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11/10/2017
Copyright © 2017 American Wood Council1
Wood ConnectionsCornucopia of Classic Connection Conundrums (DES340)
Lori Koch, P.E.Manager, Educational OutreachAmerican Wood Council
Michelle Kam-Biron, P.E., S.E. S.E.C.BSenior Director, EducationAmerican Wood Council
Co r nu cop i a o f C l a s s i c Conne c t i o n Conund r ums 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.
11/10/2017
Copyright © 2017 American Wood Council2
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3
COURSE DESCRIPTION
The American Wood Council’s (AWC) National Design Specification® (NDS®) for Wood Construction and Special Design Provisions for Wind and Seismic (SDPWS) are documents referenced in US building codes and used to design wood structures worldwide. Based on numerous help desk questions and feedback from design professionals, AWC has identified some of the most commonly overlooked wood connection engineering requirements from the NDS and SDPWS. These requirements will be discussed as well as resources and examples to meet these requirements. Examples include NDS Appendix E Local Stresses in Fastener Groups, NDS 3.4.3.3 shear design of members at connections, resources for power-driven fasteners such as ISANTA ESR 1539, and detailing requirements for high capacity shear walls and diaphragms.
Co r nu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4
LEARNING OBJECTIVESUpon completion, participants will be better able to identify:
Be able to understand overlooked wood connection engineering issues.
Wood Connections
Obtain resources for complying with wood connection engineering issues.
Resources
Identify and design for local stresses in fastener groups.
Local Stresses
Identify and detail high capacity shear walls and diaphragms.
Detailing
1 3
2 4
11/10/2017
Copyright © 2017 American Wood Council3
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5
POLLING QUESTION
1. What is your profession?
a) Architect
b) Engineer
c) Code Official
d) Builder/Product Manufacturer
e) Other
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6
CONNECTION BEHAVIOR
• Balance• Strength • Ductility
Load
Displacement
high strength, poor ductility
good strength, good ductility
low strength, good ductility
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Copyright © 2017 American Wood Council4
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7
CONNECTION BEHAVIOR
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8
CONNECTION BEHAVIOR
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Copyright © 2017 American Wood Council5
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9
CONNECTION BEHAVIOR
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 0
CONNECTION BEHAVIOR
• Balance• Strength –
• Size and number of fasteners
• Ductility-• Fastener
slenderness• Spacing• End distance
Load
Displacement
high strength, poor ductility
good strength, good ductility
low strength, good ductility
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Copyright © 2017 American Wood Council6
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 1
CONNECTING WOOD - PHILOSOPHY
Fastener selection is key to connection ductility, strength, performance
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 2
• 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
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Copyright © 2017 American Wood Council7
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 3
• Wood likes compression parallel to grain• makes connecting wood very easy
CONNECTING WOOD - PHILOSOPHY
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 4
CONNECTING WOOD - PHILOSOPHY
• Wood likes compression parallel to grain• makes connecting wood very easy
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Copyright © 2017 American Wood Council8
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 5
CONNECTING WOOD - PHILOSOPHY
Mechanical fasteners
• keep them small
• use lots of them
Issue is scale of fastener relative to wood member size
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 6
CONNECTING WOOD - PHILOSOPHY
Wood likes to take on load spread over its surface
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Copyright © 2017 American Wood Council9
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 7
CONCENTRATED AT A SINGLE FASTENER
Wood is more prone to split and crush
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 8
PRE-ENGINEERED CONNECTORS
Column Cap & Base hardware
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Copyright © 2017 American Wood Council10
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 1 9
PRE-ENGINEERED CONNECTORS
Hanger hardware
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PRE-ENGINEERED CONNECTORS
Truss hardware
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Copyright © 2017 American Wood Council11
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 1
LOCAL STRESSES IN FASTENER GROUPS
2015 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.”
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 2
LOCAL STRESSES IN FASTENER GROUPS
• Closely spaced fasteners•brittle failure
Wood failure mechanisms need to be considered in design
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Copyright © 2017 American Wood Council12
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 3
LOCAL STRESSES IN FASTENER GROUPS
•Properly spaced fasteners
•increased ductility•higher capacity
Spread out the fasteners!
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 4
LOCAL STRESSES IN FASTENER GROUPS
• Appendix E NDS Expressions
– Net tension:
– Row tear-out:
nettNT AFZ ''
row
i
i
n
iRTRT
viRT
ZZ
tsFnZ
1
''
min''
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Copyright © 2017 American Wood Council13
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 5
LOCAL STRESSES IN FASTENER GROUPS
•Appendix E NDS Expressions
– Group tear-out
•Note: spacing between outer rows of fasteners paralleling the member on a single splice plate < 5″
netgrouptbottomRTtopRT
GT AFZZ
Z '
'''
22
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 6
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
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Copyright © 2017 American Wood Council14
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 7
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”
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 8
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
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Copyright © 2017 American Wood Council15
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 2 9
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
PP
3-5/8"
4" 4" 4" 4" 7" 4" 4"
3-5/8"
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 0
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
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Copyright © 2017 American Wood Council16
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 1
DOWEL DIAMETERS
Threaded length <
lm/4
lm
Dia. Fastener = D
Dia. Fastener = D
Threaded length <
lm/4lm
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 2
DOWEL DIAMETERS
Dia. Fastener = Dr
•NDS Chapter 12 Tables use Dr for lateral yield equations for lag screws and wood screws, D for bolts
lm
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Copyright © 2017 American Wood Council17
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 3
POLLING QUESTION
2. Local stresses in connections using multiple fasteners are required to be checked.
or FalseTrue
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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
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Copyright © 2017 American Wood Council18
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 5
ALTERNATIVE MATERIALS, DESIGN & METHODS
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 6
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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Copyright © 2017 American Wood Council19
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 7
ISANTA WEBSITE – TECHNICAL BULLETINS
http://isanta.org/Technical-Resources
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 3 8
FASTENERS NOT IN NDS/SDPWS
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Copyright © 2017 American Wood Council20
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FASTENERS NOT IN NDS/SDPWS
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 0
PROPRIETARY FASTENERS
• ICC Evaluation Service Reports• Search by manufacturer or
product
• “Wood screw” search shows 5 manufacturers
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Copyright © 2017 American Wood Council21
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 1
SHEAR DESIGN AT CONNECTIONS
Connections in bending members
Shear Force – within d
May ignore uniform loads
May reduce point load x/d
Reduction also applies to beam design.
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 2
SHEAR DESIGN AT CONNECTIONS
NDS 3.4.3.3 allows for adjusted shear values to be used when connection is close to end of member (less than 5 times member depth)
• Where the connection is less than 5d, of from its end, the adjusted design shear, Vr’ calculated using NDS Eq. 3.4-6
• Where the connection is at least 5d, of from its end, the adjusted design shear, Vr’ calculated using NDS Eq. 3.4-7
Split ring or shear plate Split ring or shear plate
Bolt or lag screw
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Copyright © 2017 American Wood Council22
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 3
SHEAR DESIGN AT CONNECTIONS
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 4
CONNECTING WOOD - PHILOSOPHY
Wood and tension perpendicular to grain
• Not recommended
Initiators:• notches• large diameter fasteners• hanging loads
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Copyright © 2017 American Wood Council23
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 5
NOTCHING
Problem Solution
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 6
Split
BEAM TO CONCRETE
Notched Beam Bearing
• may cause splitting
• not recommended
Split
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Copyright © 2017 American Wood Council24
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 7
BEAM TO CONCRETE
Bearing Wall
• alternate to beam notch
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 8
HANGER TO BEAM
Load suspended from lower half of beam
• Tension perpendicular to grain• May cause splits
SplitSplit
C
T
NANA
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Copyright © 2017 American Wood Council25
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 4 9
Split
HANGER TO BEAM
Lower half of beam
may cause splitsnot recommended
Exception: light load
<100 lbs
>24” o.c.
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 0
HANGER TO BEAM
Load supported in upper half of beam
• Above the neutral axis
Full wrap sling option
C
T
NANA
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Copyright © 2017 American Wood Council26
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 1
POLLING QUESTION
3. Which of the following can potentially initiate tension perpendicular to grain in wood?a) Notches
b) Small diameter fasteners
c) Hanging loads
d) All of the above
e) a) and c)
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 2
CONNECTION SERVICEABILITY
Bristlecone Pine
Giant Sequoia Western Juniper
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Copyright © 2017 American Wood Council27
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 3
CONNECTING WOOD - PHILOSOPHY
Wood, like other hygroscopic materials, moves in varying environments
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 4
MOISTURE CHANGES IN WOOD
Causes dimensional changes perpendicular to grain
Growing tree is filled with water
As wood dries, it shrinksperp. to grain
Tang
entia
lly
Radially
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Copyright © 2017 American Wood Council28
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 5
WOOD SHRINKS
Woodmagazine.com
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 6
CONNECTION SERVICEABILITY
Moisture Effects
1% change in dimension for
every 4% change MC
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Copyright © 2017 American Wood Council29
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 7
WET SERVICE FACTOR, CM
• Dowel-type connectors• bolts• drift pins• drift bolts• lag screws• wood screws• nails
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
Saturated
19% MC
Dryfabrication MCin-service MC
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 8
WET SERVICE FACTOR, CM
CM 0.4 Lateral load (D>1/4″)
CM = 1.0 if:1 fastener
2+ fasteners
split splice plates
Saturated
19% MC
Dry
fabrication MCin-service MC Table 10.3.3 footnote 2
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Copyright © 2017 American Wood Council30
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 5 9
CONNECTION SERVICEABILITY
Issue: direct water ingress
• Water is absorbed most quickly through wood end grain
No end caps or flashing
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 0
CONNECTION SERVICEABILITY
Issue: direct water ingress
• Re-direct the water flow around the connection
end caps and flashing
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Copyright © 2017 American Wood Council31
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 1
CONNECTION SERVICEABILITY
Issue: direct water ingress
Or, let water out if it gets in...
Moisture trap -No weep holes
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 2
BEAM TO COLUMN
Full-depth side plates
• may cause splitting
• wood shrinkage
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Copyright © 2017 American Wood Council32
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 3
BEAM TO COLUMN
Smaller side plates
• transmit force
• allow wood movement
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 4
BEAM TO COLUMN
Problem
• shrinkage
• tension perp
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Copyright © 2017 American Wood Council33
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 5
BEAM TO COLUMN
Problem
• shrinkage
• tension perp
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 6
BEAM TO WALL
Solution
• bolts near bottom
• minimizes effect of shrinkage
Slotted hardware
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Copyright © 2017 American Wood Council34
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 7
CONNECTION SERVICEABILITY
Beam on Shelf
• prevent contact with concrete
• provide lateral resistance and uplift
Avoid contact with cementitious materials
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 8
BEAM TO CONCRETE
Beam on Wall
• prevent contact with concrete
• provide lateral resistance and uplift
• slotted to allow longitudinal movement
• typical for sloped beam
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Copyright © 2017 American Wood Council35
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 6 9
BEAM TO MASONRY
Need 1/2” air gap between wood and masonry
• Application
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 0
COLUMN TO BASE
Problem
• no weep holes in closed shoe
• moisture entrapped
• decay can result
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Copyright © 2017 American Wood Council36
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 1
COLUMN TO BASE
Angle brackets
• anchor bolts in brackets
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 2
HIDDEN COLUMN BASE
Floor slab poured over connection
• will cause decay
• not recommended
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Copyright © 2017 American Wood Council37
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 3
COLUMN TO BASE
Floor slab poured below connection
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 4
POLLING QUESTION
4. Good design practice of connections for wood should consider which of the following:a) Use small diameter fasteners
b) Stagger closely spaced fasteners
c) Avoid direct contact with concrete or masonry
d) Avoid tension perpendicular to grain
e) All of the above
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Copyright © 2017 American Wood Council38
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 5
CH 4 –CONCRETE OR MASONRY WALL ANCHORAGE
• 4.1.5.1 Anchorage of Concrete or Masonry Walls to Diaphragm• SDC C, D, E, or F
New
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CH 4 –CONCRETE OR MASONRY WALL ANCHORAGE
Source: APA
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Copyright © 2017 American Wood Council39
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 7
IRREGULARITY
Reentrant Corner
Collector
Colle
ctor
C o r nu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 8
IRREGULARITY
Collector forces likely comply with exception per ASCE Sec. 12.10.2.1
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Copyright © 2017 American Wood Council40
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 7 9
CHAPTER 4 - LATERAL FORCE-RESISTING SYSTEMS
• Wood Diaphragms
Anchor bolting of ledger: Design for 25% more shear
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CH 4 –CONCRETE OR MASONRY WALL ANCHORAGE
Wood Diaphragms
Collector beam
Boundary nail (B.N.) diaphragm NOT subject to 25% increase
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Copyright © 2017 American Wood Council41
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 1
IRREGULARITY
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 2
EXCEPTION TO OVERSTRENGTH
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EXCEPTION TO OVERSTRENGTH
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 4
POLLING QUESTION
5. Increase in forces due to Irregularities for SDC D‐F structures apply to the diaphragm nailing.
FalseTrue or
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Copyright © 2017 American Wood Council43
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 5
SHEAR WALL - PARTS
Five parts of a shear wall
wood frame
wood structural
panels wood frame
nails
plate anchors
hold downs
2
13
5
4
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 6
SHEAR WALL TEST
8 ft x 8 ft wood structural panel shear wall cyclic test
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Copyright © 2017 American Wood Council44
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 7
SHEAR WALL TEST
Typical failure of sheathing nailing
a) Nail yielding at ad-joining panel edge b) Nail yielding and head pull through
at panel to bottom plate location
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 8
SHEAR WALL 3X REQUIREMENTS
88
At adjoining panel edges
Sill plate
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Copyright © 2017 American Wood Council45
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 8 9
CONNECTING WOOD- PHILOSOPHY
Splitting happens because wood is relatively weak perpendicular to grain
Nails too close (act like a wedge)
Cornu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9 0Nailing not staggered Nailing staggered
Framing
Wood Structural
Panel
Nail
1/8" GapBetween Panels
Nailing not staggered Nailing staggered
STAGGERED NAILING
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Copyright © 2017 American Wood Council46
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9 1
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
CONNECTING WOOD- PHILOSOPHY
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9 2
CH. 4 - SHEAR WALLS SHEATHED ON 2 SIDES
Provisions for shear walls sheathed on two sides •Table 4.3A Footnote 6
6. Where panels are applied on both faces of a shear wall and nail spacing is less than 6" on center on either side, panel joints shall be offset to fall on different framing members. Alternatively, the width of the nailed face of framing members shall be 3" nominal or greater at adjoining panel edges and nails at all panel edges shall be staggered.
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Copyright © 2017 American Wood Council47
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9 3
CH. 4 - SHEAR WALLS SHEATHED ON 2 SIDESAdjoining Panel Edge Details
Co rnu cop i a o f C l a s s i c Conne c t i o n Conund r ums 9 4
CHAPTER 4 – CONSTRUCTION REQUIREMENTS
NEW
4.3.6.1.1 Common Framing Members• 2-2x permitted to replace 3x
• Fastened together per NDS• Spacing <4” o.c. shall be
staggered• Applies broadly to all framing
4.3.7 Shear Wall Systems• 2-2x permitted to replace 3x
• Wood Structural Panels (4.3.7.1(5))• Particleboard (4.3.7.3(5))
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(2) 2X AT ADJOINING PANEL EDGES
95
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(2) 2X AT ADJOINING PANEL EDGES
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3X AT ADJOINING PANEL EDGE
Section 4.3.7.1(4). 3x framing also required at adjoining panel edges where:
• Nail spacing of 2 in. o.c.
• 10d common nails having penetration of more than 1-1/2 in. at 3 in. o.c. or less
• Nominal unit shear capacity on either side exceeds 700 plf in SDC D, E, or F
Exception: (2) 2x framing permitted in lieu of (1) 3x where fastened in accordance with the NDS to transfer the induced shear between members.
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(2) 2X AT ADJOINING PANEL EDGE
Fastener spacing – 2x stud to 2x stud connection
3”
Approximate stud to stud connection spacing for wood structural panel (WSP) walls sheathed on one side.
* Spacing based on 8’ wall and assuming only 87.5” of stud height available for stud-to-stud fastening.
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FOUNDATION BOTTOM PLATE
Plate washer:
Must extend to within ½ in. of sheathed edge of bottom plate
Exceptions:
Lower capacity sheathing materials (nominal unit shear is 400 plf or less)
Hold-downs are sized for full overturning – neglecting dead load
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FOUNDATION BOTTOM PLATE –TESTING
Failure Mode?
Small scale test specimen to induce cross grain bending
Mode A
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FOUNDATION BOTTOM PLATE – TESTING
Mode A and Mode B observed in small specimen testing
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FOUNDATION BOTTOM PLATE –TESTING
Failure Mode?
Small scale test specimen to induce cross grain bending
Mode BMode A
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FOUNDATION BOTTOM PLATE – TESTING
View of bottom plate after test.
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FOUNDATION BOTTOM PLATE – TESTING
View of bottom plate after test.Shear wall assembly in test fixture
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CHAPTER 4 - SHEAR WALL ANCHORAGE – 3”X3” DEFAULT
Shear wall anchorage provisions at foundation – Section 4.3.6.4.3
3" x 3" x 0.229" steel
slotted hole permitted
placed within ½" of sheathing material
automatically satisfied for 2x4 plate
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Shear wall anchorage provisions at foundation – Section 4.3.6.4.3
• Exception: Standard cut washers permitted• Anchor bolts designed to resist shear only
• Hold downs designed for uplift neglecting DL
• Aspect ratio < 2:1
• Limited nominal shear wall capacities• < 980 plf seismic
• < 1370 plf wind
CHAPTER 4 - SHEAR WALL ANCHORAGE – 3”X3” DEFAULT
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2018 NDS
• References ASCE 7-16• Wind Uplift Loads Increase• Change in Out-of-plane wind loads on roof• New equation for withdrawal design values for
smooth shank stainless steel nails• New provisions for Roof Sheathing Ring Shank
nails in accordance with ASTM F 1667• New design provisions for fastener head pull-thr
ough of fasteners with round heads• Revision to method for calculating of lateral desi
gn values for threaded nails in accordance with ASTM F 1575
• Revised timber rivet design value tables• Revised terminology for Fire Design of Wood
Members• Changes to the NDS Supplement
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RAILING DETAIL
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RAILING DETAIL
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COLUMN TO BASE
Column on pedestal
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COLUMN TO BASE
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COLUMN TO BASE
Column on pedestal
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POLLING QUESTION
6. Square plate washers may be omitted when:
a) Anchor bolts are designed to resist uplift
b) Hold downs designed for uplift neglecting DL
c) Aspect ratio is greater than 2:1
d) The shear capacity is > 1400plf
e) All of the above
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MORE INFO???
NDShttp://awc.org/codes-standards/publications/nds-2015
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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
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MORE INFO. - LEDGER CONNECTION
DCA 6 Prescriptive Residential Deck Construction Guide http://awc.org/codes-standards/publications/dca6
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