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 high strength, poor ductility good strength, good ductility low strength, good ductility Displacement
No end caps or flashing end caps and flashing Moisture trap - No weep holes
Saturated 19% MC fabrication MC in-service MC Dowel-type connectors bolts drift pins drift bolts lag screws wood screws nails Saturated 19% MC fabrication MC in-service MC C M = 1.0 if: 1 fastener 2+ fasteners Dry Dry C M 1.0 0.7 0.4 * Lateral load (*C M =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 C M 0.4 Lateral load (D>1/4 ) 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 shear plane D r use D r 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 shear plane
Group Action Factor, C g Group Action Factor, C g Equation method C g = n m(1 m 2n EA n 2n [( 1+ R m )( 1+ m) 1+ m ] 1 m EA ) 1+ R where: R EA EsAs = the lessor of E A m = u u 2 1 s 1 u = 1+ γ 2 E A m m m m 1 + E A EmA or E A s s s m s Group Action Factor, C g Not applicable here - loads acting along the length of the member are unit loads Bottom Plate Anchor Bolts and Washers as required
Appendix E - Local Stresses in Fastener Groups Appendix E NDS Expressions Net tension: Z ' NT = F A ' t net Row tear-out: Z Z ' RTi ' RT ' = n F ts = n i row i= 1 v Z ' RTi min
Appendix E NDS Expressions Group tear-out Z ' GT Z = ' RT top 2 Z + ' RT bottom 2 ' t + F A group net Note: spacing between outer rows of fasteners paralleling the member on a single splice plate < 5
Chapter 13 Timber Rivets Rivets Steel AISI 1035 Rockwell Hardness C32-39 F u = 145 ksi Hot-dipped galvanized Plates Steel ASTM A36 Hot-dipped galvanized if in wet service
Hidden kerf plates
Connections design software
? Questions? This concludes The American Institute of Architects Continuing Education Systems Course www.awc.org info@awc.org