Wood Design for Architects: Engineering for the Non-engineer

Karyn A. Beebe, P.E. , LEED APkaryn.beebe@apawood.org (858) 560-1298 www.apawood.org

AIA Statement

“The Wood Products Council” is a Registered Provider with The

AIA Statement

The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion forreported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

This program is registered with AIA/CES for continuing professional p g g g peducation. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

Questions related to specific materials, methods, and services will be paddressed at the conclusion of this presentation.

Copyright MaterialsCopyright Materials

This presentation is protected by US andThis presentation is protected by US and International Copyright laws. Reproduction,

distribution, display and use of the presentation without written permission of the speaker iswithout written permission of the speaker is

prohibited.

© The Wood Products Council 2012

Learning ObjectivesLearning Objectives

At the end of this program, participants will be able to:

f1. Define the design criteria such as lateral loads in the region, understand how they impact buildings, and consequently be better prepared to design for them.

2. Identify the latest changes to the International Codes with respect to engineered wood provisions

3 Th h ki d i l l th i k l d t b ildi3. Through working design examples, apply their new knowledge to building design.

4. Utilize design resources (APA literature and a list of websites and g (publications) addressing the challenges facing today’s wood building designer

Presentation AgendaPresentation Agenda

W d t t l t i l Wood as a structural material Design Criteria Building Elements The Unified Structure Design Examples

Wood as a Structural MaterialWood as a Structural Material

Wood has a strength directionWood has a strength direction

Load parallelto grain

Load perpendicularto grainto grain to grain

Stronger Weaker

Wood as a structural materialWood as a structural material

CompressionCompression Parallel – columns, posts, truss chordsPerpendicular – deformation of member

TensionParallel – Highest strength – beams, panelsPerpendicular – Weakest capacity - connections

Mechanical Properties of WoodMechanical Properties of Wood

Bending

Develop strength in extreme fiberDevelop strength in extreme fiber

High strength – to – weight ratio dCalculate maximum moment

Resisting Moment = M = S x Fbg b

S = Section Modulus = bd2/6 Fb = Allowable Bending Stress

b

Typical Units are pound-feet (lb-ft)

Mechanical Properties of Woodp

Load, w:x

Lx

Moment,M: M * /2*(L ) M L2/8M: M=w*x/2*(L-x) Mmax=wL2/8

Mechanical Properties of WoodMechanical Properties of Wood

2 Failure Modes

Strength – Have fibersStrength Have fibers

crushed, split, or otherwise

destructed?destructed?

Stiffness – How much has

the beam moved under a

given load?

Mechanical Properties of WoodMechanical Properties of Wood

D fl iDeflection

Modulus of Elasticity

Calculate maximum deflection

D fl ti li itDeflection limits

Building code vs. Manufacturers’ Recommendations

Typical units are inches (in)

Mechanical Properties of Woodp

Load, w:x

L

DeflectionDeflection,∆:

∆max=5w*L4/(384*E*I)

Maximum Deflection

Limited to reduce floor bounce and prevent cracking ofLimited to reduce floor bounce and prevent cracking of finish materials such as drywall and tile(CBC Table 1604.3)

Construction Live load deflection

Total load deflection

Roof members w/drywall clg.

L/240 L/180

Floor L/360 L/240members

LI – joists* L/480

**Per APA form E30, pg 26

Mechanical Properties of WoodMechanical Properties of Wood

Shear stressCritical at connections, reactions, point loadsTypically not failure mode in flexural membersMay control in short spans with heavy loading, cantilever, or continuous spans

Avoid stress concentrations at notches or changes inAvoid stress concentrations at notches or changes in cross sectionCalculate maximum shear forceAllowable Shear Stress = Fv >= 1.5V/AV = maximum shearA = Cross Sectional Area

Typical units for Shear are pounds (lbs)

Mechanical Properties of Woodp

Load, w:

Lx

V =wL/2Shear, V:

V=w(L/2-x)

Vmax =wL/2

V w(L/2 x)

Tension Perpendicular to GrainTension Perpendicular to Grain

Wood splits from: notches

h i l d hanging loads restraint by connector

Load Path ContinuityLoad Path Continuity

S d t l d f f t Spread out loads from fasteners

Best(multiple small fasteners)

Consider alternative(large single fastener) (multiple small fasteners)(large single fastener)

Load Path ContinuityLoad Path Continuity NotchingNotching

Tension perpendicular to grainTension perpendicular to grain

Connecting WoodConnecting Wood

Wood, like other materials, moves in varying environments

Do Not Mix IDo Not Mix I--joists with joists with Di i L bDi i L bDimension LumberDimension Lumber

Dispersal of Strength Reducing Characteristics

Wood as a Structural Material

I J i t L b

Wood as a Structural Material

I-Joist vs. LumberBoth at 16" o.c.36% less wood fiber36% less wood fiber I-Joist at 19.2" o.c &

Lumber at 16" o.c.VS46% less wood fiber VS.

I-Joist Lumber

Design Criteria: Loadsg

D d L d ( t) Dead Loads (permanent) – structure, partitions, finishes

Live LoadsLive Loads– people, furniture, snow

Wind and Seismic Impact loads

(Th ff t f l d l d ith h t d ti )(The effect of loads are lessened with shorter duration)

Vertical LoadVertical Load

Loads (2010 CBC Chapter 16 & CRC Section R301)

Dead Loads (Section 1606)Weight of permanent loads: construction materials, fixed

equipmentequipment Increases from joists to beams

Live Loads (Table 1607.1) Live Load Reduction (1607.9)Reduction in Roof Live Loads (1607.11.2)( ) Based on supported area, slope roof Decreases from joists to beams

Dead Dead Loads?Loads?

Loads (2010 CBC Chapter 16 & CRC Section R301.2)

Climatic LoadsSnow (Section 1608)Rain (Section 1611)

Lateral LoadsWind (Section 1609)Seismic (Section 1613)Seismic (Section 1613)

Lateral LoadLateral Load

Lateral Loads: National IssueLateral Loads: National Issueate a oads at o a ssueate a oads at o a ssue

Earthquake HazardWind Hazard

Loads (2010 CBC Chapter 16 & CRC Section R301)

Load Combinations (Section 1605) 21 Equations

M t h k ll bi ti f i l diMust check all combinations for maximum loadingExamples: D + L + (Lr or S or R) D + L + ωW 0.9D + E/1.4

Adjustment FactorsAdjustment Factors

Capacity +/- based on:Capacity +/ based on:Duration of LoadMoisture TemperatureChemical Treatments

(Found in the National Design Specification for Wood Construction (NDS) published by the American Forest & Paper Association)

Load Duration FactorWood capacity greater for short time loading

LOAD DURATION L d D ti T i l L dLOAD DURATION Load Duration Factor - CD

Typical Loads

Permanent 0.9 Dead Load

Ten years 1.0 Floor live load

Two months 1.15 Snow load

Seven days 1.25 Construction load

T i t 1 6 Wi d/E th kTen minutes 1.6 Wind/Earthquake

Impact 2.0 Vehicles

These factors are applied to member capacity

Design ConsiderationsDesign Considerations

End restraint conditions:Simple span has 2 supportsContinuous has 3 or more supportsCantilevered has 1 supportSupports may be beams, columns, walls…

ContinuousSimple

Cantilevered

Design ConsiderationsDesign Considerations

Loading Conditions:Loading Conditions:Uniform: Dead load, Live loads, pounds per lineal feet (plf)

Lx

Point: Interior Columns, walls, pounds (lbs), , p ( )

xL

x

Why Engineer?When a building, or portion, doesn’t meet conventional

requirements it must be engineeredrequirements it must be engineered(CBC 2308.4, CRC R301.1.3)

Building Elements

Gravity DesignGravity Design Horizontal members Panels Panels Joists Beams Beams

Vertical members StudsStuds Columns

Wood Structural PanelsWood Structural PanelsWood Structural PanelsWood Structural PanelsWood Structural PanelsWood Structural PanelsWood Structural PanelsWood Structural Panels Building Elements: PanelsBuilding Elements: Panels

Face

Core

Face

Center

Core

Back

Building Elements: PanelsBuilding Elements: Panels

OSB layers are engineered forOSB layers are engineered for strength.

Building Elements: PanelsBuilding Elements: Panels

Roof Span Deflection = L/240 Live load = 30 psf Dead load = 10 psf Dead load = 10 psf

Floor Span Deflection = L/360

Li l d 100 f Live load = 100 psf Dead load = 10 psf

Building Elements: PanelsBuilding Elements: Panels

Rated Sheathingg Floor, wall or roof Plywood or OSB

Roof Covering

A P ARATED SHEATHINGRATED SHEATHING

32/16SIZED FOR SPACING

EXPOSURE 1THICKNESS 0.451 IN.

000PS 2-10 SHEATHING PRP-108 HUD-UM-40PRP-108 HUD-UM-40

15/32 CATEGORY

Building Elements: PanelsBuilding Elements: Panels

Rated Sheathing Floor, wall or roof Plywood or OSB

A P ARATED SHEATHINGRATED SHEATHING

32/16SIZED FOR SPACING

EXPOSURE 1THICKNESS 0.451 IN.

000PS 2-10 SHEATHING PRP-108 HUD-UM-40PRP-108 HUD-UM-40

15/32 CATEGORY

Building Elements: PanelsBuilding Elements: Panels

Sturd-I-Floor Combined subfloor & underlayment Resistant to concentrated & impact loads Plywood or OSB

A P ACarpet

RATED STURD-I-FLOOR20 oc

SIZED FOR SPACINGT & G NET WIDTH 47 1/2

p& padT & G NET WIDTH 47-1/2

EXPOSURE 1THICKNESS 0.578 IN.

000PS 2-10 SINGLE FLOORPS 2 10 SINGLE FLOOR

PRP-108 HUD-UM-4019/32 CATEGORY

APA Form E30 Table 30APA Form E30 Table 30

Span Rating ConditionsSpan Rating Conditions

St th iStrength axis perpendicular to supports

Continuous across 2 or more spans

APA Form E30 Table 33

Building Elements: JoistsBuilding Elements: Joists

I j i t I-joist Used for floor & roof framing Long lengths available

Flange(LVL or lumber)( )

Web(OSB)(OSB)

Building Elements: JoistsBuilding Elements: Joists

Uniform Load

Compression

Tension

CForces are Max at LLC

CForces are Max. at L

Building Elements: JoistsBuilding Elements: Joists

Uniform Load

BC B CRule of Thumb: Hole size inversely

proportional to shear force

BC B C

Shear Force

Building Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim BoardBuilding Elements: Rim Board

Building Elements: BeamsBuilding Elements: Beams

Laminated Veneer Lumber (LVL) Laminated Veneer Lumber (LVL) Veneers bonded together Beams, headers, rafters

& scaffold planking

All grain parallelto lengthto length

Constructability

Field Notching and Drilling of LVL

Constructability

g g(Form G535)

Horizontal Hole Drilling

Vertical HolesVertical Holes

Strength reduction = 1.5 x Hole diameter/beam width(Forms S560 and G535)(Forms S560 and G535)

Example:• 6” Beam width• 1” diameter vertical holeReduction = 1 x 1.5/6Reduction = 0 25Reduction 0.25Beam is 75% of original strength

Side-loaded Multi-ply BeamsSide loaded Multi ply Beams

Connection of plies is specified in the NDS andConnection of plies is specified in the NDS and individual LVL manufacturer literature

Pre-engineered ConnectorsPre engineered Connectors

Joist and beam hangersJoist and beam hangers

Top and face mountop a d ace ou t Product specific Use correct nail Fill all holes Ensure proper p pfastener penetration

Glulam

GlulamGlulamGlulamGlulam

Engineered Lay upsEngineered Lay-ups

C iCompression zone

Inner zone

Tension zone

Critical Tension Zone

TOP StampO Sta p

Building Elements: Beams

Stock Beams – Camber is not an issue

Building Elements Beams

Camber in stock beams is usually zero or based on a 3500’ or 5000’ radius where a 20’ beam has a curvature of 1/8” or less

3500’ radius3500 radius

Zero camber

Constructability

Field Notching and Drilling of Glulam

Constructability

Field Notching and Drilling of Glulam (Form S560)

Horizontal Hole DrillingHorizontal Hole Drilling

Building Elements: Beams

Exposed Conditions

Building Elements: Beams

Treated Beams and Columns for Decks

Exposed Conditions Preservative

treatment Naturally

durable wood speciesspecies Alaskan Yellow

Cedar Port Orford

Cedar

Building Elements: BeamsBuilding Elements: Beams

LVL Hybrid Glulam with LVL LVL LaminationsLVL Hybrid Glulam with LVL Outer Laminations

Full length with no

LVL Laminations

Full length with nofinger joints required

LVL has greater gtensile strengthcompared to lumber

30F-2.1E stress level achieved

Di t b tit t f Direct substitute for many SCL products

Building Elements: BeamsBuilding Elements: Beams

Architectural AppearanceArchitectural Appearance + Full Framing Width+ IJC Depths

Maximize versatility –exposed or not

Ease of construction –no shimming required

Stud Capacityp y

Buckling capacity usually controlsBuckling capacity usually controlsBuckling controlled by: Stud length Buckled shape

Stud size (2x4 vs. 2x6) Stud grade (No.1, No. 2, Stud) Bracing in weak direction (blocking,Bracing in weak direction (blocking,

drywall)

Strong direction

Weak direction

Stud BendingStud Bending

Buckled shape

Lateral force on studs further

d th reduces the buckling capacity.

This controls the design of exterior studs subjected to studs subjected to lateral wind or seismic forces.

Built-up Lumber ColumnsBuilt up Lumber Columns

Multi-ply columnsGuidance provided in NDS for: Nailed or bolted laminated columnsNailed or bolted laminated columns Nailed Kf = 0.60 Bolted Kf = 0.75

BuiltBuilt--up Lumber Columnsup Lumber ColumnsNail spacing dictated by NDS for reduced Kf

Building Elements

Lateral DesignHorizontal members Horizontal members Diaphragms

Vertical membersVertical members Shear Walls

Lateral Load PathLateral Load PathGravity Load PathGravity Load Path

Lateral Load Path Designing Wood Structures to Resist Lateral Loads

Conventional Light Frame ConstructionConventional Light Frame Construction Prescriptive, uses bracing Limited as defined by provisions

Engineered Lateral Force Resisting SystemUses shear walls, diaphragms, collectors, etc.

Blocked DiaphragmBlocked Diaphragm Unblocked DiaphragmUnblocked Diaphragm

Engineered Shear WallsEngineered Shear WallsWoodstructuralstructuralpanels ofspecific gradeand thicknessSpecific

stud species

Specific nail size and spacing Hold-downrequirements

Base shear anchor bolts

anchors

Base shear anchor bolts

Height to width ratio ( )(SDPWS Table 4.3.4)

F h ll dFor shear walls and perforated shear walls h:w must not exceed 2:1 h:w must not exceed 2:1

or 3.5:1 ratio

Max. Shear Wall Aspect Ratios (2305.3.4)

A t ti h i ht t idth tiAspect ratio = height-to-width ratio Height = bottom of bottom plate to top of top plate Width = sheathed width of wall

2003-2006 IBC2000 IBC

1997 UBCDesign

3.5:1 3.5:1 3.5:1Zone 4 2:1 -- --Zone 0-3 3.5:1 -- --

Wind

Zone 0 3 3.5:1SDC D-F -- 2:1 2:1a

SDC A-C -- 3.5:1 2:1a

Seismic

a. May be reduced to 3.5:1 if allowable shear is reduced by 2w/h

Shear Wall Designg(SDPWS 4.3)

Segmented Force Transfer Perforated1. Aspect Ratio for

seismic 2:12. Aspect ratio up to

3.5:1, if allowable

1. Code does not provide guidance for this method

2. Different

1. Code provides specific requirements

2. The capacity is ,shear is reduced by 2w/h

approaches using rational analysis could be used

p ydetermined based on empirical equations and tables

Hold-Down PlacementTraditional

Hold-Down PlacementPerforated

The Unified Structure Lateral Loads(Wind)Lateral Loads(Wind)

Eff t i d t dF = PA Effort is devoted to determining: P – wind pressurep

Lateral Loads(Seismic)Lateral Loads(Seismic)

Eff t i d t dF = ma Effort is devoted to determining: a – acceleration

General Modes of FailureGeneral Modes of Failure

Uplift Base Shear

Racking Overturning

Breached Building Envelope -F-2 Tornado

Reference: APA Report – Midwest Tornados 2003

Easy Upgrade!Easy Upgrade!

Bottom Plate to Foundation

Lateral Force Resisting SystemsLateral Force Resisting Systems

Hold down hardwareHold-down hardware

The Unified Structure

Lateral connection strengthLateral connection strength

depends on:

Crushing (bearing) strength of g ( g) g

wood

Size of wood pieces

Fastener size and strength

Plus appropriate end use

adjustment factors (i.e. Wet

service, edge distance, end grain,

etc.)

The Unified Structure

Withdrawal ConnectionWithdrawal Connection

Strength Depends On:Depth of penetration

Wood density

Fastener size and type

Plus appropriate end use

adjustment factors i.e. wet

service, edge distance, endservice, edge distance, end

grain, etc.

Consistency CountsConsistency Counts

Nail sizes Nail sizes Are you using the right nail? Specify pennyweight, type,

di t d l th

8d Nail Sizes

Type Length Wire Dia.diameter and length Ex: 8d common = 0.131” x 2-1/2”

Type (in.) (in.)

Finish 2-1/2" 0.099

Box & casing 2 1/2" 0 113Box & casing 2-1/2 0.113

Siding 2-3/8" 0.106

Cooler 2-3/8" 0.113

Common 2-1/2" 0.131

Ring- or screw-shank 2-1/2" 0.120 or

0 131screw-shank 0.131

Consistency CountsConsistency Counts

O d i f t Overdriven fasteners

Overdriven Not Overdriven

Consistency CountsConsistency Counts

O d i F tOverdriven Fasteners

Overdriven OverdrivenOverdriven Fasteners

Overdriven Distance Action

< 20% < 1/8" N< 20% < 1/8" None

> 20% < 1/8" Add 1 fAdd 1 for every two overdrivenAny > 1/8"

APA Publication TT-012

Consistency CountsConsistency Counts

O d i F t

Overdriven Overdriven A ti

Overdriven Fasteners

Overdriven Fasteners

Overdriven Distance Action

Due to Any Thickness

SwellingNone

APA Publication TT-012

Pre-engineered ConnectorsPre engineered Connectors

Joist and beam hangers• Top and face mount• Product specific• Use correct nail• Fill all holesFill all holes• Ensure proper fastener penetration

Variable Spacing … Variable Spacing … Be Careful !Be Careful !

Consistency CountsConsistency Counts

Inconsistent Spacing & SpanInconsistent Spacing & Span

Inconsistent feel & performance

Consistency CountsConsistency Counts

Consistent Spacing & SpanConsistent Spacing & Span

Floor Sheathing Example

Answer:• From Table 12, APA form E30 (pg 33):

• For 16” oc spacing• For 16 oc spacing = 7/16” 32/16 wood structural panel (WSP)

• For 24” oc spacing = 23/32” or ¾” 48/24 WSP

Given:Given:• Span = 16” and 24” • Live load = 40 psf• Dead load = 10 psf

Design reference: APA form E30

APA Form E30 Table 12Joist Example

Answer:• From Table 8, APA form E30 (pg 26):

• For 16” oc spacing• For 16 oc spacing = 9-1/2” PRI-20

• For 24” oc spacing = 9-1/2” PRI-60 or 11-7/8” PRI-20

Given:• Spacing = 16” and 24” p g• Live load = 40 psf• Dead load = 10 psf• Simple Span = 15’

Design reference: APA form E30

APA Form E30 Table 8 Beam Example

Answer:• From Table 3A, APA form EWS X440B (pg 18):, (pg )

• 3-1/8 x 16-1/2• 3-1/2 x 15• 5-1/8 x 12• Or 5 1/2 x12• Or 5-1/2 x12

Given:• Span = 16’-3”• Span roof trusses = 24’ • Live load = 40 psf• Live load = 40 psf• Dead load = 10 psf

Design reference: APA form EWS X440BX440B

Beam SizingBeam Sizing

Given: Span = 22'Floor live load = 40 psfFloor dead load = 15 psfFloor dead load = 15 psfTributary Width = 18’

Find:Beam size for l/360 deflection

Answer: From Glulam Floor Beam, APA form C415 • For 24F-1.8E beams, see Table 1a (pg 3):

5-1/8 x 22-1/2, 5-1/2 x 22-1/2, or 6-3/4 x 21• For IJC 24F-1.8E beams, see Table 2a (pg 5):

3-1/2x24, 5-1/2 x 20 or 7 x 18•For 30F-1 8E beams see Table 3a (pg 8):For 30F 1.8E beams, see Table 3a (pg 8):

3-1/2x22, 5-1/2 x 18 or 7 x 18

Beam SizingBeam Sizing

Structural calculations:1. Define design criteria2. Check maximum bending3. Check Shear4. Check deflection

1. Span = 22‘ Floor live load = 40 psfFloor dead load = 15 psfTributary Width = 18’Tributary Width = 18Max. Deflection = l/360 Uniform load = W = (D + L)*Tributary Width

= 18’*(40 + 15)psf = 990plfSelect 6-3/4 x 21 beam to begin design

APA Form Y117 Table 5Beam SizingBeam Sizing

Structural calculations:2. Check maximum bending

Mmax = wl2/8 = 990*(22)2/8= 59,895 lb-ft

From APA Form Y117 (pg 12), Moment Capacity = M = 99,225 lb-ft

Since Mmax < M, OK

Beam SizingBeam Sizing

Structural calculations:3. Check maximum shear

Vmax = wl/2 = 990*(22)/2 = 10,890 lb

F APA F Y117 ( 12)From APA Form Y117 (pg 12), Shear Capacity = V = 25,043 lb

Since V < V OKSince Vmax < V, OK

Beam SizingBeam SizingStructural calculations:4. Check maximum deflection

∆max = 5wl4/(384EI) max ( )= 5*990plf*(22’)4/(384*9377x106lb-in2)*(12”/1’)3

= 0.56”From APA Form Y117(pg 12), EI = 9377x106 lb-in2

∆ = l/360 = 22’/360*(12”/1’) = 0.73”

Since ∆max < ∆, OK

Therefore, 6-3/4 x 21 beam works. ,If not, select new beam and repeat steps 2-4.

h i ?What is new?From SteelFrom Steel

Given:• Span = 10’• W10x12

Design reference: APA form EWS C415

APA Form C415 Table 4AAPA Form C415 Table 4A

APA Form C415 Table 5ATo WoodTo Wood

For 24F-1.8E Glulams:• See Table 4a, APA form EWS C415 (pg 11):

3 1/2x15 5 1/2x13 1/2 or 7x10 1/23-1/2x15, 5-1/2x13-1/2, or 7x10-1/2For 30F-2.1E Glulams:

• See Table 5a, APA form EWS C415 (pg 13):3-1/2x14, 5-1/8x11-7/8, or 7x9-1/2

Shear Walls: Wind v SeismicShear Walls: Wind v. Seismic

Gi 5’-4”Given:7/16” OSB

V

8d common3”/ 6” edge/field 8’

nail spacingGypsum on

it fopposite face

vH H

Shear Walls: Wind v SeismicShear Walls: Wind v. Seismic

Wi d C itWind Capacity:V=(450 plf x 1.4+100 plf) x 5.33’ = 3891 lb

Length of wallLength of wall

For wind

For gypsum from table

From table

For wind

S i i C itSeismic Capacity: V=450 plf x 5.33’ = 2399 lb

Shear Wall Design ExamplesShear Wall Design Examples

S t d Sh W ll Segmented Shear Wall Approach

Force Transfer Around

Opening Approach

Perforated Shear Wall A hApproach

Design ExampleDesign Example

26’-0”3’-6” 3’-0” 4’-0” 6’-0” 4’-0” 3’-6”2’-0”

V

6 0

6’-8”2’-8” 2’-8”

8’-0

”

6 8

V = 3,750 lbs

Segmented ApproachSegmented Approach

4’-0” 6’-0” 4’-0” 3’-6”2’-0”V

3’-6” 3’-0”

6’-8”2’-8” 2’-8”

8’-0

”

6 8

Do not consider contribution of wall below and above openings

Segmented ApproachSegmented Approach

4’-0” 6’-0” 4’-0” 3’-6”2’-0”V

3’-6” 3’-0”

6’-8”2’-8” 2’-8”

8’-0

”

6 8

v v v vH H H H H H H H

V = 3,750 lbsHeight/width Ratio = 8:3.52w/h = (2)(3 5)/8 = 0 875

v v v vH H H H H HCode Limitation

2w/h (2)(3.5)/8 0.875

Segmented ApproachSegmented Approach

1 U it Sh1. Unit ShearV = V/L = 3,750/15 = 250 lbs/ft

2. Allowable Shear 3’-6” walls2. Allowable Shear 3 6 wallsv allowable = 380 (0.875)=332 lbs/ft > 250 lbs/ft

3 All bl Sh 4’ ll (2 1 h )15/32” Rated Sheathing 8d @ 4”o.c. at 3.5’ walls

3. Allowable Shear 4’ walls (2:1 h:w)v allowable = 260lb/ft > 250 lbs/ft

15/32” Rated Sheathing 8d @ 6”o.c. @ 4’ walls

4. Hold-down forcesH = vh = 250 x 8 = 2,000 lbs

8 – hold downs @ 2000+ lb capacityNote: For simplicity Dead Load contribution and various footnote adjustments are omitted

8 – hold downs @ 2000+ lb capacity

Segmented ApproachSegmented Approach

4’-0” 6’-0” 4’-0” 3’-6”2’-0”3’-6” 3’-0” 4 0 6 -0 4 -0 3 -62 -0V

3 -6 3 -0

15/32” Rated

6’-8”2’-8” 2’-8”

8’-0

”

Rated Sheathing 8d @ 4”o.c.

V = 3 750 lbsv v v vH H H H H H H H

8 h ld d @

V = 3,750 lbsv = 250 lbs/ftH = 2,000 lbs

15/32” Rated Sheathing 8d @ 6”o.c.

8 – hold downs @ 2000+ lb capacity

S t d Sh W ll Segmented Shear Wall Approach

Force Transfer Around

Opening Approach Perforated Shear Wall

A h

Approach

Perforated Shear Wall ApproachPerforated Shear Wall Approach

26’-0”3’-6” 3’-0” 4’-0” 6’-0” 4’-0” 3’-6”2’-0”

V

26 0

6’-8”2’-8” 2’-8”

8’-0

”

6 8

H Htt

V = 3,750 lbs

v, tH

Height/width Ratio = 8:3.52w/h = (2)(3.5)/8 = 0.875

v, t v, tv, t

2w/h (2)(3.5)/8 0.875

Perforated Shear Wall ApproachPerforated Shear Wall Approach

1 U it h i th ll1 Unit shear in the wall v = 3,750/15 = 250 lb/ft

2 Percent of Full-Height Sheathed15/26 = 0.57 (57%)

3 Maximum opening height2H/3 = 6’-8”2H/3 = 6 -8

Perforated Shear Wall ApproachPerforated Shear Wall Approach

SDPWS Table 4 3 3 5 Shear Resistance Adjustment Factor C SDPWS Table 4.3.3.5 Shear Resistance Adjustment Factor, CO

57% 0.61

Perforated Shear Wall ApproachPerforated Shear Wall Approach

4 C Sh R i t Adj t t F t4 Co – Shear Resistance Adjustment FactorCo = 0.612 say 0.61

5 Adjusted Shear Resistance v allowable = 490 x 0.875 x 0.61 = 262 lbs/ft > 250 lbs/ft

15/32” Rated15/32 Rated Sheathing 8d @ 3”o.c.

Perforated Shear Wall ApproachPerforated Shear Wall Approach

6 U lift t P f t d Sh W ll d (h ld d )6. Uplift at Perforated Shear Wall ends (hold downs)H = (250/0.61) x 8 = 3,280 lbs

7. In-plane Shear AnchorageH = 250/0.61 = 410plf

8. Uplift anchorage between shear wall endst = 250/0 61 = 410 plf (at full segments only)t = 250/0.61 = 410 plf (at full segments only)

9. Deflection is determined based on the deflection of any segment of the wall divided by Co

15/32” Rated sheathing 8d @ 4”o.c. (3’-6” walls),

Segmented Approach

@ 6” o.c. (4’ walls)8 – hold downs @ 2000+ lb capacity

15/32” Rated Sheathing 8d @ 4”o.c.

Force Transfer

2 – hold downs @ 1,550 lb capacity

2 Straps – 1,250 lb

15/32” Rated Sheathing 8d @ 3”o.c.

Perforated 8d @ 3 o.c.

2 – hold downs @ 3280 lb capacity

v, tH Hv, t v, textensive plateanchoragev, t

Questions/ Comments?Questions/ Comments?

This concludes The American Institute of Architects Continuing

Education Systems Course

Karyn A. Beebe, P.E. , LEED APkaryn.beebe@apawood.org (858) 560-1298 www.apawood.org

Wood Products Council 866.966.3448 info@woodworks.org