2. INTRODUCTION
Very large floating structures are manmade islands, which
may be constructed to create floating airports, storage facilities
(for oil & natural gas), for military purposes ,to create industrial
purposes
They are easy and fast to construct
VLFS’S can easily transported,removed,expanded
Cost effective when water depth is large
Do not damage marine eco-system
Do not disrupt ocean currents
They are immune to seismic shock
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
2
3. To classify according to their geometry:
I. Pontoons.
II. Semisubmersibles.
To classify them by location:
I. CoastalVLFS.
Mega float
II. OffshoreVLFS
Mobile offshore base(MOB)
Pneumatically stabilized platform(PSP)
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
3
4. MEGA FLOAT
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
4
5. Very large pontoon floating structure
Suitable for use in calm water
Provide break water if significant wave
height is greater than 4m
Strong, reliable, lightweight
Construction carried out with modules made
on land between 100 and 300 m in length
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
5
6. Advantages
Manufacturing and assembly easy and
inexpensive
Unlimited size
Capacity of positive load
Disadvantages
suitable for inlets and bays
Low mobility
Ingress of water on deck
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
6
7. Mobile offshore base
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects 7
8. To support military operations wherever
convention all and bases are not available
Providing a landing/takeoff area and
maintenance, as well as supply and other
advanced logistical, support operations
Length of each module : 220 - 500 m
width of each module : 120 - 170 m
Numbers of each module : 3 - 5
Total length of module completely aligned:upto
2km
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
8
9. Alignment is maintained by Dynamic positioning
thrusters
Two types
Joint Mobile Offshore Base
Hybrid Mobile Offshore Base
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
9
Joint Mobile Offshore Base module
five semi-submersible steel propelled ships
Track - mile(1800m)-long connected with non-load bearing
structures
A lightweight, collapsible draw bridge allows for transfer between
modules.
10. Hybrid Mobile Offshore Base
high strength, light weight LWC60 concrete in
the steel hull and superstructure deck
fatigue is a major pitfall for a concrete hull with
a design life of 100 years.
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
10
MOB semisubmersible hybrid concept: four modules together (left) and
a single module (right)
11. Advantages
Mobility.
Suitable for all types of water
Deep and shallow waters
Benign and harsh (conditions good behaviour
at sea).
Disadvantages
Payload is limited, as is the case with all
semisubmersible vessels.
Large internal movements: danger of fatigue in
the structure
Connector technology still experimental.
High construction and operational costs
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
11
13. Number of cylindrical components packaged
in a rectangular shape to form single module
Each cylinder is sealed at the top and open to
the sea at it’s base
It can handle loads and attenuate the wave
Post tensioned cables used to help assemble
the components
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
13
14. Advantages
Manufacturing and installation process simple and
inexpensive
Suitable for all types of water
Unlimited size (modular)
Low or almost zero maintenance
Disadvantages
Experimental technology in its most basic principles:
indirect displacement.
Joining technology with tensors in need of extensive
further development and study.
Low mobility
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
14
15. APPLICATIONS OF VLFS
FLOATING AIRPORTS
The first sizeable floating runway
one-km long Mega-Float
Mega-Float in Tokyo Bay, Japan (1998)
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
15
16. MOBILE OFFSHORE BASE
large aircraft and ships may support
littoral combat operations from a secure
position without reliance on achieving
political support in other nations
10 November 2016
CE6397 Very large floating
structures:applications and design aspects 16
MOB,CHINA
17. FLOATING STORAGE FACILITIES
used for storing fuel and keeping the
explosive, inflammable fluid from populated
areas on land.
pontoon structure
Japan has two major floating oil storage
systems.
in Shirashima with a capacity of 5.6
million kilolitres
in Kamigoto with a capacity of 4.4
million kilolitres.
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
17
18. Kamigoto Floating Oil Storage Base,Japan
( 4.4million kilolitres)
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
18
19. FLOATING DOCKS, PIERS, BERTHS AND
CONTAINER TERMINALS
The floating pier is 150 m x 30 m x4 m.
must allow smooth loading and unloading of cars
equal tidal rise and fall of the pier and ferries is
advantageous
Floating Pier at Ujina, Japan
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
19
20. FLOATING EMERGENCY BASES
inherently base isolated from earthquakes
floating emergency rescue bases in earthquake
prone countries
Japan has a number of such floating rescue
bases
Emergency Rescue Base, Tokyo Bay10 November 2016
CE6397 Very large floating
structures:applications and design
aspects 20
21. FLOATING BRIDGES
1246-m long Nordhordland Floating Bridge built
in1994 at Salhus over a fjord depth of 500 m.
bridges are horizontally curved to better resist the
wave, the water current and wind forces
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
21
Nordhordland Floating Bridge, Norway
22. Analysis and Design of Floating Structures
Characteristics to be considered :
Horizontal forces due to waves much times greater than
the (non- seismic) horizontal loads on land-based
structures
In framed, tower-like structures the horizontal wave
forces produce extreme bending and overturning
moments
In a floating structure the static vertical self-weight and
payloads are carried by buoyancy.
A particular type of structural system, denoted tension-
leg system, is achieved if a highly pre-tensioned
mooring system is applied.
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
22
23. Sizing of the floating structure and its mooring system
depends on its function
VLFS’s usually constructed at shore-based building sites
remote from the deepwater installation area and without
extensive preparation of the foundation.
Owing to the corrosive sea environment, floating
structures have to be provided with a good corrosion
protection system
Possible degradation due to corrosion or crack growth
(fatigue) requires a proper system for inspection,
monitoring, maintenance and repair during use.
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
23
24. LOAD TYPES AND COMBINATIONS
1) Permanent or dead loads
2) Variable or live loads
3) Frequent and Rare Environmental loads
4) operation loads
5) Cyclic loads
6) Accidental loads
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
24
27. UNIQUENESS OF VLFS
1) Large Size
2) Environment Condition
3) Design and Analysis
4) Connection at Sea
5) Positioning
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
27
28. CONCLUSION
VLFS is a unique concept of ocean structures
because of their length,displacement,cost
Requires massive investment and considered as a
mega project
Cost of shore facilities is soaring , so offshore
floating facilities will become more attractive
21 century there will undoubtedly be significant
developments in the field of VLFS
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
28
29. REFERENCES
Miguel Lamas-Pardo a,1, GregorioIglesias b,2, LuisCarral a,3,2015,
A review of Very Large Floating Structures (VLFS) for coastal and
offshore uses, Ocean Engineering109(2015)677–690
Wanga C.M, Taya Z.Y,2011, Very Large Floating Structures:
Applications, Research and Development, Procedia Engineering 14
(2011) 62–72
Masahiko Fujikubo,2005, Structural analysis for the design of VLFS,
Marine Structures 18 (2005) 201–226
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
29
30. THANK YOU….
10 November 2016
CE6397 Very large floating
structures:applications and design
aspects
30