guide line for inspection of overhead crane structure

7/30/2019 Guide Line for Inspection of Overhead Crane Structure

1/43

GuidelinesforInspecting

OverheadCrane

Structures

May20,2011

PreparedBy:

GaryJ.Davis,P.E.DirectorofConsultingServices

Integrated

Machinery

Solutions

(IMS)

FortWorth,Texas

TexasRegisteredEngineeringFirm#11499

www.teamims.com [email protected] 8176592399


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Section Description Page

1.0 Introduction 4

1.1

Purpose

41.2 Scope 4

1.3 LimitationsofthisGuide 4

2.0 OrganizationandPersonnel 5

2.1 ImplementationofaDisciplinedPlan 5

2.2 PrerequisitesforaQualifiedInspector 5

2.3 RecommendedInspectionTeam 6

3.0 InspectionSafety 6

3.1 PreInspectionSafetyPlan 6

3.2

SafelyManeuvering

on

the

Structure 6

3.3 IdentifyingHazards 7

3.4 HighAmbientTemperatures:PrecautionsandPlanning 7

3.5 PersonalSafetyEquipment 8

4.0 PlanningandPreparation 8

4.1 CleaningtheStructure 8

4.2 AerialWorkPlatforms 8

4.3 OtherInspectionParaphernalia 9

5.0

GeneralInspection

Guidelines 10

5.1 GettingStarted 10

5.2 WheretoLook 10

5.3 OtherInspectionGuidelines 10

6.0 TrolleyStructureInspection 11

6.1 TrolleyStructureInspectionPoints 11

7.0 BridgeStructureInspection 13

7.1 BridgeGirderInspectionPoints 13

7.1 BridgeGirderInspectionNotes 15

7.2

BridgeEnd

Truck

and

End

Tie

Inspection

Points 20

7.2 BridgeEndTruckandEndTieInspectionNotes 20

7.3 BridgeMiscellaneousInspectionPoints 22

TableofContents


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Section Description Page

8.0 HighStrengthBoltedConnections 23

8.1 BoltedConnections:DescriptionandFunction 23

8.2 HowtoCheckforBroken,Damaged,andLooseBolts 23

8.3 RivetedCraneConstruction 23

8.4

RivetInspection

24

8.5 CautionsforReuseofBolts 24

8.6 CheckingforProperFastenerHardware 24

9.0 InspectionIntervals 26

9.1 WhentoInspect 26

10.0 BasicStructureBehavior 27

10.1 WheretoLook 27

10.2 Tension,Compression,andBending 27

10.3

Shear

2810.4 DeflectionandCamber 28

10.5 Buckling 29

10.6 EffectofWelding 29

10.7 StressConcentrationandFatigue 29

10.8 AttachmentsCreateDiscontinuities 32

10.9 SingleFailurepoints 34

10.10 ManufacturingQualityandFatigueResistantDesignDetails 34

11.0 TrolleyStructureBehavior 35

11.1 TrolleyStructureDesign 35

11.2

TrolleyDeflection

36

12.0 BridgeStructureBehavior 37

12.1 BridgeStructureDesign 37

12.2 BridgeStructureResponsetoLateralLoadsandSkewing 37

13.0 ExamplesofCraneStructureDamage 38

14.0 References 42


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1.1 PurposeThis guide provides a comprehensive set of recommendations for structural inspection of

overheadbridge

cranes

and

trolley

hoists.

Emphasis

is

placed

on

knowing

where

to

look

for

structuraldamage. Basicconceptsareintroducedforidentifyinghotspotsonthestructure,

andareaspronetofatigue. Thisguideisintendedforplantmaintenancepersonnelandcrane

service technicians who are responsible for periodic, visual structural inspections. This guide

will also be useful for entry level engineers and experienced engineers who are new to field

inspection.

Because structures are so reliable, it is easy to lose sight of their fundamental importance.

Failure to complete overhead crane and hoist inspections and proper equipment

maintenancecouldleadtoseriousinjury,deathordestructionofproperty1.

Implementationof

acomprehensive

and

disciplined

inspection

plan

has

the

following

benefits:

Reducedchanceoffatalityorinjurytopersonnel. Reducedliabilityexposure. Improvesequipmentproductivity. Prolongsequipmentservicelife. Ensurescompliancewithlaws,codes,andstandardsincluding:OSHA,ANSI,andASME.

1.2 ScopeThisguideisforoverheadbridgecranestructuresincluding:

Bridgegirders. Bridgeendtrucks,endties,equalizersaddles,sillbeams. Platforms,ladders,stairs,cabs. Boltedandweldedconnections. Trolleyframes,trolleyendtrucks.

1.3 LimitationsofthisGuide This information is not a substitute for prevailing inspection standards for cranes and

structures, or recommended inspection procedures provided by original equipment

manufacturers.

Thisguideisintendedtosupplementthetrainingandexperienceofpersonnelwhoarealreadyqualifiedtoperformstructuralinspectionsofoverheadcranes.

1TheCrane,HoistandMonorailAlliance,anOSHACooperativeProgram,FactSheetNo.1,ProperInspectionand

MaintenanceofOverheadCranes,http://www.mhia.org/industrygroups/osha

1.0 Introduction


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Duetothewidevarietyofcraneapplicationsandequipmentconfigurations,thisguidecanonlyprovidegenericguidance. Inspectionprovisionsforspecialapplicationsmay

not be addressed here. Special applications not addressed here include: under

running cranes, patented track systems, stacker cranes, jib cranes, portal cranes,

gantrycranes,

packaged

trolley

hoists,

crane

runways,

and

below

the

hook

equipment.

2.1 ImplementationofaDisciplinedPlan

Thefirststepindesigningahighqualityinspectionprogramistocreateacontrolleddocument

manualcontainingworkinstructionsandprocedures. Themanualshouldbealivedocument

thatiscontinuouslybeingimproved. Manualsfacilitateasystematicandrepeatableapproach,

and set definite standards. Manuals also facilitate seamless transitions during changes in

personnel.

They

help

train

new

people,

and

identify

existing

plans

to

new

managementpersonnel. Ataminimum,themanualshoulddefinethefollowing:

Personnelresponsibilitiesandauthorities. Minimumrequirementsfortrainingandcertificationofinspectors. Provideinspectionformscustomizedforvariouscranesintheplant. Standardsfordocumentationandrecordkeeping. Wheninspectionsshallbemade. Minimuminspectionintervals. Levelofdetailtobecarriedoutforvariousinspectionintervals. Criteriaforreportingsuspectandproblemareastotheresponsibleengineer.

Theentireprogramshouldbecloselymonitoredandsupervisedbyanengineerwhoisqualified

to design and inspect structures. Each inspection should be reviewed and approved by the

responsibleengineer. Toensurethatinspectionsaremeetingminimumqualitystandards,the

responsible engineer should perform inspections of recently inspected cranes (periodically at

randomintervals).

For longinterval inspections of major process cranes, hire a consulting engineer to do the

inspection. It is important that the selected firm specializes in inspection and design of

overheadmaterialhandlingequipment. Byperiodicallyhiringanoutsideexpert, itprovidesa

goodcheckonthequalityofyourinhousesystem.

2.2 PrerequisitesforaQualifiedInspector

Onlyproperlytrainedandqualifiedpersonnelshouldperform inspections. Aformaltraining

andcertificationprogramshouldbeimplementedtoensurethatinspectorsarequalified,and

remain qualified. For additional guidance on minimum requirements for crane inspectors,

2.0 OrganizationandPersonnel


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refer toCMAASpecificationNo.782002,StandardsandGuidelinesforProfessionalServices

PerformedonOverheadandTravelingCranesandAssociatedHoistingEquipment.

2.3 RecommendedInspectionTeam

Theinspector

should

have

an

assistant

present

at

all

times.

Assisting

the

inspector

is

ideal

for

trainingandqualifyingnewinspectors.

Primarydutiesfortheassistant:

Monitortheimmediateareaforhazards. Operatetheaerialplatform. Assisttheinspectorbytakingnotesandmeasurementsasrequired. Handletools,flashlight,camera,notepads,etc. Communicatewithpersonnelonthefloorandelsewhereviaradio. Intheeventofaninjurytoeithertheassistantortheinspector,theotherwillprovide

assistance.

3.1 PreInspectionSafetyPlan

Beforestartingtheinspection,followthesafetyproceduresrequiredbyyourcompany,OSHA,

andstateandlocalauthorities. Generallyrecommendedsafetyproceduresinclude:

Notifyplantpersonnel(inadvance)thataninspectionwilltakeplace. Personnelwhowork

near

the

area,

or

pass

through

the

area

should

be

notified.

Locatethebridgeawayfromcraneactivityinthesameandadjacentcraneaisles. Ifothercranesonthesamerunwaymuststayinserviceduringtheinspection,provide

ameanstopreventthemfromhittingthecranebeinginspected.

If the mainline conductor system must remain energized during the inspection, allinspection personnel must remain aware of this hazard and stay clear of the

conductors.

Iftheinspectionrequirespersonnelmaneuveringandpotentialexposuretocranesonanadjacentrunway,installaguardorabarrierorprovideothersafemeanstoprotect

theinspectorfromcontactwithadjacentcranes.

Removeallsourcesofstoredmechanicalenergyincludingsuspendedloadblocks. Disconnect,tag,andlockoutallelectricalpowertothecrane.

3.2 SafelyManeuveringontheStructure

Safe,comfortable,andcloseaccessisrequiredtoallpartsofthecrane. Ifpossible,thecrane

should be moved to an area that has good lighting, comfortable temperature, and is away

fromproductionprocesses,andadjacentcraneactivity.

3.0 InspectionSafety


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Inspectorsmaybestanding,sitting,kneeling,bending,squatting,climbing,orlayingdownto

facilitatetheinspection. Theinspectormusthavephysicalagilitytoclimbtallladders,walkon

partsoftherunway,andclimboverallpartsofthebridgeandtrolley.

Theinspectormustbeabletosafelymaneuverandpositionhimselfinareasthathavelimited

footingand

space.

One

commonly

encountered

example

of

limited

footing

is

stepping

onto

runwaybeamswherenoplatformsexist. Dependingonthespecificbuildingdesignandcrane

location,accesstotherunwaymayberequiredtoexaminetheconditionofbridgeendtrucks,

end ties, sill beams, equalizer saddles, squaring plates, girder connections, and bumper

extensions.

3.3 IdentifyingHazards

Itisimpossibletocreatealistofallpossiblehazards,butafewcommonsenseguidelinesfor

safeinspectionsareofferedhere:

Neverrushthetask. Nevermovetoalocationwhereyoucannotclearlyseethatyouwillhavesafefooting

andifrequired,stablehandholds.

Observethe condition of the walking surfaceand avoid walkingon surfacescoveredwithlubricantsordebris.

Continuouslymonitoractivitiesinallthreedimensionsofyoursurroundings. Whenclimbingandmaneuveringonthestructure,bothofyourhandsshouldbefree

forgraspinghandholds. Taketimetothinkaboutyourmovementsinadvance.

Makesurethatothersknowwhereyouare. Dontassumethatothersareawareofyour nearby presence. When passing behind someone, be sure to announce your

presence.

Even if power is disconnected and locked out from the crane, its a good habit toremainawareofexposedconductorsurfacesandnottouchthem. Youshouldbeaccustomedtoheights. Be familiar with the OSHA definition of a confined space. Never enter a confined

spacewithoutapermit.

Identifypotentialpinchpointsandlocationswhereyoucouldbecrushed. Watchforunguardedopeningsinfloorsandhandrailings.

3.4 HighAmbientTemperatures:PrecautionsandPlanning

Special attention and planning are required for inspecting cranes in hot areas. Due to the

adverseenvironment,

these

cranes

may

not

receive

the

inspection

time

they

deserve.

The

air

temperature on melt shop cranes in a steel mill can exceed 140 Fahrenheit. The crane

structuremaybehot,andglovesarerecommendedformaneuveringonthestructureduring

aninspection.

Consider inspecting high temperature cranes at night, early morning, or on cloudy days.

Whentemperaturesatthecraneelevationareextremelyhot,inspectiontimeisconsiderably


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Considerwherethebaseoftheapparatusmustbemaneuveredtoreachthelocationspreviouslyidentified.

Consider the travel path required to bring the apparatus through the plant, into theaisle,andunderthecrane.

Useatrainedequipmentoperator. Theaerialliftshouldbeoperatedbysomeoneotherthantheinspector.

4.3 OtherInspectionParaphernalia

Thefollowingitemsarerecommendedforlocalcleaningareasofinterest,markingsuspected

areas,anddocumentingareasforreports:

Camera. Useacompact,rugged,goodqualitycamera. Thecameramustbesuitableforsharpcloseupsandshouldbeweatherproof.

Mini audio recorder. For dictating verbal descriptions that can be transcribed andeditedforreports.

Mirror. Asmallinspectionmirrorwithanextensionhandle,ora4x5acryliclockermirror. Flexible borescope with optical or video display. A borescope allows closeup

inspectionofinaccessibleareassuchastheinteriorofboxgirders,endtrucks,andend

ties.

Paintstick(whiteoryellow)foridentifyingareasofinterest. Extrapensandpencils. Notepadforsketches,measurementsandnotes. Blackmarkerforidentifyingareasofinterest. Flashlight. Useagoodqualityflashlight(Magliteorequalquality). Puttyknifeforscrapingdebristocleanareasofinterest. Smallwirebrushforcleaningareasofinterest. Tapemeasure. A16or25isadequate. Useawidebladetapemeasureformaximum

reachtoinaccessiblelocations.

Ballpeenhammer. Asmall (2oz. or 4oz.) hammercanbeused fortapping on theface of girder webs or other weldments to determine the locations of internal

stiffeners. Ahammercanalsobeusedtotapontheheadsofrivetsandboltstohelp

determineiftheyarelooseorbroken.

Torpedo laser levelwithmagneticbaseorasmall lasercross level. Astraight, levelreference line is required to measure the elevation profiles of trolley rails. Use the

brightest laser available (at least 100 working range) so the beam will be visible for

usewithatapemeasure.


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5.1 GettingStarted

Starttheinspectionatthetopandworkyourwaydown. Thismeansstartingatthetopofthe

trolley.

Thenproceed

to

the

top

of

the

bridge.

Inspect

as

much

as

possible

without

using

the

aeriallift. Noteareasthatarenotaccessibleforlaterviewingfromtheaeriallift.

5.2 WheretoLook

Overheadcraneshavethesamebasicconfigurations,andageneric listofbridgeandtrolley

inspectionpoints issuggested insection6and7. Sincetherearesomanydesignvariations

forcustomcraneapplications,itisnotpossibletoidentifyallpointsofinterestinthisguide. A

basic understandingofstructure behaviorcanhelp to identifyother inspectionpoints. This

guide includes a section on basic structure behavior to help technicians identify points of

interestthatmaynotbelisted. Acustomlistofinspectionpointsshouldbemadetosuiteach

cranein

your

plant.

5.3 OtherInspectionGuidelines

Whenacrack isdiscoveredatone location,allothersimilarortypicallocationsmustbecarefullyinspected. Oneexamplewouldbewhenacrackisdiscoveredinthegirder

webadjacenttoplatformconnections. Theremaybeseveralotherconnectiondetails

identicaltowheretheoriginalcrackwasdiscovered. It isefficienttofocusattention

ontypicallocationsthatarediscovered.

Aviewingdistanceofnotmorethantwofeetisrecommendedforvisualinspections. Routinelyinspectareasthathavebeenrepairedormodified. Previously repaired areas that use patch plates present a problem for inspection.

Thepreviouslyrepairedareacannotbe inspectedbecause it iscoveredbythepatch

plate. Patchplatedareasshouldbereportedtotheresponsibleengineerasdamaged

areas that require action. The patch plate should be removed and an engineered

repair should bemade. The engineered repair procedureshould be completed bya

qualifiedstructuralengineer.

All areas of structural damage must be documented and reported to a qualifiedstructural

engineer

for

assessment

before

placing

the

crane

back

into

service.

5.0 GeneralInspectionGuidelines


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Table6.1: TrolleyStructureInspectionPoints

Item Description PointsofInterestforInspection

1Main

and

auxiliary

hoist

load

girts:bottomflange.

Wherestiffenersarewelded togirtsorwhere

othermembers

are

welded

on

or

near

the

lower

flangeofgirt. Checkweldsandadjacentbase

metal.

2

Mainandauxiliaryhoistload

girts: bottomedgesof

members.

Edgesofmembersadjacenttorunningwireropes.

Lookforscuffing,erosion,andsawingaction

fromwireropecontactwithstructure.

3Mainandauxiliaryhoistload

girts:endconnections.

Weldsandadjacentbasemetalwheregirtsare

weldedtoendtrucks. Whenthedepthofthegirt

memberislessthantheendtruck,checkfor

flexingofthewalloftheendtruckatthebottom

edgeofthegirt.

4 Sheaveboxes Weldsandbasemetal.

5 Otherloadgirts.

Similartoitems1and2. Lookforotherload

carryinggirts,includingsupportsforhoistdrums,

drumpinionsupports,andequalizersheaves.

6Trolleyendtrucks:frame

connections

Whereloadgirtsare weldedtotheendtruck,

especiallyonornearthelowerflange.Check

weldsandadjacentbasemetal.

7Trolleyendtrucks:wheel

assemblymounting.

For90and45MCBtypewheelassemblies,check

forcrackingatstiffenersandcorners.

8Trolleyendtrucks:bumper

attachments,bumper

chocks.

Weldsandbasemetal. Checkboltedconnections

persection

8.0.

9Trolleyendtrucks:bolted

splicefortrolleyframe.

Checkboltedconnectionspersection8.0. Check

weldsandbasemetalforconnectionplates.

10Trolleyendtrucks:jackingpads

orjackingbrackets.

Damagefromjacking onedgesofendtruck

flangesordirectlyonthebottomflangeplateof

theendtruck. Checkweldsandbasemetal

aroundjackinglocations.

11Trolleydrivemounting

brackets.

Lookforcracksatcornersornotches. Checkwelds

andbasemetalwherebracketsareweldedtothe

trolleyframe.

12

Hoistreducer

support

bracket.

Lookforcracksatcornersornotches. Checkwelds

andbase

metal

where

brackets

are

welded

to

the

trolleyframe.

13Torquearmbracketsfor

hollowshafttrolleyreducers.Inspectbracketarmandweldtoendtruck.

14

Bearingsupportsfordrum,

bearingsupportforexternal

drumpinion.

Checkweldsandbasemetalatconnectionto

trolleyframe.

6.0 TrolleyStructureInspections


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15

Handrails,guardrails,ladders,

platforms,stairs,cantilevered

platformsupports.

Checkweldsandbasemetal. Checktightnessof

allfasteners. Lookforloose,broken,ormissing

bolts. Checkforproperfastenerhardware. Check

formissingordamagedgatesorchains. Checkfor

sharpedgesorcornersnearpersonnelpassage

ways.

16Cabattachments,cantilevered

cabsupportstructures.

Checkboltedcabconnectionspersection8.0.

Weldsandbasemetalforconnectionplates. For

cabssuspendedoutsidethebridgegirder,inspect

thecantileveredsupportstructure.

17 Towarmforconductors.Checktowarmandtheboltedorwelded

connectiontothetrolleyframe.

Figure61

Seesection6.1fortrolleyinspectionpoints.


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Table7.1: BridgeGirderInspectionPoints


1Trolleyrailbolted

splices.

Looseandmissingsplicebolts,checkforimproper

hardware. Jointbarboltshavestraightshankstothehead

andaremadeperASTMA449. NutsareperA563gradeB.

A325boltsandnutsmayalsobeused. Check/tighten

spliceboltsevery3months. Fastenersshouldincludea

helicalspring

lock

washer per

AREA

specification.

2Trolleyrailclampsor

clips.

Checkforfracturedclamps,crackedwelds,looseand

brokenbolts. Seenote2.

3Trolleyrail:erosion

underrailbase.

Underthebaseoftherail,checkforerosionofthegirder

flangeorthewearplate(ifpresent). Seenote3.

4 Trolleyrailsupport.

Checkfortopflangecrackingattheedgeoftherailbase.

Checkfortackweldsattheedgeoftherailbase. Seenote

4.

Figure62

Viewunderneathtrolley, showingtypicalstructureinspectionpoints.

7.0 BridgeStructureInspections


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Page14of43

5 Trolleyrailelevations.

Fromoneendofthetrolleyrail,sightdowntherailhead.

Sightovertheentirelengthoftherailfordipsinelevation.

Checkforlocaldeformationofthegirderflangethat

supportstherail. Dishingordipsinthegirderflange

mayindicatebrokenintermediatediaphragmsorbroken

welds.

Checkthis

condition

at

both

trolley

rails.

See

Figure71.

6 Girdercamber.

Positionthetrolleyattheextremeendofthebridge. From

theendofthebridgeoppositethetrolley,positionyour

lineofsighttobeinlinewithoneofthetrolleyrails,and

nearlyatthesameelevationastherailhead. The

elevationoftherailnearthemiddleofthebridgespan

shouldbevisiblyhigherthanneartheends(positive

camber). Ifconditionsdonotpermitthisobservation,orif

positivecamberisnotobserved,detailedmeasurements

arerequired. Repeattheprocedurefortheothertrolley

rail.

Seenote

6.

7Torsionboxrail

support.

Forboxgirdersthatsupportthetrolleyraildirectlyover

theinsidewebplate,checkforcrackingofthegirder

flangetowebweld.

8 Trolleyendstops.

Welds,basemetal,andattachmenttogirder. Confirmthat

trolleybumpersmakesimultaneouscontactwiththeend

stopsatbothendsoftrolleytravel.

9Bridgedrivemounting

bases.

Checktheconditionofgirderwebwherebridgemachinery

isattached. Lookforoutofplanedeformationofthe

girderweborcrackingofthematerialadjacenttowhere

barsarewelded. SeeFigure72.

10Lineshaftbearing

supports.

Checkthe

condition

of

girder

web

where

bearing

supports

areattached. Lookforoutofplanedeformationofthe

girderweborcrackingofthematerialadjacenttowhere

barsarewelded. SeeFigure72.

11Platformconnections

togirder.

Checktheconditionofgirderwebwhereplatformsupport

gussetplatesareattached. Lookforoutofplane

deformationofthegirderweborcrackingofthematerial

adjacenttogussetattachments. SeeNote11. SeeFigure

73,74,75.

12

Festoon/span

conductorsupports.

Checktheconditionofgirderwebwhereconductor

supportsareattached. Lookforoutofplanedeformation

ofthe

girder

web

or

cracking

of

the

material

adjacent

to

wheregussetsorbarsarewelded.

13Pendantfestoon

supports.Checksupportmembers,weldedandboltedconnections.

14 Rivetedgirders. Inspectrivetedconstructionpersection8.

15 Girderwelds.Longitudinalflangetowebwelds. Inspectthelocationof

shopsplicesforwebandflangeplates. Seenote15.


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7.1 BridgeGirderInspectionNotes

ThefollowingitemnumberscorrespondtotheitemsinTable7.1.

2. Railclipsresistasmallupliftforcefromthetrolleyrail. SeeFigure71. Theraildeflectsdownwarddirectlyunderthetrolleywheel. Oneithersideofthetrolleywheel,therail

reactsby

deflecting

upward.

The

upward

force

is

resisted

by

the

rail

clips.

The

clips

or

weldsmaybreakduetofatigue.

3. Erosionofgirderflangematerialundertherailbaseismorelikelyinwet,corrosive,orabrasiveenvironments. Theerosioniscausedbytheslidingandcreepingactionofthe

railrelativetothegirder. Thisaction isnormalandcannotbepreventedunlessarail

pad isused. Erosionundertherails isaveryslowprocess. Itmaytakeseveralyears

beforemateriallosscanbeobserved.

4. Duetohighcarboncontent,ASCEcranerailsarenotreadilyweldable. Tackwelding(oranyotherwelding)oncranerailsmustberemovedbygrinding. NDTthegirderflange

basemetal

for

cracking

after

rail

welds

are

removed.

6. Whencambercannotbevisuallyobserved,elevationmeasurementsarerequired. Thepreferredmethodistosetaselflevelinglaserlevelnearthecenterofthespanonone

ofthegirders. At5 foot incrementsalongthe span, measureandrecordthe vertical

distancefromthelaserlinetothetopoftherailhead. Measurementsforbothgirders

shouldbetakenfromoneinstrumentsetup. Alternately,asmalltorpedolaserlevel

16Girderlowerflange

andweb.

Insideedgesofthebottomflanges,includingtheadjacent

webareafordamageduetowireropeabrasion,impact

fromloadblocks,orliftingbeams. Forcraneswithlifting

beams,alsochecktheconditionofthebottomsurfaceof

thebottomflangeforimpactfromtwoblockingaccidents.

Ifrope

guards

are

present,

inspect

the

rope

guard

attachmentstothegirder.

17 Walkingirders.Weldsandbasemetalforintermediateandfulldepth

diaphragms,girderwebs,girderflanges. Seenote17.

18 Boltedgirdersplices.Checkboltsintopandbottomflangesplicesandweb

splicespersection8.

19Girderconnection

notch.

SeeFigure7.6. Checkweldsandbasemetalatcornersand

whereweldsmeetatcorners. Checkweldswheregirder

websareweldedtohorizontalshelfplate.

20 Equalizersaddles.

SeeFigure77. Checkweldsandbasemetalwherethe

verticalsaddleplatesareweldedtothehorizontalsaddle

plate.

Alsocheck

welded

connections

to

girder.

21 Platformtruss.Weldsandbasemetalforalltrussmembersandgusset

plates. SeeFigure74.


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Figure71

Schematicillustrationofhowthetrolleyraildeflects. Theupwardforceproducedby

leveragefromthetrolleywheelisresistedbytherailclipsorclamps.

canbeusedtoobtaintherailcamberelevationsoneach individualgirder. Withthis

methodhowever,theelevationdifferenceofthegirderscannotbemeasured.

11. Forcranesthatuseatrusstosupporttheoutsideedgeoftheplatform,theplatformconnections to the girderare prone to fatiguedamage. See Figure 73. Thebridge

girderdeflects

due

to

the

trolley

load,

but

the

outrigger

truss

does

not.

The

platform

connectionthat frames intothegirderweb is forcedtotranslatevertically relativeto

the truss end. The forced vertical translation causes a large bending action at the

platformconnectiontothegirder. Figures74and75showtypicalgirderwebcracks

nearthegirdertensionflangecausedbyoutofplaneflexingofthegirderweb.

15. Shopsplicesaresometimesdifficulttolocate. TheexternalappearanceofshopsplicedmaterialmayvarybyOEM. Shopsplicesmaybefoundbynotingsubtlechangesinthe

profileofedgesand surface texture. This is difficult todetectundera thick coat of

paint. Bottomflange (tension flange)splicesshouldhavebeenground flushwiththe

basematerialbytheOEM.

17. Beforeenteringawalkingirder,reviewandfollowapplicablesafetyrequirementsforenteringandworkinginconfinedspaces.


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Figure72

Bridgemachinerysupports.

Checkgirderweb andwelds forverticalbarstoweb.

Figure73

Cranewithanoutriggertruss. Thediagonalmembersarepartofthetrussthatsupportsthe

platform,bridgemachinery,andfestoontrack.


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Page18of43

Figure74

Thegirderwebiscrackedat

thetoeofthefilletweldfor

platformconnectionbar.

Figure75

ThisisacloseupviewofFigure74. Thearrowpointstotheendofthecrack. Thecrackis

propagatingtowardthebottomflangeofthegirder. Cracksinthebottomflangeofagirder

cancauseacatastrophicgirderfailure.


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Page19of43

Figure

7

6GirderEndConnection

Figure77

Equalizedbogietruckswithrigidendtie


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Page20of43

7.2 BridgeEndTruckandEndTieInspectionNotes

ThefollowingitemnumberscorrespondtoTable7.2.

3.

Compensatingend

ties

should

be

flexible

for

bending

in

the

vertical

plane,

and

rigid

for

bending in the horizontal plane. Improper design, crane service misapplication, and

runway misalignment can make compensating end ties prone to cracking, especially at

theirverticalendconnections. Thefatiguecracksarecausedbycompletereversalofthe

bendingstress.

Table7.2: BridgeEndTruckandEndTieInspectionPoints


1Squaringplate

connection.

SeeFigure7.6. Checkboltedconnectionsforloose,broken,

ormissingbolts. Looseboltsshouldberemovedand

replacedwithnewboltsofthesamegrade,size,andlength.

Seesection

8 for

bolted

connections.

2Rigidendtie

connections.

SeeFigure77. Theendsoftherigidendtieareboltedto

thegirdersinonehorizontalplaneandtwoverticalplanes.

Seesection8forboltedconnections.

3Compensatingendtie

connections.

SeeFigure78forcompensatingendtieconnection. Check

boltspersection8.

4 Sillbeams.

Checkflangetowebwelds,checkweldsandbasemetalat

corners,abruptchangesingeometry,andwherewelds

meetatcorners.

5Endtrucks:wheel

assemblymounting.

For90and45MCBtypewheelassemblies,checkfor

crackingatstiffenersandcorners. SeeFigure7.6. Check

weldfor

shoe

plate

to

end

truck

web.

6Endtrucks:equalizer

pinsupports.

Checkweldsandbasemetalaroundthedoublerplate

supportingtheequalizerpin.

7

Torquearmbrackets

forhollowshaft

trolleyreducers.

Inspectbracketarmandweldtoendtruck.


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Page21of43

Figure78

Boltedconnectionsforcompensatingendties


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Page22of43

Table7.3: BridgeMiscellaneousInspectionPoints


1Handrails,ladders,

stairs,gates.

Weldsandbasemetal. Checkboltedconnectionsper

section8. Lookforloose,broken,ormissingbolts. Check

forproperfastenerhardware. Checkformissingor

damagedgates

or

chains.

Check

for

sharp

edges

or

corners.

2 Platforms.

Checkcondition ofplatformdeck,decksupportmembers,

andweldedconnections. Checkboltedconnectionsper

section8.

3 Mainlineguard.

Checkforbrokenmembersandbrokenwelds. Check

boltedconnectionspersection8. Bentmembersare

acceptableifatleast3clearanceremainsbetweenthe

guardandnearestobstruction. Checkconditionofsafety

tieoffcables. Ifcablesarenotpresent,theyshouldbe

installed.

4Mainlinecollector

support.

Checkfor

broken

members

and

broken

welds.

Check

boltedconnectionspersection8. Checkconditionof

safetytieoffcables. Ifcablesarenotpresent,theyshould

beinstalled.

5 Mainlinerepaircage.

Hangerconnectionsandcageframe. Checkladderper

item1. Checkforbrokenmembersandbrokenwelds.

Checkboltedconnectionspersection8. Checkcondition

ofsafetytieoffcables. Ifcablesarenotpresent,they

shouldbeinstalled.

6

Safetycables.

Checkconditionofsafetytieoffcables. Itemsthatcould

falltothefloorshouldhavesafetycablesinstalled. These

itemsinclude:

mainline

guards,

mainline

collector

supports,bumpers.

7Operatorcabstructure

andsupports.

Hangerconnectionsandcabframe. Checkforbroken

membersandbrokenwelds. Checkboltedconnectionsper

section8. Checkladders,stairsandhandrailsperitem1.


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Page23of43

8.1 BoltedConnections;DescriptionandFunction

High strength bolted connections are used for primary load path members including girders,

end

ties,

andbolted

field

splices.

They

may

also

be

used

for

cab

and

platform

connections.

High strength bolts are tightened to develop a high tensile stress in them which results in a

predictableclampingforceonthejoint. Theactualtransferofloadsthroughthejointisdueto

thefrictionforcedevelopedinthepiecestobejoined.

8.2 HowtoCheckforBroken,Damaged,andLooseBolts

Applypenetratingoiltothefastenerstobeinspected. Usingahandwrenchwithatleasta16

handle,applyfullefforttotightentheelement. Theelementtobeturned(eitherthenutorthe

bolthead)shouldbethesameelementthatwastightenedduringtheoriginalinstallation. The

turnedelementshouldhaveahardenedflatwasherunderit. Iftheelementturns,theboltis

consideredto

be

loose.

Whenalooseboltisfound,itmustbereplacedwithanewboltorremovedandinspected. For

inspection,thoroughlycleantheboltandcheckfordamageincludingdeformation,elongation,

wear,cracks,orstrippedthreads. Elongationcanbedetectedbyusingyourfingerstoinstallan

unused nut on the bolt threads. If the nut stops turning after a certain point, the bolt has

elongatedandshouldbediscarded.

Primary connections are designed to resist the crane rated capacity (the live load) plus the

weightofthebridgeandtrolleystructure(thedeadload). Sincetheliveloadisusuallyseveral

times greater than the dead load, it is usually safe to remove one or two fasteners from a

connection

containing

several

bolts

under

dean

load

only.

Consult

with

a

qualified

personbefore removing any fasteners. Do not release the crane for service until the replaced or

inspectedboltshavebeenproperlyinstalled.

Broken, damaged, and very loose bolts may be found using the hand wrench procedure

suggested here. The formal procedure for inspection of high strength bolted connections is

giveninRCSCSpecificationforStructuralJointsusingASTMA325orA490Bolts,(seereference

6). Theabovemethod ispresentedasanalternativeforsituationswheretheformalmethod

cannotbeusedduetolimitedspaceorotherpracticalconsiderations. Consultwithaqualified

structuralengineertodetermine iftheformalmethodofcheckingbolttightness iswarranted

foryourinspectionplan.

8.3 RivetedCraneConstruction

Manyrivetedcranesarestillinservice. Beforeelectricarcwelding,bridgegirders,endties,and

end trucks used builtup riveted construction, and some trolley frames consisted of large

castings. Whenproperlyinstalled,rivetsareveryeffectiveconnectorsforcranecomponents.

During installation,arivet issqueezedfromeachendcausingthebodyoftherivettoexpand

8.0 HighStrengthBoltedConnections


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Page24of43

andcompletely(ornearly)fill itshole. Rivetsare installedafterheatingtoa lightcherryred.

Whentherivetcools,itshrinksandprovidesaclampingforce. Eveniftheclampingforcewas

notgreatenoughtocarrytheload,thebodyboundrivetstillmaintainsjointalignment.

8.4 RivetInspection

Examinetheconditionoftherivetheads. Thefullcircumferenceoftherivetheadshouldbein

firmcontactwiththematerial. Usingasmallballpeenhammer,taptherivetheadatabout45

to the rivet axis. If the hammer impact sounds like a dull thud or if any movement is

observed,therivetis loose. Tightrivetswillhaveasolidringwhenhitbyahammer. Mark

thelooserivetswithapaintstickanddocumenttheirlocation.

8.5 CautionsforReuseofBolts

It may be tempting for maintenance and inspection personnel to simply retighten loose

fastenersonthespot,butA325boltscanonlyberetightenedonceortwice. Ifyoudontknow

how

many

times

the

bolt

has

been

retightened

after

the

original

installation,

it

should

bereplaced. Retighteninghighstrengthboltscausesthemto losetheabilitytostaytight. A490

bolts shall not be retightened. In general, touching up or retightening previously tightened

boltswhichmayhavebeenloosenedbythetighteningofadjacentboltsisnotconsideredtobe

reuse. HighstrengthboltsshallbetightenedperRCSCSpecificationforStructuralJointsUsing

ASTMA325orA490Bolts,(seereference6).

There should be no excessive elongation of the bolt in the threaded area which would be

presentifthebolthadbeenovertightened. Theboltcanbereusedifthenutcanbeinstalled

by hand for the full thread length, and the bolt is not otherwise damaged. When in doubt,

replacetheboltwiththesamegrade,size,andlengthastheoriginal.

8.6 CheckingforProperFastenerHardware

Figure81showstypicalhardwareusedforhighstrengthboltedconnections. Wheninspecting

primaryboltedconnections,notethefollowing:

Confirm that high strength bolts are installed in connections for primary members,including girders, end ties, and trolley splices. See Figure 82 for standard head

identificationmarksforhighstrengthbolts.

Hardenedflatwashersshallbeinstalledundertheturnedelement. Lockwashersshallnotbeusedinhighstrengthboltedconnections. When bolting to sloped surfacessuch as Sbeam flangesandchannel flanges,beveled

washersmustbeused. Figure83illustratesatypicalinstallationforbeveledwashers.


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Page25of43

Figure81

Typicalhardwareforhighstrengthboltedconnections.

(FromReference

11.)

Figure82

Standardheadidentificationmarksforhighstrengthbolts


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Page26of43

Figure83

Exampleofbeveledwasherinstallation

(FromReference11)


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Page27of43

9.1 WhentoInspect

Checkthe

original

manufacturers

manual

for

recommendations

about

inspections.

If

acopy

of

themanualisnolongeravailable,refertothefollowingreferencedocuments:

ASMEB30.22005,OverheadandGantryCranes(TopRunning Bridge,SingleorMultipleGirder,TopRunningTrolleyHoist)

OSHA29CFR1910.179(j)forOverheadandGantryCranes CMAA Specification No. 782002, Standards and Guidelinesfor Professional Services

PerformedonOverheadandTravelingCranesandAssociatedHoistingEquipment

10.1 WheretoLook

Knowledgeofwheretolookforstructuraldamageisveryimportantfortheinspector. When

inspectiontimeislimited,andthestructureiscoveredbydebris,knowledgeaboutwhereto

lookbecomesveryvaluable. Sincestructuresrespondto loads inpredictibleways,someof

themostlikelyplacestoinspectcanbeidentified.

Abasic

understanding

of

crane

structure

behavior

gives

focus

to

the

inspection.

This

section

provides basic concepts and guidelines to help determine the locations most likely to have

damage.

10.2 Tension,Compression,andBending

For beam members, look for cracks in the tension zone and at the end connections. See

Figure101.Forsimplebeams,thebottomsurfaceisintension.Themiddle2/3ofthelength

of the tension zone should be checked first. Material near the top surface of the beam is

compressed, and the bottom is pulled into tension. If there are cracks in the compression

zone, they will not grow. Cracks in the tension zone will grow, but the speed of growth

dependson

the

magnitude

of

the

loading,

and

the

number

of

loading

cycles.

9.0 InspectionIntervals

10.0 BasicStructureBehavior


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Page28of43

10.3 ShearInFigure101,thehighshearzonesarenearthebeamends. Failuresinthehighshearzones

aremorelikelytobesuddenandcatastrophic. Shearfailurescanoccurinboltedconnections

and welds. The connected base material can also fail by shear but usually the shear is

combinedwith

tension

and

compression.

Shear

can

be

visualized

as

the

tendency

of

the

materialtoslideonitself. Figure102illustratesthedifferencebetweenshearandtension. A

scissorscutspaperbyapplyingashearforce. Horizontalshearinabeamcanbeillustratedby

astackofboardsspanningbetweentwosupports. Whenyoupushdownonthemiddle,the

stackdeflectsandthesurfaceofeachboardslidesrelativetotheother. Thetendencyforthe

boardstoslideiscausedbyshear.

Figure101

Internalforcesanddeformationofasimplebeam

Figure102


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Page29of43

10.4 DeflectionandCamber

There is a common misconception that deflection indicates weakness of a structure. A

structure can have low strength and little deflection, or high strength and large deflection.

Deflection iscausedbystretchingand/orcompressingthematerial. Theactualdeformation

that

causes

visible

deflection

is

too

small

to

be

seen

with

the

unaided

eye

because

it

isdistributedoverthelengthofthemember. Localelongationorcompressionofthematerial

may only be a few thousandths of an inch long, but the cumulative effect is visible as

deflection. The beam assumes a bowed shape because the length of the top material gets

shorterandthebottombecomeslonger.

Sometimes paint will crack from these small deformations. Areas of cracked paint can

indicatehighstress,anddeserveacloselookduringaninspection.

10.5 Buckling

Somevisible

deformations/deflections

are

caused

by

buckling.

Buckling

is

caused

by

excessive

compression. Inplatematerial,bucklingcanalsooccurfromexcessiveshear. Thesurfaceofa

buckled plate will appear wavy or rippled. Free edges of plates and bars are subject to

buckling. Whenviewedalongtheedge,thebuckledplateappearswavy. Forstraight(non

plate) members such as building columns or legs of a gantry crane, buckling appears as a

bowingofthenormallystraightmember.

10.6 EffectofWelding

In general, welding creates an internal, local restraint that creates biaxial and triaxial stress

and strain conditions. Triaxial stress can be visualized as a solid cube with a perpendicular

load

applied

to

each

face.

Structural

steel

is

very

ductile,

i.e.,

it

will

undergo

a

very

largedeformationbeforefailing. Butwhensteelis loadedtriaxially(orbiaxially),itbehaves likea

brittlematerial. Whenweldscool,theyshrink inalldirections. Internalreaction forcesare

createdwhenweldsshrink. Thisisbecausethebasemetaloutsideoftheheataffectedzone

resiststheweldshrinkageforce. Oneexampleforthisiswhenthreeweldsmeetatacommon

cornerasshowninFigure108. Eachlineofweldshrinksinitslongdirection. Thepointatthe

corner is subjected to tension forces in three perpendicular directions. Since this corner

wouldbethemostlikelyspotforacracktoform,itshouldbeapriorityforinspection. Refer

to Figures 103 and 104 for common examples of welded connections that are prone to

fatiguecracking. These illustrationsalsoshowtheexpectedcrackpattern. This information

canhelptheinspectoridentifylocationsthataremostlikelytocrack.


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Page30of43

10.7 StressConcentrationandFatigue

Cracking will eventually occur in hardworked cranes with poor engineering details and/or

poorweldquality. Inorderofimportance,keepaneyeonthefollowingconditions:

1) Previouslyrepairedareas.2) Girderandendtieconnections.3) Locationswherecyclicflexingofthinwalledelementsmayoccur.4) Sharpcorners.5) Weldedattachmentstothetensionflange.6) Jaggedorflamecutedgesnotgroundsmooth.7) Weldsthatmeetincorners. SeeFigure108.8) Arcstrikes&tackwelds.9) Abruptchangesinstructuregeometry(stressconcentrations).

10) Locationswherethestateofstressregularlyfluctuatesbetweentensionandcompression(stressreversals).


31/43

Page31of43

Figure103

Examplesofconditionsthatmayresultinfatiguecracking

(FromReference13)


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Page32of43

Figure104

Examplesofconditionsthatmayresultinfatiguecracking

(FromReference13)


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Page33of43

10.8 AttachmentsCreateDiscontinuities

InFigure105,thereisatackweldatthebottomoftheverticalconnectionplate. Thisisthe

mostlikelyplacewherethecrackstarted. Tackweldscoolrapidly,makingtheadjacentbase

metalhard,brittle,andpronetocrack.

InFigure105,stress isconcentratedatthecornersformedbythesquaringplateweldedto

thebottomflangeoftheendtruck. Thestressfieldmaybevisualizedasasetofstreamlines

analogoustofluidflowingthroughaduct. Figure106 illustratestheanalogyforstressand

fluid flow. Abrupt geometry changes, inclusions, gouges, or notches create stress

concentrationsthatarepronetofatiguecracking. Figure107showshowthestressintensity

variesintheflange. Redrepresentsthehighestlevelofstress.

Figure105

Thebluearrowspointtoacrackthroughthebottomflangeofabridgeendtruck. Thiscrack

mayhavebeencausedbytheeffectofthetackweld(pinkarrow)combinedwiththestress

concentrationshowninFigure106. SeeFigure76foraviewofthecompleteconnection.


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Page34of43

Figure106

Lookforsharpcorners,notches,andabruptchangesingeometry

Figure107

Thisisaqualitativeillustrationofincreasedstresscausedbyasuddenchange

inthegeometryoftheloadpath. Theredareasindicatethehigheststress.


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Page35of43

10.9 SingleFailurePoints

Be

able

to

recognize

single

failure

points.

Look

for

areas

in

the

main

load

path

where

noredundancyexists. The loadpath isredundant ifthe failureofoneelementdoesnotcause

completefailure. Redundantloadpathshaveabackupstructurethatcansupporttheload.

Achain isanexampleofanonredundantstructure. Ifone link inthechainfails,theentire

chainhasfailed. Aredundantstructureislikeaparallelcircuit,anonredundantstructureis

likeaseriescircuit. Inspectionprioritiesshouldbeforelementsofthemainloadpaththatare

singlefailurepoints.

10.10 ManufacturingQualityandFatigueResistantDesignDetails

Preferenceshouldbegiventocranebuildersthathaveaproventrackrecordfordesignand

manufacture

of

hardworked

cranes.

The

crane

vendor

must

have

knowledge

of

the

application,andexperiencewithfatigueresistantdesign.

High quality welding is important for dynamically loaded crane structures. Geometric

imperfections suchas undercut,porosity, slag inclusions, incomplete fusion, craters, melted

corners,andhydrogenentrapmentcreatestressconcentrations. Theseflawsmaycausethe

adjacentmaterialtoyieldandcrack.

Figure108

Atriaxialstressconditioniscreatedfromlongitudinalshrinkageofthree

weldsthatmeetatacorner.


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Page36of43

11.1 TrolleyStructureDesign

Thetrolleystructureisaframeworkofbeams. Figure111showstheconstructionofasimple

trolleyframe.

Each

beam

member

in

the

frame

behaves

as

shown

is

Figure

10

1.

Locations

withthehighesttensionandshearstressshouldbe inspected. Thehighesttensionstress is

located on the bottom surface of each member, at the midpoint of its length. The highest

shear stress is at the end of each member. The maximum shear stress in the girt is at the

weldedconnectiontotheendtruck.

Figure111

Illustrationofasimpletrolleyframe

11.0 TrolleyStructureBehavior


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Page37of43

Figure 11-2

11.2 TrolleyDeflection

When loaded, the trolley frame will deflect as shown in Figure 112. Each girt that spans

betweentheendtruckswilldeflectasshown inFigure112. Whengirtsdeflect,theirends

rotateandthiscausesthetrolleyendtruckstotilttowardeachother. Thealignmentofhoist

machinerymay

be

adversely

affected

ifthe

trolley

frame

is

too

flexible.

This

is

especially

true

fortrolleyframeswitharelativelylargespanbetweenthetrolleyrails.


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Page38of43

12.1 BridgeStructureDesign

Viewed from the top, the bridge structure is a rectangular frame with rigid corners. The

bridge

girders

support

the

trolley

load

by

bending

in

a

vertical

plane

between

the

runwayrails. Theendtrucksorendtiesalsobendinaverticalplane. Forverticalloading,thebridge

structurebehavessimilartothetrolleyframeshowninfigure112. Thebridgeendtruckstilt

towardeachotherwhenthegirdersbend.

12.2 BridgeStructureResponsetoLateralloadsandSkewing

The purpose of the bridge frame is to keep the end trucks parallel. See Figure 121.

Unbalancedaccelerationsfromthebridgedrivesandlateralbridgewheelforcesfromtracking

causethe frametoskew. Lateralgirderbending fromtrolley inertia (andwind loads)along

withskewing,causethecornersoftheframetorotate. Thecornerrotationsteersthewheels

intothe

side

of

the

rail

and

tracking

performance

is

affected.

The

bridge

girders

and

end

ties

(orendtrucks)musthaveenoughstiffnesstopreventexcessivecornerrotationoftheframe.

Figure 12-1

12.0 BridgeStructureBehavior


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Page39of43

13.0 ExamplesofCraneStructureDamage

Figure131

Thespanforthisbridgewasincreasedbyinsertingadeepersectionatthecenterofthenewspan.

The dashed lines show the original girder. The horizontal dashed lines show where the original

girder

flange

overlaps

the

web

of

the

new

section.

The

splice

at

the

other

end

of

the

addedsectiondidnothaveaflangeoverlap,andthis iswherethefailureoccurred. Theflangeoverlap

creates a transition for the sudden change in girder depth. Without the flange overlap, the

reactionforceinthebottomflangeoftheoriginalgirderdoesnothaveenoughofananchor. In

thiscase,thelowerflangeforcewasdistributedintothediagonalflangeplateandthewebofthe

addedsection. Theweldedjointintheoverlapbetweentheflangeoftheoriginalsectionandthe

webofthenewsectionmustbe longenoughtocarry100%oftheforce inthebottomflangeof

theoriginalsection.


40/43

Page40of43

Figure132

ThisisacloseupofFigure141showingtypicalcrackingatthesplicebetweenthe

originalandaddedsection. Theoriginalgirderflangewasterminatedabruptlyand

weldedtothediagonalflangeoftheinsertedsection.

Figure132

Itislikelythatthecrackstartedattheflangesplice,andthen

propagatedintotheweboftheinsertedsection.(FromFigure141)


41/43

Page41of43

Figure133

ThisisacloseupfromFigure141showingthecrackpropagatingintothewebplate

oftheinsertedsection. Aholewasdrilledattheendofthecracktostop

propagation. Therespannedcranehadbeeninserviceforabout5years.

Figure13

4

Theseverticalbarssupport

the bridge drive for a high

productioncrane.Asimilar

configuration is shown in

Figure 72. The bars were

trimmed to install the

grease lines. The cutting

created a notch at the

corner which initiated a

crack that propagated into

the

girder

web.

Due

tomultiple repairs that could

nolongersupporttheload,

largesectionsofthegirder

webwerereplacedandthe

drive mounting was re

designed.


42/43

Page42of43

Figure135

This is a bridge girder looking up from

below. The vertical edge of a full depth

diaphragmis

shown.

This

girder

was

being

usedforaclassFbuckethandlingcrane.

The girders were in service only one year

beforetheyfailed. Thisfailurewasdueto

improper welding and detailing. The

girder web consisted of individual plates

welded between full depth diaphragms.

The vertical edges of the web segments

were connected to the full depth

diaphragms by intermittent fillet welds.

For box girders, most of the bending is

carried

by

the

flanges,

but

web

material

neartheflanges issubjectedtonearlythe

same strain. In this case the strain was

tensilenearthebottomflange. Thetensile

force in the web was carried by a single

sided fillet weld to the diaphragm. This

causedacyclicandeccentricloadingabout

the throat of the weld that resulted in

rapidfailureoftheweld. Thecrackedweb

welds propagated into the lower flange

which caused a complete failure of the

girder.


43/43

1. OmerW.Blodgett,DesignofWeldedStructures,JamesF.LincolnArcWeldingFoundation,Cleveland,Ohio,1976.

2. Kulak, Fisher, Struik, Guide to Design Criteria for Bolted and Riveted Joints, AmericanInstituteofSteelConstruction,Chicago,Illinois,2001.3. AmericanInstituteofSteelConstruction,SteelConstructionManual,9thed.,Chicago,1989.4. American Welding Society, Specification for Welding of Industrial and Mill Cranes and

OtherMaterialHandlingEquipment,ANSI/AWSD14.1:2005,Miami,Florida,2005.

5. American Welding Society, StructuralWelding CodeSteel,ANSI/AWSD1.1:2010, Miami,Florida,2010.

6. ResearchCouncilonStructuralConnections,SpecificationforStructuralJointsUsingASTMA325orA490Bolts,AmericanInstituteofSteelConstruction,Chicago,2004.

7. Charles G. Salmon, John E. Johnson, Steel Structures, Design and Behavior, IntextEducationalPublishers,NewYork,NY,1971.

8. U.S.DepartmentofTransportation,HighStrengthBoltsforBridges,reportNo.FHWASA91031,May,1991.

9. American Society of Mechanical Engineers, Overhead and Gantry Cranes (Top RunningBridge,SingleorMultipleGirder,TopRunningTrolleyHoist),ASMEB30.22005,NewYork,

NY,2005.

10. OccupationalSafety&HealthAdministration,29CFRPart1910.179OverheadandGantryCranes.

11. AmericanInstituteofSteelConstruction,DetailingforSteelConstruction,Chicago,1983.12. Crane Manufacturers Association of America, Inc., CMAA Specification No. 782002,

StandardsandGuidelinesforProfessionalServicesPerformedonOverheadandTraveling

CranesandAssociatedHoistingEquipment,Charlotte,NC,2002.

13. American Institute of Steel Construction,ANSI/AISC 36005, Specificationfor StructuralSteelBuildings,Chicago,2005.

14. S.Timoshenko,StrengthofMaterials,Part II,2ndedition,D.VanNostrandCo., Inc.,NewYork,1941.

14.0 References

guide line for inspection of overhead crane structure

Documents