a structures orm, behavior, and design rch 331 r. n …
TRANSCRIPT
Su2014abn Wood Connections 1
Lecture 14
Architectural Structures
ARCH 331
fourteen
wood construction:
connections
lecture
ARCHITECTURAL STRUCTURES:
FORM, BEHAVIOR, AND DESIGN
ARCH 331
DR. ANNE NICHOLS
SUMMER 2014
Su2014abn Wood Connections 2
Lecture 14
Architectural Structures
ARCH 331
Connectors
• joining
– lapping
– interlocking
– butting
• mechanical
– “third-elements”
• transfer load at a point, line or surface
– generally more than a point due to stresses
Su2014abn Wood Connections 3
Lecture 14
Architectural Structures
ARCH 331
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
Su2014abn Wood Connections 4
Lecture 14
Architectural Structures
ARCH 331
Wood Connections
• mechanical
Su2014abn Wood Connections 5
Lecture 14
Architectural Structures
ARCH 331
• connected members in tension cause
shear stress
• connected members in
compression cause
bearing stress
Bolted Joints
Su2014abn Wood Connections 6
Lecture 14
Architectural Structures
ARCH 331
Tension Members
• members with holes have reduced area
• increased tension stress
• Ae is effective net area
ee
tA
Tor
A
Pf
Su2014abn Wood Connections 7
Lecture 14
Architectural Structures
ARCH 331
Effective Net Area
• likely path to “rip” across
• bolts divide transferred force too
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Lecture 14
Architectural Structures
ARCH 331
• seen when 2 members are connected
Single Shear
4
2dv
P
A
Pf
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Lecture 14
Architectural Structures
ARCH 331
• seen when 3 members are connected
Double Shear
4
2
22
2 dv
P
A
P
A
Pf
)2
(20 PPF
Su2014abn Wood Connections 10
Lecture 14
Architectural Structures
ARCH 331
• compression & contact
• stress limited
by species &
grain direction
to load
• projected area
Bearing Stress
td
P
A
Pf
projected
p
F=
Su2014abn Wood Connections 11
Lecture 14
Architectural Structures
ARCH 331
Bolted Joints
• twisting
• tear out
– shear strength
– end distance & spacing Taylor & Line 2002
www.timber.org.au
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Lecture 14
Architectural Structures
ARCH 331
Nailed Joints
• tension stress (pullout)
• shear stress nails presumed to share
load by distance from centroid of nail
pattern
Su2014abn Wood Connections 13
Lecture 14
Architectural Structures
ARCH 331
Nailed Joints
• sized by pennyweight units / length
• embedment length
• dense wood, more capacity
*NDS
Su2014abn Wood Connections 14
Lecture 14
Architectural Structures
ARCH 331
• plates with
– nails
– rivets
– bolts
• splices
• V from beam load
related to Vlongitudinal
Connectors Resisting Beam Shear
x
y
ya
4”
2”
2”
12”
8” p
p p
4.43”
I
VQ
p
V allongitudin
pI
VQnF
areaconnected
connector
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Lecture 14
Architectural Structures
ARCH 331
Vertical Connectors
• isolate an area with vertical interfaces
pI
VQnF
areaconnected
connector
p p
p