the wood products council connection solutions forjoint design, structure magazine ... nails &...
TRANSCRIPT
Connection Solutions for Wood-frame Structures
Presented by: John Buddy Showalter, P.E. Vice President, Technology Transfer
The Wood Products Council is a Registered Provider with
. Credit(s) earned on completion of this program 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 program 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.
Copyright Materials
This presentation is protected by US and International Copyright laws. Reproduction,
distribution, display and use of the presentation without written permission of the speaker is
prohibited.
© American Wood Council 2012
Learning Objectives
At the end of this program, participants will be knowledgeable of:
1. Identify basic wood material properties and learn how to avoid splits, notching, and checking in connection solutions.
2. Recommend fastening guidelines for wood-to-steel, wood-to-concrete, and wood-to-wood connections.
3. Describe effects of moisture on wood connections and implement proper flashing to avoid problems.
4. Identify proper fastener selection in size, scope, and pattern.
initiators: • notches • large diameter fasteners • hanging loads
Split
Full wrap sling option
Split
Split
Load
Displacement
high strength, poor ductility
good strength, good ductility
low strength, good ductility
No end caps or flashing
end caps and flashing
Moisture trap - No weep holes
Saturated
19% MC
Dry 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 only 1.0 0.25 0.25 Withdrawal load - nails & spikes
• Dowel-type connectors • bolts • drift pins • drift bolts • lag screws • wood screws • nails
fabrication MC in-service MC
Saturated
19% MC
Dry CM 0.4 Lateral load (D>1/4″)
fabrication MC in-service MC
CM = 1.0 if:
1 fastener
2+ fasteners
split splice plates
Slotted hardware
Need 1/2 air gap between wood and masonry
www.tfguild.org www.timberframe.org Schmidt, R.J. (2006): Timber Pegs – Considerations for Mortise and Tenon
Joint Design, Structure Magazine, March 2006, NCSEA, 13(3):44-47.
Fastener Values
Included in U.S. design literature Fastener Type Reference Bolts NDS or NER Lag Screws NDS or NER Wood Screws NDS or NER Nails & Spikes NDS or NER Split Ring Connectors NDS Shear Plate Connectors NDS Drift Bolts & Drift Pins NDS Metal Plate Connectors NER Hangers & Framing Anchors NER Staples NER
National Evaluation Reports (NER) are developed for proprietary products
Center-Point Bending Test
Load
• 6 Yield Modes • Single & double shear • Wood-to-wood • Wood-to-Steel • Wood-to-Concrete
I
II
III
IV
Nail Types and Designations
Nail types described in Appendix L
Nail Types and Designations
Nail capacity tables in 2005 NDS
NDS 11.3.4 The length of dowel bearing shall not include the length of the tapered tip of a fastener for fastener penetration lengths less than 10D.
– l– l
shea
r pla
ne
Dr
use Dr
shear plane
Because the induced maximum moment can occur in the threads if the shear plane is not located sufficiently into the shank away from the threads
⊥
⊥
⊥
Group Action Factor, Cg
• Equation method
where:
( )( )[ ] ⎥⎦
⎤⎢⎣
⎡−
+⎥⎦
⎤⎢⎣
⎡
+−++
−=
mR
mmmRnmmC EA
nnEA
n
g 11
111)1(
2
2
ss
mm
mm
ssEA AE
AEAEAER or oflessor the=
12 −−= uum
⎥⎦
⎤⎢⎣
⎡++=
ssmm AEAEsu 112
1 γ
Group Action Factor, Cg
Group Action Factor , Cg
Not applicable here - loads acting along the length of the member are unit loads
Anchor Bolts and Washers as required
Bottom Plate
• Appendix E - 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''
• 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 AFZZZ −
−− ++= '''
'22
Chapter 13 – Timber Rivets 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
Hidden kerf plates
Connections design software
• •
?
This concludes The American Institute of Architects Continuing
Education Systems Course
www.awc.org
Questions?