structure assignment

8/7/2019 structure assignment

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Millau Bridge France

1. Introduction2. Building system

3. Structural system


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introduction

Located in southern France, the bridge will connect the motorway fromParis to Barcelona at the point where it is interrupted by the River Tarn

This new bridge, opened on the 14th December 2004, replaces the bridgecrossing the River Tarn in the centre of the town of Millau.


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introduction

This project has the highest bridge piers in world, spans 350meters and its columns range in height from 75 meters to 235meters - higher than the Eiffel Tower - with the masts rising afurther 90 meters above the road deck.The tallest will be 240meters high. Overall height an outstanding 336.4 meters.

At 2.4km long, and 270m above the river at its highest point, the

Millau viaduct spans a 2km valley in the Massif Central mountainrange and forms the final link in the A75 highway from Paris toBarcelona.


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Building system

The Millau Viaduct, designed in collaboration with engineers, illustrates

how the architect can play an integral role in bridge design.

Famous British architect Norman Foster was in charge of the viaduct's

appearance.

It has been designed to look as delicate and transparent as possible. Each ofits sections spans 342m and its columns range in height from 75m to 235m

over the river Tarn.


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Building system

The millau viaduct is a multi cable-stayed structure long of 2460m slightlycurved in plan on a radius of 20000 m & a constant up ward slope of 3.025%from north to south.

The structure is continuous along its eight cable stayed spans ,two endspans of 204 m each and six central spans of 342m each.

120 years : Predicted lifespan


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Building system

The cross section profile of the motor way consists of a dual

carriageway each carriageway bordered by a 3m emergency line and

1m shoulder next to the central reservation.

Over all deck width of 27.75.


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The piers

At 4 per pier, fifteen

metres deep and 5m

wide, the morocan wells

form the foundations

and ensure stability

At the foot of each pier,

a foundation slab, 3 to

5m thick, reinforces the

action of the wells.

19,000 tonnes : Steel

used for reinforcing theconcrete piers


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The piers

The piers of the Millau

viaduct are numbered

from 1 to 7, from the

north to the south of the

structure. Here are theirrespective heights:

P1: 94.50 m

P2: 244.96 m

P3: 221.05 m

P4: 144.21 m

P5: 136.42 m

P6: 111.94 m

P7: 77.56 m


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The deck

A trapezoidal profiled metal box girder with a maximum

height of 4.2 m at the axis with an upper orthographic

decking of metal sheets 12-14 mm thick on the greater

part of the main spans.

detail of deck/pillar joint


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The pylons

The pylons are set in to the deck.

Longitudinality, continuity is ensured between the metal sheets

of the webs of the central box girder and those of the walls of

the pylons legs.


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The pylons

Transversely, rigidity is providedby a frame which covers the

bearings found on each pier shaft.

97 m : Height of the 7 pylons

each pylon is in the form of an

inverted Y. The height of the legsof each Y is 38m.


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The cables

They are anchored along the axis of the central reservation atregular intervals of 12.51 m following the curvature of the

structure.

Consists of t 15 strands of class 1,860 which are super galvanised ,

sheathed and waxed .y 154 : Number of stays supporting the road-deck from the pylons


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The cables

Each cable is protected by white sheath. This acts as a barrier to

UV light & has discontinuous spirsls on its surface in order to

combat vibration resulting from the combined effects of wind and

rain .

The cable anchors are adjustable at the deck end fixed on the

pylons


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The materials

The deck and the pylons , entirely of metal

, are made of steels of grade S355 &

S460.

The piers are constructed in B60

concrete.this concrete is choosen more for

its durability than for its high mechanical

resistance.


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Static longitudinal scheme

&wind studis As the bridge will be exposed to winds of up to

151km/hr, side screens are used to reduce the

effects of the wind by 50%.

The speed of the wind at the level of the road

therefore reflects the speed of the wind found

at ground level around Larzac and Sauveterre.

structure assignment

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