18-maintenanceandinspectionofbridgestaycablesystems

7/31/2019 18-MaintenanceandInspectionofBridgeStayCableSystems

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MAINTENANCE ANDMAINTENANCE AND

INSPECTION OF BRIDGEINSPECTION OF BRIDGE

STAY CABLE SYSTEMSSTAY CABLE SYSTEMS

ByBy

Habib Tabat abaiHabib Tabat abai

Univers i t y o f Wisc onsinUnivers i t y o f Wisc onsin --M i lwaukeeMi lwaukee

Work shop on WindWork shop on Wind --Induc ed V ibrat ionsInduc ed V ibrat ions

St . Louis, Missour iSt . Louis, Missour i

Apr i l , 2006Apri l , 2006


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I n t roduc t ion

This w o rk i s based on NCHRPSynt hesis 353, Inspec t ion andMaint enanc e of Br idge St ay CableSyst em s, 2005.

A comprehens ive review of l i t eratu re A quest ionna ire fo r US and Canadian

agenc ies

Rev iew of t est repor t s , m aintenanc emanuals Pat e nt searc h es,


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US Invent ory

yes1991336 (1100)GeorgiaTalmadge Memorial Bridge, Savannah10

yes2003351 (1150)MissouriBill Emerson / Cape Girardeau Bridge9

yes2002366 (1200)KentuckyWilliam Natcher / Owensboro Bridge8

no1987366 (1200)FloridaSunshine Skyway Bridge7

yes1984373 (1222)LouisianaHale Boggs / Luling Bridge6

yes2003381 (1250)GeorgiaSidney Lanier Bridge, Brunswick5

yes1995381 (1250)TexasFred Hartman /Houston Ship Channel4

yes1989397 (1300)FloridaDame Point Bridge3

yes2005420 (1378)MississippiGreenville Br, US 82 Over Mississippi2

yes2005472 (1546)South CarolinaCooper River Bridge1

Surveyin?

YearSpan, m (ft)StateBridge NameNo


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Cable-St ayed Br idges int he U.S. and Canada

Cable-Stayed Bridge Constructionin the U.S.

0

2

4

6

8

10

12

14

16

18

1960

1970

1980

1990

2000

More

Years

Numb

erofBridgesBuilt

Cable-Stayed Bridge Construction inCanada

0

1

2

3

4

5

6

7

8

1960 1970 1980 1990 2000 More

Years

Numb

erofBridgesBuilt


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No. of Br idges

In t he U.S., over 40 c ab le-s t ayedbridges - t he o ldes t i s t he S i t kaHarbor Br idge in A lask a bui l t in

1970

In Canada, over 16 c able -s t ayed

bridges - t he o ldes t i s t he Nor thRom aine Br idge in Quebec bui l tin 1960.


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Moist ure ins ide Cable?

Moisture Inside Stay Cables

0.0

10.020.0

30.0

40.050.0

60.0

yes no not tested not known not

applicable

no answer

Presence of Moisture

P

ercentofBridges

U.S. Canada


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MTE Cor rosion?

MTE Corrosion

0.0

20.0

40.0

60.0

80.0

yes no not known not

applicable

no answer

Corrosion

P

ercentofBrid

ges

U.S. Canada


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Fat igue?

Fatigue of MTE

0.0

20.0

40.0

60.080.0

100.0

yes no not known not

applicable

no answer

Fatigue

P

ercentofBridges

U.S. Canada


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Crac k ing of Sheat h ing orConnect ions?

Cracking of Sheathing and Connections

0.010.020.030.040.050.060.0

70.0

yes-

sheathing

yes-

connections

yes-both

no

notknown

not

applicable

noanswe

r

Cracking

P

ercentofBrid

ges

U.S. Canada


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Met hods Ef fec t ive?Inspection, testing, monitoring and Repair Effective and

Adequate?

0.0

20.0

40.0

60.0

80.0

100.0

yes no not known

Methods Effective?

Perce

ntofBridges

U.S. Canada


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Manual Avai lab le?

Inspection & Maintenance Manual Available?

0.0

20.0

40.0

60.0

80.0

100.0

yes no not known no answer

Maintenance Manual?

PercentofBridges

U.S. Canada


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Cables Repa ired?

Cables Repaired?

0.0

20.0

40.0

60.0

80.0


Cables Repaired?

PercentofBridges

U.S. Canada


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Dam age t o Tape?

Damage to Wrapping Tape

0

20

40

60

80

yes no not known not applicable no answer

Wrapping Tape

Pe

rcentofBridg

es

U.S. Canada


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Cables Replac eable?

Can the Cables (or Strands) be Replaced?

0.0

20.0

40.0

60.0

80.0

100.0


Replaceable?

Perc

entofBridges

U.S. Canada


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NDT on St ay Cables?Non-Destructive Testing on Stay Cables?

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

magnet

ic

x-ra

y

ultrasonic

vibration-

basedforce

measuremen

ts

othe

r

notperforme

d

notknow

n

noanswe

r

NDT Methods

PercentofB

ridges

U.S. Canada


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Long-Term Moni t or ing?

Sensor Based Long-Term Monitoring?

0.020.040.060.0

80.0100.0

acoustic

wire

break

detection

vibra

tion

monitoring

force

measurem

ents

other

notperformed

notkn

own

noanswer

Monitoring

Percentof

Bridges

U.S. Canada


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Rain-Wind Vibra t ions?

Rain-Wind Vibrations?

0.020.040.060.0

80.0

ye

s

no

notknow

n

not

applicable

noanswer

Rain-Wind Vibrations

PercentofBridges

U.S. Canada


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Visc ous Dam pers Used?

Viscous Dampers Used?

0.0

20.0

40.0

60.080.0

100.0

yes - from the

beginning

yes - retrofitted

to correct

vibrations

no no answer

Viscous Dampers

PercentofBrid

ges

U.S. Canada


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Cross Cables Used?

Cross Cables Used?

0.0

20.0

40.0

60.080.0

100.0

yes - from the

beginning

yes - retrofitted

to correct

vibrations

no no answer

Cross Cables

P

ercentofBrid

ges

U.S. Canada


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Visua l Inspec t ions

I n g reat ma jor it y of cases, t h is is t he onl ym et hod ut i l ized in c ab le-s t ayed br idges.

Typ ica l ly inc lude surveys of t he ex te r io rsur faces o f c ab les, ex posed sur fac es o f

t he anc horages, c ross cab les and t he i rc onnect ions, dam pers, and c ondi t ions o fneoprene boot s and gu ide p ipes.

Inspec t ions o f neoprene r ings inside gu ide

p ipes are also per form ed in someinspect ions .


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Visual Inspec t ions (Cont .)

Boresc opes or v ideosc opes c an be used t oc hec k t he condi t ion o f t he c able andpresenc e of mois t ure inside t he gu ide p ipe.

Anc h or age c aps c an be rem o ved t o c hec k

t he cond i t ion o f w edges or but t on heads,and to c hec k fo r m o ist u re.

V isua l i nspec t ions c ould pot ent ial ly i nvolvem easurem ents o f c ab le sag and inc l ina t ion

angle by t he inspec t or f rom t he dec k levelus ing s im ple dev ic es.


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Magnet ic Flux Leak age

Long h is t o ry in inspec t ion o findust r ia l c ab les and ropes.

Syst e ms t h at c an t ravel along t hes tay c able are com m erc ial lyavai lab le .

This m et hod does not w ork w el l w i t hc ab les t ha t have s t ee l sheath ing.

The cable s ize cannot be t oo l arge ind iamete r


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Magnet ic Flux Leak age(Cont.)

The syst e m c a n ident i fy t he ex t ent ofdamage and it s loca t ion along the lengt h o fc ab le, bu t c annot ident i fy loc a t ion o fdam age w i th in the c ross sec t ion.

I n i t s c urr ent s t a t e of developm e nt , t h ism et hod c annot be used fo r inspec t ions int he anc horage zones and t he v ic in i t y o fanc horage zones. Unfor t unat e ly , t hose aret he areas w here m ost ser ious prob lem shave oc c ur red .


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Cable Forc e Measurem ent s

Using ac c e lerom e t e rs Using non-c ont ac t

sensors suc h as

laser vib rom et ers


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Cable Forc e Measurem ent s(Cont.)

This approach is t he m ost w ide lyused, and som et im es m isunders tood,NDE m et hod.

Measu rement o f c able forc es c anhe lp det erm ine i f g loba l s t i f fnessc hanges have occ ur red in c ab les .How ever, m oderat e damage, in t he

form of MTE sec t ion loss, does notnec essari l y t rans la te in t o g loba ls t i f fness c hange.


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Ult rason ic Tes t ing

A st r ess w ave is sent i nt o t he w i re ors t rand a t t he anchorage and t heref lec t ions are moni t ored and d isp layed.


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Ult rasonic Test ing (Cont .)

There has not been asys tem at i c and c ont rol ledevaluat ion o f th is m et hod t o

de te rm ine i t s degree ofe f fec t iveness fo r s t ay c ab leanchorages.

Cal ibrat ion w i t h m oc k -uprequi red.


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Seven-w i re st rand a la rger cha llenge thanind iv idua l w i res bec ause t ransm iss ion o fs t ress w aves in t hem is more c omplex .

The opera to r m ust be h ighly qua li f i ed s ince

t he judgm ent o f t he opera tor is c ruc ia l . The prob lems ar ise due to t he ancho ragem at er ia ls sur rounding t he MTE. The s t ressw ave a t t enuat es s ign i f i can t l y in a w i re

em bedded in g rout o r epoxy c om pared to aw i re in ai r .


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Th is m et hod i s not appl ied t ot he MTE in t he f ree lengt h o fcab le .

UT is t h e only k now n andprac t i ca l t es t t hat i s c u rren t l yava i lab le fo r t he assessm ent o fMTE in t he anc horage zones oft yp ic a l U.S. s t ay c ab les .


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Radiography

This met h od has t he pot e nt i al t osuc c essfu l ly assess c ond it ions o fc able anchorages w here ac c ess t ot he per im et er c an be ac h ieved.

This m e t hod w as used on t h eanc horages of the Mer id ian Br idge inCal i fornia.

Sa fe t y issue, c ost , and t ypi ca l l ylarge and heavy equipm ent haves ign i f i c an t l y l im i t ed t he ir use.


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Ac ous t i c Moni t o r ing

I t is a pass ive m on it o r i ng syst em . AM has long used t o det e c t w i re

break s in t he st ay cab le t es tspec imens.

As a w i re breaks , a s t r ess w avet ravels along t he lengt h o f t he c ab lein bot h d i rec t ions .

Ac c elerom e t ers at t ac h ed at t he

anchorage c an de t ec t t he event anddeterm ine i t s loc a t ion a long t hecab le .


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Ac ous t ic Moni t o r ing(Cont.)

The rec orded response or s ignat ure c an be ana lyzed todeterm ine i f the event i s in fac t aw i re break .

A c om m erc i al syst e m i s c u rrent l yavai lab le and has been inst a l led on anum ber of br idges.

I n g rout ed c ables , t he a t t enuat i on o ft he w ave is s ign i f i c an t l y h igher t hanin the ungrout ed c ab les .


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NDT For St ay Cab les

There is not a s i ngle m eth od t hat w ouldprov ide answ ers for a l l t he quest ionsregard ing t he c ondi t ion o f s tay c ab les .

I n most c ases , i t i s t he comb ina t i on o f NDTt echn iques toge ther w i th t he ex per ience ,

k now ledge, and judgm ent o f eng ineers ,inspec t o rs and t echn ic ians t hat c an leadt o the appropr iat e answ er .

The e ffec t i veness and accu racy o f many o ft he met hods desc r ibed above w ou ld bes ign i f icant ly enhanc ed i f base l inec om para t ive measurem ents are ava ilab le .


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Rec om m endat ions (Cont .)

Pe rform research on t he feasibi l i t y o fbu i l t -in or rem ot e inspec t ion andim ag ing sys t em s fo r mon i t o r ing o fMTE c ond it ions in t he c ab les(espec ia l ly anc horages) forincorpora t ion in to new c ab ledesigns.

Perform researc h on iden t i fy ing

appropr ia t e c ho ic e and use o fc om binat ions of NDE m et hods basedon t he c ondi t ions a t hand.


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Rec om m endat ions (Cont .)

Pe rform research on feasibi l i t y o fg lobal , 3-d im esional , physic alm apping o f s t ay cab les .

St udy t he c reat ion of a nat ional

resourc e for in form at ion on s t ayc ables and c able-s t ayed br idges

St udy c reat ion o f period ic t ra ining

program s for s t a t e eng ineers andinspectors .


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Thank You

18-maintenanceandinspectionofbridgestaycablesystems

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