Bolting-welding-1-steel structure connection.ppt

Bolting-welding

1. 1

2. 2
Thispresentationwasdevelopedasateachingaidwiththesupportofthe
AmericanInstituteofSteelConstruction.Itsobjectiveistoprovidetechnical
backgroundandinformationforboltingandwelding.Theinformation
providedisbasedoncommondesignandconstructionpracticesfor
structuresoftwelvestoriesorless.
TheAISCDigitalLibrarycasestudypresentationsdocumenttheconstruction
ofasteelframeforanofficebuilding.Thecasestudyincludesphotographs
thatweretakenthroughouttheconstructionofthestructuralsteelframe
includingdetailing,fabrication,anderection.Projectdataincludingplans,
schedules,specificationsandotherdetailsarealsoincluded.Thecasestudy
presentationsareavailableintheLearningOpportunitiessectionat
www.aisc.org.
Thispresentationprovidestechnicalinformationonboltingandwelding,as
wellastheimpactsofdetailsanddesignchoicesonschedule,cost,
sequenceandoverallprojectmanagement.
Theinformationispresentedwithconcernsofaconstructionmanageror
generalcontractorinmind.
Introduction

3. 3
•Generalknowledgeofstructuralsteel
•Anunderstandingofthedifferentwaysthatstructuralsteelisconnected
•Insightintotypesofboltsandtheirinstallation
•Anawarenessoftypesofboltedjointsusedforstructuralsteel
•Knowledgeofweldingterminology,weldtypes,andweldingprocesses
•Familiaritywithcommonweldinspectionmethodsandconsiderations
associatedwithfieldwelding
What Will You Gain From This
Presentation?

4. 4
Somebenefitsassociatedwithuseofstructuralsteelforownersare:
•Steelallowsforreducedframeconstructiontimeandtheabilitytoconstruct
inallseasons
•Steelmakeslargespansandbaysizespossible,providingmoreflexibilityfor
owners
•Steeliseasiertomodifyandreinforceifarchitecturalchangesaremadetoa
facilityoveritslife
•Steelislightweightandcanreducefoundationcosts
•Steelisdurable,long-lastingandrecyclable (AISC1999)
Benefits of Structural Steel

5. 5
Procurementandmanagementofstructuralsteelissimilartoothermaterials,
buttherearesomeuniqueaspectstosteelconstruction:
•Steelisfabricatedoff-site(aboveleft)
•On-siteerectionisarapidprocess(aboveright)
•Thisgivesuseofstructuralsteelsomeschedulingadvantages
•Coordinationofallpartiesisessentialforachievingpotentialadvantages
(AISC1999)
Unique Aspects of Steel Construction

6. 6
Connecting Structural Steel
•Theprimaryconnectionmethodsforstructuralsteelareboltingandwelding
•Astructure’sstrengthdependsonproperuseoftheseconnectionmethods
•Connectionsmadeinafabricationshoparecalledshopconnections
•Connectionsmadeinthefieldbythesteelerectorarecalledfieldconnections
•Boltingandweldingmaybeusedforshopconnectionsandfieldconnections

7. 7
•Afabricationshopwillhaveadesiredfasteningmethodsuitedtoitsequipment
andfabricationmethods
•Fieldconnectionsaretypicallybolted
•Weldingmaybeusedforfieldconnectionswhereboltingiseitherimpracticalor
undesirable
•Weldingisbettersuitedtothecontrolledenvironmentofafabricationshop
Connecting Structural Steel

8. 8

9. 9
•TheResearchCouncilonStructuralConnections(RCSC)prepares
specificationsanddocumentsrelatedtostructuralconnections
•RCSC’sSpecificationforStructuralJointsUsingASTMA325orA490Bolts
(2000)isawidelyusedspecificationwhichdiscussesjoints,fasteners,limit
states,installation,andinspections
Structural Bolting

10. 10
•Duringhoisting,connectorswillinstallaminimumoftwoboltsperconnection
•Therestoftheboltsareinstalledandtightenedafterthestructureisplumbed
•Asystematicpatternmustbefollowedwhentighteningboltssothatajointis
drawntogetherandallfastenersareproperlyinstalled
(SSTC2001)
Structural Bolting

11. 11
PertheOccupationalSafety&HealthAdministrationStandard1926.754(b)(2),“At
notimeshalltherebemorethanfourfloorsor48feet(14.6m),whicheverisless,
ofunfinishedboltingorweldingabovethefoundationoruppermostpermanently
securedfloor,exceptwherethestructuralintegrityismaintainedasaresultofthe
design.”
Structural Bolting

12. 12
•Therearemanybolttypes,installationmethods,andjointtypesusedin
structuralsteelconstruction
•Whenleftexposed,boltsmaybeusedtomakeanarchitecturalexpression
(Green,Sputo,andVeltri)
Structural Bolting
(AISC & NISD 2000)

13. 13
ASTM Bolt Types
(AISC & NISD 2000)
•A307–Lowcarbonsteel
Notcommonlyused
Onlyusedforsecondarymembers
•A325–High-strengthmediumcarbonsteel(aboveleft)
Mostcommonboltsusedinbuildingconstruction
•A490–High-strengthheattreatedsteel(aboveright)
CostmorethanA325’s,butarestrongersofewerboltsmaybenecessary
•NotethattheASTMdesignationisindicatedontheheadoftheboltsabove

14. 14
•A325andA490boltsareavailableindiametersrangingfrom1/2”to1-1/2”
•Themostcommonsizesare3/4”,7/8”,and1”
•High-strengthboltsarecommonlyavailableinincrementallengthsupto8”
(AISC)
Common Bolt Sizes

15. 15
•Hardenedsteelwashersareusedinmanystructuralconnectionstospread
pressurefromthebolttighteningprocessoveralargerarea
•Washersmayalsobeusedtocoveranoversizedorslottedhole(RCSC2000)
•Flatwashersaremostcommonlyused
•Taperedwashers(aboveleft)areusedwhenthesurfacebeingboltedhasa
slopedsurface,suchastheflangeofachanneloranSshape
•A325boltsrequireawasherundertheelement(headornut)beingturnedto
tightenthebolt(shownunderthenut,aboveright)
•A490boltsrequireawasherunderboththeheadandnut(AISC&NISD2000)
Washers

16. 16
•Gripisthedistancefrombehindtheboltheadtothebackofthenutorwasher
Itisthesumofthethicknessesofallthepartsbeingjoinedexclusiveof
washers
•Threadlengthisthethreadedportionofthebolt
•Boltlengthisthedistancefrombehindtheboltheadtotheendofthebolt
(AISC&NISD2000)
Parts of the Bolt Assembly
Head
Shank
Washer
NutWasher
Face
Grip
Thread
Length

17. 17
•Theretwobasicboltedjointtypes:
Bearing
oTheloadistransferredbetweenmembersbybearingonthebolts
Slip-critical
oTheloadistransferredbetweenmembersbyfrictioninthejoint
Bolted Joint Types

18. 18
•Boltsinbearingjointsaredesignedtomeettwolimitstates:
1.Yielding,whichisaninelasticdeformation(aboveleft)
2.Fracture,whichisafailureofthejoint(aboveleft)
•Thematerialtheboltbearsagainstisalsosubjecttoyieldingorfractureifitis
undersizedfortheload(aboveright)
•Tensionconnectionsactsimilarlytobearingconnections
Manytimes,connectionsindirecttensionarereconfiguredsothatthebolts
actinshear (AISC)
Bolted Joint Failure Modes
Bearing
Fracture
Bearing
Yield
Bearing
Yield
Bearing
Fracture

19. 19
•Inabearingjointtheconnectedelementsareassumedtoslipintobearing
againstthebodyofthebolt
•Ifthejointisdesignedasabearingjointtheloadistransferredthroughbearing
whethertheboltisinstalledsnug-tightorpretensioned (AISC)
Bearing Joints

20. 20
•Theshearplaneistheplane
betweentwoormorepieces
underloadwherethepieces
tendtomoveparallelfrom
eachother,butinopposite
directions
•Thethreadsofaboltmay
eitherbeincludedinthe
shearplaneorexcluded
fromtheshearplane
•Thecapacityofaboltis
greaterwiththethreads
excludedfromtheshear
plane
•Themostcommonlyused
boltisanASTMA3253/4”
boltwiththethreads
includedintheshearplane
(AISC&NISD2000)
Threads in the Shear Plane
Threads Included In The Shear Plane
Threads Excluded From The Shear Plane

21. 21
•Inaslip-criticaljointtheboltsmustbefullypretensionedtocauseaclamping
forcebetweentheconnectedelements
•Thisforcedevelopsfrictionalresistancebetweentheconnectedelements
•Thefrictionalresistanceallowsthejointtowithstandloadingwithoutslipping
intobearingagainstthebodyofthebolt,althoughtheboltsmuststillbe
designedforbearing
•Thefayingsurfacesinslip-criticaljointsrequirespecialpreparation (AISC)
Slip-Critical Joints

22. 22
When to Use Slip-Critical Joints
1.Jointsthataresubjecttofatigueloadwithreversaloftheloadingdirection
(notapplicabletowindbracing)
2.Jointsthatutilizeoversizedholes
3.Jointsthatutilizeslottedholes,exceptthosewithappliedloadapproximately
perpendiculartothedirectionofthelongdimensionoftheslot
4.Jointsinwhichslipatthefayingsurfaceswouldbedetrimentaltothe
performanceofthestructure
PertheRCSCSpecification(2000),Slip-criticaljointsareonlyrequiredinthe
followingapplicationsinvolvingshearorcombinedshearandtension:

23. 23
Snug-tightisthetightnessattainedwithafewhitsofanimpactwrenchorthefull
effortofanironworkerusinganordinaryspudwrenchtobringtheconnectedplies
intofirmcontact
(RCSC2000)
Snug-tight Installation

24. 24
•Installationbeyondsnug-tightiscalledpretensioning
•Turn-of-nutpretensioninginvolvesseveralsteps:
1.Theboltissnug-tightened
2.Matchmarksareplacedoneachnut,bolt,andsteelsurfaceinastraightline
3.Thepartnotturnedbythewrenchispreventedfromturning
4.Theboltistightenedwithaprescribedrotationpastthesnug-tightcondition
•Thespecifiedrotationvariesbydiameterandlength(between1/3and1turn)
(RCSC2000,AISC)
Turn-of-Nut Installation

25. 25
Calibrated Wrench Installation
•CalibratedWrenchpretensioningusesanimpactwrench(aboveleft)totighten
thebolttoaspecifiedtension
•ASkidmore-Wilhelmcalibrationdevice(aboveright)isusedtocalibratethe
impactwrenchtothetorquelevelwhichwillachievethespecifiedtension
•Asampleofboltsrepresentativeofthosetobeusedintheconnectionsare
testedtoverifythatthecorrecttensionwillbeachieved(RCSC2000,AISC)

26. 26
•F1852boltsaretwist-off-typetension-
controlbolts
•Theseboltsmustbepretensionedwitha
twist-off-typetension-controlboltinstallation
wrenchthathastwocoaxialchucks
•Theinnerchuckengagesthesplinedendof
thebolt
•Theouterchuckengagesthenut
•Thetwochucksturnoppositetoone
anothertotightenthebolt
•ThesplinedendoftheF1852boltshears
offataspecifiedtension (AISC2003)
ASTM F1852 Installation
(AISC)

27. 27
•Anotherwaytotrytoensureproperpretensioningofaboltisthroughtheuseof
directtensionindicators(DTIs)
•Thesewashershaveprotrusionsthatmustbearagainsttheunturnedelement
•Astheboltistightenedtheclampingforceflattenstheprotrusionsandreduces
thegap
•Thegapismeasuredwithafeelergage
•Whenthegapreachesthespecifiedsizetheboltisproperlypretensioned
(AISC&NISD2000)
ASTM F959 Direct Tension Indicators
Feeler Gages
DTI’s

28. 28
Itisessentialthatdirecttensionindicatorsbeproperlyorientedintheassembly
a)Theboltheadisstationarywhilethenutisturned–DTIunderbolthead
b)Theboltheadisstationarywhilethenutisturned–DTIundernut(washerrequired)
c)Thenutisstationarywhiletheboltheadisturned–DTIunderbolthead(washerrequired)
d)Thenutisstationarywhiletheboltheadisturned–DTIundernut
(RCSC2000)
Installation of DTIs
(Adapted from Figure C-8.1 RCSC 2000)

29. 29
•Boltsareinstalledinoneoffourtypesofholes(seetableabove)
•Standardholescanbeusedanywhere
•Oversizedholesmayonlybeusedinslip-criticalconnections
•Short-slottedholesareusedwiththeslotperpendiculartothedirectionofstress
•Long-slottedholesareprimarilyusedwhenconnectingtoexistingstructures
Nominal Bolt Hole Dimensions
(Table 3.1 RCSC 2000)

30. 30
•CommontoolsusedbyIronworkersincludespudwrenches,pins,and
correctionsbarsofvarioussizes(aboveleft)
•Impactwrencheswillbeneededforcertaininstallations(abovecenter)
•Electricityorcompressedairisrequireddependingontheimpactwrenchbeing
used
Ageneratoraswellasanaircompressormaybeneeded(aboveright)
Equipment Requirements

31. 31
PertheRCSCSpecification:
•Fastenercomponentsmustbeprotectedfromdirtandmoistureinclosed
containersonthejobsite
•Onlyfastenersanticipatedtobeinstalledduringtheworkshiftaretobetaken
fromprotectedstorage
•Protectedstorageisdefinedasthecontinuousprotectionoffastener
componentsinclosedcontainersinaprotectedshelter
•Anyunusedfastenersmustbepromptlyreturnedtoprotectedstorage
Storage of Components

32. 32
•Thelubricationonfastenersisvitaltotheirproperinstallation
•Awater-solubleoilisusedonmostblackbolts
•Thisoiliseasilywashedoffwhenexposedtomoisture
•Fastenersthataccumulaterustordirtmustbecleanedandrelubricatedbefore
theymaybeinstalled
•F1852bolts(shownabove)shallnotberelubricated,exceptbythe
manufacturer (RCSC2000,SSTC2001)
Storage of Components

33. 33
Storage of Galvanized Fasteners
•Galvanizedboltsandnuts(above)areprovidedbythesupplierinasetand
specialstoragerequirements
•Eachbolt/nutsetispretestedbythesupplierandshippedtogetherandmustbe
kepttogetherasanassembly
•Poorthreadfitmayresultiftheboltandnutaremismatched
•Thelubricationongalvanizedfastenersisgenerallymoredurablethanthaton
blackbolts,butprotectedstorageisstillrecommended
•A490boltsarenotallowedtobegalvanized (SSTC2001)

34. 34
•Productionlottraceabilityisrequiredbymanystandards
•Evenifnotrequired,itisgoodpracticetorecordthelotnumbersandkeepall
fastenersseparatedbylot
•Itisnecessarytokeeplotsseparateforproperpre-installationverification
testingwhichisrequiredforpretensionedandslip-criticaljoints
•Mixingboltsandnutsfromdifferentproductionlotsisnotpermitted
(SSTC2001)
Production Lots

35. 35
Inspections
•Inadditiontotheerector’squalitycontrolprogram,testsandinspectionare
specifiedbytheEngineerofRecordand/orthelocalbuildingauthority
•Alocalbuildinginspectormayrequestthattestsinadditiontothosespecified
bytheEngineerofRecordbeperformed
•Snug-tightenedjointsrequirevisualinspectionforfirmcontactandproperuse
ofwashers
•Pretensionedjointsrequirepre-installationverificationandroutineobservation
ofproperapplication
•Slip-criticaljointsrequireinspectionofthefayingsurfacesinadditiontothe
aboveinspections

36. 36
Inspections for the Construction Manager
Thereareseveralboltedconnectioninspectionsaconstructionmanagercan
perform:
•Lookattheboltstick-out(above)
Stick-outistheamounttheboltextendsbeyondtheoutsidesurfaceofthe
nut
Positiveorzerostick-outisacceptable
Negativestick-out,wheretheendoftheboltisinsidethenut,isnot
acceptable

37. 37
Inspections for the Construction Manager
•Inspecttheturn-of-nutmatchmarkstoensuretheboltshavebeenpretensioned
•IfF1852boltsareused,makesuretheendshavebeensnappedoffallbolts
(above)
Insomecases,duetoinsufficientclearancefortheinstallationwrench,
F1852boltswillbetightenedbyalternativemethodssotheendswillnotbe
snappedoff

38. 38
•Theerectormayprefercertainboltandjointtypesoverothersdueto
equipmentrequirements,experience,andinstallationtimes
•Snug-tightenedjointsarenormallythemosteconomicalboltedjoints(Ruby
2003)
•Forpretensionedjoints,F1852’sandDTI’sarepopularandcanbeeconomical
•Slip-criticaljointsarethemostcostlyjoints,andshouldonlybespecifiedwhen
necessary(Ruby2003)
Bolting Cost Considerations
Thetypesofjointsusedinastructurearesomewhatdependentontheoverall
designofthestructure,butthesearesomepointstoconsider:

39. 39

40. 40
•Anothercommonmethodforconnectingstructuralsteeliswelding
•Weldingcanbeperformedintheshoporinthefield
•Manyfabricationshopsprefertoweldratherthanbolt
•Weldinginthefieldisavoidedifpossibleduetoweldingconditionrequirements
•Thereareseveralweldingprocesses,types,andpositionstobeconsideredin
buildingconstruction
Structural Welding

41. 41
•TheAmericanWeldingSociety(AWS)isanonprofitorganizationwithagoalto
advancethescience,technologyandapplicationofweldingandrelatedjoining
disciplines
•AWSdevelopscodes,recommendedpractices,andguidesunderstrict
AmericanNationalStandardsInstitute(ANSI)procedures
•D1.1StructuralWeldingCode–Steel,oneofthemostconsultedcodesinthe
world,isproducedbyAWS (AWS2004a)
Structural Welding

42. 42
•Weldingistheprocessoffusingmultiplepiecesofmetaltogetherbyheating
thefillermetaltoaliquidstate
•Aproperlyweldedjointisstrongerthanthebasemetal
Structural Welding

43. 43
•Weldsmaybeloadedinshear,tension,compression,oracombinationofthese
•CapacitiesforweldsaregivenintheAISCSpecificationSectionJ2(2005)
•Thestrengthofaweldisdependentonmultiplefactors,including:basemetal,
fillermetal,typeofweld,throatandweldsize
Strength of Structural Welds
(Part of Table J2.5 AISC 2005)

44. 44
•TackWeld(aboveleft)
Atemporaryweldusedtoholdpartsinplacewhilemoreextensive,final
weldsaremade
•ContinuousWeld
Aweldwhichextendscontinuouslyfromoneendofajointtotheother
•StitchWeld(aboveright)
Aseriesofweldsofaspecifiedlengththatarespacedaspecifieddistance
fromeachother
Welding Terminology

45. 45
Butt
Lap Corner
Tee
Edge
•Shownabovearetypesofstructuraljointswhichareestablishedbypositionsof
theconnectedmaterialrelativetooneanother
•Lap,tee,andbuttjointsaremostcommon (AISC)
Welding Terminology

46. 46
Fillet Full penetration
single bevel
groove weld
Partial penetration
single bevel
groove weld
Plug
Full penetration
double vee
groove weld
Partial penetration
single J groove
weld
•Weldtypesdefinetheconfigurationoftheweldanditsunderlyingdesign
approach
•Filletweldsandgrooveweldsaremostcommon
•Grooveweldsfallintotwocategories
Fullpenetration–theentiremembercross-sectioniswelded
Partialpenetration–justpartofthemembercross-sectioniswelded
(AISC)
Welding Terminology

47. 47
•The most commonly used weld is the fillet weld
•Fillet welds are theoretically triangular in cross-section
•Fillet welds join two surfaces at approximately right angles to each other in
lap, tee, and corner joints
(AISC&NISD2000)
Fillet Welds
Symbolic Profiles
Actual Profiles

48. 48
•Grooveweldsarespecifiedwhenafilletweldisnotappropriateforthejob
Theconfigurationofthepiecesmaynotpermitfilletwelding
Astrengthgreaterthanthatprovidedbyafilletweldisrequired
•Grooveweldsaremadeinthespaceorgroovebetweenthetwopiecesbeing
welded (AISC&NISD2000)
Groove Welds

49. 49
•Thebevelor“J”preparationextendsovermostofortheentirefaceofthe
materialbeingjoined
•Completefusiontakesplace
•Insometypesoffullpenetrationgrooveweldsthematerialwillbebeveledfrom
onesideoftheplatewithaseparateplateontheoppositeside–calledbacking
orabackingbar (AISC&NISD2000)
Full Penetration Groove Welds

50. 50
Partialjointpenetrationweldsareusedwhenitisnotnecessaryforthestrengthof
thejointtodevelopthefullcrosssectionofthemembersbeingjoined
(AISC&NISD2000)
Partial Penetration Groove Welds

51. 51
•Therearefourrecognizedweldingpositions:
Flat–Thefaceoftheweldisapproximatelyhorizontalandweldingis
performedfromabovethejoint
Horizontal–Theaxisoftheweldishorizontal
Vertical–Theaxisisapproximatelyverticalorintheuprightposition
Overhead–Weldingisperformedfrombelowthejoint
•Theflatpositionispreferredbecauseitiseasierandmoreefficienttoweldin
thisposition (AISC&NISD2000)
Welding Positions

52. 52
•Weldsymbolsareused
tocommunicatethe
specificdetailsand
requirementsofeach
weldtothewelder
•Weldsymbolsare
includedonfabrication
anderectiondrawings
Weld Symbols
Leader Line
Horizontal Weld Line
Tail
Basic Weld Symbol
(Fillet weld symbol shown)
Note
(Indicating this is
a typical weld)
Length and Spacing of weld
(In Inches)
Size of weld
(In Inches)
Field Weld Symbol

53. 53
Weld Size
•Thesizeofaweldmustmatchthesizespecifiedonthedrawings
•Someweldsmaymeettherequiredsizeafterasinglepassofthewelder
•Largerweldsizesmayrequiremultiplepassestomeetthesizerequirement
•Commonsinglepassweldsincludefilletweldsuptoandincluding5/16inch
andthinplatebuttweldswithnopreparation
•Commonmultiplepassweldsincludesinglebevelfullpenetrationgroovewelds,
singlebevelpartialpenetrationgroovewelds,andfilletweldsover5/16inch
•Theweldintheabovepictureisamultiplepassfilletweld

54. 54
Weld Accessibility
•Accessholesarerequiredfor
somewelds,suchasthewelded
flangeconnectionshowntothe
right
Thetopaccessholeallows
foracontinuousbacking
bartobeplacedunderthe
topflange
Thebottomaccesshole
allowsforcompleteaccess
toweldtheentirewidthof
thebottomflange
•Adetailofaweldaccesshole
foraweldedflangeconnection
isshownbelow
Column
Seat Angle
Weld Access
Holes
Backing Bar
Extension Bar
(Adapted from AISC 2001)
(Adapted from AISC 2002a)

55. 55
•ShieldedMetalArcWelding(SMAW)isalsoknownasmanual,stick,orhand
welding
•Anelectricarcisproducedbetweentheendofacoatedmetalelectrodeand
thesteelcomponentstobewelded
•Theelectrodeisafillermetalcoveredwithacoating
•Theelectrode’scoatinghastwopurposes:
•Itformsagasshieldtopreventimpuritiesintheatmospherefromgetting
intotheweld
•Itcontainsafluxthatpurifiesthemoltenmetal (AISC&NISD2000)
SMAW Welding

56. 56
•GasMetalArcWelding(GMAW)isalsoknownasMIGwelding
•Itisfastandeconomical
•Acontinuouswireisfedintotheweldinggun
•Thewiremeltsandcombineswiththebasemetaltoformtheweld
•Themoltenmetalisprotectedfromtheatmospherebyagasshieldwhichisfed
throughaconduittothetipoftheweldinggun
•Thisprocessmaybeautomated (AISC&NISD2000)
GMAW Welding

57. 57
•FluxCoredArcWelding(FCAW)issimilartotheGMAWprocess
•Thedifferenceisthatthefillerwirehasacentercorewhichcontainsflux
•Withthisprocessitispossibletoweldwithorwithoutashieldinggas
Thismakesitusefulforexposedconditionswhereashieldinggasmaybe
affectedbythewind
(AISC&NISD2000)
FCAW Welding

58. 58
•SubmergedArcWelding(SAW)isonlyperformedbyautomaticor
semiautomaticmethods
•Usesacontinuouslyfedfillermetalelectrode
•Theweldpoolisprotectedfromthesurroundingatmospherebyablanketof
granularfluxfedattheweldinggun
•Resultsinadeeperweldpenetrationthantheotherprocess
•Onlyflatorhorizontalpositionsmaybeused (AISC&NISD2000)
SAW Welding

59. 59
•Equipmentusedforweldingwillvarydependingontheweldingprocessand
whethertheweldingisbeingdoneintheshoporinthefield
•AFluxCoredArcWeldingmachineforshopweldingispicturedaboveleft
•AShieldedMetalArcWeldingmachineforfieldweldingispicturedaboveright
Welding Equipment

60. 60
•Weldinginthefieldisavoidedifpossibleduetoweldingconditionrequirements
•Fieldweldingisnottobeperformedwhileitisraining,snowing,orbelow0°F
•Incertainambienttemperaturespreheatingofthematerialtobeweldedis
required
•AWSCodeD1.1(2004b)specifiesminimumpreheatandinterpass
temperatures,whicharedesignedtopreventcracking
Weather Impacts on Welding

61. 61
•Itisimportantforboththewelderandthoseworkingintheareaarounda
weldingprocesstobesafetyconscious
•Theweldingarcshouldneverbelookedatwiththenakedeye
•AWSpublishesmanysafetyandhealthfactsheetswhichareavailablefor
downloadattheirwebsite:www.aws.org
Welding Safety

62. 62
Aweldershouldweartheproperprotectivegearincluding:
Welding Safety
•Helmet
•Face shield or goggles
•Gloves
•Boots
•Heavy fabric or leather shirt
•Cuffless pants
•Leather leggings

63. 63
Weldingtoexistingstructuresduringretrofitprojectsrequirescarefulconsideration
ofnumerousfactors:
Welding in Existing Structures
•Determineweldability–Identifythesteelgradetoestablishawelding
procedure
•Selectanddesigntheweld–Filletweldsarepreferredandavoidoverwelding
•Surfacepreparation–Removecontaminantssuchaspaint,oil,andgrease
•Loadsduringretrofit–Anengineershoulddeterminetheextenttowhicha
memberwillbepermittedtocarryloadswhileheating,welding,orcutting
•Firehazards–Followallgoverningfirecodes,regulations,andsafetyrulesto
avoidfires
•ForcompletedetailsseetheAISCRehabilitationandRetrofitGuide(2002b)

64. 64
Weld Inspections
•Inadditiontotheerector’squalitycontrolprogram,testsandinspectionsare
specifiedbytheEngineerofRecordand/orthelocalbuildingauthority
•Alocalbuildinginspectormayrequestthattestsinadditiontothosespecified
bytheEngineerofRecordbeperformed
•Someproblemsthatcanbefoundinweldsinclude:
Lackoffusion
Porosity
Cracks
Insufficient penetration
•Thereareseveralweldtestsandinspectionsthatarecommonlyused
Wrongsize
Poor workmanship

65. 65
•Visualinspectionisthemostfrequentlyusedinspectionandistheonly
inspectionrequiredunlessthespecificationcallsforamorestringentinspection
method
•Inspectionisdonebythewelderbefore,during,andafterwelding
•Whenoutsideinspectionisrequireditshouldalsobedonebefore,during,and
afterwelding
•Minorproblemscanbeidentifiedandcorrectedbeforetheweldiscomplete
(AISC&NISD2000)
Visual Inspection

66. 66
•Dyepenetranttestinglocatesminutesurfacecracksandporosity
•Dyetypesthatmaybeusedinclude:
Colorcontrastdye-whichshowsupunderordinarylight
Fluorescentdye–whichshowsupunderblacklight
•Thedyeisnormallyappliedbysprayingitdirectlyontheweld
(AISC&NISD2000)
Dye Penetrant Test

67. 67
•Magneticparticleinspectionusespowderedmagneticparticlestoindicate
defectsinmagneticmaterials
•Amagneticfieldisinducedinthepart
•Themagneticpowderisattractedtoandoutlinescrackswithinthematerial
(AISC&NISD2000)
Magnetic Particle Inspection

68. 68
•Ultrasonicinspectioncanbeusedtodetectflawsinsidewelds
•Highfrequencysoundwavesaredirectedintothemetalwithaprobeheldata
specificangle
•Theflawsreflectsomeenergybacktotheprobe
•Flawsshowupasindicationsonascreen(above)andaresubjectto
interpretationbyaninspector
(AISC&NISD2000)
Ultrasonic Inspection

69. 69
•Radiographicinspection,orX-ray,canalsobeusedtodetectflawsinsidewelds
•Invisiblerayspenetratethemetalandrevealflawsonanx-rayfilmor
fluorescentscreen(above)
•Thisisthemostcostlyoftheinspectionmethods
(AISC&NISD2000)
Radiographic Inspection

70. 70
•Filletweldislessexpensivethangrooveweld
Nospecialpreparation
Nobackingrequired
Lessvolumeofweld
•Partialpenetrationgrooveweldislessexpensivethanfull
penetrationgrooveweld
•Laborrepresentsthemajorityofthecostassociatedwithwelding
Welding Cost Considerations

71. 71
•Boltingisgenerallyafasteroperationthanwelding
•Boltingdoesnothavethetemperatureandweatherconditionrequirementsthat
areassociatedwithwelding
•Unexpectedweatherchangesmaydelayweldingoperations
Bolting and Welding
Scheduling Considerations

72. 72
Structural Steel: The Material of Choice

73. 73
References
AISC. (n.d.). Steel Connections: Behavior and Practice[35mm Slide Show with Script].
American Institute of Steel Construction, Inc. Chicago, IL.
AISC. (2001). LRFD Manual of Steel Construction, Third Edition.American Institute of Steel
Construction, Inc. Chicago, IL.
AISC. (2002a). Seismic Provisions for Structural Steel Buildings.American Institute of Steel
Construction, Inc. Chicago, IL.
AISC. (2002b). Design Guide 15 –AISC Rehabilitation and Retrofit Guide.American Institute of
Steel Construction, Inc. Chicago, IL.
AISC.(2003).HighStrengthBolts:APrimerforStructuralEngineers.AmericanInstituteofSteel
Construction,Inc.Chicago,IL.
AISC & NISD. (2000). Detailer Training Series[CD-ROM set]. American Institute of Steel
Construction, Inc. and National Institute of Steel Detailing. Chicago, IL. (Available from
AISC, One East Wacker Drive, Suite 3100, Chicago, IL 60601).
American Welding Society, (AWS). (2004a). American Welding Society Web Site. Available at:
http://www.aws.org/. Viewed August, 2004.
American Welding Society, (AWS). (2004b). “Structural Welding Code.” ANSI/AWS D1.1-2004,
Miami, FL.
Green, P. S., Sputo, T., and Veltri, P. (n.d.). Connections Teaching Toolkit –A Teaching Guide
for Structural Steel Connections.American Institute of Steel Construction, Inc. Chicago, IL.
Research Council on Structural Connections, (RCSC). (2000). Specification for Structural Joints
Using ASTM A325 or A490 Bolts.American Institute of Steel Construction, Inc. Chicago, IL.
Ruby, D.I. (2003) . “All About Bolts.” AISC Modern Steel Construction,May.
SSTC. (2001). Structural Bolting Handbook.Steel Structures Technology Center, Inc. Novi, MI.