Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeProject Description: 1.1 Project Location

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Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeProject Description: 1.2 The Akashi Kaikyo Bridge (AKB) the longest suspension bridge in the world is a three-span, two-hinged stiffening girder system suspension bridge that spans the Akashi Strait between Maiko, Tarumi-ward in Kobe, and Matsuho, on Awaji Island.1.3 The construction began in May 1988, and took a total of ten years. * *

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge

1.4 Road specifications

1.5 Span arrangement: 960 m + 1991m + 960 m1.6 Physical conditions

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Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeII. Physical conditions2.1 The Akashi Strait between Osaka Bay and Harimanada is about 4 kilometers wide. 2.2 The part spanned by the bridge has a maximum depth of 110 meters and a maximum current speed of 4.5 meters per second. 2.3 The Strait has been a productive fishing area and an important seaway. * * Sample of Akashi stratum

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeII. Physical conditions2.4 Geological Profile along the Bridge cross the Strait The Strait is composed of from top to bottom alluvium, diluvium. the Kobe stratum, the Akashi stratum, and granite. The Akashi stratum consists of gravel 40% of whose particle size is 10~20 cm in diameter. The Kobe stratum is an unconsolidated stratum of hard muddy silt and predominating consolidated sand, or sandstone.* * Sample of Akashi stratum taken by wide-armature boring device

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeFoundations 3.1 Anchorage foundations3.1.1 A1 anchorage on the Kobe side was constructed with the underground slurry wall method. 3.1.2 A huge manmade founda-tion circular in shape for A1, measures 85 meters in diameter and 63.5 meters in depth, the largest an-chorage foundation in the world.3.1.3 A4 anchorage was con-structed by a retaining wall with spread foundation. * *A1 Anchorage Foundation

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge3.2 Tower Foundations3.2.1 The foundations of the main towers transmit the 120,000 ton weight of the bridge from the main towers to the support ground. 3.2.2 The support ground, 60 meters under water, was excavated by grab bucket dredger.* *

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge3.2.3 The caissons were prefabricated, towed to the site, installed in placed, and grouted with underwater and standard concretes. 3.2.4 The circular shape of the caissons is undirectional and therefore more stable and easier to handle in the strong currents of the Strait. 3.2.5 A new type of under-water concrete "under-water nondisintegration concrete," was developed for the foundations. * *

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeIV. Towers4.1 The tower top saddles transmit the 100,000 ton weight of the bridge from the cables to the foundations. 4.2 The towers are divided horizontally into thirty tiers, each of which is divided vertically into three blocks so as not to exceed 160 tons in weight. * *

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge4.3 For better aerodynamic performance, the tower shafts are designed cruciform in cross section, and have been equipped with stabilizers called tuned mass dampers (TMD)

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Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeV. Main Cables5.1 The main cables are made of parallel wire strands (PWS). Each cable consists of 290 strands, each strand 127 wires, each measuring 5.23 millimeters in diameter. 5.2 The strands are hexagonal in shape and prefabricated. * *

Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo BridgeV. Main Cables5.3 The length of the wire used totals 300,000 kilometers, enough to circle the earth 7.5 times. 5.4 Cable specifications

VI. Construction of Stiffening Girder

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Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge

Anchorage foundation for A1

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Bridge Engineering (9-2) Suspension BridgesA Case Study of Akashi Kaikyo Bridge Towing Caisson

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