fifteen butting mechanical third-elements wood construction: - PowerPoint PPT Presentation

E LEMENTS OF A RCHITECTURAL S TRUCTURES : Connectors F ORM, B EHAVIOR, AND D ESIGN ARCH 614 • joining D R. A NNE N ICHOLS – lapping S PRING 2019 – interlocking lecture fifteen – butting • mechanical – “ third-elements ” wood construction: • transfer load at a point, line or surface connections – generally more than a point due to stresses Wood Connections 1 Elements of Architectural Structures S2009abn Wood Connections 2 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 Wood Connections Wood Connectors • mechanical • 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 4 Elements of Architectural Structures S2007abn Wood Connections 3 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 1

Bolted Joints Tension Members • • members with holes have reduced area connected members in tension cause shear stress   • increased tension stress P T    f or   • A e is effective net area t   A A e e • connected members in compression cause bearing stress Wood Connections 5 Elements of Architectural Structures S2007abn Wood Connections 6 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 Effective Net Area Single Shear • • likely path to “ rip ” across seen when 2 members are connected • bolts divide transferred force too P P   f  v 2 A d 4 Wood Connections 8 Elements of Architectural Structures S2007abn Wood Connections 7 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 2

Double Shear Bearing Stress • • seen when 3 members are connected compression & contact • stress limited      P F 0 P 2 ( ) F= 2 by species & grain direction to load • projected area P P P 2 2    P P f    v f 2 A A 2 d p 4 A td projected Wood Connections 9 Elements of Architectural Structures S2007abn Wood Connections 10 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 Bolted Joints Nailed Joints • twisting • tension stress (pullout) • shear stress nails presumed to share load by distance from centroid of nail pattern www.timber.org.au • tear out – shear strength – end distance & spacing Taylor & Line 2002 Wood Connections 11 Elements of Architectural Structures S2007abn Wood Connections 12 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 3

Nailed Joints Connectors Resisting Beam Shear • sized by pennyweight units / length • plates with p • embedment length – nails p y p 8” – rivets • dense wood, more capacity 2” 4.43” 4” x y a – bolts 2” *NDS 12” • splices V VQ  longitudin al • V from beam load p I related to V longitudinal VQ   connected area nF p connector I Wood Connections 13 Elements of Architectural Structures S2007abn Wood Connections 14 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 Lecture 15 ARCH 614 Vertical Connectors • isolate an area with vertical interfaces VQ p   connected area nF p p connector p I Wood Connections 15 Elements of Architectural Structures S2007abn Lecture 15 ARCH 614 4