The Akashi Kaikyo bridge - longest suspension bridge in the world

Case Study of the Longest Suspension Bridge in the world - The Akashi Kaikyo Bridge. In this presentation, various structural features of this bridge are discussed and a few videos provided helps us to get a better understanding of it.

1. CEN-391 TECHNICAL COMMUNICATIONS Indian Institute of TECNOLOGY, ROORKEE Autumn Semester:- 2016-17 BY:- ADARSH (14113004) Civil Engineering(3 rd yr)

2. The Akashi Kaikyō Bridge THE LONGEST SUSPENSION BRIDGE IN THE WORLd 2

3. INTRODUCTION Situated in Japan, designed by Satoshi Kashima. Built over the Akashi Strait, links the city of Kobe on Japanese mainland to Iwaya on Awaji island. Construction period:- 1988-1998. Construction company:- Matsuo Bridge Co. Original plan:- contained railway lines, about to be cancelled by the government. 1985 – Decision taken to built only road bridge; construction started in 1988. 3

4. FEATURES 3 records:- Longest suspension bridge(1991 m central span), highest towers in a suspension bridge(297 m), most expensive bridge ever built(500 billion yen). 2 million workers involved in the construction. Carries 6 lanes of roadway. Annual revenue of 19 billion yen from toll. 4

5. STRUCTURAL Features Materials The Suspension Bridge Stronger Cables Building underwater Taller towers Wind resistant Earthquake resistant 5

6. Materials First steel bridge:- IRONBRIDGE (30 m). Need for lighter components Major component used is steel. Use of pre-fabricated steel shapes:- both in towers and the deck. Contains 250,000 tonnes of steel. Advanced technology to take care of rusting. 6

7. THE SUSPENSION BRIDGE First suspension bridge:- Menai Strait Bridge(177 m). Concept used :- Anchorage of cables. Construction of foundation. 2 Big holes dug into the ground. Each filled with around 230,000 cu. m. of concrete. Metal frames added for anchorage. Casting of concrete on these metal frames. 7

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10. Stronger cABLES Weight of each main cable:- 25,000 tonnes . 36,830 wires in one cable . Diameter :- 112 cm. Strand length:- 4070 m(approx.) Enough wires to circle the earth 7 times. 10

11. BUILDING UNDERWATER Use of caisson, made of steel. Dimensions of caisson:- dia-80 m, height-70 m. First – sink it into the water upto the bed. Second – fill it with concrete. Can be done manually or mechanically. Use of super-concrete in the foundation. Speciality :- hardening under seawater. 11

12. TALLER TOWERS Height of tower:- 297 m Cruciform cross-section :- increased stability. Comprised of 30 steel sections. Connections done by Advanced robot welding 1.5 million bolts. 13

13. Triangular stiffening steel girders. Lighter in weight as compared to steel boxes. Complete passage of wind. Testing in one of the largest wind tunnels. Length of prototype :- 40 m. Tested against a wind speed of 300 km/hr. Suggested to deflect the wind and also stiffen against it. Mesh provided in the centre of roadway and a huge beam below the roadway 15 Wind resistant

14. Earthquake resistant Testing of dampers by man made quake. 1995 earthquake. Increased the length by a metre. Capable of resisting 8.5 magnitude earthquake. Use of 20 Tuned Mass Dampers(TMD) . Reduces the deflection in the towers . 17

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16. Some Classic examples 19 Verrazano Narrows Bridge Golden Gate Bridge Brooklyn Bridge

17. THANK YOU 20