complete case study of the structure components of the millau via duct and its design concept

1. MILLAU
VIADUCT
MILLAU
VIADUCT

2. MILLAU VIADUCT
• The Millau Viaduct is in southern France and crosses the River
Tarn in the Massif Central mountains.
• It was designed by the British architect Lord Foster and at 300m
(984 feet) it is the highest road bridge in the world, weighing
36,000 tonnes.
• The central pillar is higher than the famous French icon, the Eiffel
Tower.
• The Bridge opened in December 2004 and is possibly one of the
most breath taking bridges ever built.

3. • The bridge towers above the
Tarn Valley and the aim of
Lord Foster was to design a
bridge with the ‘delicacy of a
butter fly’.
• Lord Foster designed a bridge
that enhances the natural
beauty of the valley, with the
environment dominating the
scene rather than the bridge.
• The bridge appears to float on
the clouds despite the fact that
it has seven pillars and a
roadway of 1½ miles in length.

4. CONSTRUCTION OF MILLAU VIADUCT

5. Steel deck with multiple sub-bended
spans.
Steel deck with continuous spans
of constant depth.
Steel or concrete deck with multiple
cables-stayed spans
Concrete bridge including an arch with an
opening 600m wide over the River Tarn
Viaduct with continuous spans
of variable depth in concrete or composite
material

6. 7 piers P1 to P7
2 abutments C0 & C8
6 spans 342 m long
2 side -spans 204 m long

7. 6 STAGES OF CONSTRUCTION
1. Raising the piers
2. Throwing the deck
3. Joining the deck
4. Installing the pylons
5. The stays
6. Finishings

8. RAISING THE PIERS

9. Piers - The piers are the towering part of the structure with the tallest
one reaching over 245 meters tall. The piers hold the road way and the
pylons.
1. The piers were constructed using reinforced concrete. The piers have
the design of tapering down from top to bottom. The seven piers are
identical except for the length due to the valley bottom.
2. The piers have been constructed using an automatic rail climbing
system or ACS. The system required the bottom section the pier be
constructed then the climbing system attached to rail secured to the
pier. Allowing the system to move up the piers independently .
3. The ACS would pour 4 meter sections of concrete at a time allowing
accurate pours and ensuring structural stability.
4. The ACS enabled the piers to be built on schedule. The system
allowed for a correct pour each time it moved up the pier.

10. The pier design : flexible
piers at their base =strong
distortion of the deck
Pier design : piers with flexural
rigidity at their base=Less
distortion of the deck
Pier Design

12. Usage of Temporary Piers

13. THROWING THE DECK

14. • THEY OPTED FOR STEEL
DECK OVER THE
CONVENTIONAL CONCRETE
BLOCK,AS IT IS NOT
ECONOMICALAND SAFE TO
LIFT CONCRETE OVER
SUCH HEIGHTS.
FABRICATION OF THE DECK
SECTION WAS DONE ON
STEEL FACTORY .
AROUND 2200 SECTIONS
EACH WEIGHING UPTO 90
TONNES AND WERE SOME
WERE 22 LONG.
Steel Decks

15. 7 temporary piers
help support the weight
of the deck,as the
longest deck could
support was half the
span.
Two deck segments
were launched from
each end of the bridge
Launching the deck

16. •Computerized launchers
push the pre-fabricated
deck segments on to the
piers.
•Each cycle moves the deck
600 mm.
• Total of 5000 cycles
required.
•The cycle is repeated every
4 minutes
Hydraulic launchers

17. •Weight of steel box girder deck
sags as span is completed.
•Nose recovery system attached to
raise the deck to the level of the
next pier.
•This aligns the deck for the level
and curvature of the next pier.
•The precision carried out in the
nose recovery system was due to
the use of GPS system as the
accuracy was upto 4mm.
NOSE RECOVERY

18. Moving the deck could be
accomplished three ways:
manual, semi-automatic and
automatic.
Manual mode was used for
adjustments and any necessary
instant corrections.
In the semi-automatic mode,
each movement was made step
by step, or, in other words, raise,
push, lower, and then withdraw.
Automatic mode completed each
entire launch cycle.

19. In all, 18 launches — six
from the north side of the
bridge and 12 from the
south — were required to
position the deck, with the
last launch accomplished on
May 28, 2004.

20. INSTALLING THE PYLONS

21. Each pylon of the viaduct is equipped with a monoaxial
layer of eleven pairs of stays laid face to face.
Depending on their length, the stays were made of 55 to
91 high tensile steel cables, or strands, themselves
formed of seven strands of steel
Each strand has triple protection against corrosion and
the stay-cables weight about 1,500 tons
The exterior envelope of the stays is itself coated along
its entire length with a double helical weatherstrip. The
idea is to avoid running water which, in high winds,
could cause vibration in the stays and compromise the
stability of the viaduct.
The stays were installed using a well-tried technique.
After threading one strand in the outer protective sheath,
it is pulled up on to the pylon to its final location.
The strand is then fixed in the upper and lower
anchorage points. A 'shuttle' then brings the other strands
one by one, and they are then stretched to tension."

22. • MAJOR MATERIALS :
• 1. STEEL :
• Steel is used in many places where concrete was earlier used
• The cost of steel and concrete was about 390 million euros (520
million dollars).
• The project required about 19,000 metric tons of steel for the reinforced
concrete, and 5,000 metric tons of pre-stressed steel for the cables and
shrouds.
• The bridge is constructed out of 2,078 steel pieces made by the EIFFEL
Company, the successor of the company that built the Eiffel Tower
• The deck and pylons are made of steel sheets of grade S355 and S460.

23. • 2. CONCRETE :
• The project required about 127,000 m³ of concrete.
• The concrete of the abutments and piles amounted to 85 000 m3, 40
times the Eiffel Tower
• The massive piers are made from type B60 concrete, a high-strength
concrete with durability characteristics more than its mechanical
resistance.
• During construction of the bridge concrete pours were made 4m tall

24. • 3. Stay Cable material :
• The stay cables are made from T15 strands of class 1,860MPa which are super-
galvanized, sheathed, and waxed.
• The cables are protected by a white, aerodynamic sheath made from non-
injected PEHD (high-density polyethylene)
• Developed by through a collaboration between Buonomo, Servant, Virlogeux,
Cremer, Goyet and Del Forno
•

25. • ENVIRONMENT FRIENDLY USE OF MATERIALS
• Steel was used in most places instead of concrete which reduced the use of
trucks.
• Included a system for collecting and processing rainwater and other waste which
would be accumulated during road washing
• Excess construction materials were carefully stored to use them for other
operations
• - wood was sent to paper mills
• - oil and lubricants were sent for recycling
• Various sites of production zones had been selected with an intention to keep
hedge and bush felling to the minimum

26. PROBLEMS ENCOUNTERED
• CONSTRUCTION
• MAJOR CHALLENGES:
1. Build the tallest bridge piers in the world.
2. Put a 36000 ton free way on top of them.
3. Erect 7 steel pylons each weights 700 tons.
4. Land

27. • There are 7 piers that are numbered from the northern end of the valley. Number 1 was to cause
problems because of steep slope. Number 2 was the tallest across the river number 3 was not
much shorter from no. 2. Then 4, 5, 6 and 7 found the genital slope to the south.
• 16000 tons of steel bars are used. The shape of each pair is complicated as a result each time
they removed the section of red steel sheltering they have to change the shape of the mold to fit
the profile of the next 4 meter section man handling these steel panels way up to 15 tons of
piece is no picnic. And with the combine height of 7 piers totaling well over a kilometer they
had to change the shape of the mold over 250 times.
• Every 3 days each team on each pair went through this whole cycle then they repeated the
process but it was time consuming.Month after month the piers climbed higher finally by
November 2003 they reached their full height. At 245 meters pair 2 becomes the highest bridge
pier in the world. The piers were exactly on the location where it had to be with 2cm deviation.
1. PIERS

28. 2. FREE WAY ON TOP OF THEM.
• Second problem was putting a 36000 ton free way on top of the piers. Working at
these heights could be lethal. Around 235 people died in the process.
• Therefore the team decided to fabricate the entire rope deck on the safety of solid
grounds instead of concrete, steel was used for the deck which in theory would be
much safer then lifting concrete sections hundreds of meters in the position.
EIFFEL, the steel firm took up the challenge.
• This involved manufacturing 2200 separate sections weighing up to 90 tons and
some of them 22 meters long. Their accuracy was measured with laser to within a
fraction of a millimeter. The triangular side panel were welded on either side to
create width for a 4 lane high way. They automated the manufacturing with a two
headed welding robot and a plasma cutting machine each cutting pattern or template
was programmed in to the computer then the machine automatically blazes its way
through the steel.

29. • Another problem faced with construction was the need to eliminate error in position.
• The pylons were of such enormous heights that being off even the slightest at the
bottom of the pylon could spell disaster at the top of the pylon in the form of meters off
the intended mark.
• When considering the pylons, other challenges faced included: pouring the cement in a
timely manner as to prevent from setting, hurricane grade winds faced by workers, and
the intricate design of each pylon moving to the overall construction of the bridge.
• This made constructing the platform a challenge all its own. Spans of this great length
in the past have spelled disaster in the form of collapse of the structure and death of
workers.
• The road spans also would be at the highest point putting the winds at even larger
velocities. Placing the 700 ton pylons atop the bridge and adding even more weight to
the roadways also served as challenges that could result in the destruction and abrupt
end of the Millau Viaduct.
3. Erect the steel pylons

30. 4. LAND
• Another challenge to overcome was the need to drill and bury the
foundations of the massive pylons deep into the bed rock.
• The challenge here was that there are cavities throughout the country
side that have fractured the limestone. These cavities are necessary to
the survival of the local cheese industry. This terrain is responsible for
containing the bacteria responsible for the blue mold necessary to
make Roquefort cheese.
• The cracked limestone meant one thing, landslides! Not far into the
project this problem became a reality, with a landslide pushing rock
and dirt into the first pylon. This landslide however, did not hurt the
pylon.

32. FINISHINGS
The surface (the covering of the road) of the millau viaduct is the result of several months of research. It was designed to withstand any distortion
of deck & provide the necessary qualities for comfortable motorway driving. It took less than four days work to lay it. Final finishing touches:
electric lighting, signposts, operating systems, final road covering.

33. THANK YOU!
• MD MEHRAJ ALI
• 12 CEB 421
• A3CB-01
• GE0096