THE FASTENERS AND...Diameter (head & shank Length Ex: 10d common (0.312” head dia. 0.148” shank...

10/9/2019

Copyright © 2019 American Wood Council1

THE FASTENERS AND

THE FURIOUS

(DES341)

Lori Koch, P.E.Manager, Educational OutreachAmerican Wood Council

Michelle Kam-Biron, P.E., S.E. S.E.C.BSenior Director, EducationAmerican Wood Council

T H E F A S T E N E R S A N D T H E F U R I O U S 2

Participants may download the presentation here: http://www.awc.org/education/resources

The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider # 50111237.

Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.

This course is registered with AIA CES for continuing professional education. 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 addressed at the conclusion of this presentation.

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COURSE DESCRIPTION

Due to the great success of DES340-Cornucopia of Classic Connection Conundrums presentation, this program includes discussion about wood-based connection design based on numerous help desk questions and feedback from design professionals. AWC has identified some commonly overlooked wood-based connection engineering requirements from the National Design Specification® (NDS®) for Wood Constructionand Special Design Provisions for Wind and Seismic (SDPWS) for discussion. Connection detailing requirements and design examples will also be provided.


LEARNING OBJECTIVESUpon completion, participants will be better able to identify:

Describe and analyze wood-based connection engineering issues.

Wood Connections

Acquire resources for complying with wood-based connection design.

Resources

Identify lateral connection details.

Detailing

Specify proper fasteners for shear walls, diaphragms, and other wood-based assemblies.

Proper fasteners

1 3

2 4

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POLLING QUESTION

1. What is your profession?

a) Architect

b) Engineer

c) Code Official

d) Fire Service

e) Builder/Product Manufacturer/Other


• Fasteners – NDS and Beyond• Nails – 2018 NDS Changes• Detailing Considerations

OUTLINE

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FASTENER VALUES

• Included in U.S. design literature

Evaluation Reports (ER) are developed

for proprietary products

Fastener Type Reference

Bolts NDS or ER

Lag Screws NDS or ER

Wood Screws NDS or ER

Nails & Spikes NDS or ER

Split Ring Connectors NDS

Shear Plate Connectors NDS

Drift Bolts & Drift Pins NDS

Metal Plate Connectors ER

Hangers & Framing Anchors

ER

Staples ER


NDS CHAPTER 12 TABULATED SHEAR VALUES

• Lag screws – assumed penetration = 8D

• For p between 4D and 8D, multiply tabulated values by p/8D

• Wood screws – assumed penetration = 10D


• Nails – assumed penetration = 10D


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NDS CHAPTER 12 TABULATED VALUES

T H E F A S T E N E R S A N D T H E F U R I O U S 1 0

DOWEL LENGTHS

• Fasteners in withdrawal – NDS 12.1 & 12.2

• Lag screws – does not include length of tapered tip – minimum penetration = 4D

• Wood screws – includes length of tapered tip – minimum penetration = 6D

• Nails – includes length of tapered tip – minimum penetration = 6D

• Fasteners in shear (lateral) – NDS 12.3.5.3

• Tapered tip fasteners – use ½ tip length (E)

• Lag screws – tip length published in Appendix L

• Nails and wood screws – tip length assumed to be 2D

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• Model wood cells as a bundle of straws• Bundle is very strong parallel to axis of the straws

BASIC CONCEPTS

Stronger Less strong

Parallel Perpendicular


• Model wood cells as a bundle of straws• Bundle is very strong parallel to axis of the straws

BASIC CONCEPTS

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CONNECTING WOOD- PHILOSOPHY

Splitting happens because wood is relatively weak perpendicular to grain

Nails too close (act like a wedge)

T H E F A S T E N E R S A N D T H E F U R I O U S 1 4Nailing not staggered Nailing staggered

Framing

Wood Structural

Panel

Nail

1/8" GapBetween Panels

Nailing not staggered Nailing staggered

STAGGERED NAILING

3/8” min.

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Splitting will not occur perpendicular to grain, no matter how close nails are

Splitting occurs parallel to grain

Staggering

Staggering a line of nails parallel to wood grain

minimizes splitting


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POLLING QUESTION

2. The shear capacity for the fasteners is based on which of the following assumed penetrations:

a) 8D for lag screws

b) 10D for wood screws

c) 10D for nails

d) All of the above


• Wood likes compression parallel to grain• makes connecting wood very easy

CONNECTING WOOD - PHILOSOPHY

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• Wood likes compression parallel to grain• makes connecting wood very easy



Mechanical fasteners

• keep them small

• use lots of them

Issue is scale of fastener relative to wood member size

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Wood likes to take on load spread over its surface


CONCENTRATED AT A SINGLE FASTENER

Wood is more prone to split and crush

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PRE-FABRICATED CONNECTORS

Column Cap & Base hardware



Hanger hardware

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Truss hardware


NDS CHAPTER 14 – TIMBER RIVETSMany applications

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Rivets• Steel AISI 1035• Rockwell Hardness C32-39• Fu = 145 ksi• Hot-dipped galvanized

Plates• Steel ASTM A36• Hot-dipped galvanized if in

wet service

TIMBER RIVETS


NDS CHAPTER 14 – TIMBER RIVETSMany applications

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TIMBER RIVETS


DOWEL BEARING STRENGTHS IN WSP

• Why does TR-12 provide dowel bearing strengths for fasteners of all sizes for plywood but limits fastener D to ¼” in OSB?

• Insufficient data to address the Fe║ and Fe┴ for range of diameters. Limited data on large diameter bolts (up to ¾-inch) in plywood (APA Tech Note E825)

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NAILS - DIAPHRAGMS


NAILS – SHEAR WALLS

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ALTERNATIVE MATERIALS, DESIGN & METHODS


FASTENERS NOT IN NDS/SDPWS

• Yield Mode Equations can be applied to any dowel-shaped fastener• Fastener dimensions and yield strength come from manufacturer

• ICC-ES (www.icc-es.org) Evaluation Service Reports • Searchable database • ESR 1539 (ISANTA) Power-driven staples

& nails

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ISANTA WEBSITE – TECHNICAL BULLETINS

http://isanta.org/Technical-Resources



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PROPRIETARY FASTENERS

• ICC Evaluation Service Reports• Search by manufacturer or

product

• “Wood screw” search shows 5 manufacturers

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JOIST HANGERS

• Joist hangers and similar hardware are proprietary – and not covered in NDS

• Capacities can be published by manufacturer, or in third-party testing report (ICC-ES, IAPMO, etc.)

• Installation requirements are per manufacturer’s specifications


FASTENERS IN TREATED WOOD

• What about fasteners in wet conditions and preservative treated wood?

• Corrosion Resistance IRC R317.3• Screws, bolts, nails

• Hot-dipped galvanized

• Stainless

• Silicon bronze

• Copper

• Hangers and anchors• Galvanized

• Stainless

• Saltwater exposure – DCA6• Stainless

• Other fasteners/hardware• Approved by building official

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2304.10.5 Fasteners and connectors in contact with preservative-treated and fire-retardant-treated wood.

2304.10.5.1 Fasteners and connectors for preservative-treated wood.

2304.10.5.2 Fastenings for wood foundations.

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2304.10.5 Fasteners and connectors in contact with preservative-treated and fire-retardant-treated wood.

2304.10.5.1 Fasteners and connectors for preservative-treated wood.

2304.10.5.2 Fastenings for wood foundations.

2304.10.5.3 Fasteners for fire-retardant-treated wood used in exterior applications or wet or damp locations.

2304.10.5.4 Fasteners for fire-retardant-treated wood used in interior applications.


POLLING QUESTION

3. Which of the following is true about fasteners in treated wood:

a) Obtain FRT lumber adj. design values from preservative company

b) Obtain FRT lumber adj. design values from FRT company

c) Fasteners shall have corrosion resistant coating.

d) All of the above

e) b. and c.

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• Fastener – NDS and Beyond• Nails – 2018 NDS Changes• Detailing Consideration

OUTLINE


NAILS!!!

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TYPICAL NAIL HEADS

ASTM F1667ASTM F1667

ESR 1539ESR 1539 Photos courtesy of Hitachi – Falcon - Hitachi

Photos courtesy Falcon Fasteners


TYPICAL NAIL SHANKS

Photos courtesy of Falcon Fasteners

Sketches courtesy ISANTA

ASTM F1667ASTM F1667

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NAILS!!

Avoid problems by specifying:PennyweightTypeDiameter (head & shankLength

Ex: 10d common (0.312” head dia. 0.148” shank dia. X 3” shank length)


MINIMUM DESIGN LOADS

• Reference Loads• Minimum Load Standards• ASCE 7-16

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ASCE 7-16 WIND LOAD CHANGES

Figure 26.5-1B Basic Wind Speeds for Risk Category II Buildings and Other Structures


ASCE 7-10 WIND LOAD

Figure 26.5-1A Basic Wind Speeds for Risk Category II Buildings and Other Structures

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ASCE 7-16 WIND LOAD CHANGES

ASCE 7-16 Wind Load ProvisionsBy Donald R. Scott

Structure Magazinehttps://www.structuremag.org/?p=13360


1

• Increase in hurricane regions

• Larger roof zones

• Interior roof zones increase most

C&C Loads

ASCE 7 WIND LOAD CHANGES

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ASCE 7 WIND LOAD CHANGES

C&C Roof Coefficients

Roof Slope

Ratio of ASCE 7-16/ASCE 7-10Roof GCp - GCpi Roof Overhang GCp - GCpi

3r 3e 2r 2n 2e 1 3r 3e 2r 2n 2e 1

7 < Θ ≤ 20 1.36 1.14 1.69 1.69 1.16 2.02 1.27 1.11 1.59 1.59 1.14 -

20 < Θ ≤ 27 1.36 0.96 1.43 1.43 0.89 1.56 1.27 0.97 1.36 1.36 0.91 -

27 < Θ ≤ 45 1.58 2.45 1.43 1.58 1.43 1.68 1.40 2.00 1.30 1.40 1.30 -


ASCE/SEI 7-16 WIND LOAD CHANGES

C&C Wind Pressure Calculations

qz =0.00256 Kz Kzt Kd Ke V2

q = 0.6 qz (conversion to ASD)

pmax = q[(GCpf) – (GCpi)]

qz = velocity pressure at height z, psf (section 26.10-1)Kz = velocity pressure exposure coefficient = 0.72 (section 26.10.1)Kzt = topographic factor = 1.0 (section 26.8.2)Kd = wind directionality factor = 0.85 (section 26.6)Ke = ground elevation factor = 1.0 (section 26.9)V = basic wind speed, mph (section 26.5)GCpf = external pressure coefficients (section 30.4)GCpi = internal pressure coefficients = 0.18 (section 26.13)pmax = maximum pressure, psf

Offset?Offset?

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CHAPTER 12


ROOF SHEATHING RING SHANK NAILS

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SMOOTH SHANK NAILS OR SPIKES


SMOOTH SHANK NAIL WITHDRAWAL STRENGTH

0

5

10

15

20

25

30

35

40

45

0.55 0.5 0.45 0.4 0.35

Pounds per in

ch of pen

etration

Wood specific gravity

ASD Withdrawal Strength(Smooth shank, 8d common nail)

Carbon steel (bright or galvanized) Stainless steel

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POLLING QUESTION

4. The stainless steel nail withdrawal equation produces higher values of withdrawal strength than the NDS steel wire nail equation

a) True

b) False


DEFORMED SHANK NAILS

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RSRS NAIL WITHDRAWAL


FASTENER HEAD PULL-THROUGH

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FASTENER UPLIFT CAPACITY



Fastener Uplift Capacity = lesser of W’ and WH’

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FASTENER UPLIFT DESIGN EXAMPLE

Fastener Uplift Capacity - Roof Sheathing Ring Shank Nail

7/16 OSB

2x6

RSRS



Fastener Uplift Capacity - Roof Sheathing Ring Shank Nail (cont.)

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Fastener head pull-through of 67 lbs is less than withdrawal capacity of 88 lbs and controls design capacity. See NDS Table 11.3.1 for application of additional adjustment factors for connections based on end use conditions.

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2018 WFCM Table 3.10


POLLING QUESTION

5. Wood is strong perpendicular to grain and less strong parallel to grain

a) True

b) False

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• Fastener – NDS and Beyond• Nails – 2018 NDS Changes• Detailing Consideration

OUTLINE


LOCAL STRESSES IN FASTENER GROUPS

2018 NDS - 11.1.2 Stresses in Members at Connections“Local stresses in connections using multiple fasteners shall be checked in accordance with principles of engineering mechanics. One method for determining these stresses is provided in Appendix E.”

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• Closely spaced fasteners•brittle failure

Wood failure mechanisms need to be considered in design



•Properly spaced fasteners

•increased ductility•higher capacity

Spread out the fasteners!

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• Appendix E NDS Equations

– Net tension:

– Row tear-out:

nettNT AFZ ''

row

i

i

n

iRTRT

viRT

ZZ

tsFnZ

1

''

min''



•Appendix E NDS Equations

– Group tear-out

•Note: spacing between outer rows of fasteners paralleling the member on a single splice plate < 5″

netgrouptbottomRTtopRT

GT AFZZ

Z '

'''

22

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EXAMPLE: BOLTED SPLICE – LOCAL STRESSES•Assume 1” diameter x 5” long bolts

•2x12 No. 2 Southern Pine main and side members

Net Section Tension Check

ZNT’ = Ft’ Anet

Ft’ = 450(1.25) = 562.5 psi

Anet = 13.7 in2

ZNT’ = 7,706 lbs

Note: hole size for net area includes 1/16” oversizing per NDS 12.1.3.2


EXAMPLE: BOLTED SPLICE – LOCAL STRESSESRow Tear-Out Check

ZRTi’ = ni Fv’ t scritical

ni = 3

Fv’ = 175(1.25) = 219 psi

t = 1.5”

scritical = 4”

ZRTi’ = 3,938 lbs for one row

ZRT’ = 7,875 lbs for two rows

Note: scritical is the minimum of the end distance and the in-row bolt spacing = 4”

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EXAMPLE: BOLTED SPLICE – LOCAL STRESSESGroup Tear-Out Check

ZGT’ = ZRT1’/2 + ZRT2’/2 + Ft’ Agroup-net

ZRT1’ = ZRT2’ = 3,938 lbs

Ft’ = 450(1.25) = 562.5 psi

Agroup-net = 4.41 in2

ZGT’ = 6,418 lbs

Note: hole size for net area includes 1/16” oversizing per NDS 12.1.3.2


EXAMPLE: BOLTED SPLICE – LOCAL STRESSES

Final Bolt Capacity

Z’ = 9,562 lbs

ZNT’ = 7,706 lbs

ZRT’ = 7,875 lbs

ZGT’ = 6,418 lbs

4"

7"

38"

P P

P P

3-5/8"

4" 4" 4" 4" 7" 4" 4"

3-5/8"

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EXAMPLE: BOLTED SPLICE – LOCAL STRESSES

srow = spacing between bolt rows

Trade‐offs for Bolt Design Values vs. Net Section Capacities (lbs)

Bolt

Diameter

(in.)

Adjusted

Multiple Bolt

Capacity nZ'

Net Section

Tension ZNT'

Row Tear‐

out ZRT' Group Tear‐out ZGT'

srow=4" srow=5"

1 9562 7706 7875 6418 7260

7/8 8368 7910 7875 6521 7365

3/4 7174 8121 7875 6627 7471


Segmented1. Traditional method2. Current Code design

values based on data dating back to 1950’s.

3. Hold-downs at each end of full height segment.

SDPWS 4.3.5.1

Force Transfer1. Code does not provide

guidance for this method2. Different approaches

using rational analysis could be used

3. Portions above and below openings act as coupling beams

Perforated1. Code provides specific

requirements2. Based on semi-empirical

method developed from shear wall testing equations and tables

SDPWS 4.3.5.2 SDPWS 4.3.5.3

WOOD SHEAR WALL DESIGN

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FTAO STRAP LENGTHS


FTAO STRAP LENGTHS

DiekmanCantilever BeamDrag Strut

Detailing to transfer the loads around the opening

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FTAO STRAP LENGTHS


FTAO STRAP LENGTHS

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FTAO RESEARCH

Joint Research Project

• APA - The Engineered Wood Association (Skaggs & Yeh)

• University of British Columbia (Lam & Li)• USDA Forest Products Laboratory

(Rammer & Wacker)

Study began 2009

https://www.apawood.org/publication-search?q=M410&tid=1


FTAO

https://awc.org/education/main/lists/des-design-considerations/des415-resolving-wood-shear-wall-design-puzzles-with-force-transfer-around-openings

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RESOURCES:

• APA M410 - “Advancements in Force Transfer Around Openings for Wood Framed Shear Walls” https://www.apawood.org/publication-search?q=t555&tid=1


RESOURCES:

• APA FTAO Calculator https://www.apawood.org/ftao-dl

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MORE INFO???

NDShttps://awc.org/codes-standards/publications/nds-2018


MORE INFO???

https://www.apawood.org/publication-search?q=connection+details&tid=1

Form EWS T300J

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MORE INFO???

AWC Calculators http://awc.org/codes-standards/calculators-software

TR 12 - General Dowel Equations for Calculating Lateral Connection Values (2014) http://awc.org/codes-standards/publications/tr12


MORE INFO.

DCA 6 Prescriptive Residential Deck Construction Guide http://awc.org/codes-standards/publications/dca6

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T h i s p r e s e n t a t i o n i s p r o t e c t e d b y U S a n d I n t e r n a t i o n a l C o p y r i g h t l a w s . R e p r o d u c t i o n , d i s t r i b u t i o n , d i s p l a y a n d u s e o f t h e p r e s e n t a t i o n w i t h o u t w r i t t e n p e r m i s s i o n o f A m e r i c a n W o o d C o u n c i l ( A W C ) i s

p r o h i b i t e d . © A m e r i c a n W o o d C o u n c i l 2 0 1 7

in [email protected] | www.awc.org

This concludes the American Institute of Architects Continuing Education Systems Course

THE FASTENERS AND...Diameter (head & shank Length Ex: 10d common (0.312” head dia. 0.148” shank...

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