Golden gate bridge, San Francisco

A complete presentation about the legendary Golden Gate bridge.

1. INTRODUCTION HISTORY PRESENT TIME-LINE KEY-DATES BRIDGE DESIGN FACTS FUTURE AESTHETICS PHOTOGRAPHS

2. The Golden Gate Bridge was the largest suspension bridge in the world When it was completed in 1937 and has become an internationally recognized symbol of San Francisco and the united states. Chief Engineer of golden gate bridge was Joseph B. Strauss . The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening into the San Francisco Bay from the Pacific Ocean. It connects the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County as part of US Highway 101 and California State Highway 1. It is currently the second longest suspension bridge in the United States after the Verrazano-Narrows Bridge in New York City. NTRODUCTION I

3. H ISTORY Rope Bridge : A bridge constructed chiefly of rope. In its simplest form, it can be one or two ropes that bridge a river, enabling the traveller to be supported in their crossing and not be swept away. One rope above another, for feet and hands, may be referred to as a commando bridge. Inca Rope Bridge : Inca rope bridges were simple suspension bridges over canyons and gorges ( pongos ) to provide access for the Inca Empire. Bridges of this type were suitable for use since the Inca people did not use wheeled transport - traffic was limited to pedestrians and livestock.

4. H ISTORY Simple Suspension Bridge : A simple suspension bridge is an early bridge type and is still formed from native materials, chiefly grass rope, in some areas of South America. These rope bridges must be periodically renewed owing to the limited lifetime of the materials, and rope components are made and contributed by families as contributions to a community endeavor.

5. P RESENT Suspension Bridge : The main forces in a suspension bridge are tension in the main cables and compression in the pillars. Since almost all the force on the pillars is vertically downwards and they are also stabilized by the main cables, they can be made quite slender. Assuming a negligible cable weight compared to the deck and vehicles being supported, a suspension bridge's main cables will form a parabola (very similar to a catenary, the form the unloaded cables take before the deck is added). This can be seen from the cable's constant gradient increase with linear (deck) distance, this increase in gradient at each connection with the deck providing a net upward support force. Combined with the relatively simple constraints placed upon the actual deck, this makes the suspension bridge much simpler to design and analyze than a cable stayed design, where the deck is in compression.

6. P RESENT Advantages over other bridge types : 1. The center span may be made long in proportion to the materials required, allowing the bridge to economically span a very wide canyon or waterway. 2. It can be built high over water to allow the passage of tall ships. 3. Neither temporary central supports nor access from beneath is required for construction, allowing it to span a rift or waterway. 4. Being flexible it can flex under wind and seismic conditions, where a more rigid bridge would have to be made stronger and heavier. 5. Since they can provide the same strength and stability of other design schemes with less weight and bulk suspension bridges are often less expensive to construct and maintain. Other Bridges : cantilever bridge, cable stayed bridge, beam bridge, and arch bridge.

7. Pre-Historic Times Iron became known to man Abraham Darby-I leased a furnace at Coalbrookdale 1709 1747 Smelting of iron ore with coke instead of charcoal 1755 Use of cast iron utensils for the first time 1767 First iron rails were cast 1767 First iron bridge was built-The Severn Bridge 1937 Golden Gate Bridge at San Francisco T IME LINE T

8. K EY DATES 1872 Earliest discussion of building a bridge across the Golden Gate Strait. Joseph B. Strauss submits his final plans for the Golden Gate Bridge to the District Board of Directors. August 27 , 1930 Voters within the 6 counties of the District approve a $35 million bond issue to finance construction of the Golden Gate Bridge.  The vote is 145,657 YES and 46,954 NO.  On January 5, 1933, Construction of the Golden Gate Bridge begins. November 4, 1930 Golden Gate Bridge opens to pedestrian traffic. May 27, 1937 Golden Gate Ferry begins service between Sausalito and San Francisco. August 15, 1970 Golden Gate Transit service begins. January 1, 1972 One billionth car crosses the Golden Gate Bridge. February 22, 1985 Construction is complete on the replacement of the original Golden Gate Bridge roadway with a modern orthotropic steel plate deck. August 15, 1985

9. K EY DATES Golden Gate Bridge designated a double-fine-zone. September 13, 1996 United States Postal Service unveils Golden Gate Bridge commemorative stamp. September 3, 1998 Golden Gate Bridge turns 65 years old. May 27, 2002 New Bridge toll rates: $5.00 cash, $4.00 FasTrak and $2.50 per axle (for vehicles exceeding two axles) September 1, 2002

10. B RIDGE DESIGN Length, Width, Height, Weight Total length of Bridge including approaches : 2,737 m Length of suspension span including main span and side spans : 1,966 m Length of main span portion of suspended structure : 1,280 m Length of one side span : 343 m Width of Bridge : 27 m Width of roadway between curbs : 19 m Width of sidewalk : 3 m Clearance above mean higher high water : 67 m Total weight of each anchorage : 54,400,000 kg Original combined weight of Bridge, anchorages, and approaches: 811,500,000 kg Total weight of Bridge, anchorages, and approaches (1986) : 804,700,000 kg Weight of Bridge, excluding anchorages and approaches, and including the suspended structure, main towers, piers and fenders, bottom lateral system and orthotropic redecking : 380,800,000 kg

11. B RIDGE DESIGN Bridge Deflection, Load Capacity Max transverse deflection, at center span : 8.4 m Maximum downward deflection, at center span : 3.3 m Maximum upward deflection, at center span : 1.77 m Live load capacity per lineal foot : 1,814.4 kg As an example of how the Bridge is built to move, during the winter storms in 1982, the main span bowed approximately 6 to 7 feet The three maximum deflections noted above at the center of the suspension bridge are due to the following loading conditions: 1. The transverse deflection is due to a sustained transverse wind load. The maximum transverse movement of 27.7 ft is based on the maximum allowable longitudinal movement of the wind locks at the support towers; 2. The maximum downward deflection is due to a condition with maximum live load on the center span, no live load on the side spans and maximum design temperature to elongate the main cables; and 3. The maximum upward deflection is due to a condition opposite to condition 2 above, with maximum live load on side spans, no live load on center span and minimum design temperature to shorten the cable length.

12. B RIDGE DESIGN Main Tower Stats The Golden Gate Bridge has two main towers that support the two main cables. Height of tower above water : 227 m Height of tower above roadway : 152 m Tower base dimension (each leg) : 10 x 16 m Load on each tower from main cables: 56,000,000 kg Weight of both main towers : 40,200,000 kg Transverse deflection of towers : 0.32 m Longitudinal deflection of towers: Shoreward: 0.56 m Channel ward: 0.46 m The south tower foundation depth below mean low water is: 34m To build south tower pier to support the south tower, construction workers pumped 35.6 million liters of water out of the fender that was constructed first.

13. B RIDGE DESIGN Main Cable Stats The Bridge has two main cables which pass over the tops of the two main towers and are secured at either end in giant anchorages. The main cables rest on top of the towers in huge steel castings called saddles. Diameter of one main cable with wrapping : .92 m Length of one main cable : 2,332 m Total length of wire used in both main cables : 129,000 km No. of galvanized wires in one main cable that are 0.192” in diameter: 27,572 Number of strands in one main cable : 61 Weight of both Main Cables, Suspender Cables & Accessories: 22,200,000 kg The wire comprising each main cable was laid by spinning the wire using  a loom-type shuttle that moved back and forth as it laid the wire in place to form the cables. The spinning of the main cable wires was completed in 6 months and 9 days .

14. B RIDGE DESIGN Concrete Quantities Cu. m. San Francisco Pier and Fender 99,400 Marin Pier 18,000 Anchorages, Pylons, and Cable Housing 139,160 Approaches 21,800 Paving 19,115 Structural Steel Quantities Kg. Main Towers 40,280,000 Suspended Structure 21,772,000 Anchorages 3,991,000 Approaches 9,250,000

15. ACTS F WHY THE NAME ‘GOLDEN GATE’ ? The Golden Gate Strait is the entrance to the San Francisco Bay from the Pacific Ocean. The strait is approximately three-miles long by one-mile wide with currents ranging from 4.5 to 7.5 mile. It is generally accepted that the strait was named " Chrysopylae ", or Golden Gate, by John C. Fremont, Captain, topographical Engineers of the U.S. Army. It reminded him of a harbor in Instanbul named Chrysoceras or Golden Horn.

16. F ACTS HOW MANY PEOPLE WORKED ON THE BRIDGE DURING ITS CONSTRUCTION? We do not have the exact employment figures. The Bridge was built by 10 different prime contractors and their subcontractors. WERE HARD HATS USED DURING CONSTRUCTION? Yes they were and here is how they came to be. The E.D. Bullard Company was founded in 1898 in San Francisco, CA, where the firm manufactured equipment for miners in western states. It was considered the first "hard hat," which revolutionized construction and mine worker safety.

17. F ACTS WHAT WOULD IT COST TO BUILD THE GOLDEN GATE BRIDGE TODAY? The cost to construct a new Golden Gate Bridge would be approximately $1.8 billion in 2005 dollars. The total price depends on a many factors including the extent of the environmental reviews and the cost of labor and materials. WHERE WAS THE STEEL FABRICATED FOR THE CONSTRUCTION OF THE GOLDEN GATE BRIDGE? Manufactured by Bethlehem Steel in plants in Trenton, New Jersey and Sparrows Point, Maryland and in plants in three Pennsylvania towns: Bethlehem, Pottstown, and Steelton. WHAT'S THE HALFWAY-TO-HELL CLUB ? The most conspicuous precaution was the safety net, suspended under the floor of the Bridge from end to end.  During construction, the net saved the lives of 19 men who became known as the " Half-Way-to-Hell Club ."

18. F ACTS DOES THE GOLDEN GATE BRIDGE HAVE THE WORLD'S LONGEST SUSPENSION SPAN? 1998 1,991 meters Akashi-Kaikyo Bridge, Japan 6,532 feet 1931 1,067 meters 3,500 feet George Washington Bridge, N.Y. 1973 1,074 meters 3,523 feet First Bosphorous , Turkey 1992 1,090 meters 3,576 feet Second Bosphorous , Turkey 1988 1,100 meters 3,609 feet Minami Bisan-Seto Bridge, Japan 1957 1,158 meters 3,800 feet Mackinac Straits Bridge, Michigan 1997 1,210 meters 3,970 feet High Coast Bridge, Sweden 1937 1,280 meters 4,200 feet Golden Gate Bridge, San Frs. 1964 1,299 meters 4,260 feet Verrazano Narrows Bridge, N.Y. 1997 1,377 meters 4,518 feet Tsing Ma Bridge, China 1999 1,385 meters 4,544 feet Jiangyin Yangtze Bridge, China 1981 1,410 meters 4.626 feet Humber Bridge, England 1997 1,624 meters 5,328 feet Great Belt East Bridge, Denmark Year Opened  Main Span Length SUSPENSION BRIDGES

19. F ACTS WHAT ARE THE ORIGINAL RIVETS REPLACED WITH WHEN THEY BECOME CORRODED? Since 1970, as various construction projects and painting projects occur across the Bridge, the original rivets are being replaced with ASTM A-325 high-strength bolts of equal diameter. In the early 1970s, corroded rivets were replaced with ASTM A-325 high-strength bolts dipped in organic zinc rich primer prior to installation. HAS THE GOLDEN GATE BRIDGE EVER BEEN CLOSED? Yes, the Golden Gate Bridge has been closed due to weather conditions only three times: December 1, 1951, for three hours : gusting winds reached 69 miles per hour. December 23, 1982, almost two hours: high winds of up to 70 miles per hour. December 3, 1983, 3 hours and 27 minutes : Wind reached 75 miles per hour. All three times the bridge survived and suffered no structural damages. F ACTS F

20. F UTURE Self-Anchored Suspension Bridge : It is a suspension bridge in which the main cables do not attach to the ground via large anchorages; instead, the main cables attach to the ends of the road deck, which experiences compression equal to the tension in the cables. The result of this design is that the bridge does not exert any horizontal pulling forces on the ground; the bridge foundations need only support the bridge's weight. Therefore, the self-anchored suspension bridge design is well-suited for construction atop elevated piers, or in areas of unstable soils where anchorages would be difficult to construct. Suspension bridge with the main cables attached to the ground (black squares) Self-anchored suspension bridge; the main cables are attached to the end of the road deck F UTURE F

21. ESTHETICS A The color of the bridge is an orange vermillion called international orange. The color was selected by consulting Architect ILVING MORROW Because orange color blends well with the natural surrounding yet enhances the bridge’s visibility in fog. The Golden Gate Bridge is painted international orange. The international orange paint used on the Golden Gate Bridge is specially formulated to protect the bridge from the danger of rust from the moisture of the frequent fog that rolls in from the pacific ocean through the Golden Gate to S an Francisco Bay. The colour of the bridge…!

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26. Giedion , Sigfried , Space, Time and Architecture Websites: www.wikipedia.com www.goldengate.com www.structure.com www.google.com

27. Thank You…

28. G OLDEN GATE BRIDGE Marin Anchorage ( January 1933 through February 1936) San Francisco Anchorage (January 1933 through February 1936) Marin Pier (January 1933 through June 1933) San Francisco Trestle (March 1933 through February 1934) San Francisco Pier (March 1934 through December 1934) San Francisco Trestle Repair (November 1933 through March 1934) Marin Tower (November 1933 through October 1934) San Francisco Tower (January 1935 through June 1935 ) Catwalk Cables (July 1935 ) Suspension Cables (October 1935 through March 1936) Cable Compression (May 1936) Roadway Steel (June 1936 through November 1936) Deck Surface (January 1937 through April 1937) Jan, 1933 Apr, 1937 Jan, 1933 Apr, 1937 Back