Key Connection Design Considerations - WoodSolutions · KEY CONNECTION DESIGN CONSIDERATIONS ... - Stick frame, Bearers, Joists and Rafters –minimal connection design Unique architectural

Nathan BenbowBE (Hons.) MIEAust

[email protected]

KEY CONNECTION DESIGN

CONSIDERATIONS

• 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 -

Nathan BenbowBE (Hons.) MIEAust

[email protected]

THANK YOU