Suspension Bridge Freyssinet technologies

FREYSSINET SUSPENSION BRIDGES TECHNOLOGIES

2Freyssinet suspension bridges technologies

• Which technology have almost not changed since 70

years?


Suspension bridge cable

Freyssinet has done:

more than 200 stay cable bridges

and 22 suspension bridges


The start: Main suspension cableBundle of big strands

• Traditional system:– Bundle of big strands

• Old system, used up to 600m• Low anticorrosion protection

Design life ~ 20 to 35 ans


Main suspension cableThe past and now:

• Traditional solutions– Air spinning (USA)

– PPWS (Japan)

Very little evolution since 1935

Golden gate


Main suspension cableFreyssinet propose 2 solutions

• Freyssinet New solutions1. Cohestrand suspension cable

– Individually protected strand – For span up to 500m

2. F Spinning: Freyssinet Spinning– Bundle of wire, same cross section with

dehumidification– Fast erection process– Lower cost– Very compact anchorage chamber


Main suspension cable1.Cohestrand: Technology derived from the stay technology.

• Cable system using the same– Mechanical propreties

– Corrosion protection (no gangrene effect)

– Installation with light equipment

• Main problem to be solved: – Take the longitudinal sliding force in the collar

Bonding compound


Main suspension cable1. Cohestrand

• 7 wire strand 15.7 (stay type) :– 1770 or 1860 MPa

– fatigue class 300 MPa

• Anticorrosion protection – Galvanisation

– Special resin filing allowing a 7MPA shearing capacitybetween HDPE and steel.

– Outer HDPE (1,5mm)


Main suspension cableMain cable anchored with H2000 stay anchor.


Main suspension cableMulti-tubes saddle

• Individual strand deviation


Main suspension cableNo bolt collar

• Friction taken by conical wedges, self locking band, no bolts

• All strand receive equal hydrostatic pressure


Main suspension cable5 years testing

• Checking of the collar behaviour during 5 years

• A shearing of 1 MPa at 70°C indicate a displacement of less than1.5mm over 100 y


Main suspension cableDynamic test

• Dynamic test on a

19 strand bundle


• Dynamic test simulating a hanger force

• After 4,3 millions cycles (equivalent to a 50 y trafic), The collar isdismantle with no sign of wear or tear.

Force

Time

50 cycles : representing haner replacement

250 000 cycles : 0.6 A(l)

2 millions cycles : Bc trucks then 2 millions cycles : 0.6 A(l)

Main suspension cabledynamic test


Main suspension cableSliding test

• on 75 T15 collar :– Strand pulling

– Until failure

• Conclusion : Sliding

safety factor of 6 at SLS


Kanne bridge (Belgique)

• 2nd bridge using this technology

• Road bridge spanning 96m.

• 2 x 75 strands cables


Kanne

• Prefab cable

• Pylon head– Back stay crossing main cable

– Cable placed with crane


Kanne

• Clamping of collar with

3 jacks at 1000kN


Placing of the main cable fully finished withcable collars


Waiting for hangers


Stressing of hangers from the bottom.


Kanne during adjustment of hangers


1. Cohestrand systemCONCLUSIONS

• Cohestrand the most durable solution– Limitation at 500m main span with 2 main cables or 700m with

4 main cables

– A free maintenance system requiring no dehumidificationperfect for medium span bridges

– Design life of 100 years

– Safety factor can be reduced from 3.5 to 2.5 since the steel hasno transverse stress


2. The F Spinning

• For very long span bridges only Air spinning and PPWS have been used

• Cross section is the same bundle ofwires

• Corrosion protection is poor exceptwith dehumidification


Air spinning

• Traditional air spinning is using a wheel on a cable car.

• "strand shoe » at Anchorage


Air spinning

• (cat-walk) access– To group all wires

– Compact the cable


Air spinning (USA)

• Cable compaction

• Corrosion protection:– Zinc paste placing

or

– Déshumidification

• Expansive and slow system


PPWS (JAPAN)

• Launching of group of wire (127- 169) prefabricated (PWS)

• Pulling with winches or heavy cable car

• résine ou au zinc anchorages


PPWS

• Placing of cable bundle

• Compaction


New F Spinning System

• The Freyssinet Spinning

• Freyssinet have developped and patented a new system :– Special Multi 7 wires PWS + drying option in the free length

– No prefabrication of the PWS

– Anchoring by individual wedges, allowing compact anchoragechamber


F Spinning assembly

• 6 galvanised wire dia.5,2 mm + 1 wire dia. 5,3 mm

• Equivalent to a 7 wire strand

• Eg. One F Spinning of 133 wireinclude 19 quasi strand of 7 wires

+

X 19


F Spinning system

• On site fabrication


F Spinning on site fabrication

Eg. 5 rows of 14x 5mm wires, on 2 parallel racks

Assembly of 19x7 wires

Wire assembledin 7 parallelwires


F Spinning erection

• Similar as PPWS : – Pulling directly from wire with winches or cable car

– But fabrication directly during the pulling automatic

– No anchorage during the pulling


F Spinning anchoring

• After erection,– The F Spinning is splitted in 19 « strands »

– Anchoring with Freyssinet stay jaws

• 19 x 7 = 133 fils, so the maximum used in PWS with no anchorage to move

• Anchorage up to 2000 strands.

• Up to 340 strands manufactured

with classical equipment.


Anchorage chamber

• Anchorage could be place at the back of anchorage chamber

• This avoid any relay bar

• Chamber get more compact

• Tuning could be done by isotension


Example Chiloe bridge

• 2 Spans of 1200m

• Main cable with 9120 wire diameter 5.22mm– So 1304 « quasi strand" of 7 wires, so 4 x 326 strands

anchorages

– Launching in 69 PWS of 133 wires

• Conclusions : – Erection in 2 months (2 to 3 times less) PPWS (4 months, air

spinning 6 months

– Anchorage reduced from (11m x 10 m) to (3m x 4m)


Classical chamber


FPWS chamber


FPWS chamber


Combinaison suspension stay cable

Example of a Tancarville bridge :

Span 608m:

Suspension bridge: Main cable: 3000t

Combined suspension stay cable: 1500t main cable + 320 t stay cable


Inventory, Visual Inspection, Risk Analysis and decision support, Investigation & Health Monitoring

ScanPrint®Inspection & Maintenance Database system

Risk Based Inspection & Maintenance Manual

InstrumentationRisk Based Health Monitoring

Integration of traditional sensors

Remote Surveillance in real time of the healthiness, behavior environmental conditions

Monitoring during construction

FOS®Fiber Optic System

SoundPrint®Acoustic Monitoring

Wire detection and crack follow-up

CableScan®Control of Cable Condition

SlotStress®Stress Measurement in Concrete

Upus®PC bars tension Measurement

Tensiomag®PC Strand Tension Measurement

P-wave®Inspection of concrete pipelines

6. Monitoring and asset managementAdvitam products for structural assessment & maintenance


ScanPrint : Inspection & Maintenance system• Management of inventory data : description of structural stock• Visual inspection• Data analysis• Decision and scheduling of maintenance actions : investigationand repair

6. Monitoring and asset managementInspection & maintenance


3. Maintenance and replacementRoutine maintenance

• Stay cables require solely inspection to meet the design lifetime

• Freyssinet proposes a maintenance manual– Periodic visual inspection

– Witness strand replacement is possible (20 years)

• ScanPrintTM software for inspection & maintenance records


Rion Antirion

•Computerized maintenance manuals•Monitoring•Risk assessment


Vasco De Gama

•Computerized maintenance manuals•Risk assessment


Normandy bridge•Computerized maintenance manuals


Confédération Bridge

•Computerized maintenance manuals•Risk assessment


Parsons Transportation GroupMackinac suspension bridge66% of time saved at second inspection


BDS New York: bridge data system

Development of a Customized Application

• Software for Continuous inspection follow-up of all Bridges in New York City


Zilwaukee bridge


The system detects and localizes the sounds emitted by the energy released

during wire breakage

Sensors are distributed on the structure allowing a global and continuous monitoring

Structure Post tensioned structure

Cable / strand / wire

Acoustic sensor

InstrumentationRisk Based Health Monitoring

Integration of traditional sensors

Remote Surveillance in real time of the healthiness, behavior environmental conditions

Monitoring during construction

FOS®Fiber Optic System

SoundPrint®Acoustic Monitoring

Wire detection and crack follow-up

Library of acoustic signature of known events allow identification of captured noises


3. Maintenance and replacementPermanent monitoring

• SoundPrintTM acoustic monitoring– Detection of wire breaks

Wave propagation enables

wire break localization

Recalculation of safety factor

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SE

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OR

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WIRE BREAK !

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SoundPrint allows early detection and localization of internal wire breaks

And filtering of ambient noise

Processing center

structure

Local DAQ Unit

Sensors

Internet

Real time Internet access

Internet

Owner

Road traffic

Grouted wire


Cable Stayed Bridges


Suspension Bridges


3. Maintenance and replacementPermanent monitoring

• Accelerometers placed along cables– Vibration amplitude

– Damping assessment






P-wave®Control of concrete pipelines

CableScan identify presence of section loss or broken wires in accessible cables


Cable Scan

• Magnetostriction pulse• Generate high frequency (acoustic)

vibrations in suspender• Acoustic pulse travels up & down

suspender rope • Defects reflect a portion of the pulse • Reflections are measured to identify

the presence of section loss or broken wires

Tran

smitt

ed W

ave

Reflected Wave

Acoustic Pulse Generator & Detector

Corrosion


Cable scanInspection of G. Washington Bridge


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UPUS





P-wave®Control of concrete pipelines

Utrasonic tension measurement in bars.

Improve and replace traditional lift off method.


Collar bolt force checkingUPUS

Tension control on bolts of Collars on suspension bridges

Prestressed bars in Nuclear plants

Lifting control

Monaco Dam

Documents

Suspension Bridge Freyssinet technologies