Shear WallsShear WallsShear WallsShear Walls

Section 3Section 3

Typical Shear WallTypical Shear WallTypical Shear WallTypical Shear Wall

Even Distributionof Shear Walls

Even Distributionof Shear Walls

Location of Shear Location of Shear WallsWalls

Location of Shear Location of Shear WallsWalls

Create box structureCreate box structure

Equal length & Equal length & symmetricalsymmetrical

Create box structureCreate box structure

Equal length & Equal length & symmetricalsymmetrical

Break inBreak inLoad PathLoad Path

InteriorInteriorPartitionPartition

InteriorInteriorShear WallShear Wall

Continuous Load PathContinuous Load PathFloor Must Support Shear WallFloor Must Support Shear Wall

Cripple WallCripple Wall

ExteriorExteriorShear WallShear Wall

Vertical Offset of Vertical Offset of Shear WallShear Wall

Vertical Offset of Vertical Offset of Shear WallShear Wall

Shear Shear Wall OverWall Over

Floor Floor BeamBeam

Shear Shear Wall OverWall Over

Floor Floor BeamBeam

Horizontal Shear Horizontal Shear ForcesForces

Horizontal Shear Horizontal Shear ForcesForces

Uplift Uplift Forces OnForces On

Shear Shear WallWall

Uplift Uplift Forces OnForces On

Shear Shear WallWall

STIFFNESSControl Sidesway

STIFFNESSControl SideswayEarthquake ForceEarthquake Force

ConnectionFor Uplift

Resistance

ConnectionFor Uplift

ResistanceConnectionFor SlidingResistance

ConnectionFor SlidingResistance

STRENGTHSTRENGTH

ResistShear

Two Functions of a Two Functions of a Shear WallShear Wall

Two Functions of a Two Functions of a Shear WallShear Wall

What Provides Shear What Provides Shear Wall Strength?Wall Strength?

What Provides Shear What Provides Shear Wall Strength?Wall Strength?

LumberLumber

SheathinSheathingg

FastenerFastenerss

LumberLumberStrengtStrengt

hhFailureFailure

LumberLumberStrengtStrengt

hhFailureFailure

Sheathing Strength Sheathing Strength FailureFailure

Sheathing Strength Sheathing Strength FailureFailure

FastenFastenerer

StrengtStrengthh

FailureFailure

FastenFastenerer

StrengtStrengthh

FailureFailure

Combining Different Combining Different Material StrengthsMaterial Strengths

Combining Different Combining Different Material StrengthsMaterial Strengths

Different sheathing materials Different sheathing materials DO NOT combine strengthDO NOT combine strength

Sheathing materials reach Sheathing materials reach ultimate strength at different ultimate strength at different wall displacementswall displacements

Different MaximumDisplacements

Wall Displacement

Sheathing Material Sheathing Material StrengthsStrengths

Sheathing Material Sheathing Material StrengthsStrengths

Earthquake ForceEarthquake Force

Resisting Forcefrom ConnectionResisting Forcefrom Connection

End Studin TensionEnd Studin Tension

End Stud inCompression

End Stud inCompression

C T

C T

Earthquake ForceEarthquake Force

Most Important Most Important FactorsFactors

Most Important Most Important FactorsFactors

ARESTIFFER

THAN

ARESTIFFER

THANLong Short WallsLong Short Walls

TallNarrowWalls

TallNarrowWalls

Allowable Aspect Allowable Aspect RatiosRatios

Allowable Aspect Allowable Aspect RatiosRatios

Northridge EarthquakeNorthridge EarthquakeShowed Us:Showed Us:

Northridge EarthquakeNorthridge EarthquakeShowed Us:Showed Us:

Most materials did NOT Most materials did NOT do as well as predicteddo as well as predicted

More material and wider More material and wider walls neededwalls needed

Reduced Code ValuesReduced Code ValuesReduced Code ValuesReduced Code Values

Drywall Drywall FailureFailureDrywall Drywall FailureFailure

Stucco FailureStucco FailureStucco FailureStucco Failure

NarrowNarrowPanelPanel

FailureFailure

NarrowNarrowPanelPanel

FailureFailure

Successful Plywood Successful Plywood CoverageCoverage

Successful Plywood Successful Plywood CoverageCoverage

Wood Structural Wood Structural Panel Shear WallsPanel Shear WallsWood Structural Wood Structural

Panel Shear WallsPanel Shear Walls

Lumber typeLumber type

Lumber sizeLumber size

Condition of existing Condition of existing woodwood

Douglas Fir-LarchDouglas Fir-LarchDouglas Fir-LarchDouglas Fir-Larch Hem FirHem FirHem FirHem Fir

StrongerStrongerStrongerStronger WeakerWeakerWeakerWeaker

Effect Of Lumber Species Effect Of Lumber Species On StrengthOn Strength

Effect Of Lumber Species Effect Of Lumber Species On StrengthOn Strength

Structural 1Structural 1

Allowable Shears (lbs/ft)Based on Lumber SpeciesAllowable Shears (lbs/ft)Based on Lumber Species

RedwoodOpen GrainRedwood

Open GrainHem-

FirDouglasFir-Larch

Nail Spacin

g at Panel Edges

Common

Nail Sizes

Wood Structural Panel

ThicknessPanel Grade

15/32 inStructural 1 8d 4 430 355 280280

15/32 inStructural 1 8d 3 550 450 360360

15/32 in15/32 in 10d10d 33 665665 545545 430430

Use Proper Size StudUse Proper Size StudUse Proper Size StudUse Proper Size Stud

Framing members split at Framing members split at ultimate loads when sheathing ultimate loads when sheathing nails are closely spacednails are closely spaced

Shear Walls: 17% stronger Shear Walls: 17% stronger when 3” framing used when 3” framing used throughoutthroughout

2” 2” AdjoininAdjoining Studg Stud

2” 2” AdjoininAdjoining Studg Stud

Install Proper Size Install Proper Size BlockingBlocking

Install Proper Size Install Proper Size BlockingBlocking

Fasten all edges to framing Fasten all edges to framing members or blockingmembers or blocking

Provide blocking if panel Provide blocking if panel members are unsupported members are unsupported between framing membersbetween framing members

Cripple Wall BlockingCripple Wall BlockingCripple Wall BlockingCripple Wall Blocking

3” Flat Blocking3” Flat Blocking3” Flat Blocking3” Flat Blocking

ReinforcReinforced ed

Window Window Opening Opening in Shear in Shear

WallWall

ReinforcReinforced ed

Window Window Opening Opening in Shear in Shear

WallWall

Blocking For Blocking For Opening Opening

ReinforcemeReinforcementnt

Blocking For Blocking For Opening Opening

ReinforcemeReinforcementnt

How is the Length ofHow is the Length ofShear Wall Measured?Shear Wall Measured?How is the Length ofHow is the Length of

Shear Wall Measured?Shear Wall Measured?

Horizontally along sheathing Horizontally along sheathing between wall ends with hold-between wall ends with hold-downsdowns

NOTNOT length of plywood length of plywood

ISIS measured by hold-down measured by hold-down locationlocation

What’s What’s Wrong?Wrong?What’s What’s Wrong?Wrong?

Too close to Too close to end wall; end wall; countersunkcountersunk

Too close to Too close to end wall; end wall; countersunkcountersunk

What’s What’s Wrong?Wrong?What’s What’s Wrong?Wrong?

Too far Too far from shear from shear wall endwall end

Too far Too far from shear from shear wall endwall end

Acceptable Hold-Down Acceptable Hold-Down LocationLocation

Acceptable Hold-Down Acceptable Hold-Down LocationLocation

Lumber GradeLumber GradeLumber GradeLumber Grade

Effect of Lumber Effect of Lumber Grade onGrade on

Hold-Down CapacityHold-Down Capacity

Effect of Lumber Effect of Lumber Grade onGrade on

Hold-Down CapacityHold-Down Capacity

Penetration Through Penetration Through Shear WallShear Wall

Penetration Through Penetration Through Shear WallShear Wall

Wood DecayWood DecayWood DecayWood Decay

Termite Termite DamageDamageTermite Termite DamageDamage

Crawl Space Crawl Space VentilationVentilation

Crawl Space Crawl Space VentilationVentilation

Installing the Installing the SheathingSheathing

Installing the Installing the SheathingSheathing

Use specified wood Use specified wood structural panelstructural panel

OSBOSB

PlywoodPlywood

Construction of Construction of Oriented Strand Board Oriented Strand Board

PanelPanel

Construction of Construction of Oriented Strand Board Oriented Strand Board

PanelPanel

Construction of Construction of PlywoodPlywood

Construction of Construction of PlywoodPlywood

3 ply3 layer panel3 ply3 layer panel

4 ply3 layer panel4 ply3 layer panel

5 ply5 layer panel5 ply5 layer panel

Minimum Minimum Recommended Recommended

ThicknessThickness

Minimum Minimum Recommended Recommended

ThicknessThickness 15/32”15/32”

Both 4-ply and 5-plyBoth 4-ply and 5-ply

More plies More plies stronger stronger sheathingsheathing

Use Correct Panel Use Correct Panel GradeGrade

Use Correct Panel Use Correct Panel GradeGrade

Sheathing OrientationSheathing OrientationSheathing OrientationSheathing Orientation

2” studvertical orhorizontal

3” stud

3” block

nail edges

Use proper size panelUse proper size panel 2:1 aspect ratio2:1 aspect ratio 4’ x 8’ panel minimum4’ x 8’ panel minimum

Mark stud locations on panelsMark stud locations on panels Avoid improper fasteningAvoid improper fastening

Maintain fire resistive and Maintain fire resistive and sound-rated constructionsound-rated construction Don’t change anything!Don’t change anything!

Cripple Wall Cripple Wall VentilationVentilation

Cripple Wall Cripple Wall VentilationVentilation

Shear WallShear WallFastenersFasteners

Shear WallShear WallFastenersFasteners

Use Common NailsUse Common NailsUse Common NailsUse Common Nails

Use ProperUse Proper

Nail LengthNail Lengthandand

Head SizeHead Size

Use ProperUse Proper

Nail LengthNail Lengthandand

Head SizeHead Size

Performance Performance Losses for Nail Losses for Nail SubstitutionsSubstitutions

Performance Performance Losses for Nail Losses for Nail SubstitutionsSubstitutions

Nail Gun With Flush Nail Gun With Flush AttachmentAttachment

Nail Gun With Flush Nail Gun With Flush AttachmentAttachment

Round-Round-Head NailsHead Nails(P-Nails)(P-Nails)

Round-Round-Head NailsHead Nails(P-Nails)(P-Nails)

ModifiedModifiedRound-Round-

Head Nails Head Nails (P-Nails)(P-Nails)

ModifiedModifiedRound-Round-

Head Nails Head Nails (P-Nails)(P-Nails)

Clipped Nail Clipped Nail HeadHead

Clipped Nail Clipped Nail HeadHead

Smaller nail head Smaller nail head areas areas smaller smaller

shear wall strengthsshear wall strengths

Smaller nail head Smaller nail head areas areas smaller smaller

shear wall strengthsshear wall strengths

1994 1994 UBC:UBC:1994 1994 UBC:UBC:

Nail should “not fracture the Nail should “not fracture the surface of the sheathing”surface of the sheathing”Nail should “not fracture the Nail should “not fracture the surface of the sheathing”surface of the sheathing”

1997 1997 UBC:UBC:1997 1997 UBC:UBC:

The “head or crown of the The “head or crown of the nail is flush with the surface nail is flush with the surface of the sheathing”of the sheathing”

The “head or crown of the The “head or crown of the nail is flush with the surface nail is flush with the surface of the sheathing”of the sheathing”

Overdriven nails reduce Overdriven nails reduce shear wall strengthshear wall strength

Overdriven nails reduce Overdriven nails reduce shear wall strengthshear wall strength

OverdrivOverdriven Nailsen NailsOverdrivOverdriven Nailsen Nails

Improper Improper Edge Edge

DistanceDistance

Improper Improper Edge Edge

DistanceDistance

ImportantImportantImportantImportant

Install nails flush to sheathingInstall nails flush to sheathing

Maintain proper sheathing edge Maintain proper sheathing edge distancedistance

Check for splittingCheck for splitting

Remove improperly installed nailsRemove improperly installed nails

Provide proper edge nailingProvide proper edge nailing

OOPS!OOPS!OOPS!OOPS!

How to Nail a Shear How to Nail a Shear WallWall

How to Nail a Shear How to Nail a Shear WallWall

Edge nailEdge nail:: hold-down stud(s)hold-down stud(s) upper top plateupper top plate sill or sole platesill or sole plate blocking for individual panel edgesblocking for individual panel edges blocking for opening reinforcementblocking for opening reinforcement

Field nailField nail the studs between the panel the studs between the panel edgesedges