2012 Wood Frame Construction Manual:
Construction Manual: Connections
Presented by:
William L. Coulbourne, PE
Copyright © 2013 American Wood Council
Copyright Materials
 This presentation is protected by US and International
Copyright laws. Reproduction, distribution, display and
use of the presentation without written permission is
prohibited.
 © American Wood Council 2013
Copyright © 2013 American Wood Council
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Learning Objectives
At the end of this program, participants will:
Be able to describe various methods for making 
connections
Understand how connections are expected to perform
Understand various locations in a load path that require sound connections
require sound connections
Understand what type of connections provide continuity to the foundation
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WFCM
 Basis for this webinar series is the 2012 Wood Frame Construction Manual (WFCM)
 Basis follows WFCM Prescriptive Provisions (Chapter 3)
Basis follows WFCM Prescriptive Provisions (Chapter 3)
 Prescriptive provisions are provided for:
 WFCM 3.2 Connections
 WFCM 3.3 Floor systems
 WFCM 3.4 Wall systems
 WFCM 3.5 Roof systems
WFCM 3 5 Roof systems
 Provisions provide construction details and load tables
 WFCM also has engineering design in Chapter 2
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Agenda
Connections in vertical load paths
 Important connections from roof to ground
 Issues important to connection design
 Load tables in WFCM
Connections in lateral load paths
 Lateral load resistance strategies
 Lateral load resistance tables from AWC
Lateral load resistance tables from AWC
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Connections in Vertical Load Paths
1
2
3
5
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Prescriptive Roof Systems
(WFCM Section 3.5)
Roof framing
 Open ceiling plans that eliminate collar ties or ceiling joists must have ridge beam
must have ridge beam
Roof sheathing
 Sheathing support must be fully supported by roof framing members
 Sheathing edges supported by blocking or edge clips
• See WFCM 2.5.4.3 and 3.5.4.2
Roof diaphragm bracing
 For wind speeds > 130 mph, must block and nail @ panel edges perpendicular to roof framing in first two bays 7
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Roof Sheathing to Framing Connection
Design considerations
Must resist loads in two directions:
Lateral
Uplift
‒ Withdrawal of nail shank from roof framing
‒ Shear in plane of roof
Source: FEMA
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1
Roof Fastener
C&C uplift pressures – small Effective Wind Area (10 sf)
 p = q(GCpf
(GC f – GCpi) = 18.4(‐1.7‐.18) = ‐36.4 psf
GC i) 18 4( 1 7 18) 36 4 f
(roof edge zone 2)
 Withdrawal capacity of 8d nail in Hem‐fir framing = 21 lb/in x 2 in x 1.6 (Load duration factor) = 67.2 lbs
 Spacing = (67.2 lbs/36.4 psf/2 ft)x 12 in.ft = 11 in. (
(use 6 in. o.c.)
)
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Roof Fastener
Lateral load into roof diaphragm (from Webinar 1 – lateral load = 129 plf) x 2 ft
spacing 258 lbs at each rafter
spacing = 258 lbs
at each rafter
 Distributed along rafter length (20 ft) = 12.9 plf of rafter
 Shear resistance in one 8d nail = 63 lbs.  Nail spacing is set by withdrawal capacity
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WFCM Roof Sheathing Requirements
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Roof to Wall Connection
248 lbs
258 lbs
67 lbs
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2
Connectors for 3 Directions
Typical wind connectors:
Design uplift/Allowable uplift + Design lateral/Allowable lateral
+ Design shear/Allowable shear < 1
1.0
0
WFCM Table 3.4A - Tabulated connections are greater of
lateral and shear connection requirements
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Roof Diaphragm Blocking
Needed or not needed?
Source: Simpson Strong-Tie
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Correction to Question from Webinar 2
Rafter Tie vs. Collar Tie
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Rafter Tie Adjustments
WFCM Rafter Tie Connection Adjustments
WFCM Rafter Tie Connection Adjustments
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Wall Systems (WFCM Section 3.4)
Studs
 Limitations on wall heights
 Requirements for attaching headers to studs to q
g
accommodate loads
 Limitations on stud notching
Walls
 Double top plate splice requirements
 Wall sheathing coverage and nailing is specified for shear g
g
g p
walls
 Hold‐downs required at ends of shear walls to resist overturning
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Top Wall Plate to Wall Studs
Source: FEMA
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3
Window Header to Exterior Wall
Source: FEMA
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Header Connection Requirements
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3
Window Header Connection
For our example building, roof span = 20 ft.
Interpolate values in Table 3.7
If the header span is 10 ft., the header connection load at each end must be prorated between the loads for 24 ft. roof span and 12 ft. roof span
U = 846 lbs x .75 (for framing 8 ft. from corners) = 634 lbs.
L = 643 lbs. x .92 (for framing 8 ft. from corners) = 592 lbs.
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Wall to Floor Framing
U = 128 lbs
S = 145 lbs
L = 172 lbs
Source: FEMA
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Uplift and Shear Loads at Floor
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Uplift and Shear Loads at Floor
Uplift = 96 lbs x 1.33 (stud spacing) = 128 lbs.
Shear = 218 lbs x 20/40 (aspect ratio) x 1.33 (
(stud spacing) = 145 lbs.
)
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Lateral Loads at Floor
Lateral load at stud = 129 plf x 1.33 (for 16” stud spacing) = 172 lbs
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Floor Support Beam to Foundation (Pile)
U = 960 lbs
S = 1090 lbs
L = 1290 lbs
Source: FEMA
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5
Loads on Floor Support Beam
Uplift loads from Load Path Point #4 summed over floor beam span
W i ht f fl
Weight of floor system reduces uplift (not t
d
lift ( t
included in WFCM tables)
Lateral loads from Load Path Point #4 summed over floor beam span
Shear loads from Load Path Point #4 summed over floor beam span
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Connection not covered by WFCM (or anywhere else in prescriptive literature)
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Loads on Floor Support Beam
Assume beam span is 10 ft. (4 spans @ 10 ft. = 40 ft.)

Uplift load = 96 plf
x 10 ft. = 960 lbs.
If floor weight is considered to reduce uplift, floor weight = 20 psf x 5 ft. x 0.6 = 60 plf x 10 ft. beam span = 600 lbs.
Lateral load = 129 plf x 10 ft. = 1290 lbs.
Lateral load = 129 plf
x 10 ft = 1290 lbs
Shear load = 109 plf x 10 ft. = 1090 lbs. Copyright © 2013 American Wood Council
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Floor to Foundation Connection
Source: FEMA
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Connections in Lateral Load Paths
1
2T
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2C
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Distribution of Loads into Shear Walls
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Connections in Lateral Load Paths
 1 Nailing of sheathing on shear wall to resist racking

Racking movement creates tension at left 2T
corner and compression at right corner
Tension and compression are equal but opposite reactions – resisted with hold downs tying wall system to floor or beam
downs tying wall system to floor or beam system Copyright © 2013 American Wood Council
2C
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8d nail – 3/8” thick sheathing – nailed into 2” width framing
with nails 6” o.c. resists 755 plf of shear
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Shear Wall Methods
Segmented
Perforated
Shear transfer around openings
Wood structural panels used for shear and uplift
Wind/Seismic Commentary (2008)
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Segmented Shear Wall Sheathing
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Shear Wall Hold‐down Requirements
From Webinar 1 – shear along 20 ft. side of building =
436 plf; T = vh = 436 plf x 10 ft. wall = 4360 lbs.
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Segmented Shear Walls
Source: FEMA
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Shear Wall Aspect Ratios
2008 AWC Special Design Provisions for Wind and Seismic
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Shear Wall Hold‐down
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Shear Wall Hold‐down
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Perforated Shear Walls
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Perforated Shear Walls
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Wall Sheathing for Shear and Uplift
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Questions?
www.awc.org
info@awc.org
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THANK YOU!
Follow-up email with:
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• WFCM - www.awc.org/standards/wfcm.html
th 2012 WFCM: Foundation Design to Resist • Sept
Sept. 25
25th 2012 WFCM: Foundation Design to Resist
Flood Loads and WFCM Calculated Wind Loads
• NEW! Nov. 21st Prescriptive Residential Wood Deck Construction Guide (DCA 6)
• NEW! Jan. 16th AWC’s Code Conforming Wood Design
•
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