Designing for Wind Loads in High Seismic Regions Presented by Ricky McLain, MS, PE, SE Oakland Wood Solu:ons Fair May 17, 2016
DesigningforWindLoadsinHighSeismicRegions
PresentedbyRickyMcLain,MS,PE,SEOaklandWoodSolu:onsFairMay17,2016
“TheWoodProductsCouncil”isaRegisteredProviderwithTheAmericanIns:tuteofArchitectsCon:nuingEduca:onSystems(AIA/CES),Provider#G516.Credit(s)earnedoncomple:onofthiscoursewillbereportedtoAIACESforAIAmembers.Cer:ficatesofComple:onforbothAIAmembersandnon-AIAmembersareavailableuponrequest.
ThiscourseisregisteredwithAIACESforcon:nuingprofessionaleduca:on.Assuch,itdoesnotincludecontentthatmaybedeemedorconstruedtobeanapprovalorendorsementbytheAIAofanymaterialofconstruc:onoranymethodormannerofhandling,using,distribu:ng,ordealinginanymaterialorproduct.________________________________ Ques:onsrelatedtospecificmaterials,methods,andserviceswillbeaddressedattheconclusionofthispresenta:on.
CourseDescrip8on
Inregionsofthecountrywherehighseismicitytendstocontrollateralbuildingdesign,windloadsandtheireffectsonastructurecaneasilybeoverlooked.Intendedforstructuralengineerswhoarewellversedinseismicdesign,thispresenta:onwilladdressthedesignofwood-framebuildingsforwindloadsinhighseismicregions,withafocuson:mesavingdesign:psandbestprac:cesassociatedwiththeeffectsofout-of-planewindforcesonwalldesignandroofupliZ.Differencesbetweenseismicandwindloadswillbehighlighted,alongwithseveralrulesofthumbthatcanbeappliedwhenconsideringwhichforceshouldcontrol.Walldesignforout-of-planewindloadswillbepresentedasastraigh\orwardthree-stepprocesswithuniqueconsidera:onsandop:onsforwood-frametallwalls.Calcula:onsformagnitudeofroofupliZwindloadswillbereviewed,aswill:psforminimizingtheireffectsonthestructurebelowwhilemaintainingloadpathcon:nuity.
LearningObjec8ves
1. Explorewindloadcalcula:onsandprovisionsspecifictowood-framestructurespertheInterna:onalBuildingCodeandreferencedstandards.
2. Highlightthekeydifferencesbetweenseismicandwindforcesandreviewtheuniquedesignconsidera:onsassociatedwiththeeffectsofwindloadsonwoodstructures.
3. Reviewwallframingdesignstepsforout-of-planewindloadsandcombinedaxialandout-of-planewindloads.
4. Discusscalcula:onsanddetailingbestprac:cesfordesigningwood-frameroofstoresistupliZwindforces.
Overview
• Calcula:ngWindLoads• UpliZ• WallDesign• Seismic/WindComparisons
WindLoadDemand
CBC:BaseCode–ReferencesASCE7fordetermina8onofwindforceson
structuresoruseCBC1609.6
ASCE7:ReferencedStandard.Providesinforma8onrequiredtodeterminewindforcesona
structure
Calcula8ngWindLoads
• ASCE7-05:ASDWindLoads§ Chpt.6:ContainedAllProvisions
• ASCE7-10:Ul8mateWindLoads§ Chpt.26:GeneralRequirements§ Chpt.27:MWFRS–Direc8onal§ Chpt.28:MWFRS–Enveloped§ Chpt.29:OtherStructures§ Chpt.30:Components&Cladding§ Appendices
• ASCE7-16:(mostlikelyref.inCBC2019)§ LowerWindSpeedsinCA
WindSpeedByLoca8onSoYware
windspeed.atcouncil.org
WindLoadsTypes
2TypesofWindLoads• MWFRS–MainWindForceResis8ngSystem
Anassemblageofstructuralelementsassignedtoprovidesupportandstabilityfortheoverallstructure.Thesystemgenerallyreceiveswindloadingfrommorethanonesurface.Eg.Shearwalls,diaphragms
• C&C–Components&CladdingElementsofthebuildingenvelopethatdonotqualifyaspartoftheMWFRS.Eg.Wallstuds
MWFRSMethodOp8ons
TwoMethodsofCalcula8ngMWFRSloads:• Envelope:Pressurecoefficientsrepresent“pseudo”loadingthatenvelopethedesiredmoment,shear...Limitedtolow-rise
• Direc8onal:Pressurecoefficientsreflectwindloadingoneachsurfaceasafunc:onofwinddirec:on
Example–Direc8onalLoads
84’
34’
10’6’ 8’5’
6’
6’
6’
6’
6’4’
29’24’
10’
3’3’
P=(11.3psf*(5’+3’)+(30.2)*3’)*(84’/2)=7,602lb
νdiaphragm=7,602lb/34’νdiaphragm=224plf
P
Example–EnvelopeLoads
84’
34’
10’6’ 8’5’
6’
6’
6’
6’
6’4’
29’24’
10’
3’3’
P
6.8’12.5psf8.3psf
77.2’
P=(8.3psf*(5’+3’)+(30.2)*3’)*(84’/2)+((12.5psf-8.3psf)*(5’+3’))*6.8’*(77.2’/84’)=6,804lb
(Direc:onalmethodgaveus7,602lb~10%reduc8on)
CBC’sAlternateAll-HeightsMethod
CBCSec:on1609.6providesanalterna:vetotheDirec:onalWindLoadProcedureinASCE7AlternateAll-HeightsMethodLimita:onssuchas:• BuildingHeight≤75Z• BuildingHeight/Width≤4• Buildinghassimplediaphragm• Others(CBC1609.6.1)
Pnet=0.00256V2KzCnetKzt
CBC’sAlternateAll-HeightsMethod
Pnet=0.00256V2KzCnetKzt• V=Basicwindspeed(ASCE7)• Kz=Exposurecoefficient(ASCE7)• Kzt=Topographicfactor(ASCE7)• Cnet=Net-pressurecoefficient(CBCTable1609.6.2)
CBC’sAlternateAll-HeightsMethod
CBCTable1609.6.2
Overview
• Calcula:ngWindLoads• UpliZ• WallDesign• Seismic/WindComparisons
UpliY:MWFRSorC&C?
ConsidermemberpartofMWFRSif:• TributaryArea>700Y2perASCE7-1030.2.3• LoadcomingfrommorethanonesurfaceperASCE7-1026.2
UpliY:MWFRSorC&C?
ASCE7-1026.2commentaryprovidessomediscussiononupliZ&MWFRSvs.C&C.
ComponentsreceivewindloadsdirectlyorfromcladdingandtransfertheloadtotheMWFRS.Examplesofcomponentsincludefasteners,purlins,girts,studs,roofdecking,androoftrusses.ComponentscanbepartoftheMWFRSwhentheyactasshearwallsorroofdiaphragms,buttheymayalsobeloadedasindividualcomponents.
UpliY:MWFRSorC&C?
AWC’sWFCMcommentaryC1.1.2statesthatMWFRSisusedforallupliZcondi:ons:
TheraConaleforusingMWFRSloadsforcompuCngtheupliDofroofassembliesrecognizesthatthespaCalandtemporalpressurefluctuaConsthatcausethehighercoefficientsforcomponentsandcladdingareeffecCvelyaveragedbywindeffectsondifferentroofsurfaces.
RoofUpliY&Effec8veWindArea
Forwinddesign,tributaryareadoesnotnecessarily=effec:vewindareaEffec:veWindArea(EWA)-Twocases:• Areaofbuildingsurfacecontribu:ngtoforcebeing
considered(tributaryarea)• Longandnarrowarea(wallstuds,rooftrusses):width
ofeffec:veareamaybetakenas1/3length;increaseseffec:vearea,decreasesload(perASCE7-10sec:on26.2commentary);EWA=L2/3
Effec8veWindAreaExample
44’-0”
Trusses@2’o.c.
44’-0”
Trusses@2’o.c.
Trib.A=(44)(2)=88Y2 EWA=442/3=645Y2
MethodstoResistUpliYLoads
• Mechanicalconnectors(straps,hurricane:es,screws,threadedrods)
• Sheathing
• DeadLoads
Source:strong:e.com
UpliYWindLoads
Truss/RaZertoTopPlateConnec:on
WhathappenstotheupliDloadaDerthis?
UpliYResistance:MechanicalConnectors
Source:IIBHS
UpliYResistance:DirectLoadPath
ImportanttodetailupliZrestraintconnectorstoprovidedirectloadpath
UpliYWindLoads
UpliYResistance:WallSheathing
• Whenjoints,fastenersareconsidered,canusesheathingtoresistupliZonlyorupliZ&shear
• SDPWSSec:on4.4
SDPWSFigure4J
UsingDeadLoadtoResistUpliY
Source:Strong:e
Deadloadfromabove(Wall,Floor,Roof)canbeusedtoresistsomeorallupliZforces,dependingonmagnitude
LoadCombina:onsofASCE7-10:06.D-0.6W
UpliYExampleCalcula8on
• RoofFramingRaYer• 20’Span• 2’Spacing• 2’Overhang• 115mphExposureB• RoofH=80Y• 65’x220’
Photocredit:MawTodd&PB
Architects
MWFRS-ExternalPressureCoefficient
Lookatwindac8ngonbuilding’slongside:L=65Y,h/L=80/65=1.23Cp=1.3,-0.18
ASCE7-10Fig.27.4-1
• GCp:(0.85)(-1.3)=1.105(26.9.4&Fig.27.4-1)• GCpi:±0.18(Table26.11-1)• qh=0.00256KzKztKdV2
§ Kz:0.93–Table27.3-1
§ Kzt:1.00-Figure26.8-1§ Kd:0.85-Table26.6-1§ Vu:115mph
• qh=26.8psf• p=(26.8psf)(-1.105+(-0.18))=34.4psf
MWFRS-Runningthenumbers
MWFRS-RoofOverhangpersec8on27.4.4• ForOverhangs:ASCE727.4.4–useCp=0.8onundersideofoverhang,usesametoppressurescalculatedfortyp.roof
• poh=(26.8psf)(-0.8)(0.85)=18.2psf• pext=(26.8psf)(-1.105)=29.6psf• pohnet=18.2+29.6=47.8psf
Poh
pext
PerASCE7-10sec:on27.4.4
pint
MWRFS-DeterminingtheUpliYLoad
• p=(34.4psf)(2Y)=68.8plf• poh=(47.8psf)(2Y)=95.6plf
68.8plf
UpliZ=0.6(95.6plf(2Z.)+68.8plf*20Z/2)=528lbsDeadLoad=0.6((2+20/2)*10psf*2Z)=144lbsNetUpliYatLeYSupport=528lbs-144lbs=384lbsNote:Itiscommonprac:cetouse2setsofdeadloads:highestpoten:aldeadloadsforgravity,lowestpoten:aldeadloadsforupliZ
95.6plf
C&C-ExternalPressureCoefficient3zoneswithdifferingwindloads:1:Field2:Perimeter3:Salientcornersa=smallerof10%ofleasthorizontaldimensionor0.4h,butnotlessthaneither4%ofleasthorizontaldimensionof3Z
ASCE7-10Fig.30.4-2A
C&C-ExternalPressureCoefficient–Fig.30.4-2A
EWA=H2/3=222/3=161Z2
GCP=-1.4FOROVERHANGGCP=-1.1FORINTERIOR ASCE7-10Fig.30.4-2A
• GCp:-1.1(Figure30.4-2A)• GCpi:±0.18(Table26.11-1)• qh=0.00256KzKztKdV2
§ Kz:0.93-Table30.3-1
§ Kzt:1.00-Figure26.8-1§ Kd:0.85-Table26.6-1§ Vu:115mph
• qh=26.8psf• p=(26.8psf)(-1.1+(-0.18))=34.3psf
C&C-Runningthenumbers–Zone2
C&C-RoofOverhangpersec8on30.10• ForOverhangsFigures30.4-2A&30.10-1areu8lized• poh=26.8psf(1.7+0.18)=50.4psf• ps=pw=34.3psf• pohnet=50.4+34.3=84.7psf
ps
pW
pOH
ASCE7-10Fig.30.4-2A
PerASCE7-10Fig.30.10-1
C&C-DeterminingtheUpliYLoad
• p=(34.3psf)(2Y)=68.6plf• poh=(84.7psf)(2Y)=169.4plf
68.6plf
UpliZ=0.6(169.4plf(2Z.)+68.6plf*20Z/2)=615lbsDeadLoad=0.6((2+20/2)*10psf*2Z)=144lbsNetUpliYatLeYSupport=615lbs-144lbs=471lbsNote:Itiscommonprac:cetouse2setsofdeadloads:highestpoten:aldeadloadsforgravity,lowestpoten:aldeadloadsforupliZ
169.4plf
DeterminingtheUpliYLoad
384lbsMWFRSOR471lbsC&[email protected]
Uplift Resistance Shear Wall Overturning Resistance
KeyDifferences:• Rodloca:on• Loaddirec:on• Framing
Requirements• Loadpath• Shrinkage/
compressionloca:on
GraphicsSource:Strong:e
OverturningResistancevs.UpliYResistance
RoofFraming:CompressionEdgeBracing
• Bendingcausescompressioninoneedgeofmember• Roofsheathingbracescompressionflangeofroofjoists
Compressionedge
Tensionedge
Loadingdirec:on
RoofFraming:CompressionEdgeBracing
• WhataboutUpliZ?Needfulldepthblocking/bridgingorbowomchordbracing
BowomChordBracing
Someinsurancecompaniesrequireabuilding’srooftoberatedforwindupliZresistance
WindUpliYRequirements:Insurance
Somedesignersandownersaren’tawarethattherearewoodassemblieswhichmeetFMupliZrequirementsULandFactoryMutual(FM)havedonetes:ng&researchonroofupliZassemblies.ULassignsra:ngsbasedonmax.upliZresistanceallowedforanassemblyinpsf,suchasClass30,60,90FMrequiresafactorofsafetyof2,i.e.FMUpliZRa:ngof90requiredforroofswith45psfupliZforces
WindUpliYRequirements:Insurance
Source:APAFormG310
WindUpliY:SolarPanels
Resources:DSAFormIR16-8SEAOCPV2
Overview
• Calcula:ngWindLoads• UpliZ• WallDesign• Seismic/WindComparisons
PanelsL/dRa:oUnbracedLengthWallVeneerWindonlyloadingC&CDesignProper:esHinges
WallDesignConsidera8ons
3StepProcess:ExteriorWallDesign
• StrengthCheck1:Gravity(axial)+MainWindForceLoads
• StrengthCheck2:FullComponentsandCladdingWindLoads,NoAxial(orminimalaxial)
• DeflecAonCheck:ReducedComponentsandCladdingWindLoads
WallDesignConsidera8ons
BasisforMWFRSvs.C&CWindLoadsforWallDesign:
• Considera:onsinWindDesignofWoodStructures• FreedownloadfromAWCavailableat:
hwp://www.awc.org/pdf/codes-standards/publica:ons/archives/AWC-Considera:ons-0310.pdf
StrengthCheck1forStudDesign
StrengthCheckasaVer8calLoadSuppor8ngelement:• ApplyVer:calDead,Live,Roofand/orSnowLoads• Applyout-of-planelateralloads
• MWFRSwindloads(ASCE7-10Chapter27or28)• Seismicwallforces(ASCE7-1012.11.1)
• CombinedBending&AxialLoadCheckperAWCNDS3.9• Usestandardloadcombina:ons
• CBCSec:on1605or• ASCE7-10Chapter2
DesignTip:BoFomplatecrushingmaygovernoverStudCapacity
DeterminingUnbracedLength
Whatistheunbracedlength,lu?Strong&weakaxis
WallSheathingProvidesWeakAxisBracing
L
NDSCommentary:“Experiencehasshownthatanycodeallowedthicknessofgypsumboard,hardwoodplywood,orotherinteriorfinishadequatelyfasteneddirectlytostudswillprovideadequatelateralsupportofthestudacrossitsthicknessirrespec:veofthetypeorthicknessofexteriorsheathingand/orfinishused.”
DesignConsidera8ons
SlendernessLimits(NDS20153.7.1.4)MaxEffec:veUnbracedLength=50d,d=depthininches
Maxof75dduringconstruc:on
1½” depth 6’-3” max unbraced length. 9’-4” during construction.
3½” (2x4) Max Height: 14’-7” 5½” (2x6) Max Height: 22’-11” 7¼” (2x8) Max Height: 30’-2”
Studorcolumncanbebracedagainstbucklinginthisdirec:onbysheathing.
Studorcolumnisnotbracedagainstbucklinginthisdirec:onbysheathing.
StrengthCheck2forStudDesign
StrengthCheckforComponents&CladdingWindLoads• Noaxialloading• C&CWindloadsonly• Checkstudforbendingandshear
DesignTip:BeawareofASCE7DefiniAonofEffecAveWindAreatodecreasetherequiredC&Cwindload
StrengthCheck2forStudDesign
StrengthCheckforComponents&CladdingWinds• Noaxialloading• C&CtransverseWindloadsonly• Checkstudbendingandshear.
DesignTip:Forbendingstresscheck,beawareofRepeAAveUsefactorCrofNDSandWallStudRepeAAveMemberFactorofSDPWS3.1.1.ChangeinSDPWS2015referencedfromIBC2015(CBC2016)allowsapplicaAonofWallStudRepeAAveFactortoStud
STIFFNESS.SeeSDPWS3.1.1
Deflec8onCheckforStudDesignDeflec8onCheckforComponentsandCladdingWinds
• Checkout-of-planedeflec:ontoCBCTable1604.3orothermorestringentrequirements.
Note:Thischecko]engovernstallwalls
DesignTip:Readallthefootnotes!CBCTable1604.3footnotefallowsthefollowingC&CWindloadreducAon:
MulAplycalculatedC&CWindLoadsby0.42whenusingVULT(ASCE7-10)OR0.70whenusingVASD(ASCE7-05andearlier)fordeflecAon
WallStudDesignAidWesternWoodProductsAssocia:on(WWPA)DesignSuite:hwp://www.wwpa.org/TECHGUIDE/DesignSoZware/tabid/859/Default.aspx
Example:OfficeBuildingWallStuds
2StoryBuilding
13’tallwoodframedwalls.
Assumestuds16”o.c.
110mphExposureC
LeastHorizontalDim.=90Z
WallStudDesign:StrengthCheck1
GravityLoads:
RoofDeadLoad=20psf; FloorDeadLoad=30psf
RoofLiveLoad=20psf; FloorLiveLoad=65psf
WallDeadLoad=18psf; WallDeflec:on=L/360
Roof&FloorTributaryWidth=(22Z)(0.5)=11Z
WallTributaryWidth=13Z+13Z=26Z
WDL=(11Z)(20psf+30psf)+(26Z)(18psf)=1018plf
WRL=(11Z)(20psf)=220plf
WLL=(11Z)(65psf)=715plf
ControllingLoadCombo:D+L=1018+715=1733plf
WallStudDesign:StrengthCheck1
GravityLoads:
AxialLoadPerStud=(1733plf)(1.333Z)=2310lb
Bowomplatecrushing:2310/(1.5”*5.5”)=280psi<625psi:OK
MWFRSWindLoads:
ULT.=28.5psf;ASD=(28.5psf)(0.6)=17.1psfASCETable27.6-1
WallStudDesign:StrengthCheck1
2x6DF#2Studs@16”o.c.OKforStrengthCheck1
Member #
Location :
Sits on Sill Plate ? Yes
** Dimension Lumber ** ** Dimension Lumber **
Yes Nominal Size : ( 1 ) 2 x 6 Sill Plate Nominal Size : 2 x 6
DochDN.2 Species = Species or Symbol = DochDN.2
No.226 Grade = Grade = No.226
2400f-2.0E 1500f-1.4E
Bearing at < 3" of Sill End? No
Height ( H ) = 13 ft - 0 in P = 2310 lb =
Unbraced Length ( l 1 ) = 13 ft - 0 in w = 22.8 plf = Wind
Unbraced Length ( l 2 ) = 2 ft - 0 in lu = 13 ft - 0 in 13
(pressed-down buttons are selected)
Yes Repetitive Use ?
No 1.00 Incised for PT ?
No Flat Use :
< 19% 1.60 Moisture Content : for P only, fc (psi) = 280 < 533 = Fc //
< 100 Temperature (° F) : for P + w, fc (psi) = 280 < 558 = Fc //
1.00 C D = 1.00 (P) & 1.60 (P+w) (1.3/2) fb (psi) = 497 < 1346 = Fb
1.60 K = 1.00 (fc / F'c)2 + fb / [F'b (1 - fc / Fce)] = 0.95 < 1.00 OK
∆ / H = 120 Mid-H Deflection due to w, ∆ (inch) = 0.85 < H / 120 OK
Section Properties
Post/Stud Sill PL
breadth (b) = 1.5 in 1.5 Sill PL
depth (d) = 5.5 in 5.5 Bending Comp // E Comp -|
Area (A) = 8.3 in^2 8.3 Wet Service CM = 1.00 1.00 1.00 1.00
Section Modulus (S) = 7.6 in^3 Temperature Ct = 1.00 1.00 1.00 1.00
Moment of Inertial (I) = 20.8 in^4 Beam Stability CL = 1.00 N/A N/A N/A
Size CF = 1.30 1.10 N/A N/A
Flat Use Cfu = 1.00 N/A N/A N/A
Sill PL Incising Ci = 1.00 1.00 1.00 1.00
Fb Fc // E Fc -| Emin Repetitive Member Cr = 1.15 N/A N/A N/A
Reference 900 1350 1600000 625 580000 Column Stability (P) CP = N/A 0.36 N/A N/A
Adjusted (P) 533 1600000 781 580000 Column Stability (P+w) CPw = N/A 0.23 N/A N/A
Adjusted (P+w) 1346 558 1600000 781 580000 Bearing Area Cb = N/A N/A N/A 1.25
1485
2152.8 2376
Adjustment Factors
How to
Enter Data
Designed on: April 12, 2016
DL + FL
Douglas Fir-Larch
No.2
Design Values (psi)
Douglas Fir-Larch
No.2
Studs
Strength Check 1
PrintOrder Pro VersionDeveloped by:
Forum Engineers
P
H
w
Setup
ASD Method
YesNo
YesNo
<19% >19%
<100 100~125 125~150
YesNo
No Yes
Set Duration Factors
Set Ef f ectiv e-Length Factor
Version: 3.1
Set Def lection Limit
WallStudDesign:StrengthCheck2
C&CWindLoads:ASCE7Fig.30.4-1
a=Lesserof:
• 10%leasthorizontaldimension(LHD)90’*0.1=9’• 0.4h=0.4*26=10.4’.
Butnotlessthan:
• 0.04LHD=3.6’or3’
Usea=9’forzone5
StrengthCheck2:C&CWindLoads
Wallstudsare13’long
EWA=h2/3=56Z2
Zone4:
GCpf=-0.97
GCpi=-0.18(Table26.11-1)
Zone5:
GCpf=-1.1
ASCE7-10Figure30.4-1
Runningthenumbers–Zone4
• GCpf:0.97(Figure30.4-1)• GCpi:0.18(Table26.11-1)• qh=0.00256KzKztKdV2
§ Kh:0.98-Table30.3-1
§ Kzt:1.00-Figure26.8-1§ Kd:0.85-Table26.6-1§ V:110mph
• qh=25.8psf• p=25.8psf(0.97+0.18)=29.7psf• 0.6W=0.6(29.7)=17.8psf
StrengthCheck2&Deflec8onCheck(Zone4)
2x6DF#2Studs@16”o.c.OKforStrengthCheck2&Deflec:onCheck
Member #
Location :
Sits on Sill Plate ? Yes
** Dimension Lumber ** ** Dimension Lumber **
Yes Nominal Size : ( 1 ) 2 x 6 Sill Plate Nominal Size : 2 x 6
DochDN.2 Species = Species or Symbol = DochDN.2
No.226 Grade = Grade = No.226
2400f-2.0E 1500f-1.4E
Bearing at < 3" of Sill End? No
Height ( H ) = 13 ft - 0 in P = 1357 lb =
Unbraced Length ( l 1 ) = 13 ft - 0 in w = 23.7 plf = Wind
Unbraced Length ( l 2 ) = 2 ft - 0 in lu = 13 ft - 0 in 13
(pressed-down buttons are selected)
Yes Repetitive Use ?
No 1.00 Incised for PT ?
No Flat Use :
< 19% 1.60 Moisture Content : for P only, fc (psi) = 164 < 533 = Fc //
< 100 Temperature (° F) : for P + w, fc (psi) = 164 < 558 = Fc //
1.00 C D = 1.00 (P) & 1.60 (P+w) (1.3/2) fb (psi) = 516 < 1346 = Fb
1.60 K = 1.00 (fc / F'c)2 + fb / [F'b (1 - fc / Fce)] = 0.62 < 1.00 OK
∆ / H = 360 Mid-H Deflection due to w, ∆ (inch) = 0.32 < H / 360 OK
Section Properties
Post/Stud Sill PL
breadth (b) = 1.5 in 1.5 Sill PL
depth (d) = 5.5 in 5.5 Bending Comp // E Comp -|
Area (A) = 8.3 in^2 8.3 Wet Service CM = 1.00 1.00 1.00 1.00
Section Modulus (S) = 7.6 in^3 Temperature Ct = 1.00 1.00 1.00 1.00
Moment of Inertial (I) = 20.8 in^4 Beam Stability CL = 1.00 N/A N/A N/A
Size CF = 1.30 1.10 N/A N/A
Flat Use Cfu = 1.00 N/A N/A N/A
Sill PL Incising Ci = 1.00 1.00 1.00 1.00
Fb Fc // E Fc -| Emin Repetitive Member Cr = 1.15 N/A N/A N/A
Reference 900 1350 1600000 625 580000 Column Stability (P) CP = N/A 0.36 N/A N/A
Adjusted (P) 533 1600000 781 580000 Column Stability (P+w) CPw = N/A 0.23 N/A N/A
Adjusted (P+w) 1346 558 1600000 781 580000 Bearing Area Cb = N/A N/A N/A 1.25
1485
2152.8 2376
Adjustment Factors
How to
Enter Data
Designed on: April 12, 2016
DL + FL
Douglas Fir-Larch
No.2
Design Values (psi)
Douglas Fir-Larch
No.2
Studs
Strength Check 1
PrintOrder Pro VersionDeveloped by:
Forum Engineers
P
H
w
Setup
ASD Method
YesNo
YesNo
<19% >19%
<100 100~125 125~150
YesNo
No Yes
Set Duration Factors
Set Ef f ectiv e-Length Factor
Version: 3.1
Set Def lection Limit
• GCp:1.1(Figure30.4-1)• GCpi:0.18(Table26.11-1)• qh=0.00256KzKztKdV2
§ Kh:0.98-Table30.3-1
§ Kzt:1.00-Figure26.8-1§ Kd:0.85-Table26.6-1§ V:110mph
• qh=25.8psf• p=25.8psf(1.1+0.18)=33psf• 0.6W=0.6(33)=19.8psf
Runningthenumbers–Zone5
StrengthCheck2&Deflec8onCheck(Zone5)
2x6DF#2Studs@16”o.c.OKforStrengthCheck2&Deflec:onCheck
Member #
Location :
Sits on Sill Plate ? Yes
** Dimension Lumber ** ** Dimension Lumber **
Yes Nominal Size : ( 1 ) 2 x 6 Sill Plate Nominal Size : 2 x 6
DochDN.2 Species = Species or Symbol = DochDN.2
No.226 Grade = Grade = No.226
2400f-2.0E 1500f-1.4E
Bearing at < 3" of Sill End? No
Height ( H ) = 13 ft - 0 in P = 1357 lb =
Unbraced Length ( l 1 ) = 13 ft - 0 in w = 26.4 plf = Wind
Unbraced Length ( l 2 ) = 2 ft - 0 in lu = 13 ft - 0 in 13
(pressed-down buttons are selected)
Yes Repetitive Use ?
No 1.00 Incised for PT ?
No Flat Use :
< 19% 1.60 Moisture Content : for P only, fc (psi) = 164 < 533 = Fc //
< 100 Temperature (° F) : for P + w, fc (psi) = 164 < 558 = Fc //
1.00 C D = 1.00 (P) & 1.60 (P+w) (1.3/2) fb (psi) = 575 < 1346 = Fb
1.60 K = 1.00 (fc / F'c)2 + fb / [F'b (1 - fc / Fce)] = 0.68 < 1.00 OK
∆ / H = 360 Mid-H Deflection due to w, ∆ (inch) = 0.36 < H / 360 OK
Section Properties
Post/Stud Sill PL
breadth (b) = 1.5 in 1.5 Sill PL
depth (d) = 5.5 in 5.5 Bending Comp // E Comp -|
Area (A) = 8.3 in^2 8.3 Wet Service CM = 1.00 1.00 1.00 1.00
Section Modulus (S) = 7.6 in^3 Temperature Ct = 1.00 1.00 1.00 1.00
Moment of Inertial (I) = 20.8 in^4 Beam Stability CL = 1.00 N/A N/A N/A
Size CF = 1.30 1.10 N/A N/A
Flat Use Cfu = 1.00 N/A N/A N/A
Sill PL Incising Ci = 1.00 1.00 1.00 1.00
Fb Fc // E Fc -| Emin Repetitive Member Cr = 1.15 N/A N/A N/A
Reference 900 1350 1600000 625 580000 Column Stability (P) CP = N/A 0.36 N/A N/A
Adjusted (P) 533 1600000 781 580000 Column Stability (P+w) CPw = N/A 0.23 N/A N/A
Adjusted (P+w) 1346 558 1600000 781 580000 Bearing Area Cb = N/A N/A N/A 1.25
1485
2152.8 2376
Adjustment Factors
How to
Enter Data
Designed on: April 12, 2016
DL + FL
Douglas Fir-Larch
No.2
Design Values (psi)
Douglas Fir-Larch
No.2
Studs
Strength Check 1
PrintOrder Pro VersionDeveloped by:
Forum Engineers
P
H
w
Setup
ASD Method
YesNo
YesNo
<19% >19%
<100 100~125 125~150
YesNo
No Yes
Set Duration Factors
Set Ef f ectiv e-Length Factor
Version: 3.1
Set Def lection Limit
TallWallsinCommercialDesign
ExampleTallWoodWall§ CorteMadera,CA§ 25’WallHeight§ ASDWind:C&C:30psf;MWFRS:21.7psf§ NonLoad-BearingStuds§ L/240Deflec:onCriteriaStudOp8on MaterialCost
2x12DF-L#[email protected]”o.c. $2.40/sf
1.75”x11.875”[email protected]”o.c. $2.90/sf
2x10DF-L#1@12”o.c. $3.20/sf
1.75”x9.5”LSL@12”o.c. $3.80/sf
1.625”x10.5”[email protected]”o.c. N/A
OutofPlaneForces:TietoDiaphragm
OutofPlaneForces:TietoDiaphragm
WoodFramedStair/ElevatorShaYWalls
WoodFramedStair/ElevatorShaYWalls
WoodFramedStair/ElevatorShaYWalls
StairwayShaYEnclosures&Framing
StairFraming(Landing&Stringers)
ShaYwall
Consider“Hinge”atwallplatesforout-of-planewind&seismicloadsduetolackofadjacentfloor:• SpanPlates
Horizontally(nojoints)• Installaddi8onal
member(rim)tospanhorizontally
StairExteriorWallDetail
StairwayShaYEnclosures&Framing
IntermediateStairLanding
WhenStairShaYWallisExteriorWall
WallPlatesatTypicalFloorEleva8on–CreatesPoten8al“Hinge”
WallFramingatShaYs
8’TallWalls 10’TallWalls 12’TallWalls
2-2x4 7’-10”B/6’-4”D 7’-0”B/5’-10”D 6’-4”B/5’-6”D
3-2x4 10’-3”B/7’-3”D 9’-2”B/6’-8”D 8’-4”B/6’-4”D
2-2x6 11’-5”B/9’-11”D 10’-3”B/9’-2”D 9’-4”B/8’-8”D
3-2x6 15’-0”B/11’-4”D 13’-5”B/10’-6”D 12’-3”B/9’-11”D
HowfarcanjustwallplatesspanatshaYstudbreaks?Requiresnojointsintheseplates:
Assump8ons:DF#2L/360Deflec8onCriteria18psfC&C(bending)12.6psfC&C(deflec8on)
B–spancontrolledbybendingD–spancontrolledbydeflec:on
WallFramingatShaYs
IntermediateStairLanding
Framing
ShaYwall
StairExteriorWallDetail
StairSha]Side
ExteriorSideConsider“Hinge”atwallplatesforout-of-planewind&seismicloadsduetolackofadjacentfloor:• Installaddi8onal
member(rim)tospanhorizontally
• Op8onsincludesolidsawnlumber(4xor6x),glulam,PSL
• Ifmul8-plymember,uniquedesignconsidera8ons
StairwayShaYEnclosures&Framing
WallFramingatShaYs
FloorPlan
WallFramingatShaYs
ConnecAonsareKey
WallFramingatShaYsFramingPlan 1 2
3
WallFramingatShaYsStraponoutsideofbeam/clipangleoninsideofbeamAwachestorim/blockingonadjacentwall
ExteriorWall SpanningRim
StairTopLandingFraming
CorridorFloorFraming
Interio
rWall
WallFramingatShaYsMiterbeamsatcornerStraponoutsideofbeams/clipangleoninsideofbeamsAwachperpendicularbeamstogether
SpanningRim
SpanningRim
StairIntermediateLandingFraming
WallFramingatShaYsClipanglesoninside/outsideofbeamAwachestorim/blockingonadjacentwall
SpanningRim
ExteriorWallInteriorWall
Exterio
rWall
StairIntermediateLandingFraming
StairwayShaYEnclosures&Framing
IntermediateStairLanding
ExteriorWallPlateEleva8onsShiYedDowntoIntermediate
LandingEleva8on
• EliminatesHingeEffect• AvoidsInterferencewith
LandingWindows
WhenStairShaYWallisExteriorWall
DroppedHeaders:OutofPlaneBraced?
OutofPlaneBracing
SmallRetailBuilding–NorthernCA
SmallRetailBuilding–NorthernCA
CanthisExteriorWallPassDeflec8onCheck?
“HingePoint”createsastructuralweaknessinthewall
GableEndwithslopedceiling
2StoryExteriorWall
Overview
• Calcula:ngWindLoads• UpliZ• WallDesign• Seismic/WindComparisons
DifferencesBetweenWind&Seismic
Wind Seismic
Shearwall&DiaphragmCapacity
40%Increase BaseValue
ShearwallA/R 3.5/1* 2/1*
DiaphragmA/R 3/1unblocked 3/1unblocked
OverstrengthFactoronCollectors
None 3(insomecondi8ons)
Re-distribu8onofforcestoupperstories
NotRequired Required
GypsumShearwalls Permiued OnlypermiuedinSDCA-D
DissimilarMaterialShearwalls
Permiuedtocombinecapaci8esofWSP&gypsum
Can’tcombinecapaci8es.Use2xsmallercap.orlargersinglesidedcapacity,whicheverisgreater
DriYCheck UsesServiceorLowerLoads UsesStrengthLoads
GypsumShearwalls• Lowercapaci:esthanWSPShearwalls(about1/3capacity)• SDPWSTable4.3C,Sec:on4.3.7.5providescapaci:es&
requirements• NotpermiwedinSDCEorF
DifferencesBetweenWind&Seismic
Wind Seismic
LateralForceVariables
SurroundingTopographyAreaSpecificWindGustsDegreeofBuilding“Openness”
StructureMassLateralForceResis8ngSystemSiteSpecificSoilCondi8ons
Occupancy/ImportanceRisk
10%IncreaseIItoIII&IV 25%IncreaseIItoIII50%IncreaseIItoIV
SurroundingTopography
ExposureBtoC:Increasevaries,usually~25%
Nochange
Massofstructure
Noimpactonwindforces Directly8edtoseismicforces
TypeofLFRS Noimpactonwindforces Directly8edtoseismicforces
ExampleBuildings:Wind
ExampleBuildings:Seismic
ExampleBuilding:Seismicvs.Wind
1StoryCommercialRetailBuilding84’-0”x34’-0”13’WallHeight+3’ParapetR=6.5I=1.0Sdsrequiredtomakebaseshearsequal:ExposureB:1.08longbldgdim.0.52shortbldgdim.ExposureC:1.64longbldgdim.0.8shortbldgdim.
ExampleBuilding:Seismicvs.Wind
2StorySchool,ClassroomWing210’-0”x80’-0”13’WallHeightR=6.5I=1.25(seismic)Sdsrequiredtomakebaseshearsequal:ExposureB:0.39longbldgdim.0.32shortbldgdim.ExposureC:0.58longbldgdim.0.47shortbldgdim.
ExampleBuilding:Seismicvs.Wind
3StoryOfficeBuilding142’-0”x66’-0”14’WallHeightR=6.5I=1.0Sdsrequiredtomakebaseshearsequal:ExposureB:0.65longbldgdim.0.3shortbldgdim.ExposureC:0.93longbldgdim.0.43shortbldgdim.
ExampleBuilding:Seismicvs.Wind
4StoryMul:-FamilyBuilding75’-0”x75’-0”10’WallHeightR=6.5I=1.0Sdsrequiredtomakebaseshearsequal:ExposureB:0.4short&longbldgdim.ExposureC:0.56short&longbldgdim.
ExampleBuildings:Seismicvs.Wind
Bldg LongDimSds ShortDimSds
1Story,84’x34’ 1.64 0.8
2Story,210’x80’ 0.58 0.47
3Story,142’x66’ 0.93 0.43
4Story,75’x75’ 0.56 0.56
Buildingassump:ons:LightFramewoodconstruc:onincludingshearwallsExteriorfinish:StuccoWindExposureC
Shearwall&DiaphragmDeflec8on
Whencalcula:ngshearwallanddiaphragmdeflec:ons,valuesofapparentshears:ffness,Ga,arerequired,butarenotprovidedforwinddesigninSDPWS
Shearwall&DiaphragmDeflec8onAWCFAQ:Cantheeffec8veshears8ffnessvalues,Ga,inSDPWSbeusedforcalcula8onofdiaphragmandshearwalldeflec8onsduetowindloads?Valuesofapparentshears:ffness,Ga,aretabulatedinseismiccolumnsoftheSDPWStofacilitatecalcula:onofseismicstorydriZinaccordancewithASCE7MinimumDesignLoadsforBuildingsandOtherStructures.ValuesofGaareequallyapplicableforcalcula:onofthesheardeforma:oncomponentoftotaldeflec:onduetowindloadsuptotheASDwindunitshearvaluecalculatedasvw/2.0.Thislevelofunitshearforwindisiden:calto1.4:mestheASDseismicunitshearcapacityforwhichapparentshears:ffnessvalueswereoriginallydeveloped.hwp://awc.org/faqs/general/can-the-effec:ve-shear-s:ffness-values-ga-in-special-design-provisions-for-wind-and-seismic-%28sdpws%29-be-used-for-calcula:on-of-diaphragm-and-shear-wall-deflec:ons-due-to-wind-loads
ShearwallDeflec8onCriteriaforWind
Unlikeseismic,nocodeinforma:onexistsondeflec:on/driZcriteriaofstructuresduetowindloads
Serviceabilitychecktominimizedamagetocladdingandnonstructuralwalls
ASCE7-10:C.2.2DriDofWallsandFrames.LateraldeflecConordriDofstructuresanddeformaConofhorizontaldiaphragmsandbracingsystemsduetowindeffectsshallnotimpairtheserviceabilityofthestructure.Whatwindforceshouldbeused?Whatdri]criteriashouldbeapplied?
Allowable=?
ShearwallDeflec8onCriteriaforWindWindForcesConsensusisthatASDdesignlevelforcesaretooconserva:veforbuilding/framedriZcheckduetowind• CommentarytoASCE7-10AppendixCsuggeststhatsome
recommendusing10yearreturnperiodwindforces:• ~70%of700returnperiodwind(ul:matewindspeed
forriskcategoryIIbuildings)• Others(AISCDesignGuide3)recommendusing75%of50
yearreturnperiodforcesDri]CriteriaCanvarywidelywithbriwlenessoffinishesbutgenerallyrecommenda:onsareintherangeofH/240toH/600
Ques8ons?
ThisconcludesTheAmericanIns:tuteofArchitectsCon:nuingEduca:onSystemsCourse RickyMcLain,MS,PE,SE
TechnicalDirector–ArchitecturalandEngineeringSolu:[email protected](802)498-3310
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