Lateral Design of Mid-Rise Wood Structures for Wind Loads
-
Upload
trinhkhanh -
Category
Documents
-
view
225 -
download
6
Transcript of Lateral Design of Mid-Rise Wood Structures for Wind Loads
![Page 1: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/1.jpg)
LateralDesignofMid-RiseWoodStructuresforWindLoads
PresentedbyRickyMcLain,MS,PE,SEHoustonWoodSolutionsFairSeptember14,2016
![Page 2: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/2.jpg)
“TheWoodProductsCouncil”isaRegisteredProviderwithTheAmericanInstituteofArchitectsContinuingEducationSystems(AIA/CES),Provider#G516.
Credit(s)earnedoncompletionofthiscoursewillbereportedtoAIACESforAIAmembers.CertificatesofCompletionforbothAIAmembersandnon-AIAmembersareavailableuponrequest.
ThiscourseisregisteredwithAIACESforcontinuingprofessionaleducation.Assuch,itdoesnotincludecontentthatmaybedeemedorconstruedtobeanapprovalorendorsementbytheAIAofanymaterialofconstructionoranymethodormannerofhandling,using,distributing,ordealinginanymaterialorproduct.________________________________Questionsrelatedtospecificmaterials,methods,andserviceswillbeaddressedattheconclusionofthispresentation.
![Page 3: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/3.jpg)
CourseDescription
Asincreasesinurbandensitybecomenecessarytoaddressgrowingpopulations,manybuildingdesignersanddevelopersareleveragingwood’sabilitytoachievemultiple,simultaneousobjectiveswithmid-risestructures—oneofwhichiseffectiveperformancewhensubjecttowindforces.Thispresentationexaminesdesignprocessesforlateralframingcomponents,whicharecriticaltothedesignofcode-compliantmid-risewoodstructuressubjecttowindloads.Topicsinthishighlytechnicalpresentationwillincludewindloadspaths,stackedmulti-storyshearwalls,accumulatedshearwallforcesanddeflections,discontinuousshearwalls,andanchorageofshearwallstoconcretepodiumslabs.
![Page 4: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/4.jpg)
LearningObjectives
1. Reviewwindloadpathsinmulti-story,wood-framestructures.
2. Explorethedifferencesbetweenshearwallsanddiaphragmswhenstackingmultiplestoriesofwood-framelateralforce-resistingsystems.
3. Examinecommonshearwalldesignchecksforcomponentsinmulti-storybuildingsdesignedtoresistaccumulatedwindforces.
4. Demonstrateeffectivedetailingpracticesforwoodshearwalltie-downattachmentstoconcretepodiumsandfoundations.
![Page 5: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/5.jpg)
Follow the
load
![Page 6: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/6.jpg)
Loadpath,loadpath,loadpath!
Cables(load path)
CompleteLoadPaths
![Page 7: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/7.jpg)
….You’retheoneinthebasket!
![Page 8: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/8.jpg)
Multi-StoryWoodDesign
Photocredit:MattTodd&PBArchitects
Following the load…
![Page 9: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/9.jpg)
LoadPathContinuity
Photocredit:MattTodd&PBArchitectsKaruna IHolst Architecture
Photo: Terry Malone
![Page 10: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/10.jpg)
Multi-StoryConsiderations
• WindLoadPaths• Multi-StoryStackedShearWallEffects• AccumulationofOverturningLoads• ShearWallDeflection• DiaphragmModeling• DiscontinuousShearWalls
![Page 11: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/11.jpg)
WindLoadDistributiontoShearwalls
![Page 12: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/12.jpg)
WindLoadDistributiontoShearwalls
![Page 13: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/13.jpg)
WindLoadDistributiontoShearwalls
Photocredit:MattTodd&PBArchitects
![Page 14: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/14.jpg)
Multi-StoryWindLoadDesign
Photocredit:MattTodd&PBArchitects
DesignPrinciplesaretheSame
Rememberto:FOLLOWTHELOAD!
![Page 15: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/15.jpg)
Multi-StoryWindLoadDesign
WINDSURFACELOADSONWALLS
![Page 16: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/16.jpg)
Multi-StoryWindLoadDesign
WINDINTODIAPHRAGMSASUNIFORMLINEARLOADS
![Page 17: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/17.jpg)
Multi-StoryWindLoadDesign
DIAPHRAGMSSPANBETWEEN
SHEARWALLS
WINDINTOSHEARWALLSASCONCENTRATEDLOADS
![Page 18: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/18.jpg)
Multi-StoryWindLoadDesign
DIAPHRAGMWINDFORCESDONOTACCUMULATE-THEYAREISOLATEDATEACHLEVEL
SHEARWALLWINDFORCESDOACCUMULATE-UPPERLEVELFORCESADDTOLOWERLEVELFORCES
![Page 19: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/19.jpg)
PublishedMulti-StoryShearWallDesignExamples
Freedownloadatwoodworks.org
SEAOCStructural/SeismicDesignManualVolume2PublishedbyICC
![Page 20: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/20.jpg)
Multi-StoryWindDesign
ElevationSource:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
![Page 21: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/21.jpg)
Multi-StoryWindDesign
FloorPlanSource:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
![Page 22: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/22.jpg)
Multi-StoryWindDesign
Shearwall LayoutSource:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
Shearwall designwe’lllookat
![Page 23: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/23.jpg)
Multi-StoryWindDesign
Shearwall LayoutSource:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
![Page 24: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/24.jpg)
ComponentsofShearWallDesign
Collector&DragDesign
ShearWallConstruction
ShearTransferDetailing
ShearResistance
![Page 25: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/25.jpg)
ComponentsofShearWallDesign
Typ.ShearWallElevationWindForcesPerStory29’-0”
10’-0”Typ.
F5 =5.2k
F4 =3.8k
F3 =3.7k
F2 =3.6k
F1 =3.4k
FP =1.7k
![Page 26: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/26.jpg)
ComponentsofShearWallDesign
Typ.ShearWallElevationAccumulatedWindForces29’-0”
10’-0”Typ.
F =5.2k
F=9k
F=12.7k
F=16.3k
F=19.7k
F=21.4k
![Page 27: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/27.jpg)
ComponentsofShearWallDesign
Holdown
Anchorage
BoundaryPosts
CompressionTension
OverturningResistance
![Page 28: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/28.jpg)
OverturningForceCalculation
F =5.2k
F=9k
F=12.7k
F=16.3k
F=19.7k
T=C=F*h/L
T&Carecumulativeatlowerstories
Lismomentarm,notentirewalllength
1.9k
5.1k
9.6k
15.4k
22.5k
h
LAssumeL=29ft-1ft=28ft
![Page 29: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/29.jpg)
SolePlateCrushing
![Page 30: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/30.jpg)
SolePlateCrushing
Compressionforcesperpendiculartograincancauselocalizedwoodcrushing.NDSvaluesforwithmetalplatebearingonwood resultinamaximumwoodcrushingof0.04”.Relationshipisnon-linear
![Page 31: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/31.jpg)
SolePlateCrushing
NDSCommentaryC4.2.6:whenajointismadeoftwowoodmembersandbothareloadedperpendiculartograin,theamountofdeformationwillbeapproximately2.5timesthatofametalplatetowoodjoint.
Source:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
![Page 32: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/32.jpg)
CompressionPostSize&SolePlateCrush
Level Compression RequiredBearingArea
PostSize
Story SolePlateCrush
5xSolePlateCrush
5th Floor 1.9k 4.4in2 (2)-2x4 0.011” 0.057”
4th Floor 5.1k 11.9in2 (2)-4x4 0.013” 0.067”
3rd Floor 9.6 k 22.6 in2 (2)-4x4 0.034” 0.171”
2nd Floor 15.4k 36.3in2 (3)-4x4 0.039” 0.195”
1st Floor 22.5k 39.8in2 (4)-4x4 0.026” 0.13”
Floors2-5useS-P-F#2SolePlate,Fcperp =425psiFloor1useSYP#2SolePlate,Fcperp =565psi
![Page 33: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/33.jpg)
StorytoStoryCompressionForceTransfer
Source:W
oodW
orks
Five-StoryWoo
d-Fram
eStructureoverPod
iumSlabDesignExam
ple
![Page 34: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/34.jpg)
RimJoistBuckling&Crushing
![Page 35: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/35.jpg)
IncreasingCompressionPostSize
Source:W
oodW
orks
Five-StoryWoo
d-Fram
eStructureoverPod
iumSlabDesignExam
ple
![Page 36: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/36.jpg)
OverturningTension
EqualandOppositeForces
CompressionTension
![Page 37: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/37.jpg)
UsingDeadLoadtoResistOverturning
Source:Strongtie
Deadloadfromabove(Wall,Floor,Roof)canbeusedtoresistsomeoralloverturningforces,dependingonmagnitude
LoadCombinationsofASCE7-10:06.D+0.6W
![Page 38: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/38.jpg)
ShearWallHoldownOptions
StandardHoldownInstallationStrapHoldown
Installation
…………
………
Continuous RodTiedown Systems
6+kipstorytostorycapacities
13+kipcapacities
100+kipcapacities20+kips/level
![Page 39: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/39.jpg)
ThreadedRodTieDownw/TakeUpDevice
Source:Strongtie Source:hardyframe.com
![Page 40: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/40.jpg)
ThreadedRodTieDownw/oTakeUpDevice
![Page 41: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/41.jpg)
ComponentsofShearWallDesign
Tensionaccumulatesinrod.Bearingplatesseelocaloverturningonly.Tensionzone
boundaryframingincompression!
ContinuousRodHoldown System
Overturningrestraintat
bearingplateattopofstory
1.9k
3.2k
4.5k
5.8k
7.1k
1.9k
5.1k
9.6k
15.4k
22.5k
F =5.2k
F=9k
F=12.7k
F=16.3k
F=19.7k
![Page 42: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/42.jpg)
TieDownRodSize&Elongation
Level PlateHght
Tension RodDia.
Steel RodCapacity
RodElong.
5thFloor
10ft 1.9k 3/8” A36 2.4k 0.10”
4thFloor
10ft 5.1k 5/8” A36 6.7k 0.09”
3rdFloor
10ft 9.6 k 5/8” A193 14.4 k 0.18”
2ndFloor
10ft 15.4k 3/4” A193 20.7 k 0.19”
1stFloor
10ft 22.5k 7/8” A193 28.2 k 0.2”
![Page 43: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/43.jpg)
BearingPlateCrushing
![Page 44: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/44.jpg)
BearingPlateSize&Thickness
LevelBearingPlate Bearing
LoadAllow.BearingCapacity
BearingPlateCrush
W L T HoleArea
Abrng
5thFloor
3 in 3.5in 3/8” 0.25in2
10.25in2
1.9k 4.4k 0.012”
4thFloor
3in 3.5in 3/8” 0.518in2
9.98in2 3.2k 4.2 k 0.022”
3rdFloor
3in 5.5in 1/2” 0.518in2
15.98in2
4.5k 6.8 k 0.018”
2ndFloor
3in 5.5in 1/2” 0.69in2
15.8in2 5.8k 6.7 k 0.03”
1stFloor
3 in 8.5in 7/8” 0.89in2
24.6in2 7.0k 10.4k 0.014”
![Page 45: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/45.jpg)
Shearwall Deformation– SystemStretch
Totalsystemstretchincludes:• RodElongation• Take-updevice
displacement• BearingPlateCrushing• SolePlateCrushing
Source:WoodWorks Five-StoryWood-FrameStructureoverPodiumSlabDesignExample
![Page 46: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/46.jpg)
AccumulativeMovement
Level RodElong.
Shrinkage SolePlateCrush
BearingPlateCrush
TakeUpDeflect.Elong.
TotalDisplac.
5thFloor
0.1” 0.03” 0.057” 0.012” 0.03” 0.23”
4thFloor
0.09” 0.03” 0.067” 0.022” 0.03” 0.24”
3rdFloor
0.18” 0.03” 0.171” 0.018” 0.03” 0.43”
2ndFloor
0.19” 0.03” 0.195” 0.03” 0.03” 0.48”
1stFloor
0.2” 0.03” 0.13” 0.014” 0.03” 0.4”
WithShrinkageCompensatingDevices
![Page 47: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/47.jpg)
ShearWallDeflection
SDPWS2008Eq 4.3-1
SDPWS2008Eq.C4.3.2-1
Deflection
Bendingofboundaryelements
IBC2000to2015Eq.23-2
![Page 48: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/48.jpg)
ShearWallDeflection
SDPWS2008Eq 4.3-1
SDPWS2008Eq.C4.3.2-1
Deflection
ShearDeformationofSheathingPanels&
Slipofnails@paneltopanelconnections
IBC2000to2015Eq.23-2
![Page 49: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/49.jpg)
ShearWallDeflection
SDPWS2008Eq 4.3-1
SDPWS2008Eq.C4.3.2-1
IBC2000to2015Eq.23-2
Deflection
RigidBodyRotation
b
h
Δa
![Page 50: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/50.jpg)
Shearwall Deflection
Level UnitShear
EndPostA
EndPostE
Ga TotalDisplace.
Deflection
5thFloor
179plf 10.5in2 1400ksi
10k/in 0.23” 0.26”
4thFloor
310plf 24.5in2 1400ksi
10k/in 0.24” 0.4”
3rdFloor
438plf 24.5in2 1400ksi
10k/in 0.43” 0.59”
2ndFloor
562plf 36.8in2 1400ksi
13k/in 0.48” 0.6”
1stFloor
679plf 49in2 1400ksi
13k/in 0.4” 0.67”
![Page 51: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/51.jpg)
Shearwall DeflectionMethods
Multiplemethodsforcalculatingaccumulativeshearwall deflectionexistMechanicsBasedApproach:• Usessinglestorydeflection
equationateachfloor• Includesrotational&crushing
effects• UsesSDPWS3partequation
Othermethodsexistwhichusealternatedeflectionequations,FEM
![Page 52: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/52.jpg)
Shearwall DeflectionCriteriaforWind
Unlikeseismic,nocodeinformationexistsondeflection/driftcriteriaofstructuresduetowindloads
Serviceabilitychecktominimizedamagetocladdingandnonstructuralwalls
ASCE7-10:C.2.2DriftofWallsandFrames.Lateraldeflectionordriftofstructuresanddeformationofhorizontaldiaphragmsandbracingsystemsduetowindeffectsshallnotimpairtheserviceabilityofthestructure.
Whatwindforceshouldbeused?Whatdriftcriteriashouldbeapplied?
Allowable=?
![Page 53: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/53.jpg)
Shearwall DeflectionCriteriaforWind
WindForcesConsensusisthatASDdesignlevelforcesaretooconservativeforbuilding/framedriftcheckduetowind• CommentarytoASCE7-10AppendixCsuggeststhatsome
recommendusing10yearreturnperiodwindforces:• ~70%of700returnperiodwind(ultimatewindspeed
forriskcategoryIIbuildings)• Others(AISCDesignGuide3)recommendusing75%of50
yearreturnperiodforces
DriftCriteriaCanvarywidelywithbrittlenessoffinishesbutgenerallyrecommendationsareintherangeofH/240toH/600
![Page 54: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/54.jpg)
DiaphragmModelingMethods
Possible Shear Wall Layouts
Typical Unit
7654321
D
C
B
A
NotusingallsharedwallsforShear
RobustDiaphragmAspectRatio
![Page 55: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/55.jpg)
DiaphragmModelingMethods
Possible Shear Wall Layouts
Typical Unit
7654321
D
C
B
A
Butmaybenotmuchwallavailableonexterior
RobustDiaphragmAspectRatio
![Page 56: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/56.jpg)
LightFrameWoodDiaphragmsoftendefaulttoFlexibleDiaphragms
CodeBasis:ASCE7-1026.2Definitions(Wind)Diaphragmsconstructedofwoodstructuralpanelsarepermittedtobeidealizedasflexible
CodeBasis:ASCE7-1012.3.1.1(Seismic)Diaphragmsconstructedofuntopped steeldeckingorwoodstructuralpanelsarepermittedtobeidealizedasflexible ifanyofthefollowingconditionsexist:[…]c.Instructuresoflight-frameconstructionwhereallofthefollowingconditionsaremet:
1.Toppingofconcreteorsimilarmaterials isnotplacedoverwoodstructuralpaneldiaphragmsexceptfornonstructuraltoppingnogreaterthan11/2in.thick.2.Eachlineofverticalelementsoftheseismic forceresistingsystemcomplieswiththeallowablestorydriftofTable12.12-1..
RigidorFlexibleDiaphragm?
![Page 57: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/57.jpg)
Hypothetical FlexibleDiaphragm Distribution
Typical Unit
7654321
D
C
B
A
Areatributarytocorridorwallline
Areatributarytoexteriorwall
line
23%
23%
27%27%
Largeportionofloadonlittle
wall
Changing wall construction does NOT impact load to wall line
![Page 58: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/58.jpg)
Hypothetical RigidDiaphragm Distribution
Typical Unit
7654321
D
C
B
A
Longer,stifferwallsreceivemoreload
Diaphragmassumedtoberigidbody.
10%
10%
40%40%
Narrow,flexiblewallsreceiveless
load
Changing wall construction impacts load to wall line
![Page 59: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/59.jpg)
ASCE7-1012.3.1.3(Seismic)
[Diaphragms]arepermittedtobeidealizedasflexiblewherethecomputedmaximum in-planedeflectionofthediaphragmunderlateralloadismorethantwotimestheaveragestorydriftofadjoiningverticalelementsoftheseismic force-resistingsystemoftheassociatedstoryunderequivalent
tributarylateralloadasshowninFig.12.3-1.
IBC2012Chapter2Definition(Wind&Seismic)
Adiaphragmisrigid forthepurposeofdistributionofstoryshearandtorsionalmomentwhenthelateraldeformationofthediaphragmislessthanorequaltotwotimestheaveragestorydrift.
CanaRigidDiaphragmbeJustified?
Average drift of walls
Maximum diaphragm deflection
![Page 60: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/60.jpg)
SomeAdvantagesofRigidDiaphragm
• Moreload(plf)tolongerinterior/corridorwalls• Lessload(plf)tonarrowwallswhereoverturningrestraintistougher• Cantuneloadstowallsandwalllinesbychangingstiffnessofwalls
SomeDisadvantagesofRigidDiaphragm
• Considerationsoftorsionalloadingnecessary• Morecomplicatedcalculationstodistributeloadtoshearwalls• Mayunderestimate“Real”loadstonarrowexteriorwalls• Justificationofrigidassumption
RigidDiaphragmAnalysis
![Page 61: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/61.jpg)
Semi-RigidDiaphragmAnalysis
• Neitheridealizedflexiblenoridealizedrigid• Explicitmodelingofdiaphragmdeformationswithshearwalldeformationstodistributelateralloads
• Noteasy.
EnvelopingMethod
• IdealizedasBOTHflexibleandrigid.• Individualcomponentsdesignedforworstcasefromeachapproach• Beenaroundawhile,officiallyrecognizedinthe2015SDPWS
TwoMoreDiaphragmApproaches
![Page 62: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/62.jpg)
Possible Shear Wall Layouts
Typical Unit
7654321
D
C
B
A
TheCantileverDiaphragmOption
![Page 63: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/63.jpg)
Possible Shear Wall Layouts
Typical Unit
7654321
D
C
B
A
RobustAspectRatiobutonlysupportedon3sides…
![Page 64: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/64.jpg)
OpenFrontStructure CantileverDiaphragm
CantileveredDiaphragmsinSDPWS2008
AWCSDPWS2008Figure4AAWCSDPWS2008Figure4B
![Page 65: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/65.jpg)
OpenFrontStructureSDPWS4.2.5.1.1L≤25ftL/W≤1,onestory
≤2/3,multi-story
CantileveredDiaphragmsinSDPWS2008
Exception:Wherecalculationsshowthediaphragmdeflectionscanbetolerated,thelength,L,canbeincreasedtoL/W≤1.5forWSPsheatheddiaphragms.
![Page 66: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/66.jpg)
CantileveredDiaphragmSDPWS4.2.5.2Lc ≤25ftLc/W≤2/3
CantileveredDiaphragmsinSDPWS2008
![Page 67: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/67.jpg)
Possible Shear Wall Layouts
Typical Unit
7654321
D
C
B
A
OpenFrontStructureorCantileveredDiaphragm?
![Page 68: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/68.jpg)
CantileveredDiaphragmsinSDPWS2015
OpenFrontStructurewithaCantileveredDiaphragm
AWCSDPWS2015Figure4A
![Page 69: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/69.jpg)
CantileveredDiaphragm SDPWS4.2.5.2L’/W’≤1.5WhenTorsionally Irregular
L’/W’≤1,onestory2/3,multi-story
L’≤35 ft
OpenFrontStructure&CantileveredDiaphragmsinSDPWS2015
Provideddiaphragmsmodelledasrigidorsemi-rigidandforseismic,thestorydriftateachedgeofthestructurewithinallowablestorydriftofASCE7.Storydriftsincludetorsionandaccidentaltorsionalloadsanddeformationsofthediaphragm.
![Page 70: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/70.jpg)
CantileveredDiaphragm SDPWS4.2.5.2L’/W’≤1.5WhenTorsionally Irregular
L’/W’≤1,onestory≤2/3,multi-story
L’≤35 ft
OpenFrontStructure&CantileveredDiaphragmsinSDPWS2015
IfL’≤6ft ,sectiondoesn’tapply.Exception:
![Page 71: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/71.jpg)
WindLoadDistributiontoShearwalls
![Page 72: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/72.jpg)
TieDownAttachmenttoConcrete
Source:Strongtie
![Page 73: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/73.jpg)
TieDownBoltwithWasher
Source:Strongtie
![Page 74: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/74.jpg)
TieDownBoltwithWasher- Reinforcing
Source:Strongtie
![Page 75: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/75.jpg)
TieDownAnchorChairinCastSlab
Source:EarthboundAnchors
![Page 76: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/76.jpg)
EmbeddedSteelPlates– WeldonRods
![Page 77: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/77.jpg)
TieDownAnchors– PrecastThroughBolt
![Page 78: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/78.jpg)
TieDownAnchors– ThroughPodium
![Page 79: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/79.jpg)
LateralLoadPathContinuity:WallElevation
ShearWall
ShearWall
Header
Header
Headerdistributesuppershearwall
endpostconcentrated load
towallbelowHeaderalso
distributes uppershearwallshearto
wallbelow
Postsinlowerwalltransfer
upperwallendpost
concentratedloadsto
foundation
Wallplatesactasdragstrutstotransfershearloadsfromupperwalltolowerwall
Note:anymembersupportingadiscontinuous wallmustbedesigned fortheover-strengthfactorunderASCE7-10Section12.3.3.3,forSDCB-F
![Page 80: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/80.jpg)
OffsetShearWallOverturningResistance
Source:Strongtie
![Page 81: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/81.jpg)
TieDowntoSteelBeamAttachment
Source:Strongtie
![Page 82: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/82.jpg)
Recap
• WindLoadPaths• Multi-StoryStackedShearWallEffects• AccumulationofOverturningLoads• ShearWallDeflection• DiaphragmModeling• DiscontinuousShearWalls
![Page 83: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/83.jpg)
Questions?
ThisconcludesTheAmericanInstituteofArchitectsContinuingEducationSystemsCourse
RickyMcLain,MS,PE,SE
[email protected](802)498-3310
Visitwww.woodworks.org formoreeducationalmaterials,casestudies,designexamples,aprojectgallery,andmore
![Page 84: Lateral Design of Mid-Rise Wood Structures for Wind Loads](https://reader034.fdocuments.us/reader034/viewer/2022042611/586b7fea1a28ab21638b9203/html5/thumbnails/84.jpg)
ThispresentationisprotectedbyUSandInternationalCopyrightlaws.
Reproduction,distribution,displayanduseofthepresentationwithoutwrittenpermission
ofthespeakerisprohibited.
©TheWoodProductsCouncil2016
CopyrightMaterials