Connection Design with the
NDS and Technical Report 12
Michelle Kam-Biron, PE, SE, SECB
Director, Education
American Wood Council
Lori Koch, PE
Project Engineer
American Wood Council
1
Copyright Materials
This presentation is protected by US and
International Copyright laws.
laws Reproduction
Reproduction,
distribution, display and use of the presentation
without written permission of the speaker is
prohibited.
© American Wood Council 2015
2
Copyright © 2015 American Wood Council. All rights reserved.
1
•
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
materials,
methods, and services will
be addressed at the conclusion of
this presentation.
3
Course Description
This course will feature techniques for designing connections for wood
members utilizing AWC's 2015 National Design Specification® (NDS®)
for Wood Construction and Technical Report 12 - General Dowel
Equations
i
for
f C
Calculating
l l i Laterall Connection
C
i Values
l
(
(TR12).
2) Topics
i will
ill
include connection design philosophy and behavior, an overview of
common fastener types, changes in the 2015 NDS related to crosslaminated timber, and design examples per TR12.
4
Copyright © 2015 American Wood Council. All rights reserved.
2
Learning Objectives
• On completion of this course, participants will:
1. Be familiar with current wood member connection solutions
and applicable design requirements.
2. Be familiar with Technical Report 12 and provisions for
connection design beyond NDS requirements.
3. Be able to recommend fastening guidelines for wood to
steel, wood to concrete, and wood to wood connections.
4. Be able to describe effects of moisture on wood member
connections and implement proper detailing to mitigate
issues that may occur.
5
Polling Question
1. What is your profession?
a) Architect
b) Engineer
E i
c) Code Official
d) Building Designer
e) Other
6
Copyright © 2015 American Wood Council. All rights reserved.
3
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
7
Basic Concepts
• Model wood cells as a bundle of straws
• Bundle is very strong parallel to axis of the straws
Parallel
Stronger
Perpendicular
Less strong
8
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4
Connecting Wood - Philosophy
• Wood likes compression parallel to grain
• makes connecting wood very easy
9
Connecting Wood - Philosophy
• Wood likes compression parallel to grain
• makes connecting wood very easy
10
Copyright © 2015 American Wood Council. All rights reserved.
5
Connecting Wood - Philosophy
• Wood likes to take on load spread over its surface
11
Connecting Wood - Philosophy
• Wood and tension perpendicular to grain
•
Not recommended
Initiators:
• notches
• large diameter fasteners
• hanging loads
12
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6
Notching
Problem
Solution
13
Beam to Concrete
• Notched Beam Bearing
•
may cause splitting
•
not recommended
Split
14
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7
Beam to Concrete
• Notched Bearing
g Wall
alternate to beam notch
•
15
Hanger to Beam
• Load suspended from
lower half of beam
• Tension perpendicular
to grain
• May cause splits
Split
Split

C
N
A
N
A
T
16
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8
Hanger to Beam
Lower half of beam
•
may cause splits
•
not recommended
Exception: light load
Split
•
<100 lbs
•
>24” o.c.
17
Hanger to Beam
Full wrap
sling option
Load supported in upper
half of beam
•
•
Extended plates puts
wood in compression
when loaded
C
compression
N
A
N
A
T
18
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9
Connecting Wood- Philosophy
• Splitting happens because wood is
relatively weak perpendicular to grain
•
Nails too close (act like a wedge)
19
Connecting Wood - Philosophy
Staggered Nailing
Framing
Wood Structural
Panel
Nail
1/8" Gap
Between Panels
Nailing not staggered
Nailing not staggered
Nailing staggered
Nailing staggered
Copyright © 2015 American Wood Council. All rights reserved.
20
10
Connecting Wood- Philosophy
Splitting occurs parallel to
grain
Staggering
Splitting will not occur
perpendicular to grain,
no matter how close
nails are
Staggering
gg
g a line of
nails parallel to wood
grain minimizes
splitting
21
Connecting Wood - Philosophy
• Wood, like other hygroscopic materials, moves in varying
environments
22
Copyright © 2015 American Wood Council. All rights reserved.
11
Connecting Wood - Philosophy
• Fastener selection is key to connection ductility, strength,
performance
23
Polling Question
2. Tension perpendicular to grain can be
caused by?
a) Notches in the beam
Notches in the beam
b) Hanging loads
c) Large diameter fasteners
d) All of the above
24
Copyright © 2015 American Wood Council. All rights reserved.
12
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
25
Connection Behavior
• Balance
• Strength –
• Ductility-
L d
Load
high strength
strength, poor ductility
good strength, good
ductility
low strength, good ductility
Displacement
26
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13
Connection Behavior
27
Connection Behavior
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14
Connection Behavior
30
Connection Behavior
• Balance
• Strength –
• Size
Si and
d number
b off
fasteners
• Ductility• Fastener slenderness
• Spacing
• End distance
Load
high strength, poor ductility
good strength, good ductility
low strength, good ductility
Displacement
31
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15
Wood Frame Shear Walls
• Elements of a wood shear wall
V
Sheathing
panels of
specific grade
and thickness
Specific
stud species
Hold-down
anchors
Specific nail
size and
spacing
requirements
v
T
Base shear anchors
C
32
Shear Wall Test
• 8 ft x 8 ft wood structural
panel shear wall cyclic test
33
Copyright © 2015 American Wood Council. All rights reserved.
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Shear Wall Test
• Typical failure of sheathing nailing
a) Nail yielding at adjoining
panel
panel edge
b) Nail yielding and head pull through at
to bottom plate location
34
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
35
Copyright © 2015 American Wood Council. All rights reserved.
17
Connection Serviceability
• Issue: direct water ingress
• Water is absorbed most quickly through wood end grain
No end
caps or
flashing
36
Connection Serviceability
• Issue: direct water ingress
• Re-direct the water flow
around the connection
end caps and flashing
37
Copyright © 2015 American Wood Council. All rights reserved.
18
Connection Serviceability
• Issue: direct water ingress
• Or, let water out if it gets in...
Moisture trap No weep holes
38
Moisture Changes In Wood
Causes dimensional changes perpendicular to
grain
Tangentially
Growing
tree is
filled
with
water
As wood
dries, it
shrinks
perp. to
grain
Radially
39
Copyright © 2015 American Wood Council. All rights reserved.
19
Wood Shrinks
Woodmagazine.com
40
Connection Serviceability
• Moisture Effects
1% change in
dimension for
every 4%
change MC
41
Copyright © 2015 American Wood Council. All rights reserved.
20
Wet Service Factor, CM
• Dowel-type connectors
• bolts
• drift pins
• drift bolts
• lag screws
• wood screws
• nails
Saturated
19% MC
fabrication MC
in-service MC
Dry
CM
1.0
1.0
1.0
0.7
0.7
0.25
0.4* Lateral load (*CM=0.7 for D<1/4″)
1.0 Withdrawal load - lag & wood screws only
0.25 Withdrawal load - nails & spikes
42
Wet Service Factor, CM
CM = 1.0 if:
Saturated
19% MC
1 fastener
2+ fasteners
Dryy
CM
0.4
Lateral load (D>1/4″) split splice
plates
fabrication MC
in-service MC
Table 10.3.3 footnote 2
43
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21
Beam to Column
• Full-depth
p side p
plates
•
may cause splitting
•
wood shrinkage
44
Beam to Column
• Smaller side plates
p
•
transmit force
•
allow wood movement
45
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22
Beam to Column
• Problem
•
shrinkage
•
tension perp
46
Beam to Wall
• Solution
•
bolts near bottom
•
minimizes effect of
shrinkage
Slotted hardware
47
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Connection Serviceability
• Avoid contact with cementitious materials
• Beam on Shelf
•
prevent contact with
concrete
•
provide lateral
resistance and uplift
48
Beam to Concrete
• Beam on Wall
•
prevent contact with
concrete
•
provide lateral
resistance and uplift
•
slotted to allow
longitudinal movement
•
typical for sloped beam
49
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24
Beam to Masonry
• Application
• Application
Need 1/2” air gap between
wood and masonry
50
Column to Base
• Problem
•
no weep holes in closed
shoe
•
moisture entrapped
•
decay can result
51
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25
Column to Base
• Angle
g brackets
•
anchor bolts in brackets
52
Hidden Column Base
• Floor slab p
poured over
connection
•
will cause decay
•
not recommended
53
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26
Column to Base
• Floor slab p
poured below
connection
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Polling Question
3. Proper detailing of wood members and connections exposed to the exterior environment include:
a) Re‐directing the water flow around the connection.
b) Separating wood from concrete and masonry
c) Protecting the end grain
d) Incorporating weep holes
Incorporating weep holes
e) All of the above
55
Copyright © 2015 American Wood Council. All rights reserved.
27
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
56
Mechanical Connectors
57
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28
Traditional Connectors
• All-wood solution
• time tested
• practical
• extreme efficiencies
available with computer
numeric control (CNC)
machining
www.tfguild.org
www.timberframe.org
58
Traditional Connectors
• Long History > 100
years
• Uses automated
Computer numerical
Control (CNC) milling
technology
• machine joints
• pre-drill holes
• Timber Framer’s Guild
www.tfguild.org
http://www.tfguild.org/download
s/TFEC-1-2010-with-Commentary.p
df
Copyright © 2015 American Wood Council. All rights reserved.
59
29
Traditional Connectors
• Wood dowel connection design
technology now available
Schmidt, R.J. (2006): Timber Pegs – Considerations for Mortise and Tenon Joint
Design, Structure Magazine, March 2006, NCSEA, 13(3):44-47.
http://www.structuremag.org/wp-content/uploads/2014/09/SF-Timber-Pegs-March60
061.pdf
Mechanical Connectors
•Common Fasteners
• Nails
• Staples
p
• Wood Screws
• Metal plate
connectors
• Lag screws
• Bolts
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30
Typical Panel Connectors
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Typical Panel Connectors
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31
Fastener Values
• Included in U.S. design literature
Fastener Type
Bolts
B
l
Lag Screws
Wood Screws
Nails & Spikes
Split Ring Connectors
Shear Plate Connectors
Drift Bolts & Drift Pins
Metal Plate Connectors
Reference
NDS or ER
NDS or ER
NDS or ER
NDS or ER
NDS
NDS
NDS
ER
Hangers & Framing
Anchors
ER
Staples
ER
Evaluation Reports
(ER) are developed
for proprietary
products
64
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
65
Copyright © 2015 American Wood Council. All rights reserved.
32
Governing Codes for Wood Design
2015 NDS referenced in 2015 IBC
66
ANSI Accreditation
• AWC –ANSI-accredited standards developer
• Consensus Body
y
•
Wood Design Standards Committee
67
Copyright © 2015 American Wood Council. All rights reserved.
33
2015 NDS Chapter Reorganization
2012 NDS
2015 NDS
• 1-3 General
• 1-3 General
• 4-9 Products
• 4-10 Products +CLT
• 10-13 Connections
• 11-14 Connections
• 14 Shear Walls & Diaphragms
• Shear Walls & Diaphragms
• 15 Special Loading
• 15 Special Loading
• 16 Fi
Fire
• 16 Fi
Fire
68
NDS Chapter 11 – Mechanical Connections
•
ASD and LRFD accommodated through Table 11.3.1
•
Dowel fasteners
•
Split ring/shear plate
•
Timber rivets
•
Spike grids
New chapter numbering for 2015 NDS!
Copyright © 2015 American Wood Council. All rights reserved.
69
34
NDS Dowel-fastener Connections
• 2015 NDS Chapter 12 (New location)
• Can be used for any dowel-shaped fastener
• Includes
I l d llateral
t
l and
d withdrawal
ithd
l provisions
i i
•
Bolts
•
Lag screws
•
Wood screws
•
Nails
•
Spikes
•
Drift bolts
•
Drift pins
70
Dowel-fastener withdrawal
• Withdrawal calculated based on fastener penetration
W value is per inch of fastener penetration
•
•
Threaded fasteners use thread penetration
• Lag screws
•
W = 1800 G3/2 D¾
• Wood screws
•
W = 2850 G2 D
• Nails (smooth shank)
•
W = 1380 G5/2 D
No withdrawal in end grain allowe
d for nails or wood screws!
71
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35
Yield Modes
MODE I
•bearing-dominated
b i d i
d
yield of wood fibers
MODE II
•pivoting of fastener
with localized crushing
of wood fibers
72
Yield Modes
MODE III
•fastener yield in
b di att one
bending
plastic hinge and
bearing –
dominated yield
of wood fibers
MODE IV
•fastener yield in
bending
g at two
plastic hinges and
bearing –
dominated yield
of wood fibers
73
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36
Dowel Bearing Strength
74
Fastener Bending Yield Test
Center-Point Bending Test
Load
75
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37
Fastener Bending Yield Strength
76
Yield Limit Equations
• 4 Modes of failure
• 6 Yield equations Lowest Yield “Z” value = Connection Capacity
• Single & double
77
shear
Copyright © 2015 American Wood Council. All rights reserved.
38
Yield Limit Equations
78
Yield Limit Equations
Also applied in TR
12 equations!
79
Copyright © 2015 American Wood Council. All rights reserved.
39
Spacing, End, & Edge Distance
80
Spacing, End, & Edge Distance
81
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40
Spacing, End, & Edge Distance
82
Spacing, End, & Edge Distance
• Unless special detailing is provided to accommodate
cross-grain shrinkage of the wood member.
Copyright © 2015 American Wood Council. All rights reserved.
83
41
Polling Question
4. The NDS Yield Limit Equations are used to determine:
a) Lateral capacity of connections
Lateral capacity of connections
b) Withdrawal capacity of connections
c) Lateral and withdrawal capacities of connections
d) None of the above
84
NDS Appendix E
• Appendix E – Local Stresses in Fastener Groups (Non-
mandatory)
Groups of closely spaced fasteners loaded parallel to grain
•
•
Net Section Tension Capacity
•
Row Tear-Out Capacity
•
Group Tear-Out Capacity
Example problems
•
•
Staggered rows of bolts
•
Single row of bolts
•
Row of split rings
85
Copyright © 2015 American Wood Council. All rights reserved.
42
Chapter 12-Dowels
86
Chapter 12-Dowels
87
Copyright © 2015 American Wood Council. All rights reserved.
43
Dowel Diameters
Threaded
lm
length < lm/4
Dia. Fastener = D
Threaded
lm
length < lm/4
Dia. Fastener = D
88
Dowel Diameters
lm
Dia. Fastener = Dr
• NDS Chapter 12 Tables use Dr for lateral yield equations
• Assumes shear plane passes through threads
89
Copyright © 2015 American Wood Council. All rights reserved.
44
Chapter 12 – Dowel-type Fasteners
New
90
Chapter 12 – Dowel-type Fasteners
New
91
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45
Chapter 12 – Dowel-type Fasteners
New
92
Chapter 12 – Dowel-type Fasteners
New
Nonuniform
for CLT
Copyright © 2015 American Wood Council. All rights reserved.
93
46
Chapter 12 – Dowel-type Fasteners
• Adjust lm or ls to compensate for orthogonal
grain orientations in adjacent layers
• Parallel to grain: Fe/Fe‖‖
Example: ½” bolt in southern pine 3-ply CLT
with 1-½” laminations
lm = t1‖ + t2 + t3‖ = 3(1.5) = 4.5”
lm-adj = t1‖ + t2(Fe/Fe‖) + t3‖
=1.5 +1.5(3650/6150) +1.5 = 3.9”
94
Chapter 12 – Dowel-type Fasteners
New
95
Copyright © 2015 American Wood Council. All rights reserved.
47
Chapter 12 – Dowel-type Fasteners
• Lateral – any end grain
•
D<1/4” Cegg=0.67
• Lateral – any CLT edge
New
•
D>1/4” Ceg=0.67
96
Technical Report 12
• Background and derivation of the mechanics-based approach
for calculating lateral connection capacity used in the NDS
• Provides
P
id additional
dditi
l fl
flexibility
ibilit and
db
broader
d applicability
li bilit to
t the
th
NDS provisions
• Connections with gaps between members
• Connecting wood to members with hollow cross sections
http://www.awc.org/codes-standards/publications
Copyright © 2015 American Wood Council. All rights reserved.
97
48
Technical Report 12
98
Technical Report 12
99
Copyright © 2015 American Wood Council. All rights reserved.
49
Technical Report 12
100
Technical Report 12
•Allows for evaluation of connections with gaps between connected
members
101
Copyright © 2015 American Wood Council. All rights reserved.
50
Technical Report 12
• Tapered tip fasteners
NDS 12.5.3 defines “E” as length of tapered tip
•
•
•
Lag screws – E defined in Appendix L
•
Wood screws, nails – E assumed to be 2D
Tapered tip does not count towards bearing length (Lm) in
TR12 Tapered tip equations.
102
Technical Report 12
• Tapered tip equations
•
Mode Im
•
Mode Is
•
Mode II
•
Mode IIIm
•
Mode IIIs
•
Mode IV
TR12 shows NDS ap
proximations are
<1% different fro
m using expanded
equation!
103
Copyright © 2015 American Wood Council. All rights reserved.
51
Technical Report 12
• TR12 presents mechanics-based equations
• Gives same results as NDS energy-based approach
• Equations in TR12 calculate P, must be divided by Rd (NDS Table
12.3.1B) to convert to NDS Z basis
• TR12 Appendix being released later in 2015
104
Technical Report 12 Appendix
• New for 2015!
• Contains additional data for
TR12 equation inputs
•
Dowel bearing values for:
•
•
•
•
•
•
Wood
Steel
Concrete
Stainless steel
Aluminum
Dowel bending values for
fastener
as e e materials:
a e as
•
•
•
Steel and stainless steel bolts
and lag screws
Low-to-medium carbon steel
nails
Hardened steel nails (including
post-frame ring-shank)
105
Copyright © 2015 American Wood Council. All rights reserved.
52
Example Problem #1
• Calculate W for ¼” diameter, 2.5” long lag screw connecting
2-2x SYP (G = 0.55) members
•
W = 1800 G3/2 D¾ = 260 lbs/in (calculate or NDS Table 12
12.2A)
2A)
•
Calculate penetration into main member for withdrawal capacity
NDS Appendix L gives lag screw dimensions
•
•
Length of unthreaded section = ¾”
•
Length of threaded section (including tip) = 1¾”
•
Length of threaded section (excluding tip) = 119/32”
•
p = screw length
l
th – length
l
th off side
id member
b – length
l
th off ti
tip
•
p = 2.5” – 1.5” – (1¾” - 119/32”) = 0.84” of penetration
•
Unadjusted capacity = W*p = (260 lbs/in * 0.84 in) = 219 lbs
•
Apply adjustment factors per Table 11.3.1 to get adjusted W’
106
Example Problem #2
• Calculate unadjusted Z for ½” diameter bolt connecting two
2x DF-L (G = 0.5) members with a 1” gap between them
Both members loaded p
parallel to g
grain ((K = 1))
•
•
D = 0.5”
•
Fe = 5600 psi (NDS Table 12.3.3); qs = qm = Fell* D = 5600 psi * 0.5” = 2800 lb/in
•
Ls = Lm = 1.5”
•
Fyb = 45,000 psi
•
g = 1”
ll
107
Copyright © 2015 American Wood Council. All rights reserved.
53
Example Problem #2
• Calculate unadjusted Z for ½” diameter bolt connecting two
2x DF-L (G = 0.5) members with a 1” gap between them
Mm = Ms = (FbD3)/6 = (45,000 psi)*(0.5”^3)/6 = 937.5 lb-in
•
•
Substituting values into TR12 equations yields P values
•
Divide P values by Rd to obtain Z
Mode
P (lbs)
Rd
Z (lbs)
Im
Is
II
IIIm
IIIs
IV
4200
4200
1163
1211
1211
1285
4K = 4
4K = 4
3.6K= 3.6
3.2K = 3.2
3.2K = 3.2
3.2K = 3.2
1050
1050
323
378
378
402
Z = 323 lbs
108
Example Problem #3
• Compare lateral Z values for single shear nail connection at 6D,
8D, 10D, and 12D penetration using TR12 tapered tip equations
•
8d common nail D = 0.131”,
0 131” tapered tip length
length, E = 2D = 0.262”
0 262”
•
Main member Fem = 4,700 psi (loaded parallel to grain); ASTM
A653, Grade 33 steel side member, thickness = 0.06”, Fes = 61,850
psi
•
Lm = p (penetration into main member); Ls = 0.06” (side member
thickness)
Penetration
P
t ti
Depth (p)
Z (lbs)
Controlling
C
t lli
mode
12D (1.57")
10D (1.31")
8D (1.05")
6D (0.79")
97
97
97
79
IIIs
IIIs
IIIs
II
Copyright © 2015 American Wood Council. All rights reserved.
109
54
Example Problem #3
• Compare Z values for single shear nail connection at 6D, 8D, 10D,
and 12D penetration using NDS Lm assumption for tapered tip
•
8d common nail D = 0.131”,
0 131” tapered tip length
length, E = 2D = 0.262”
0 262”
•
Main member Fem = 4,700 psi (loaded parallel to grain); ASTM
A653, Grade 33 steel side member, thickness = 0.06”, Fes = 61,850
psi
•
Lm = p – E/2 (NDS assumption) ; Ls = 0.06” (side member
thickness)
Penetration
P
t ti
Depth (p)
Z (lbs)
Controlling
C
t lli
mode
12D (1.57")
10D (1.31")
8D (1.05")
6D (0.79")
97
97
97
78
IIIs
IIIs
IIIs
II
110
Polling Question
5. Technical Report 12 provides a _________
approach for calculating the capacity of
laterally loaded connections.
connections
a) Mechanics‐based
b) Energy‐based
c) Hybrid model
d) None of the above
111
Copyright © 2015 American Wood Council. All rights reserved.
55
Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
112
Software Solutions Exist
•WWPA Lumber Design
Suite
• Beams
B
and
d JJoists
i t
• Post and Studs
• Wood to Wood
Shear Connections
(nails, bolts, wood
screws and lag
screws)
http://www2.wwpa.org/TECHGUIDEPAGES/DesignSoftware/tabi
d/859/Default.aspx
113
Copyright © 2015 American Wood Council. All rights reserved.
56
Example Problem – Connections Calculator
• AWC Connections Calculator
• Can calculate lateral and withdrawal capacities
• http://awc.org/codes-standards/calculators-software/connectioncalc
Calculators
114
Example Problem – Connections Calculator
Z’
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Outline
• Wood connection design
philosophy
• Connection behavior
• Serviceability challenges
• Connection hardware and
fastening systems
• Connection techniques
• Design software
• Where to get more
information
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More info???
• 2012 NDS
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More info???
• M4.4 Special
i l Design
i
Considerations
id
i
• Mechanical Connections
• Dowel-Type Fasteners
• Split Ring and Shear Plates Connectors
• Timber Rivets
http://www.awc.org/pdf/2012ASD-LRFD_Manual_WEB.pdf
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More info???
2015
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Copyright © 2015 American Wood Council. All rights reserved.
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More info???
•
Technical papers on Timber rivets:
http://www.awc.org/helpoutreach/faq/faqFiles/Timber_rive
ts.html
•
Timber rivets in structural composite lumber
•
Simplified analysis of timber rivet connections
•
Timber rivet connections in U.S. domestic species
•
Timber Rivets-Structure Magazine
•
Seismic Behavior of Timber Rivets in Wood Construction
•
Seismic Performance of Riveted Connections in Heavy
Timber Construction
•
Timber rivet suppliers
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More info???
• Load-carrying behavior of steel-to-timber dowel connections:
http://timber.ce.wsu.edu/Resources/papers/2-4-1.pdf
• New Concealed Connectors Bring
g More Options
p
for Timber
Structures http://www.structuremag.org/Archives/20071/p42-43D-Insights-ConcealedConnectorsJan07.pdf
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Take Home Messages...
• Transfer loads in compression / bearing whenever possible
• Allow for dimensional changes in the wood due to potential in-
service moisture cycling
y
g
• Avoid the use of details which induce tension perp stresses in
the wood
• Avoid moisture entrapment in connections
• Separate wood from direct contact with masonry or concrete
• Avoid eccentricity in joint details
• Minimize exposure of end grain
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Connections
…and
and you
thought
connecting
wood was
complicated!
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Questions?
• This concludes The American Institute of Architects Continuing
Education Systems Course
American Wood Council
info@awc.org
www.awc.org
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Copyright © 2015 American Wood Council. All rights reserved.
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