lets look at some of its technical and engineering details. 

Total length of the Golden Gate Bridge from abutment to abutment is 8,981 feet (2,737 m).The Golden Gate Bridge's clearance above high water averages 220 feet (67 m) while its towers, at 746 feet (227 m) above the water, were the world's tallest on a suspension bridge until 1998 when bridges in Denmark and Japan were completed.

It receives a new coat of rust resistant bronze paint every five years. This prevents rust damaging the structural integrity of the bridge.

Total weight of Bridge, anchorages, and approaches (1937) is 894,500 tons (811,500,000 kg).

At midspan, the maximum downward deflection (or the distance the Bridge was built to move downward) is 10.8 ft (3.3. m). The maximum upward deflection is 5.8 ft (1.8 m).

 The Golden Gate Bridge has two main towers that support the two main cables.

The height of a tower above water is 746 ft (227 m).

The height of a tower above roadway is 500 ft (152 m).

Tower base dimension (each leg) is 33 ft x 54 ft (10 m x 16 m).

The load on each tower from main cables is 61,500 tons (56,000,000 kg).

The weight of both main towers is 44,000 tons (40,200,000 kg).

Transverse deflection of towers is 12.5 in (0.32 m).

Longitudinal deflection of towers (shoreward) is 22 in (0.56 m) and (channelward) is 18 in (0.46 m).

The south tower foundation depth below mean low water is 110 ft (34 m).

To build south tower pier to support the south tower, construction workers pumped 9.41 million gallons (35.6 million liters) of water out of the fender that was constructed first.

The bridge has two main cable which support the entire load of the bridge and the length of steel can be used to cover the entire earth 4 times
 The main cables rest on top of the 746-foot main towers in huge steel saddles.
Diameter of one main cable including the exterior wrapping is 36 3/8 in (0.92 m).
Length of one main cable is 7,650 ft (2,332 m).
Total length of galvanized steel wire used in both main cables is 80,000 mi (129,000 km).
Number of galvanized steel wires in one main cable that are 0.192 inches in diameter is 27,572.
Number of bundles or strands of galvanized steel wire in one main cable is 61.
Average number of galvanized steel wires in each of the 61 bundles is 452.
Weight of both main cables, suspender cables, and accessories is 24,500 tons (22,200,000 kg).
For a suspension bridge to work properly the 3 things should  be in equilibrium i.e. ΣFx=0 and ΣFy=0 are met, static equilibrium isn’t guaranteed; the second condition must be applied to guarantee static equilibrium: ΣT=0 Nm, and  how clearly a suspension bridge work we will discuss in some other blog.
Thank you.