The Akashi Kaikyo Bridge in Japan is the world's longest suspension bridge. It spans the Akashi Strait and connects Kobe to Awaji Island. When completed in 1998, it held the records for highest and longest suspension bridges at 280m tall and 1991m long. The bridge cost $4.3 billion to build and took over 10 years to construct using over 1 million cubic meters of concrete and 81,000 tons of steel. New techniques had to be developed to build the deep foundations in open sea conditions.

1. A case study on
AKASHI KAIKYO BRIDGE
The longest suspension bridge in the world
Submitted by:
Vivek Kumar
Yamini Purohit
Manaswini Naugain
Ayush Sahu
Deepanshu Yadav
Saurav Paul
Naveen Yaduvanshi
Divyom
Sai Naren
Submitted to:
Mr Rahul Silori

2. Introduction
● The Akashi-kaikyo bridge popularly known as the 'Pearl Bridge' is a suspension bridge
in Japan that crosses the Akashi strait. It links Kobe in mainland Japan and the rural
fishing island of Awaji as a part of Honshu-Shikhoku Highway.
● Carries 6 lanes of E'28 Kobe-Awaji-Naruto expressway along with 4 emergency lanes.
● At the time of completion, this bridge held 3 world record
1.At 280m, it was the highest suspension bridge in the world.
2.Wiith the central span measuring almost 2km, it was the longest suspension
bridge.
3.At a cost of $4.3 billion, it was the most expensive bridge project
● The list of Suspension Bridges that are famous in India are as follows:
1. Howrah Bridge(705m)
2. Lakshman Jhula
3. Ram jhula
4. Sudama Setu

3. Utility of a Suspension Bridge
● Requirement of Long spans- The suspension cables experiences tensile
forces hence, will never “buckle” and highly efficient use of high strength
steel materials becomes possible with reduced deadweight. This makes
longer spans achievable. They are practical for spans up to around 2 km or
even larger
● For busy roadways and waterways- During construction, temporary central
supports do not need to be built, and access to the construction is not
required from beneath. This means busy roadways and waterways do not
need to be disrupted
● Suspension bridges are flexible, thus can easily tackle outside forces e.g
Earthquakes, cyclones, Typhoons, etc.

4. Akashi kaikyo bridge

5. https://celp1.files.wordpress.com/2015/10/wpid-wp-1445241148193.jpeg
Main Components of Suspension Bridge

6. Working of suspension bridge
● The load transfer mechanism for Suspension
Bridge is as same as Cable stayed Bridge
● When the load of the vehicle comes under the
deck of the bridge then the equivalent weight
acts downwards, to remain in a position of
equilibrium the cables come under the tension
and suspenders also comes under the tension.
● Now in order to balance the horizontal
component of Tension force, the cables attached
to anchor box also comes under tension and
balances the horizontal component and all the
vertical component is balanced by tower taking
as a compressive force.
Source:-http://www.warwickallen.com/bridges/SuspensionBridges.htm

8. History and Reasons to build this bridge
● Before the Akashi Kaikyo Bridge was built, ferries carried passengers
across the Akashi Strait in Japan.
● In 1955, 168 children were killed when two ferries sank in the strait
during a severe storm.
● This incident compelled the Japanese government to develop plans for a
suspension bridge to cross the strait.
● The original plan called for a mixed road-railway bridge, but when
construction on the bridge began in April 1986, the construction was
restricted to road only, with six lanes.
● The Akashi Strait is an international waterway that necessitated the
provision of a 1,500m wide shipping lane.

9. Timeline
1959
Ministry of
Construction
commenced highway
study
1970
Honshu-Shikoku
Bridge Authority
founded
1973
Ministry of
Construction
approved
construction plans
1985-86
Government decided
to construct Akashi
Kaikyo Bridge and
Geological study of
construction site
commenced
1987-88
Construction survey
for tower foundation
commenced and
on-site construction
commenced
1998
Opened for traffic

10. Architecture
● The bridge has three spans.
● Central span is 1991 m and other two spans are 960 m long.
● The bridge was designed with a two-hinged stiffening girder system.
● The bridge is strong enough to withstand wind loads of about 286
km/hr, earthquake measuring 8.5 on Richter scale and harsh sea
currents.
● The bridge also contains pendulums that are designed to operate at the
resonance frequency of the bridge to damp forces.
● The bridge can expand because of heating up to 2 metres (7 ft) over the
course of a day.

11. Material used for the construction
● Attempts were made to use lighter components
● Major component used- Steel (Prefabricated)
● Other materials included super concrete (for
foundation & Deck), bolts, stones, etc.
○

12. Construction Challenges
● Material – Introduction of Stronger & Lighter Stuff
● Building Underwater – With Caisson
● Taller Towers – Using Steel
● Destructive force of nature – the wind
● Earthquakes

13. Concept and Construction processes
● The concept of this bridge was to cater the traffic load coming on the 6-lane freeway.
● But before that the bridge had to carry its own self weight. The load coming on the bridge
was distributed as 91% to support its own weight and only the remaining 9% was for
traffic load.
● The basic concept consisted of erecting two towers and passing steel cables through it.
The girder was connected to the cable by means of hangar cables(suspenders).
1
Construction of tower
foundation
2 Construction of towers
3
Fixing of steel cables to
towers
4 Placing the roadway

14. Construction of tower foundation
The usual method of building foundation by placing
pre-cast concrete cylinders over each other was
abandoned and a new solution was brought up.
Why?

15. Construction of tower foundation
● Two enormous steel moulds were built in the dry docks and
were then towed to sea and sunk at the precise location.
● The steel moulds were 70m tall, 80m wide and weighed
about 15000 tonnes.
● The moulds were sunk by filling with seawater.
● A new type of super-concrete was developed which
hardened in seawater.

16. Construction of tower foundation

17. ● 1991m span required to hang cables from points 152 m
above the deck and 297 m in total.
● Slender stone towers would have buckled under the load.
● Any stone tower capable of not buckling required nearly
50m wide base. This would has struck the passages of
ships and compromised the aesthetics of bridge.
What was done?
Construction of towers

18. Construction of towers

19. Fixing of steel cables to towers
● Each cable consists of 290 strands and each strand further
contains 127 wires (5.23mm dia) made of high tensile
galvanised steel.
● The strands are prefabricated and the wires have a tensile
strength of 176.52 Mpa.
● The cable was threaded over the tower using a helicopter. It was
lifted from Kobe threaded around the first and second towers and
tied at the Awaji end.
● These were laid on the saddles fixed on the towers and then
anchored on anchorage block constructed on the shores.

20. https://i.kinja-img.com/gawker-medcenter,h

21. ● Excavation for foundations was done and
230,000 m3
of concrete was filled in it.
● Steel frames were set inside the concrete
and the cables were fixed firmly in them.
Before fixing, the cables were passed
over another saddle inside the anchor
tower.
http://ffden-2.phys.uaf.edu/webproj/211_fall_2014/Elliott_Anderson/Elliott_Anderson/Picture%20URL%27s/anchorage.JPG

22. Placing the roadway
● The deck was made of steel girder which was arranged in a triangular
shape.
● For extra strength a vertical stabilizer was provided throughout the
length of the bridge which balanced pressure below the roadway and
reduced vibrations.
● A steel mesh grating was installed down the centre and along the
sides of the deck. This allowed wind to pass right through the
roadway and stopped the pressure building up.
● The massive 100 ton steel sections of the roadway was carried out by
floating cranes and assembled.
● The deck was connected to cables with the help of vertical
suspenders.

23. https://www.youtube.com/watch?v=oPkC6dHEv4Y

25. New techniques developed for Akashi kaikyo
bridge
● Due to the violent nature of the sea, the usual method of constructing bridge
foundation by laying concrete cylinders on top of each other was not possible
so, engineers introduced a new concept of casting the foundation in steel
moulds.
● Super-concrete was developed to aid the setting of cement in seawater.
● Super-strength steel wire was developed for the cable by changing the alloy
proportions. This super-strength cable was so strong that a 5mm thick wire
could carry 3 family cars.

26. Conclusion
● The Akashi Kaikyo Bridge has been set as a benchmark for future bridge
constructions. The Mazena Bridge in Italy will soon overtake Akashi
Kaikyo as the world’s longest bridge.
● As the span increases the length of the cable increases and this leads to
an increase in the load to be carried by the bridge. But With the advent of
carbon fibre, it will be lighter than steel and stronger leading to huger
spans.

27. OMG
It took two million workers, ten
years, 81,000 tones of steel and
1.4 million cubic metres of
concrete to construct the bridge.
The steel cable used would circle
the world seven times.

28. References
http://www.fhwa.dot.gov/publications/publicroads/98julau g/worlds.cfm
http://everything2.com/title/Akashi%2520Kaikyo%2520Bri dge
http://structurae.net/structures/akashi-kaikyo-bridge
http://en.wikipedia.org/wiki/Akashi_Kaikyo_Bridge
http://www.pbs.org/wgbh/buildingbig/wonder/structure/ak ashi_kaikyo.html
http://www.technologystudent.com/index.htm
http://natgeotv.com/ca/big-bigger-biggest/videos/the- akashi-kaikyo-bridge
http://www.technologystudent.com/culture1/akashi1.htm
https://www.pinterest.com/awajicity/peal-bridge-akashi- 31
https://www.youtube.com/watch?v=_9hk6x3p1so

29. Here we go

30. THANKYOU