Lect17 Wood Construction Connections

ARCHITECTURAL STRUCTURES: FORM, BEHAVIOR, AND DESIGN ARCH 331 DR. ANNE NICHOLS FALL 2013 lecture

seventeen

wood construction: connections Wood Connections 1 Lecture 17

Architectural Structures ARCH 331

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Connectors • joining – lapping – interlocking – butting

• mechanical – “third-elements”

• transfer load at a point, line or surface – generally more than a point due to stresses Wood Connections 2 Lecture 17

Architectural Structures ARCH 331

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Wood Connectors • adhesives – used in a controlled environment – can be used with nails

• mechanical – bolts – lag bolts or lag screws – nails – split ring and shear plate connectors – timber rivets

Wood Connections 3 Lecture 17

Architectural Structures ARCH 331

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Wood Connections • mechanical

Wood Connections 4 Lecture 17

Architectural Structures ARCH 331

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Bolted Joints •

connected members in tension cause shear stress

•

connected members in compression cause bearing stress

Wood Connections 5 Lecture 17

Architectural Structures ARCH 331

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Tension Members • members with holes have reduced area • increased tension stress P T  f  or t • Ae is effective net area 

Ae 

Wood Connections 6 Lecture 17

Architectural Structures ARCH 331

  Ae 

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Effective Net Area • likely path to “rip” across • bolts divide transferred force too

Wood Connections 7 Lecture 17

Architectural Structures ARCH 331

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Single Shear •

seen when 2 members are connected

P P fv   2 A d 4 Wood Connections 8 Lecture 17

Architectural Structures ARCH 331

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Double Shear •

seen when 3 members are connected

F  0   P  2( P ) 2

P

P

P fv   2  22 2A A d 4 Wood Connections 9 Lecture 17

Architectural Structures ARCH 331

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Bearing Stress • •

•

compression & contact stress limited F= by species & grain direction to load projected area

fp  Wood Connections 10 Lecture 17

P A projected

P  td

Architectural Structures ARCH 331

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Bolted Joints • twisting

www.timber.org.au

• tear out – shear strength – end distance & spacing Wood Connections 11 Lecture 17

Architectural Structures ARCH 331

Taylor & Line 2002

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Nailed Joints • tension stress (pullout) • shear stress nails presumed to share load by distance from centroid of nail pattern

Wood Connections 12 Lecture 17

Architectural Structures ARCH 331

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Nailed Joints • sized by pennyweight units / length • embedment length • dense wood, more capacity *NDS

Wood Connections 13 Lecture 17

Architectural Structures ARCH 331

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Connectors Resisting Beam Shear • plates with – nails – rivets – bolts

p p

y 8” 4.43” ya

x

2” 4” 2” 12”

• splices • V from beam load related to Vlongitudinal

nFconnector  Wood Connections 14 Lecture 17

p

Architectural Structures ARCH 331

Vlongitudinal p

VQ  I

VQconnected area I

p F2013abn

Vertical Connectors • isolate an area with vertical interfaces

nFconnector 

Wood Connections 15 Lecture 17

VQconnected area I

p

Architectural Structures ARCH 331

p p

p

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