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WoodworksPresenta.on
PresentedbyNormanScheel,P.E.,S.E.,SECB,F.SEAOC,F.ASCE,LEEDAPBD+C,LEEDAPHOMES
Disclaimer:Thispresenta1onwasdevelopedbyathirdpartyandisnotfundedbyWoodWorksortheSo=woodLumberBoard.
WoodworksPresenta.on
PresentedbyNormanScheel,P.E.,S.E.,SECB,F.SEAOC,F.ASCE,LEEDAPBD+C,LEEDAPHOMES
“TheWoodProductsCouncil”isaRegisteredProviderwithTheAmericanInsKtuteofArchitectsConKnuingEducaKonSystems(AIA/CES),Provider#G516.Credit(s)earnedoncompleKonofthiscoursewillbereportedtoAIACESforAIAmembers.CerKficatesofCompleKonforbothAIAmembersandnon-AIAmembersareavailableuponrequest.
ThiscourseisregisteredwithAIACESforconKnuingprofessionaleducaKon.Assuch,itdoesnotincludecontentthatmaybedeemedorconstruedtobeanapprovalorendorsementbytheAIAofanymaterialofconstrucKonoranymethodormannerofhandling,using,distribuKng,ordealinginanymaterialorproduct.__________________________________
QuesKonsrelatedtospecificmaterials,methods,andserviceswillbeaddressedattheconclusionofthispresentaKon.
CourseDescrip.on
ThiscourseisintendedforengineersandarchitectswhospecifymetalplatedwoodtrussesforuseincommercialandmulK-familybuildingprojects.Metalplateconnectedwoodtrusses(MPCWT)havelongbeenusedasacosteffecKvemethodtoachievelongspansinroofandfloorapplicaKons.ThispresentaKonwillcoversharedresponsibiliKesbetweenthedesignprofessionalofrecordandthetrussdesigner:theproperspecificaKonofdesignloads,includingexamplesoftrussesusedasdiaphragmchords,andshopdrawingreviews.Bracing,largecanKlevers,over-framing,secKonaltrusses,andsheartransferscenarioswillalsobediscussed.
LearningObjec.ves
1.Reviewthestandard-of-pracKceforsharedresponsibilityoftrussdesignbetweenthedesignprofessionalofrecord,responsibleforthebuildingasawhole,andthetrussmanufactureranddesignerprovidingstructuralcomponentsusedinthebuilding.2.OutlinecriKcalandusefulinformaKontoincludeinbuildingconstrucKondocumentstoimprovetrussmanufacturersabilitytodeliverhighperformingcomponents.3.OverviewhowtoreadtrussshopdrawingstoverifyconformancewiththeintendedspecificaKons.4.ExaminedifferentconfiguraKonsandtrussdetailstodemonstratehowmetalplateconnectedwoodtrussescanmeettheneedsofavarietyofbuildingprojects.
A<endeeBreakdown
Engineers50%
Architects30%
BuildingOfficials&Others20%
• DesignResponsibili.es
• DesignLoads• Ver.calLoads• LateralLoads(wind&seismic)
• Sheartransfer(collectors)• Chords
• Bracing• Webs• Chords(T.C.&B.C.)• Overframing• Sec.onalTrusses• GableEndBracing
• ShopDrawings• Layouts• TrussDrawings
• SpecialUses• TrussMyths
CourseOutline
DesignResponsibili.es
Construc.
on
Documents
CodeDefinedTerms
Contractor
TrussDesignDrawing
TrussDesignEngineer
TrussDesigner
RegisteredDesignProfessional
TrussManufacturer
TrussPlacementDiagram
TrussSubmi<alPackage DeferredSubmi<als
IndicatesLicensedPersons
* *
*
*
SimplifyTheProcess
• LoadsappliedtoTrusses
• TrussReac.ons
ImportantforEORReview
• GableEndBracing
• EndWallBracing
• PermanentWebBracingRestraint
• UpliWConnec.ons
• LateralLoadConnec.onstoTopPlates
• TrussHangerstoGirders
• TrussHangerstoBeams
• GirdertoGirderHangers
• Overframing&TopChordBracing
References
SeeIBC/CBCSecKon2303.4forCodeRequirements
pertainingtoWoodTrusses.
References
References
References
SeeTPI1-2007,Chapter2forDesignResponsibiliKespertainingtoWoodTrusses.
References
References
References
References
References
DesignLoads Ver.cal
SimpleCase
EasyenoughStaKcallyDeterminate
WARNING:DoNotUsePinnedReac.ons
FORCE
MOVEMENT
0.85#
2508#
Addinteriorbearings,notsosimple.Ifdesigned,supportswillbeatajoint.
SimpleCase
Addinteriorbearings,notsosimple.Ifnotdesigned,supportsmaybeinthemiddleofpanelsornearajoint.
SimpleCase
PreliminaryDesign
Max.Span=60’
Min.Depth(in.)=Span(W.)–10
FlatTrusses
Examples:
40’span,min.30”deepaverage
50’span,min.40”deepaverage
60’span,min.50”deepaverage
SlopingFlatshaveheelheightover21”
PreliminaryDesign(Cont.)
GableTrusses
Min.Slopes:
40’for3/12
50’for4/12
60’for5/12(cap)
Es.ma.ngDeflec.ons&InteriorReac.ons
TreatasBearing–
UseMomentofIner.a(I)foreffec.vedepthfordeflec.on
Calcula.onforMomentofIner.a(I)
Calcula.onforMomentofIner.a(I)cont.
FlatTruss
Dbl.Howe(4/12pitch)Truss
Dbl.Howe(6/12pitch)Truss
Deflec.onvs.LoadGraph0 1.580 0.800 0.410 4166 8333
500 1.180 0.680 0.3501000 0.780 0.560 0.2901500 0.390 0.440 0.2302000 0.070 0.320 0.200
1250
K=STIFFNESS (LBS./IN.)
DBL. HOWE TRUSS (4/12)
DBL. HOWE TRUSS (6/12) FLAT TRUSS
DL+LL DEFLECTION (IN.)
LOAD (LBS.) DBL. HOWE TRUSS (6/12) FLAT TRUSS DBL. HOWE
TRUSS (4/12)
DEFLECTION VS. LOAD
1.580
1.180
0.780
0.390
0.070
0.800
0.680
0.560
0.440
0.320
0.4100.350
0.2900.230 0.200
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.800
0 500 1000 1500 2000
CONCENTRATED LOAD (LBS.)
DEF
LEC
TIO
N (L
L +
DL)
Flat Truss Dbl. Howe Truss (4/12 Pitch) Dbl. Howe Truss (6/12 Pitch)
ForGableTruss,usesameasFlatTrussanduse0.8overalleffec.vedepth
Example:
40’span,4/12pitch
0.8xdepth=0.8x4x20=64”
Resultsarewithin10%forDeflec.onsandReac.ons.ThisisOKforPreliminaryDesign.
Reasons:
• Deflec.onsaresmall
• BeamReac.onsareapproximateifTrussiscon.nuous
CODEREQUIREMENTS
OldvsNewCodeLoading
1.22.848
-0.48.4815
0.587.5814
1.46.6813
2.06.0812
2.05.0711
1.84.2610
1.53.559
0.82.237
0.41.626-0.21.215-0.80.804
DifferenceDeadLoadSlopeIncrease(14PSF)
LiveLoadDecrease
Slope/12
2006 IBC
MinimumRoofLiveLoads(TributaryAreaReduc.on)
2012IBC
DesignLoads Lateral
SimpleCollectorTruss
ComplicatedCollectorTruss
ShearTransfertoCenterCollectorTruss
BRAINBREAK
TrussHistory
ATRIBUTETOCEASER
NowBacktoSeriousStuff
Pre-EngineeredGangNailTrusses
ShearTransferPerpendiculartoTrusses
BlockingDetails
Pre-EngineeredGangNailTrussesFramingDetails
Bracing
ShopDrawings
TrussMyths
TrussMyths
• Thetrusscompanyhandleseverythingfromthetopplateup.
• Beamsbelowtrussesprovidetheinfinitelyrigidsupportasmodeledinthecomputeranalysis.
• Axialforcesintrussmembersareatthemembercenterlines.
• Thepin/rollermodeledinthecomputerisaccurate.
TrussMyths
• Trussjointsareall“pin”connected.
• Theengineerwhosealedthetrussdrawingshasseentheplans.
• Thedesignprofessionalwillincorporatethetrussdesignsintothebuildingdesign.
• Ifinteriorwallstouchthebo<omchorditwilloverstressthemembers.
TrussMyths
• Collectortrusses(sheartransfertrusses)atthegableendneedtobestructural(withwebinsteadofver.calsonly)ifthetrusshasheelsateachend.
• Scissortrussesimposelateralloadsontheexteriorwallsattheheels.
• Alevelreturnwillsupporttheendofalongoverhang.
BRAINBREAK
SpecialUses
102
103
Six-Sided Roof
HorizontalThrust&TensionCalcsforOctagon
HorizontalThrust&TensionCalcsforOctagon
14
Applications
§ Concrete forming
68
Completed Arch Wall
69
Arch Truss Setup
70
Arch Truss Swing
71
Arch Walls
76
Arch Vault Section
77
Arched Girder Framing
78
Section Set
85
Vaulted Trusses
86
Girder-to-Girder
104
Compression Ring
12
Applications
§ Agricultural structures
Ques.ons?ThisconcludesTheAmericanInsKtuteofArchitectsConKnuingEducaKonSystemsCourse
REFERENCESTRUSSDETAILS