Connection Design with the NDS and Technical Report 12 · PDF fileinclude connection design...
Transcript of Connection Design with the NDS and Technical Report 12 · PDF fileinclude connection design...
Copyright © 2015 American Wood Council. All rights reserved. 1
Connection Design with the NDS and Technical Report 12
Lori Koch, PEProject EngineerAmerican Wood Council
Michelle Kam-Biron, PE, SE, SECBDirector, EducationAmerican Wood Council 1
This presentation is protected by US and International Copyright laws Reproduction
Copyright Materials
International Copyright laws. 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. 2
• The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems
• This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemedContinuing 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
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 ofhandling, using, distributing, or dealing in any material or product.
• Questions related to specific materials methods and services will
3
upon request. materials, methods, and services will be addressed at the conclusion of this presentation.
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
i f C l l i l C i l ( 2) i illEquations for Calculating Lateral Connection Values (TR12). Topics will include connection design philosophy and behavior, an overview of common fastener types, changes in the 2015 NDS related to cross-laminated timber, and design examples per TR12.
4
Copyright © 2015 American Wood Council. All rights reserved. 3
Learning Objectives
• On completion of this course, participants will:
1. Be familiar with current wood member connection solutions1. 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.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 Question1. What is your profession?
a) Architect
b) E ib) Engineer
c) Code Official
d) Building Designer
e) Other
6
Copyright © 2015 American Wood Council. All rights reserved. 4
Outline
• Wood connection design philosophyConnection behavior• Connection behavior
• Serviceability challenges• Connection hardware and
fastening systems• Connection techniques • Design software• Where to get more
information
7
• Model wood cells as a bundle of straws• Bundle is very strong parallel to axis of the straws
Basic Concepts
Parallel Perpendicular
Stronger Less strong
8
Copyright © 2015 American Wood Council. All rights reserved. 5
Connecting Wood - Philosophy
• Wood likes compression parallel to grain• makes connecting wood very easy
9
• Wood likes compression parallel to grain• makes connecting wood very easy
Connecting Wood - Philosophy
10
Copyright © 2015 American Wood Council. All rights reserved. 6
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• large diameter fasteners• hanging loads
12
Copyright © 2015 American Wood Council. All rights reserved. 7
Notching
Problem Solution
13
Beam to Concrete
• Notched Beam Bearing• may cause splitting
Split
• may cause splitting• not recommended
14
Copyright © 2015 American Wood Council. All rights reserved. 8
Beam to Concrete
• Notched Bearing Wallg• alternate to beam notch
15
Hanger to Beam
• Load suspended from lower half of beam
• Tension perpendicular to grain
• May cause splits SplitSplit
C
T
NA
NA
16
Copyright © 2015 American Wood Council. All rights reserved. 9
Hanger to Beam
Lower half of beam• may cause splitsmay cause splits• not recommended
Exception: light load• <100 lbs• >24” o.c.SplitSplit
17
Hanger to Beam
• Load supported in upper half of beam
Full wrap sling option
• Extended plates puts wood in compression when loaded
C
compression T
NA
NA
18
Copyright © 2015 American Wood Council. All rights reserved. 10
Connecting Wood- Philosophy
• Splitting happens because wood is relatively weak perpendicular to grain
• Nails too close (act like a wedge)
19
Framing
Staggered Nailing
Connecting Wood - Philosophy
Wood Structural
Panel
Nail
1/8" GapBetween Panels
Nailing not staggered Nailing staggeredNailing not staggered Nailing staggered20
Copyright © 2015 American Wood Council. All rights reserved. 11
Splitting occurs parallel to grain
Connecting Wood- Philosophy
Splitting will not occur
Staggering
Staggering a line of perpendicular to grain,
no matter how close nails are
gg gnails 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. 12
Connecting Wood - Philosophy• Fastener selection is key to connection ductility, strength,
performance
23
Polling Question2. Tension perpendicular to grain can be
caused by?
a) Notches in the beama) 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. 13
Outline
• Wood connection design philosophyConnection behavior• Connection behavior
• Serviceability challenges• Connection hardware and
fastening systems• Connection techniques • Design software• Where to get more
information
25
Connection Behavior
• Balance• Strength – L d high strength poor ductilityStrength • Ductility-
Load high strength, poor ductility
good strength, good ductility
Displacement
low strength, good ductility
26
Copyright © 2015 American Wood Council. All rights reserved. 14
Connection Behavior
27
Connection Behavior
28
Copyright © 2015 American Wood Council. All rights reserved. 15
Connection Behavior
30
Connection Behavior
Load high strength, poor ductility• Balance• Strength –
Si d b fgood strength, good ductility
low strength, good ductility
• Size and number of fasteners
• Ductility-• Fastener slenderness• Spacing• End distance
Displacement
31
Copyright © 2015 American Wood Council. All rights reserved. 16
Wood Frame Shear Walls• Elements of a wood shear wall
SheathingV
Specific nail
Sheathingpanels ofspecific gradeand thicknessSpecific
stud species
size and spacing requirements
Base shear anchors
Hold-downanchors
T C
v
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. 17
Shear Wall Test• Typical failure of sheathing nailing
a) Nail yielding at adjoining b) Nail yielding and head pull through at panel panel edge to bottom plate location
34
Outline
• Wood connection design philosophyConnection behavior• 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. 18
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. 19
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 graingrain
Growing tree is filled with water
As wood dries, it shrinksperp. to grain
ntia
llyTa
nge
Radially
39
Copyright © 2015 American Wood Council. All rights reserved. 20
Wood Shrinks
Woodmagazine.com40
Connection Serviceability• Moisture Effects
1% change in dimension for
every 4%every 4% change MC
41
Copyright © 2015 American Wood Council. All rights reserved. 21
Wet Service Factor, CM
• Dowel-type connectors• boltsSaturated • drift pins• drift bolts• lag screws• wood screws• nails
Saturated
19% MC
Dryfabrication MCin-service MC
CM 1.0 0.7 0.4* Lateral load (*CM=0.7 for D<1/4″)1.0 0.7 1.0 Withdrawal load - lag & wood screws only1.0 0.25 0.25 Withdrawal load - nails & spikes
Dry
42
Wet Service Factor, CM
CCMM = 1.0 if:= 1.0 if:Saturated CCMM 1.0 if: 1.0 if:1 fastener
2+ fasteners
19% MC
Dry
CM 0.4 Lateral load (D>1/4″) split splice plates
y
fabrication MCin-service MC Table 10.3.3 footnote 2
43
Copyright © 2015 American Wood Council. All rights reserved. 22
Beam to Column
• Full-depth side platesp p• may cause splitting• wood shrinkage
44
Beam to Column
• Smaller side platesp• transmit force• allow wood movement
45
Copyright © 2015 American Wood Council. All rights reserved. 23
Beam to Column
• Problem• shrinkage• tension perp
46
Beam to Wall
• Solution• bolts near bottom• minimizes effect of
shrinkage
Slotted hardware
47
Copyright © 2015 American Wood Council. All rights reserved. 24
• Avoid contact with cementitious materials
Connection Serviceability
• 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
Copyright © 2015 American Wood Council. All rights reserved. 25
Beam to Masonry
• Application
• 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
Copyright © 2015 American Wood Council. All rights reserved. 26
Column to Base
• Angle bracketsg• anchor bolts in brackets
52
Hidden Column Base
• Floor slab poured over pconnection
• will cause decay• not recommended
53
Copyright © 2015 American Wood Council. All rights reserved. 27
Column to Base
• Floor slab poured below pconnection
54
Polling Question3. 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 holesd) Incorporating weep holes
e) All of the above
55
Copyright © 2015 American Wood Council. All rights reserved. 28
Outline
• Wood connection design philosophyConnection behavior• Connection behavior
• Serviceability challenges• Connection hardware and
fastening systems• Connection techniques • Design software• Where to get more
information
56
Mechanical Connectors
57
Copyright © 2015 American Wood Council. All rights reserved. 29
Traditional Connectors
• All-wood solution• time tested• practical• extreme efficiencies
available with computer numeric control (CNC) machining
www.tfguild.orgwww.timberframe.org
58
• Long History > 100 years
• Uses automated
Traditional Connectors
• Uses automated Computer numerical Control (CNC) milling technology • machine joints• pre-drill holes
• Timber Framer’s Guild -www.tfguild.org
http://www.tfguild.org/downloads/TFEC-1-2010-with-Commentary.p
df 59
Copyright © 2015 American Wood Council. All rights reserved. 30
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-March-061.pdf 60
Mechanical Connectors
•Common Fasteners• Nails • Staples p• Wood Screws• Metal plate
connectors• Lag screws • Bolts
61
Copyright © 2015 American Wood Council. All rights reserved. 31
Typical Panel Connectors
62
Typical Panel Connectors
63
Copyright © 2015 American Wood Council. All rights reserved. 32
• Included in U.S. design literature
Fastener Values
Fastener Type Reference
B l NDS ER
Evaluation Reports (ER) are developed for proprietary products
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
64
Outline
• Wood connection design philosophyConnection behavior• 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. 33
Governing Codes for Wood Design
2015 NDS referenced in 2015 IBC
66
ANSI Accreditation
• AWC –ANSI-accredited standards developer• Consensus Bodyy
• Wood Design Standards Committee
67
Copyright © 2015 American Wood Council. All rights reserved. 34
2015 NDS Chapter Reorganization
2012 NDS
• 1-3 General
2015 NDS
• 1-3 General
• 4-9 Products
• 10-13 Connections
• 14 Shear Walls & Diaphragms
• 15 Special Loading
16 Fi
• 4-10 Products +CLT
• 11-14 Connections
• Shear Walls & Diaphragms
• 15 Special Loading
16 Fi
68
• 16 Fire • 16 Fire
NDS Chapter 11 – Mechanical Connections• ASD and LRFD accommodated through Table 11.3.1• Dowel fasteners• Split ring/shear plateSplit ring/shear plate• Timber rivets• Spike grids
New chapter numbering for 2015 NDS! 69
Copyright © 2015 American Wood Council. All rights reserved. 35
NDS Dowel-fastener Connections• 2015 NDS Chapter 12 (New location)• Can be used for any dowel-shaped fastener
I l d l t l d ithd l i i• Includes lateral and withdrawal provisions• Bolts• Lag screws• Wood screws• Nails
Spikes• Spikes• Drift bolts• Drift pins
70
Dowel-fastener withdrawal• Withdrawal calculated based on fastener penetration
• W value is per inch of fastener penetrationThreaded fasteners use thread penetration• Threaded fasteners use thread penetration
• Lag screws• W = 1800 G3/2 D¾
• Wood screws• W = 2850 G2 DNails (smooth shank)• Nails (smooth shank)
• W = 1380 G5/2 D No withdrawal in end grain allowed for nails or wood screws!
71
Copyright © 2015 American Wood Council. All rights reserved. 36
Yield Modes
MODE Ib i d i d•bearing-dominated
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 tbending at one plastic hinge and bearing –dominated yield of wood fibersMODE IV•fastener yield in bending at two gplastic hinges and bearing –dominated yield of wood fibers
73
Copyright © 2015 American Wood Council. All rights reserved. 37
Dowel Bearing Strength
74
Fastener Bending Yield Test
Center-Point Bending Test
Load
75
Copyright © 2015 American Wood Council. All rights reserved. 38
Fastener Bending Yield Strength
76
Yield Limit Equations
•4 Modes of failure•6 Yield equations•Single & double shear
Lowest Yield “Z” value = Connection Capacity
77
Copyright © 2015 American Wood Council. All rights reserved. 39
Yield Limit Equations
78
Yield Limit Equations
Also applied in TR12 equations!
79
Copyright © 2015 American Wood Council. All rights reserved. 40
Spacing, End, & Edge Distance
80
Spacing, End, & Edge Distance
81
Copyright © 2015 American Wood Council. All rights reserved. 41
Spacing, End, & Edge Distance
82
Spacing, End, & Edge Distance
• Unless special detailing is provided to accommodate cross-grain shrinkage of the wood member.
83
Copyright © 2015 American Wood Council. All rights reserved. 42
Polling Question4. The NDS Yield Limit Equations are used to
determine:
a) Lateral capacity of connectionsa) 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• 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. 43
Chapter 12-Dowels
86
Chapter 12-Dowels
87
Copyright © 2015 American Wood Council. All rights reserved. 44
Dowel DiametersThreaded length < lm/4 lm
Dia. Fastener = D
Dia. Fastener = D
Threaded length < lm/4 lm
88
Dowel Diameters
l
Dia. Fastener = Dr
lm
• 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. 45
Chapter 12 – Dowel-type Fasteners
New
90
Chapter 12 – Dowel-type Fasteners
New
91
Copyright © 2015 American Wood Council. All rights reserved. 46
Chapter 12 – Dowel-type Fasteners
New
92
Chapter 12 – Dowel-type Fasteners
New
93
Non-uniform for CLT
Copyright © 2015 American Wood Council. All rights reserved. 47
• Adjust lm or ls to compensate for orthogonal grain orientations in adjacent layers
• Parallel to grain: Fe/Fe‖
Chapter 12 – Dowel-type Fasteners
‖Example: ½” bolt in southern pine 3-ply CLT
with 1-½” laminationslm = 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. 48
Chapter 12 – Dowel-type Fasteners
• Lateral – any end grain• D<1/4” Ceg=0.67g
• Lateral – any CLT edge• D>1/4” Ceg=0.67
New
96
Technical Report 12
• Background and derivation of the mechanics-based approach for calculating lateral connection capacity used in the NDSP id dditi l fl ibilit d b d li bilit t th• Provides additional flexibility and broader applicability to the NDS provisions
• Connections with gaps between members• Connecting wood to members with hollow cross sections
http://www.awc.org/codes-standards/publications97
Copyright © 2015 American Wood Council. All rights reserved. 49
Technical Report 12
98
Technical Report 12
99
Copyright © 2015 American Wood Council. All rights reserved. 50
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. 51
Technical Report 12• Tapered tip fasteners
• NDS 12.5.3 defines “E” as length of tapered tip• Lag screws – E defined in Appendix L• 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 I
• Mode IV
• Mode Is
• Mode II
• Mode IIIm
TR12 shows NDS approximations are <1% different from
• Mode IIIs
<1% different from using expanded
equation!
103
Copyright © 2015 American Wood Council. All rights reserved. 52
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 materials: as e e a e a s• 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. 53
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 2A)• W = 1800 G3/2 D¾ = 260 lbs/in (calculate or NDS Table 12.2A)• 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”
l th l th f id b l th f ti• p = screw length – length of side member – length of 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 parallel to grain (K = 1)p g ( )
• D = 0.5”
• Fell= 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”
107
Copyright © 2015 American Wood Council. All rights reserved. 54
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 4200 4K = 4 1050Is 4200 4K = 4 1050II 1163 3.6K= 3.6 323
IIIm 1211 3.2K = 3.2 378IIIs 1211 3.2K = 3.2 378IV 1285 3.2K = 3.2 402
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” tapered tip length E = 2D = 0 262”• 8d common nail D = 0.131”, tapered tip length, E = 2D = 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)
P t ti C t lliPenetration Depth (p) Z (lbs) Controlling
mode12D (1.57") 97 IIIs10D (1.31") 97 IIIs8D (1.05") 97 IIIs6D (0.79") 79 II
109
Copyright © 2015 American Wood Council. All rights reserved. 55
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” tapered tip length E = 2D = 0 262”• 8d common nail D = 0.131”, tapered tip length, E = 2D = 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)
P t ti C t lliPenetration Depth (p) Z (lbs) Controlling
mode12D (1.57") 97 IIIs10D (1.31") 97 IIIs8D (1.05") 97 IIIs6D (0.79") 78 II
110
Polling Question5. Technical Report 12 provides a _________
approach for calculating the capacity of laterally loaded connectionslaterally loaded connections.
a) Mechanics‐based
b) Energy‐based
c) Hybrid model
d) None of the above
111
Copyright © 2015 American Wood Council. All rights reserved. 56
Outline
• Wood connection design philosophyConnection behavior• Connection behavior
• Serviceability challenges• Connection hardware and
fastening systems• Connection techniques • Design software• Where to get more
information
112
•WWPA Lumber Design Suite
B d J i t
Software Solutions Exist
• Beams and Joists• Post and Studs• Wood to Wood
Shear Connections (nails, bolts, wood screws and lag screws)
http://www2.wwpa.org/TECHGUIDEPAGES/DesignSoftware/tabid/859/Default.aspx
screws)
113
Copyright © 2015 American Wood Council. All rights reserved. 57
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’
115
Copyright © 2015 American Wood Council. All rights reserved. 58
Outline
• Wood connection design philosophyConnection behavior• Connection behavior
• Serviceability challenges• Connection hardware and
fastening systems• Connection techniques • Design software• Where to get more
information
116
More info???
• 2012 NDS
117
Copyright © 2015 American Wood Council. All rights reserved. 59
i l i id i
More info???
• M4.4 Special Design Considerations• Mechanical Connections• Dowel-Type Fasteners• Split Ring and Shear Plates Connectors• Timber Rivets
http://www.awc.org/pdf/2012ASD-LRFD_Manual_WEB.pdf
118
More info???
2015
119
Copyright © 2015 American Wood Council. All rights reserved. 60
• Technical papers on Timber rivets: http://www.awc.org/helpoutreach/faq/faqFiles/Timber_rivets.html
More info???
• 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
120
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 More Options for Timber g p
Structures http://www.structuremag.org/Archives/2007-1/p42-43D-Insights-ConcealedConnectorsJan07.pdf
121
Copyright © 2015 American Wood Council. All rights reserved. 61
Take Home Messages...• Transfer loads in compression / bearing whenever possible• Allow for dimensional changes in the wood due to potential in-
service moisture cyclingy 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
122
Connections
and you…and you thought connecting wood was complicated!
123
Copyright © 2015 American Wood Council. All rights reserved. 62
124
• This concludes The American Institute of Architects Continuing Education Systems Course
Questions?
American Wood [email protected]
125