clark - connection solutions for wood framed … adiscussion ofcommonfastener types,this seminar...

Connection Solutions forWood Framed Structures

Bob Clark, APAWood Solutions FairChicago, IL May 22,2014

“The Wood Products Council” isa Registered Provider with The

This course is registered withAIA CES for continuinga Registered Provider with The

American Institute of ArchitectsContinuing Education Systems(AIA/CES), Provider #G516.

AIA CES for continuingprofessional education. Assuch, it does not includecontent that may be deemedor construed to be an

Credit(s) earned on completion

or construed to be anapproval or endorsement bythe AIA of any material ofconstruction or any method ormanner ofof this course will be reported to

AIA CES for AIA members.Certificates of Completion forboth AIA members and non AIA

b l bl

manner ofhandling, using, distributing,or dealing in any material orproduct.

members are available uponrequest.

___________________________________________

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

Course Description

This seminar will feature a discussion of common fastener types,This seminar will feature a discussion of common fastener types,how design values are determined for each, and relevant woodconnection philosophies. Topics will include the orthotropicnature of wood commodity and specialty connectors and thenature of wood, commodity and specialty connectors and theuse of small diameter fasteners in portal frames and combinedshear and uplift systems. Techniques for designing efficient,durable and structurally safe connections will also be discussed,along with tips for minimizing environmental effects on woodconnections and what additional resources are available.connections and what additional resources are available.

Learning Objectives

• Understand the wide variety of connectors available for wood framedstructures and how they can be used effectively to meet specificdesign situations.

• Learn how design properties are established for wood connectors andearn how design properties are established for wood connectors andwhat adjustment factors must be applied to ensure their properperformance in accordance with the 2005 NDS and 2012 NDS.

• Explain how to ensure both the structural performance and long term• Explain how to ensure both the structural performance and long termdurability of wood framed structures by minimizing environmentalimpacts on connections.

d d l ll k d• Use design and construction examples to illustrate key points andhighlight the additional resources available related to woodconnection design and detailing.

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

Wood and compressionWood and compressionperpendicular to grainCompare wood cells to aCompare wood cells to abundle of strawsBundle crushes underBundle crushes underperpendicular load

Strength, stiffness, durability,

F

g , , y,and dimensional stability

Face

Core

Center

Core

B kBack

W d d t i di l t iWood and tension perpendicular to grainThe evil of wood connections

InitiatorsNotchesNotchesLarge diameter fastenersHanging loads

Load spread over its surface increasesLoad spread over its surface increasesredundancy and reduces stress concentrationsconcentrations

Mechanical fastenersKeep them smallpUse lots of themKeep scale of fastener psmall relative to wood member

Concentrated at a single fastener –Concentrated at a single fastenerWood is more prone to split and crush

T l tTruss platesDesign metal

l tplateconnectionsusing the latestusing the latestedition of ANSI/TPI 1

Steel bolts and plates in heavy trussesSteel bolts and plates in heavy trusses

A single large bolt?A single large bolt? Looks can be deceivingLooks can be deceiving...

S ik G idSpike GridConnectors

Hanger to Beam L d d dHanger to Beam Load suspendedfrom lower half of beambeam

another case of tensionperpendicular to grainSplit

Hanger to Beam L d t dHanger to Beam Load supportedin upper half of beamFull wrap sling option beam

Extended plates puts wood in

Full wrap sling option

compressionwhen loaded

compression

NotchingNotchingProblem SolutionTension perpendicularTension perpendicularto grain

N t hiNotching Beam to ConcreteBeam to Concrete

Sloped BeamSloped Beam

SplitPotential Splits

Beam to ConcreteSloped Beam

Beam to Concrete C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

Wood, like other materials, moves inWood, like other materials, moves invarying environments

Shrinkage due toShrinkage due tomoisture loss

Solid Sawn Glulam

B hBeam hangersFasteners in top of

t d b

SplitSplit

supported beamWood shrinkageMay splitNot recommended

Gap under beamGap under beam

B hBeam hangersFasteners in b tt fbottom ofsupported beamW d h i kWood shrinkageallowedPrevents lateralPrevents lateralmovement

SeparatedSeparatedConnectors

• shrinkageshrinkage• tension

perpendicular toperpendicular tograin

SlottedSlottedconnections

Allows forAllows forshrinkage and movement under load

F ll d th id l tFull-depth side platesMay cause splittingRestrains wood shrinkage

S ll id l tSmaller side platesTransmit forceAllow wood movement

Starlight TheaterStarlight TheaterRock Valley Community College – Rockford, IL

Starlight TheaterStarlight TheaterRock Valley Community College – Rockford, IL

BeforeBefore

Splits

AfterAfter

Back to Basics: 1/8-inch SpacingOnline Video

Back to Basics: 1/8-inch Spacing3,631 views

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

A li tiApplicationNeed 1/2” air gap b t dbetween woodand masonry

Beam on shelfPrevent contact withconcrete

Beam on MasonryBearing plate underg pbeamPrevent contact withmasonry

Connectors thatConnectors thattrap water:

Direct waterDirect wateringressNo weep holesNo weep holes

Arch base to supportEnd grain moistureEnd grain moistureuptakePotential for decayPotential for decay

A h b t tArch base to support• Avoids decay

Direct water ingressDirect water ingressWater is absorbed most quickly through wood end grainend grain

No end caps or flashing

Direct water ingressgRe-direct the water flow around the connectionPreservative treated glulam

end caps and flashing

Bearing plateAnchor bolts in b i l t

Floor slab poured over connection

bearing plateSlotted column end

Can cause decayNot recommended

Closed ShoeNo weep holesNo weep holesMoistureDDecay

Where’s the plate?Grout substitutedMoisture may wick into wood

Elevated Base PlatesElevated Base Plates

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

Fastener Schedule for Structural MembersFastener Schedule for Structural Members

Alternate AttachmentsAlternate Attachments

A few 10d nailsA few 10d nails

There areThere areeven more!

N il N l tNail NomenclatureThere is no control over nail nomenclature!Manufacturers can and will call fasteners anything that they want.8d is not a clear specification!Avoid problems by specifying

i ht t di t d l thpennyweight, type, diameter and lengthExample: 10d common (0.148” shank dia. X 3” shank length)shank length)

Fastener InterchangeabilityFastener InterchangeabilityESR-1539 (45 pages)

Has “conversion” tables for prescriptive requirements

For example, if model code requires 8d commons at 6” oc, then what fastener type and spacing is “equivalent”type and spacing is equivalent

Has values for engineered designs for staples and a variety of other power-driven fastenerspower driven fastenersAvailable from International Staple, Nail and Tool Association (ISANTA)

Power Driven Fastener ConsiderationsPower Driven Fastener ConsiderationsPower driven fasteners rely on velocity to drive fasteners and not mass.

“ fThey do not have the “clamping” action that the last swing ofa hammer provides.

Thin galvanizing - power driven fasteners that are “ l i d” thi l t d t t ti i“galvanized” are thinly coated to prevent rusting inthe box.

The protection is scraped off of the fastener during driving.Overdriving - if the “gun” is improperly adjusted, overdriven fasteners can be expected.

Adjusting air pressure is NOT the correct way to prevent over-j g p y pdriven fasteners.

Overdriven FastenersOverdriven Fasteners

N il i t ll tiNail installationOverdriving reduces performance

O d i ilOverdriven nailsAPA Recommendations – PrescriptiveIf < 20% fasteners overdriven by <1/8” then they mayIf < 20% fasteners overdriven by <1/8 , then they maybe ignored.If > 20% fasteners overdriven by >1/8”, then add 1

f fadditional fastener for every 2 overdriven.

O d i ilOverdriven nailsAPA Recommendations – Mechanics BasedIf < 20% fasteners overdriven by <1/8” then theyIf < 20% fasteners overdriven by <1/8 , then theymay be ignored. Otherwise, re-analyze capacity based on average hi k f l d f h b fthickness of panel measured from the bottom of

the nail head.(i.e. 5/8 CAT panel with fasteners overdriven by 1/8” = capacity of 1/2 CAT panel.) - Adjust nailing schedule accordingly.

Caution for tight nailing patternsCaution for tight nailing patternsIf the additional nails violate the minimum

i i t (3” f 2 i hspacing requirements (3” o.c. for 2 inchlumber for splitting), use staples and ignore the original nailsignore the original nails.

Staggered NailingFraming

Staggered Nailing

Wood StructuralPanel

Nail

1/8" GapBetween Panels

Nailing not staggered Nailing staggeredNailing not staggered Nailing staggered

Splitting occurs parallel to grain

Staggering

Splitting will not occur di l t i tt Staggering a line of nails parallelperpendicular to grain, no matterhow close nails are

Staggering a line of nails parallelto wood grain minimizes splitting

Tightly nailed shear wallTightly nailed shear wallStaggered nailing in shear wall helps preventwall helps preventsplitting of framing

Components and Claddingp g

Hurricane KatrinaAPA Report SPE-1125

Components and Claddingp g

Midwest Tornadoes 2003APA Report SPE-1118

Nail Base for Sidingg

Sidingfastener

ss

Siding attachment at energy efficient corners

Attachment base for utility vents, siding trim, etc.

New Table in 2015 IRCNew Table in 2015 IRCCladding Attachment Schedule for Fasteners into Wood Structural Panel Sheathing (Stud Penetration Not Required)

ApplicationNumber and

Type of FastenerSpacing ofFasteners

Ring shank roofing nail 12"Exterior wall covering (weighing3 psf or less) attachment to woodstructural panel sheathing, either

g g(0.120" min. dia.)

12" o.c.

Ring shank nail(0.148" min. dia.)

15" o.c.p gdirect or over foam sheathing amaximum of 2 inches thick.

( )

#6 screw(0.138" min. dia.) 12" o.c.

#8#8 screw(0.164" min. dia.) 16" o.c.

Uplift – a Big Challengep g g

Midwest Tornadoes 2003APA Report SPE-1118

Rafter to Top PlateRafter to Top PlateUse connectorsVery low cost

Combined Shear & Uplift ReferencesCombined Shear & Uplift ReferencesSSTD-10 (since early 1990’s) 2006 IRC R301.2.1.1IBHS Guidelines (added by 2006 errata)Standard for Residential Construction in High-Wind Regions (ICC 600) 2009 IRC R301.2.1.1Special Design Provisions for Wind and Seismic (SDPWS)Special Design Provisions for Wind and Seismic (SDPWS)

SSTD-10 IBHS ICC 600 SDPWS

S t R t SR 101System Report SR-101APA System Reports are a new series of publicationsseries of publicationsHelp building officials and design professionals identify innovative design solutionsinnovative design solutionsEvaluates engineered wood systems that may not be directly prescribed in the codesUsed as alternatives to the code-prescribed systems for p ycode compliance

Step 1 – Design the shear wallsp gStep 2 – Determine required upliftStep 3 – Determine combined shear & uplift nailing

Anchor Bolt & WasherAnchor bolt shall have a steel plate washer under each nutplate washer under each nutnot less than 0.229”x3”x3”

Standard Cut Washer RequirementStandard Cut Washer RequirementDiagonally slottedplate washer permittedp p

Slot width up to 3/16” larger h b l di

Nut

Standard

Steel

than bolt diameter

Slot length not to exceed 1¾”

cut washer

platewasher

not to exceed 1¾

Provided standard cutwasher between steel plate washer & nut

Missing WasherMissing Washer

Anchor Bolts?Anchor Bolts?

Hurricane KatrinaAPA Report SPE-1125

System Report SR-103System Report SR 103New system reportMethod to provide bracing for raised heel trusses

T d i h

Prescriptive

Two design approaches:

Prescriptive“follow the recipe” Generally small variables don’t matter There are no calculationsmatter. There are no calculationsor strength values assigned.

Engineered“do the calculations”All variables are accounted for in calculations

T b l t d V l i NDSTabulated Values in NDSThe tabulated values for nails, bolts, lag screws and other connectors are nominal and based on certainconnectors are nominal and based on certainassumptions.They must be adjusted to account for actual conditions. Examples:Examples:

CD = Load duration factorCM = Wet service factorC G i fCg = Group action factorC = Geometry factorCtn = Toe-nail factor

LOAD DURATION Load Duration Factor - CD

Typical Loads

Permanent 0.9 Dead LoadPermanent 0.9 Dead Load

Ten years 1.0 Floor live load

Two months 1.15 Snow load

Seven days 1.25 Construction load

Ten minutes 1.6 Wind/Earthquake

Impact 2 0 VehiclesImpact 2.0 Vehicles

These factors are applied to member capacity

S i E d & Ed Di tSpacing, End, & Edge DistancesParallel to grain

T il F t CToe-nail Factor, CtnCorrect toe nailing Fig. 11A5/6 dj t t f l t l5/6 adjustment for lateral2/3 adjustment for withdrawal

“Ai N il” F t C“Air Nail” Factor, CairCair= 0.00

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

Adh i li tiAdhesive applications

1. Manufactured components1. Manufactured components

2. Field construction – floors

3. Repair – epoxy*Glued joints are the most unpredictableDifficult to mix glued and mechanical connections

* McGraw-hill handbook of engineered wood construction

The APA Glued Nailed Floor SystemThe APA Glued Nailed Floor System Continuous BeadContinuous Bead

Glue Everything!Glue Everything! Lay Panel in Fresh AdhesiveLay Panel in Fresh Adhesive

Fully Fasten with Clamping ForceFully Fasten with Clamping Force

Supported IntermediatePanel Edges SupportsPanel Edges Supports

6" o.c. 12" o.c.

Fasteners maximum 3/8" from panel edges

Check local codes for increased nail schedules

High wind areas may require increased nailg y qschedules

Gluing is notrecommended forbonding wall or roof sheathing to framingDiffi lt t fi d d iDifficult to find designvalues for adhesivesP hibit d i SDC D EProhibited in SDC D, E,or F (IBC 2305.3010)

H b t it ti ?How about composite action?Theoretically possible!True composite action requires rigid structural adhesives. (Construction adhesives creep under load and do not give 100% compositeunder load and do not give 100% compositeaction.)Structural adhesives are very hard toStructural adhesives are very hard-to-impossible to do successfully in the field.They also are dangerous to applyThey also are dangerous to apply.

C ti W dConnecting WoodWood MovesWood and Moisture Don’t MixMechanical ConnectionsMechanical ConnectionsGlued ConnectionsI f ti SInformation Sources

Connection CalculatorConnection Calculator

http://www.awc.org/calculators

APA PublicationsT300 – Glulam connection detailsE830 – Screw and plywood connectionsE825 - Bolt and plywood connectionsT325 R f f i f i d lifT325 – Roof fastening for wind upliftY250 – Shear transfer at engineered floorsA410 R f t fit f i d liftA410 – Roof retrofit for wind upliftD485 – Corrosion resistant fasteners

APA PublicationsAPA PublicationsTT-035 – Corrosion resistant fastenersTT-036 – Glued floorsTT-039 – Nail withdrawalTT-070 – Nail pull throughTT 045 Mi il t tiTT-045 – Min. nail penetrationTT-012 – Overdriven fastenersTT-056 – Power driven fastenersTT 056 Power driven fastenersTT-050/051 – Screw withdrawalTT-058 – Slant nailingTT-061 – Nailing thin flange I-joistTT-020 – Dowel bearing strength

It’s easy to create strong durable woodIt s easy to create strong durable woodconnections• Avoid the use of details which induce tensionAvoid the use of details which induce tension

perpendicular to grain stresses in the wood• Allow for dimensional changes in the woodAllow for dimensional changes in the wood

due to potential in-service moisture cycling• Minimize exposure of end grainp g• Avoid moisture entrapment in connections• Use smaller multiple fastener connectionsUse smaller multiple fastener connections

This concludes The American Institute of ArchitectsThis concludes The American Institute of ArchitectsContinuing Education Systems Course

This presentation was developed by a third party and is not funded by WoodWorks or the softwood lumber check-off.

Bob Clarkbob.clark@apawood.org (734) 823-5412 www.apawood.org