Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge I. Project Description: 1.1 Project Location 1 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge I. Project 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. 2 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge 1.4 Road specifications 1.5 Span arrangement: 960 m m m 1.6 Physical conditionsPhysical conditions 3 Tuesday, May 12, 2015 Road Name#28 National Highway Classification1st grade, 2nd class Number of Lanes6 Design Speed100 km/h

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge  II. Physical conditionsPhysical conditions  2.1 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.  4 Tuesday, May 12, 2015 Sample of Akashi stratum

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge  II. Physical conditionsPhysical conditions  2.4 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.  5 Tuesday, May 12, 2015 Sample of Akashi stratum taken by wide-armature boring device

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge III. Foundations 3.1 Anchorage foundationsAnchorage foundations A1 anchorage on the Kobe side was constructed with the underground slurry wall method 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 A4 anchorage was con- structed by a retaining wall with spread foundation. 6 Tuesday, May 12, 2015 A1 Anchorage Foundation

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge 3.2 Tower Foundations The foundations of the main towers transmit the 120,000 ton weight of the bridge from the main towers to the support ground The support ground, 60 meters under water, was excavated by grab bucket dredger. 7 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge The caissons were prefabricated, towed to the site, installed in placed, and grouted with underwater and standard concretes.towed to the site The circular shape of the caissons is undirectional and therefore more stable and easier to handle in the strong currents of the Strait A new type of under-water concrete— "under-water nondisintegration concrete," was developed for the foundations. 8 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge IV. Towers 4.1 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. 9 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge 4.3 For better aerodynamic performance, the tower shafts are designed cruciform in cross section, and have been equipped with stabilizers called tuned mass dampers (TMD) 10 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge V. Main Cables 5.1 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. 11 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge V. Main Cables 5.3 The length of the wire used totals 300,000 kilometers, enough to circle the earth 7.5 times. 5.4 Cable specificationsCable specifications VI. Construction of Stiffening GirderConstruction of Stiffening Girder 12 Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge Anchorage foundation for A1 13 Tuesday, May 12, 2015Tuesday, May 12, 2015

Bridge Engineering (9-2) Suspension Bridges—A Case Study of Akashi Kaikyo Bridge Towing Caisson 14 Tuesday, May 12, Tuesday, May 12, 2015