key connection design considerations - woodsolutions · key connection design considerations ... -...
TRANSCRIPT
• My Journey
• Connection Types
• Design Considerations
• AS1720 vs EC5
• Design Tables/Software
KEY CONNECTION DESIGN
CONSIDERATIONS
MY JOURNEYTIMBER DESIGN DEVELOPMENTSmall residential projects
- AS 1684.1 – Residential timber framed construction- AS 1720.1 – Timber structures- Stick frame, Bearers, Joists and Rafters – minimal connection design
Unique architectural residential projects- Non-standard arrangements- Large spans- Exposed beams- Cassette floors- Detailed connections
MY JOURNEYTIMBER DESIGN DEVELOPMENTMass timber design
- Post and Beam (Glulam)
- Cross Laminated Timber (CLT)- Different connection design- Eurocode 5
MY JOURNEYTIMBER DESIGN DEVELOPMENTMass timber construction
MY JOURNEYTIMBER DESIGN DEVELOPMENTRothoblaas – Rothoschool (Cortaccia, Italy)
- CLT Design
- Connection Design
CONNECTION TYPES
FASTENERSNails
Round nailsSquare nails
SmoothCorrugated
ScrewsCoach screws
Partially threadedFully threaded
Double threaded
BoltsHex head
Carriage/Cup head
Rivets
SCREW REINFORCEMENT
CONNECTION DESIGN
CONSIDERATIONSGrain Orientation
- Side grain- End grain (Avoid if possible!)
Changes in moisture content- Shrinkage/Swelling- Splitting
Density- Greater density = greater strength
Timber species- Unique characteristics
End/Edge distance/Spacing- Fastener group (cumulative stress)
Connection type- Fixed- Pinned
Fire resistance
Serviceability
LOAD PATH (DESIGN ACTIONS)- Crucial to understand the load path
- Loads >> with every additional storey
- What actions are the connectors/fasteners required to resist?
DUCTILITY (SEISMIC)Capacity design (Chain analogy)
- Stiff/brittle timber structural elements
- Ductile steel connections
AS1720 VS EC5Type 1 (Shear) Type 2 (Withdrawal)
AS1720 VS EC5AS1720.1
‘Joint Strength Groups’ based on timber species densities.
Unseasoned: J1-J6 and Seasoned: JD1 – JD6.
AS1720 VS EC5AS1720.1
Tables specify characteristic capacities
AS1720 VS EC5EC5
Shear: - 1st term - Johansen Yield Theory
- 2nd term - Rope effect
Rope effect
AS1720 VS EC5AS1720 – Simplified minimum spacing's, edge and end distances.
AS1720 VS EC5EC5 – Complicated minimum spacings, edge and end distances.
AS1720 VS EC5 – FIRE RESISTANCEEC5 is more detailed but also more complex.
AS1720.4 is very limited in its guidance.
Unprotected connectors:- AS1720.4 assumes fire resistance is negligible
without testing to prove otherwise.
- EC5 makes some allowance for fire resistance for
specific connection types.
Deflection of member during fire: - AS 1720.4 responsibility of designer
- AS 1530.4 Span/30 max.
- Additional deflection/rotation at connection??
AS1720 VS EC5 – FIRE RESISTANCEClad
- Fire resistance plasterboard
- Sacrificial timber
Conceal- Recess connection into timber elements
Provide cover to fasteners- Increase spacings
- Increase end/edge distances
- Plug fixings
AS1720 VS EC5 – FIRE RESISTANCECharring rates
Comparisons of the different models show:- Good agreement above 600kg/m3
- Significant differences below 500kg/m3
EC5 conductive model upper-bound of experimental results
DESIGN GUIDES/TABLES
- Quick way to specify a connection
- Listen to/seek advice from your builders
SOFTWARE
Shear connectors -
Tension hold-downs -
- Joint reinforcement
- Screwed connections
Shear -
Concealed hangers -
Moment connections etc. -
CLT panel lap connections -
CLT panel to beam connections -
CLT floor to wall connections -
Shear connectors -
Tension connectors etc. -
- Bolted splice connections
- Shear connections
- Carpentry connections
- Joist hanger design
- Connector selector
- Anchor design
Roof truss design -
Wall frame design -
Floor truss design -
