Transcript Bridge Engineering (9-2) Suspension Bridges—A Case Study

Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
Project Description:
1.1 Project Location
I.
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Saturday, July 18, 2015
Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
Project Description:
1.2 The Akashi Kaikyo Bridge
(AKB) the longest
suspension bridge in the
world is a three-span, twohinged 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.
I.
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Saturday, July 18, 2015
Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
1.4
Road specifications
Road Name
#28 National Highway
Classification
1st grade, 2nd class
Number of Lanes
6
Design Speed
100 km/h
1.5 Span arrangement: 960 m + 1991m + 960 m
1.6 Physical conditions
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Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
 II.
Physical 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.

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Sample of Akashi stratum
Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
 II. Physical 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.

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Sample of Akashi stratum taken by
wide-armature boring device
Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
Foundations
3.1 Anchorage foundations
3.1.1 A1 anchorage on the Kobe
side was constructed with
the underground slurry
wall method.
3.1.2 A huge manmade foundation circular in shape for
A1, measures 85 meters in
diameter and 63.5 meters
in depth, the largest anchorage foundation in the
world.
3.1.3 A4 anchorage was constructed by a retaining
wall with spread
foundation.
III.
A1 Anchorage Foundation
Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
3.2 Tower Foundations
3.2.1 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.
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Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
3.2.3 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 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.
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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)
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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.
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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
specifications
VI. Construction of
Stiffening Girder
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Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
Anchorage foundation for A1
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Bridge Engineering (9-2)
Suspension Bridges—A Case Study of Akashi
Kaikyo Bridge
Towing Caisson
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