monitoring and maintenance of the millau viaduct millau viaduct : normandie viaduct : t moy,max 1,03...
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OSLO BRUKONFERANSEN 2019 04/11/2019
Isabelle Metais
Monitoring and maintenance
of the Millau Viaduct
EIFFAGE Infrastructures
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Chirajara bridge in Colombia
▪ Part of a concession
▪ Key feature of the last sector
▪ 446 m Cable stayed bridge
▪ 20 M$ project
▪ Rebuilding of a new bridge after a
collapse on existing foundations
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Chirajara bridge in Colombia
▪ 446,3 m length
▪ 286,3 m central span
▪ 150 m opening under the deck
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- Longueur : 2 460 m
- Travées : 204 m, 6 x 342 m, 204 m
- Hauteur des piles : de 78 à 245 m
- Hauteur des pylônes : 90 m
The highest multi cable-stayed bridgeWorld record of highest piers
- Total length: 2 460 m
- Spans: 204m & 342m
- Height of the piers: 78m to 245m
- Height of the pylons: 90m
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27.75 m
4.20m
4.60m
Concrete
Steel
Chosen material
The high complexity of the site,
which makes access difficult to
those areas with steep slopes, has
led to :
- Limit the number of piers
- Restrict their position to the top
or bottom of the slopes
Constraints of the site
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Chosen solution
▪ Main features :
‒ Height of piers and pylons
‒ Length of the bridge
‒ Repeatability of the structure
▪ EIFFAGE’s choice:
‒ Prefabrication of the desk
▪ Advantages :
‒ Quality workmanship of the structures
(durability)
‒ Safety (Works-at-height are limited)
‒ Hazards in construction are reduced
‒ Speed of execution
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Limestones
Hettangien & Sinémurien
Marls
Toarcien & Domérien
Limestones
Bajocien
North South
Geotechnical studies
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Chevêtre : 5 dernières
levées
Fût double : 90 m
Précontrainte structurelle de pile
Précontrainte de clouage du tablier
Bossages
Prestressing
Elevation Cross section
Two separate
columns over the
uppermost of 90 m
Structural prestressing
of the pile
Vertical prestressing
tendons
End anchoring
Two separate
columns over the
uppermost of 90 m
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Monitoring objectives
▪ The contracting authority has fixed the Viaduct monitoring objectives in the Appendix 10 of the
contract. Monitoring was divided into 3 phases with different objectives :‒ construction
‒ delivery
‒ Operation
▪ During construction:‒ Control of the geometry and movements especially during launching of the deck
‒ Control of the viaduct’s behaviour to confirm the compliance with the calculations
▪ On completion, the baseline status has been registered as a “zero point” reference for long-term
monitoring and first stages of maintenance
▪ During operational phase, long-term monitoring includes 3 aspects :‒ Specific parameter controls linked to vehicle and passenger safety
‒ Check on ageing of the viaduct
‒ Check on structural behaviour
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Accelerometers are located :
* at the nose of the deck
* under and above the pylons
* inside the deck
Static measurements during launching operations
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Laser receiver is located inside the heads of the piers
Laser located on the spacer at - 90 m
2 actions are possible :
- Send a message by automaton ENERPAC when the vigilance thresholds are exceeded
- Launching is stopped when the alert thresholds are exceeded
Seuil d’alerte
Seuil de vigilance
P1 / P7 50mm 35mm
P6 80mm 60mm
P2 à P5 100mm 80mm
Responding cells :
2 circles locate the thresholds between -90 and the head of the pier
Filters
Tracking the piers
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On completion, at deliveryDynamic measurements carried out before
The opening to traffic
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Horizontal modes Vertical modes
Mode shapes of the first modes of the deck
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▪ Monitoring of the foundations
▪ Tracking of the concrete structures
▪ Tracking of the temperature effects
▪ Tracking of the wind effects
▪ Monitoring of the cable stays
▪ Following the geometry of the
structure
During operational phase
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During operational phase
Location of the boxes acquiring the instrumentation of the viaduct
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Monitoring the foundations
1. Visual inspection every 6 months since 2007
2. Measurements of the inclinometers (detection of slippery phenomena)
3. Measurements of foundation settlements by direct levelling
4. Measurements of the movements next to P1 and P3 (big backfills)
5. Measurements of the movements next to P3 and P7 (stitched walls)
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Tracking of the concrete structures
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Tracking of the temperature effects
Sensors are located on the deck
‒ 1 section being equipped, located in span between P2 and P3
‒ 27 sensors
‒ Temperature readings every 30 min entre 2005 et 2013
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Equivalent Max(Ttab) and Max(Tatm) Equivalent Max(Ttab) and daily solar radiation
Millau viaduct :
Normandie viaduct :
01,100093,003,1 max,max, −+= thatmmoy RTT
thatmmoy RTT 0017,0max,max, +=
Study of long-term thermal effects
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Vertical gradient
Equivalent with daily solar radiation
Millau : 𝑴𝒂𝒙 𝑮𝑻𝒛 = 𝟎. 𝟎𝟎𝟐𝑹𝒕𝒉
Normandie : 𝑴𝒂𝒙 𝑮𝑻𝒛 = 𝟎. 𝟎𝟎𝟑𝑹𝒕𝒉
Vertical
gradient
ERs 12°C
assumptions 25°C
Measurements 18°C
Eurocode 18°C
Horizontal gradient
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
00:00:00 04:48:00 09:36:00 14:24:00 19:12:00 00:00:00 04:48:00
tem
pé
ratu
re (
°C)
heure
Comparaison du gradient horizontal et de la différence de températures aux âmes de rive Est et Ouest28 juin 2011 (jour de fort gradient horizontal)
Gradient horizontal équivalent
T° 4O - 4E
Horizontalgradient
ERs neglected
assumptions neglected
Measurements 4.6°C
Eurocode 5°C
Millau : GTy = 4,6°C
Normandie : GTy ~ 5°C
- GTz - GTy
Comparison Measurements - assumptions
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Study of a strong wind sequence
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Klaus Windstorm (24 January 2009)
Horizontal Vertical
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L4S - Efforts dans les haubans
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
114 134 154 174 194 214 234 254 274
Avancement (m)
Eff
ort
(kN
)
10N théorique
10N mesuré
8N théorique
8N mesuré
6S théorique
6S mesuré
11S théorique
11S mesuré
pi7P7
Comparison of measures and calculated values
▪ L4S – Tension in strands of cable stays
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Manual excitation of the first modes
Anemometer sensor to measure the wind
speed during testing
Monitoring of damping in cable stays
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Conclusion
How to comply 120 years « useful project life »
▪ A good design
▪ Tighten some calculation assumptions
(vertical prestressing of the piers)
▪ Establish an technical expert to follow the
studies, the works and the operations
▪ Carefully choose the materials (especially
for their durability qualities)
▪ Tighten constructive arrangements
(concrete cover, thickness of the steel,
installation of dehumidifiers)
▪ Specific quality procedures
▪ Good workmanship
▪ A strong and powerful engineering that
is to be competent, reactive and
independent
▪ Monitoring and maintenance
programme to put in place from the
design throughout the service life :– All parts of the structure should be easily accessible
– Late reinforcement (cable stays, prestressing) should
be possible
– Weather tracking and behaviour tracking at all
phases: construction, delivery, operation
– Measurements dedicated to operation – safe for traffic
and users - (wind speed, vibrations, opening or
extension joints)
– Control of tension and durability of the cable-stays
– Control of ageing of the concrete
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