9_Inspection of Steel Bridges

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Sustainable BridgesSustainable Bridges

Workshop IWorkshop I

Inspection and Condition Assessment of Railway BridgesInspection and Condition Assessment of Railway Bridges

Berlin, October 23Berlin, October 23rdrd 2424thth, 2006, 2006

Inspection of Steel BridgesInspection of Steel Bridges

Christian KammelChristian Kammel RWTH AachenRWTH Aachen


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ContentContent

Condition assessment of steel railway bridges,Condition assessment of steel railway bridges,

statestate--ofof--thethe--artart

Inspection methods for bolted, riveted and weldedInspection methods for bolted, riveted and welded

connectionsconnections

Criteria for replacement of components andCriteria for replacement of components and

connectionsconnections

Condition assessment examplesCondition assessment examples


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Condition Assessment oCondition Assessment of steel railway bridgesf steel railway bridges

No European standard availableNo European standard available

Engineering Critical Assessment methods for inEngineering Critical Assessment methods for in--serviceservice

inspection, e.g. BS 7910inspection, e.g. BS 7910-- or SINTAPor SINTAP--ProcedureProcedure

Assessment methods according toAssessment methods according to RilRil 804 and804 and RilRil 805805

Inspection plan according toInspection plan according to prENprEN 10901090--22

Standardisation at the European level intendedStandardisation at the European level intended

StateState--ofof--thethe--artart


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Tasks of Condition AssessmentTasks of Condition Assessment

Allowable loads for a given defectAllowable loads for a given defect

Critical defect for a given loadCritical defect for a given load

Minimum material properties for a given defect and loadsMinimum material properties for a given defect and loads

Remaining lifeRemaining life

Determination of inspection intervalsDetermination of inspection intervals

Criteria to be identifiedCriteria to be identified


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Conventional methodsConventional methods(assessment based on conventional design methods)(assessment based on conventional design methods)

Outcomes of conventional inspectionsOutcomes of conventional inspections

Engineering Critical assessment (ECA)Engineering Critical assessment (ECA) ECA use a combination of conventional design procedures and frECA use a combination of conventional design procedures and fractureacture

mechanics calculationsmechanics calculations

assessment of the significance and acceptability of imperfectioassessment of the significance and acceptability of imperfections for thens for the

strength and usability of structuresstrength and usability of structures

fitnessfitness--forfor--service proceduresservice procedures

Structure

Result of inspection Safe UnsafeAccepted OK Customers and societys risk

Rejected Producers risk OK (but unwanted)

Condition assessment methods for steel railway bridgesCondition assessment methods for steel railway bridges


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Application of ECA for inApplication of ECA for in--service inspectionservice inspection(deterioration may be monitored during a number of inspections i(deterioration may be monitored during a number of inspections in order to follow then order to follow the

growth of cracks, the progress of corrosion, etc.)growth of cracks, the progress of corrosion, etc.)

Levels ofLevels ofSINTAPSINTAP--procedureprocedure

Level Title Format of TensileData

Format of Toughness Data MismatchAllowance?

0 Default Yield stress only Estimation of yield/tensile ratio (Y/T) forFAD. Toughness from Charpy energy.

No

1 Basic Yield stress & UTSonly

Estimation of strain hardening exponentfrom Y/T for FAD. Fracture toughness as

equivalent Kmat.

No

2 Mismatch Yield stress & UTSof Parent Plate andweld

Estimation of strain hardening exponentof parent plate and weld metal from Y/Tfor FAD. Fracture toughness asequivalent Kmat for relevant zone.

Yes

3 Stress-Strain

Full stress-straincurve of Parent Plate(and weld metal)

FAD determined from measured stress-strain values. Mismatch option based onequivalent material stress-strain curve

Optional

4 Constraint Full stress-straincurve

Modification of FAD based on T and Qstress approaches.

Possible

5 J-Integral Full stress- straincurve

Estimation of J-integral as a function ofapplied loading from numerical analysis.

Optional

6 LBB Yield stress & UTSonly

Application to pressurised componentswith sub-critical crack growth

No

Condition assessment methods for steel railway bridges


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Aspect BS 7910 SINTAPOrigins Largely UK contributions 9 European countries contributed

Failure modes Brittle Fracture, Plastic Collapse,

Ductile Tearing, Fatigue,Corrosion, Creep

Brittle fracture, Plastic Collapse,Ductile Tearing

Structure Based on failure mode: extensivesystem of annexes

Based on data quality and hierarchyof procedure; four main chapters

Concept of

fracture andcollapse treatment

Predominantly FAD based Option of interpretation as FAD or

CDF

Fracture modes Mainly I but guidance on II and III Only Mode I

Toughnesstreatment

K, J or CTOD FAD defined only in terms ofequivalent Kmat. J used for CDF.Allowance for ductile tearing can bemade. CTOD data converted toequivalent K or J.

CharacteristicInput Values

Generalized guidance ontoughness treatment (Number oftests, weld testing) and tensileproperties.

Specific sections for definition ofcharacteristic values of tensileproperties, fracture toughness andimperfection dimensions, includingstatistical treatment for toughnessdata.

Probabilisticapproaches/safetyfactors

Guidance on Reliability, PartialSafety Factors and ReserveFactors

As for BS 7910 but additionalguidance on probabilistic methodsand associated software.

Weld Strength

Mismatch

Qualitative guidance as an annex Inherent part of procedure with

specific recommendations.

ConstraintTreatment

No specific guidance Explicit recommendations are given.

Industry specificguidance

Pipeline and Offshore None

Software Various systems available Demonstration software available forlevels 0-3 inclusive, and forprobabilistic analysis at level 1.

PrinciplePrinciple

differences ofdifferences of

BS 7910 andBS 7910 and

SINTAPSINTAP

Condition assessment methods for steel railway bridges


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RilRil 804804 (defines return frequencies of(defines return frequencies ofbasicbasic andand comprehensivecomprehensivebridge inspections)bridge inspections)

standard (basic) inspectionstandard (basic) inspection 3 years return period:3 years return period:

structural safety, bearings, sealing, drainstructural safety, bearings, sealing, drain--age, cracks, deformation, corrosion etc.age, cracks, deformation, corrosion etc.

main (comprehensive) inspectionmain (comprehensive) inspection 6 years return period:6 years return period:foundation, massive components, steel structure, riveted and bolfoundation, massive components, steel structure, riveted and bolted connections, difficultted connections, difficult

accessible components, rust grade, material testing etc.accessible components, rust grade, material testing etc.

RilRil 805805 (defines 5 different levels of assessment intensity accounting f(defines 5 different levels of assessment intensity accounting for the individualor the individualcurrent condition)current condition)

LevelLevel 1:1: Estimation of structural safetyEstimation of structural safety

Level 2:Level 2: ApproximativeApproximative determination of structural safetydetermination of structural safety

Level 3:Level 3: Assessment of structural safetyAssessment of structural safetywithoutwithout consideration ofconsideration offatiguefatigue

Level 4:Level 4: Assessment of structural safetyAssessment of structural safetywithwith consideration ofconsideration offatiguefatigue

Level 5:Level 5: Confirmation of assessment usingConfirmation of assessment using measurementmeasurement in addition to level 3 and 4in addition to level 3 and 4

For bridges in service for more thanFor bridges in service for more than 60 years60 years at leastat least Level 4Level 4 or, if necessary,or, if necessary, Level 5Level 5 isis

obligatoryobligatory



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Operating time intervalOperating time interval((RilRil 805805--Procedure used by German railway; if components show cracks or iProcedure used by German railway; if components show cracks or if assessment of thef assessment of the

remaining service life results in insufficient service liferemaining service life results in insufficient service life < 15 years< 15 years))

Stepwise procedure:Stepwise procedure:

1.1. Determination of the current structural conditionDetermination of the current structural condition

2.2. Determination of imposed loadsDetermination of imposed loads

3.3. Structural safety assessmentStructural safety assessment

4.4. Fatigue assessmentFatigue assessment

5.5. Assessment of operating time intervalsAssessment of operating time intervals

Time interval:Time interval: depending on detectable defect during inspections (e.g. crack ledepending on detectable defect during inspections (e.g. crack length angth a00= rivet head= rivet head

radius + 5 mm at rivet holes), stress level,radius + 5 mm at rivet holes), stress level,tonnage, probability of failure Ptonnage, probability of failure Pff (safety index(safety index ))


Nocrack

Nocrack

detected

detected

Nocrack

Nocrack

detected

detected

MinimumMinimum

safety indexsafety index

Remaining life [years]Remaining life [years]

Individual operating time intervalIndividual operating time intervalRelation between probability of failure PRelation between probability of failure Pff and safety indexand safety index ))


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Requirements for inspection subject to prEN 1090Requirements for inspection subject to prEN 1090--22

prENprEN 10901090--22

Execution of steel structures andExecution of steel structures and aluminiumaluminium structuresstructures Part 2:Part 2:

Technical requirements for the execution of steel structuresTechnical requirements for the execution of steel structures Stage 49Stage 49

Inspection planInspection planDocumentation ofDocumentation of

a)a) scope of inspectionscope of inspection

b)b) location and frequency of measurements;location and frequency of measurements;

c)c) acceptance criteria;acceptance criteria;

d)d) actions for dealing with nonconformities,actions for dealing with nonconformities,corrections and concessions;corrections and concessions;

e)e) release/rejection procedures.release/rejection procedures.

Methods and testing devicesMethods and testing devices

a)a) Visual inspectionVisual inspectionb)b) NDTNDT

c)c) Inspection and testing instruments selectedInspection and testing instruments selected

from those listed in ISO 7976from those listed in ISO 7976--1,1, --22

d)d) Accuracy shall be assessed in accordance with the relevant partAccuracy shall be assessed in accordance with the relevant part of ISO 8322of ISO 8322


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Inspection and acceptance criteria available forInspection and acceptance criteria available for

-- Bridge superBridge super--structurestructure

-- Orthotropic decksOrthotropic decks

-- Verticality of bridge columnsVerticality of bridge columns-- Bridge supportsBridge supports

-- Hollow sectionsHollow sections

-- Local Hardness and quality of cut surfacesLocal Hardness and quality of cut surfaces

-- Inspection of corrosion protectionInspection of corrosion protection of membersof members

incl. overincl. over--painting, overpainting, over--coating, subsequent welding, surface repair by metal sprayingcoating, subsequent welding, surface repair by metal spraying

-- Inspection and repair of bolted connectionsInspection and repair of bolted connections

-- Inspection and repair of hot rivetsInspection and repair of hot rivets

-- Inspection and repair of welded connectionsInspection and repair of welded connections

Requirements for inspection subject to prEN 1090Requirements for inspection subject to prEN 1090--22


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Inspection of components

Inspection of corrosion protectionInspection of corrosion protectionin accordance with EN ISO 12944in accordance with EN ISO 12944--7; for paints and varnishes acc. to EN ISO 19840;7; for paints and varnishes acc. to EN ISO 19840;

defect: excessive corrosion, loss of surface treatment;defect: excessive corrosion, loss of surface treatment;

remaining thickness of the surface coating (zinc, paint etc.) caremaining thickness of the surface coating (zinc, paint etc.) can be metered byn be metered by

magnetmagnet--inductive devices, if coating is noninductive devices, if coating is non--ferromagneticferromagnetic(alternative ultrasonic, eddy current method)(alternative ultrasonic, eddy current method)

Actions for correctionActions for correctionassessment with reduced cross section;assessment with reduced cross section;

if necessary, calculation of strengtheningif necessary, calculation of strengtheningmeasures for members to increase theirmeasures for members to increase their

resistance against crack growth;resistance against crack growth;

replacement by new members orreplacement by new members or

componentscomponents

+

+

=

2

2

angle3

req

actlamella

h

e8

h

e82A2

3

th1

N

NA

with

Nact = maximum permissible number of load cycles, determined by a fracture mechanics

calculation using a certain stress range calculated with the actual cross sectionNreq = number of load cycles with a certain stress range between two inspections

Aangle= cross section of the rolled angle profiles

e = distance between the neutral axis of rolled angle profiles to the outer edge of one ofits flanges

B < C e = 0,27B

B = C e = 0,30B

B > C e = 0,37B

Figure Calculation of the required cross section Alamella to strengthen a plate girder undercyclic bending load, to increase the maximum permissible number of load cyclesHensenHensen 19921992


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Inspection of bolted connections

Visual inspectionVisual inspectiontypical bolt defects: missing bolt/nut, residual gaps max. 2 mm,typical bolt defects: missing bolt/nut, residual gaps max. 2 mm, excessive corrosion,excessive corrosion,

bolt protrusion shall be not less than one full thread pitchbolt protrusion shall be not less than one full thread pitch

Sequential inspection methodSequential inspection methodacc. to ISO 8422; applicable to bolt groups or groups of rivetsacc. to ISO 8422; applicable to bolt groups or groups of rivets

Inspection of bolt preloadInspection of bolt preloaddefect:defect: lossloss ofofpreload due to relaxation and settlement;preload due to relaxation and settlement;

apply specific torque moment and inspect further rotation angleapply specific torque moment and inspect further rotation angle of the nut;of the nut;recommended: less than 15recommended: less than 15 rotation at 110% of specified minimum preloading forcerotation at 110% of specified minimum preloading force

Ultrasonic method for direct measurement of preload forceUltrasonic method for direct measurement of preload force

Actions for correctionActions for correctionretightening up to 110% of specified minimum preloading force;retightening up to 110% of specified minimum preloading force;

replacement by new bolt assemblies, check of holes for cracks, preplacement by new bolt assemblies, check of holes for cracks, pits or hole distortionits or hole distortion

and if appropriate, reaming of holes with larger diameterand if appropriate, reaming of holes with larger diameter


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Sequential inspection for bolted connections acc. to ISO 8422Sequential inspection for bolted connections acc. to ISO 8422


Random sample testRandom sample test

type Atype A

type Btype B

Number of assembliesinspected

0

1

2

3

4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17Numberofdefectiveassemb

lies

Minimum n of inspections : 5

Maximum nof inspections :16

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142

Number of assemblies

inspected

Numberof

defective

assemblies

Minimum n of inspections : 14

Maximum n of inspections : 40


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4

0

1

2

3

4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

A

A

R

R

A

5


EXAMPLES

A The 4th and 8th bolts were found defective. Inspection was continued until crossing the vertical truncation line.

The result is acceptance of the bolt tightening operation, subject to corrective actions on the two defective bolts.

R The 2nd, 6th and 12th bolts were found defective. Exit from the uncertainty zone is into the refusal zone.

The result is negative and the inspection is extended to 100% of the bolt assemblies.

1: Refusal Zone

2: Uncertainty zone

3: Acceptance zone4: Number of assemblies inspected

5: Number of defective assemblies

Example of sequentialExample of sequential

inspection diagraminspection diagram

Random sample test (type B in case of significant effects of fatRandom sample test (type B in case of significant effects of fatigue);igue);

minimum of 14 and maximum of 40 bolt assemblies to be inspectedminimum of 14 and maximum of 40 bolt assemblies to be inspected

Sequential inspection for bolted connections acc. to ISO 8422Sequential inspection for bolted connections acc. to ISO 8422


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elative difference of the running time (t - t0) / t0 of a longitudinal and a transversalultrasonic wave as a function of bolt strain

developed bydeveloped byFraunhoferFraunhofer--IZfPIZfP SaarbrSaarbrckencken

Comparison of bolt strains evaluated from combined ultrasonic method and fromconventional strain gauge measurement

Advances in ultrasonic testing for bolted connectionsAdvances in ultrasonic testing for bolted connections

Combined Ultrasonic methodCombined Ultrasonic methodInnovative technique for directInnovative technique for direct

measurement of actual bolt stressesmeasurement of actual bolt stresses


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Inspection of riveted connections

Visual inspectionVisual inspectiontypical rivet defects: nontypical rivet defects: non--satisfactory contact,satisfactory contact,

cracks or pits, excessive corrosion, loss of precracks or pits, excessive corrosion, loss of pre--stressstress

Inspection of satisfactory contactInspection of satisfactory contactby lightly ringing the rivet head with a hammer of 0,5 kg;by lightly ringing the rivet head with a hammer of 0,5 kg;

useuse sequentialsequential inspection method type A acc. to ISO 8422inspection method type A acc. to ISO 8422

Actions for correctionActions for correctionreplacement by new rivets;replacement by new rivets;

cutting out by means of a chisel or by cutting;cutting out by means of a chisel or by cutting;

check of holes for cracks, pits or hole distortioncheck of holes for cracks, pits or hole distortion

and if appropriate,and if appropriate, reaming of holes with larger diameterreaming of holes with larger diameter


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Hot rivet characteristicsHot rivet characteristics

Rivet propertiesRivet properties Calculative friction coefficientCalculative friction coefficient = 0,25= 0,25

Distinction betweenDistinction between loadload--bearing rivetsbearing rivets inin

structural connections andstructural connections and tack rivetstack rivets toto

transfer clamp forcestransfer clamp forces

PrePre--stress in rivetsstress in rivets Usually between 20 to 220 N/mm acc. to literatureUsually between 20 to 220 N/mm acc. to literature

Average preAverage pre--stress approx. 100 N/mm dependingstress approx. 100 N/mm depending

on diameteron diameter

Clamp length has main influence on preClamp length has main influence on pre--stressstress

Serviceability may be affected in case of loss of preServiceability may be affected in case of loss of pre--stressstress

External loads

Stress distribution in

case of load-bearingby bearing forces

Stress distribution incase of load-bearingby friction

Stress distribution in pliesStress distribution in pliesof riveted connectionsof riveted connections

0

50

100

150

200

250

300

0 20 40 60 80 100 120 14

Clamp length [mm]

Pre-

stress

[N/mm]

22: maximum values

22: minimum values

25: measured values

20: maximum values

20: minimum values

20: measured values

PrePre--stress depending on clamp lengthstress depending on clamp lengthand diameter for rivet material St44and diameter for rivet material St44


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Defect 1: Rivet shank to long Defect 2: Closing head tosmall, Rivet shank to thin Defect 3: Closing head to smallor offset, Rivet shank withoutcontact

Defect 4: Plies in skew position Defect 5: Excentric applicationof rivet header or rivet punch

Defect 6: Offset rivet heads dueto corrections

Defect 7: Rivet punch put on inskew position

Defect 8: Rivet header put on inskew position

Defect 9: Insufficient headform, damage by rivet header

Defect 10: Rivet header to

small, peripheral rim at closinghead

Defect 11: Bulged-out closing

head

Defect 12: Rivet punch and

closing head in skew position

Investigation on tolerableInvestigation on tolerablecorrosion of rivetscorrosion of rivets

Aim: Influence of rivetAim: Influence of rivetdefects on predefects on pre--stressstress

Hot rivet defectsHot rivet defects

Kennel 1951Kennel 1951


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Effect of representativeEffect of representativecorrosion damagescorrosion damages

Inclinedcorrosion /

deformation(angle 22,5)

Constantcorrosion of

4 mm (56 V-%)

Constantcorrosion of

2 mm (32 V-%)

No damage

damage type 3damage type 2damage type 1damage type 0

39.0

26.0

13.0

16.5

31.0

26.0

39.0

26.0

35.0

26.0

Rivet head degradationRivet head degradation

Numerical modelling of rivet preNumerical modelling of rivet pre--stressstressand decrease of resistance capacityand decrease of resistance capacity


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Investigation on tolerable corrosion of rivetsInvestigation on tolerable corrosion of rivets

DT 0: Stress up to yield strength fy

DT 1: Stress in shaft up to 170 N/mm

DT 2: Stress in shaft up to 118 N/mm - Failure by slipping

DT 3: Stress in shaft up to 101 N/mm - Failure by slipping

Influence of rivet head degradationInfluence of rivet head degradation

exemplary calculationexemplary calculation

for rivetsfor rivets 2626

0.0

50.0

100.0

150.0

200.0

250.0

0.00% 0.01% 0.02% 0.03% 0.04% 0.05% 0.06% 0.07% 0.08% 0.09% 0.10%

Extension of rivet shank

Stress[N/mm]

KL=33 - S0KL=33 - S1

KL=33 - S2

KL=33 - S3

Conclusion:Conclusion:

Constant corrosion up to 50 VConstant corrosion up to 50 V--%%

uncritical for preuncritical for pre--stressstress

Inclined corrosion more criticalInclined corrosion more critical


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Test setTest set--up with representative rivet head degradationup with representative rivet head degradation

Direction of machining Direction of machining

Washer

Load cell

Nut for tightening


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40

45

50

55

60

65

0 10 20 30 40 50 60 70 80 90

Zeit [min]

Nietkraft [kN]

Einbau

und

Setzung

Abfrsen in 12 Schritten

Nachspannen des Niet

auf 53 kN

Abfrsen in 6 Schritten

Rivet force [kN]

Time [min]

Installationandsettlement

Milling in 12 stepsMilling in 12 steps Milling in 6 steps

Re-stressing of rivetup to 53 kN = 100 N/mm2

Decrease ofDecrease ofrivet force for oblique millingrivet force for oblique milling(inclination angle of 30(inclination angle of 30))

Remaining preRemaining pre--stress of rivetsstress of rivets


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Relation between rivet force and corrosion/millingRelation between rivet force and corrosion/millingfor rivet head degradation parallel to pliesfor rivet head degradation parallel to plies

50%

55%

60%

65%

70%

75%

80%

85%

90%

95%

100%

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Milling / Corrosion [mm]

Rivet force[%]

Volume of rivet head[%]

78%

50% of the

height of rivet head

42% of theheight of rivet head

Remaining preRemaining pre--stress of rivetsstress of rivets


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FatigueFatigue test:

Pre-stress of 80 N/mm

1,5 x stress amplitude (120 N/mm)

2 Mio load cycles

Result: No failureResult: No failure

Result ofResult ofcalculation:calculation:Inclined or constant degradation to a remainingInclined or constant degradation to a remaining head volume of 56% is safehead volume of 56% is safeProposedProposed ultimate limit for rivet head:ultimate limit for rivet head: 100 N/mm100 N/mm

ProposedProposed serviceability limitserviceability limit for riveted connections:for riveted connections: 90% of initial rivet force90% of initial rivet force

Result: Inclined degradation to remainingResult: Inclined degradation to remaining head volume of 78% is tolerablehead volume of 78% is tolerable

Proposed criteria for replacement of rivetsProposed criteria for replacement of rivets

Result ofResult oftests:tests:Minor corrosion: decrease of preMinor corrosion: decrease of pre--stress is caused by reduction of head stiffness, not by yieldingstress is caused by reduction of head stiffness, not by yielding

Increased corrosion: yielding occurs locally limited with load tIncreased corrosion: yielding occurs locally limited with load transfer into lower stressed areasransfer into lower stressed areas

Recommendation:Recommendation:

Replacement of rivets, if head degradation reaches serviceabilitReplacement of rivets, if head degradation reaches serviceability limity limit


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Inspection of welded connections

Visual inspectionVisual inspectionto be performed in accordance with EN 970;to be performed in accordance with EN 970;

typical weld defects: surface cracks, notches, cavities, slag, stypical weld defects: surface cracks, notches, cavities, slag, spatter, arc strikespatter, arc strikes

Standard NDTStandard NDT--techniquestechniquesto detectto detect internal imperfections and fatigue cracks, usually starting frominternal imperfections and fatigue cracks, usually starting from HAZ;HAZ;selectionselection acc. to EN 12062:acc. to EN 12062:

a)a) liquidliquid penetrantpenetrant testing (EN 571)testing (EN 571)

b)b) magnetic particle inspection (EN 1290)magnetic particle inspection (EN 1290)

c)c) ultrasonic testing (EN 1713, EN 1714)ultrasonic testing (EN 1713, EN 1714)

d)d) radiographic testing (EN 1435)radiographic testing (EN 1435)

e)e) eddy current testing (EN 1711)eddy current testing (EN 1711)

Acceptance criteria for welds acc. to EN ISO 5817 (quality levelAcceptance criteria for welds acc. to EN ISO 5817 (quality level B at least)B at least)

Actions for correctionActions for correctionWeld improvement by Ultrasonic Impact Treatment (UIT) = HammerinWeld improvement by Ultrasonic Impact Treatment (UIT) = Hammering by ultrasonicg by ultrasonic

pulsespulses fatigue resistance can be increased by 1,5fatigue resistance can be increased by 1,5 2,1;2,1;

crack arrest by drilling at crack tip; replacement of welds by ncrack arrest by drilling at crack tip; replacement of welds by new onesew ones


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Visualization byVisualization by

macro specimenmacro specimen

crack initiation startingcrack initiation startingfrom residual gaps offrom residual gaps of

actual root penetrationactual root penetration

Problem:Problem: Fatigue crackFatigue crackpropagation in weldspropagation in welds sometimes not detectablesometimes not detectableby traditional NDTby traditional NDT--methods, e.g. formethods, e.g. for cruciform jointscruciform joints

Inspection of welded connections


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Advances in ultrasonic test methods for weldsAdvances in ultrasonic test methods for welds

Crack detection in TCrack detection in T--jointsjoints

and cruciform jointsand cruciform joints

Echoes of edge wavesEchoes of edge waves

at a nonat a non--penetrated weldpenetrated weld

Application of acoustic lensesApplication of acoustic lenses

EmitterEmitter

ReceiverReceiver

Acoustic axis of theAcoustic axis of the

reflected sound beamreflected sound beam


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x = 2a

x = a

Test setup using diagonalTest setup using diagonal

focused sound beamsfocused sound beams

Ultrasonic testing deviceUltrasonic testing device

Innovative ultrasonic testing of cruciform jointInnovative ultrasonic testing of cruciform joint



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x = a

Ultrasonic testingUltrasonic testing

of cruciform jointof cruciform joint

0

4

8

12

16

20

24

0 20 40 60 80 100 120 140 160 180 200

Testing position [mm]Fatiguecracklength[mm]

line of rest 6

line of rest 5

line of rest 4

line of rest 3

line of rest 2

line of rest 1

line of rest 0

Crack length + Residual gap measurementCrack length + Residual gap measurement

Macro specimenMacro specimen

BrittleBrittle

fracturefracture

Lines of rest of fatigue crackLines of rest of fatigue crack



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Example 1:Example 1: KKlnln HauptbahnhofHauptbahnhof


Condition assessment according toCondition assessment according to RilRil 805805 Application of sApplication of stepwise assessment procedure (Determination of current structuratepwise assessment procedure (Determination of current structural condition,l condition,

imposed loads, structural safety assessment, fatigue assessment,imposed loads, structural safety assessment, fatigue assessment, assessment of operating time intervals)assessment of operating time intervals)

Strain measurements to gain information about realistic fatigueStrain measurements to gain information about realistic fatigue loadsloads

Comparison of calculated and measured fatigue stressesComparison of calculated and measured fatigue stresses

Determination of appropriate operating time interval for individDetermination of appropriate operating time interval for individual bridge spansual bridge spans

Single span bridge each with two riveted mainSingle span bridge each with two riveted main

girders and a span length of 8,35 mgirders and a span length of 8,35 m


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Figure Example for a measured strain-time-history

Figure PC plug-in data acquisition device


Example 1:Example 1: KKlnln HauptbahnhofHauptbahnhof

Results of condition assessmentResults of condition assessment Measured stresses are lower than calculated onesMeasured stresses are lower than calculated ones

No remedial actions necessaryNo remedial actions necessary

Determination of appropriate operating time interval for individDetermination of appropriate operating time interval for individual bridge spansual bridge spans

Train type 215Train type 215


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Example 2: Canal bridgeExample 2: Canal bridge RendsburgRendsburgCondition assessment and inspectionCondition assessment and inspection Measurements to gain information about the real structuralMeasurements to gain information about the real structuralbehaviourbehaviour under criticalunder critical horizontalhorizontal loadsaloadsa

due todue tobraking and tractionbraking and traction ofoftrainstrains

Good agreement between calculated and measured stresses (calculaGood agreement between calculated and measured stresses (calculation under deteriorated conditions)tion under deteriorated conditions)

Inspection with NDT proves necessity of remedial measuresInspection with NDT proves necessity of remedial measures

Determination of operating time intervalDetermination of operating time interval

Train for braking testTrain for braking test

on canal bridge (built in 1912)on canal bridge (built in 1912)

Static systemStatic system

Comparison of calculatedComparison of calculated

and measured stressesand measured stresses

StressStress--time history measured during braking testtime history measured during braking test

at diagonal bracings of longitudinal sides of piersat diagonal bracings of longitudinal sides of piers


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Available ReportAvailable Report

Sustainable Bridges Deliverable D3.4:Sustainable Bridges Deliverable D3.4:

Condition assessment and inspection of steelCondition assessment and inspection of steelrailway bridges, including stress measurementsrailway bridges, including stress measurements

in riveted, bolted and welded structuresin riveted, bolted and welded structures


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Related WorkRelated Work

NDT toolboxNDT toolbox


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Related WorkRelated Work

Representative of a common type of steel bridges in EuropeRepresentative of a common type of steel bridges in Europe

--Located inLocated inAvesnesAvesnes, central France, central France

a)a) Test of damage detection and assessment methodsTest of damage detection and assessment methods

(corrosion, cracking, capacity);(corrosion, cracking, capacity);

b)b) Monitoring by repeated measurementsMonitoring by repeated measurements

Repair and strengtheningRepair and strengthening (WP6)(WP6)

Field test of old riveted steel bridgeField test of old riveted steel bridge (WP7)(WP7)

Demonstration activitiesDemonstration activities --

Bridge MonitoringBridge Monitoring (WP8)(WP8)


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Thank you for your attention!Thank you for your attention!

Questions and comments?Questions and comments?

Date post:	03-Apr-2018
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9_Inspection of Steel Bridges

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