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Lumber - Bending - CSA O86
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Lumber size and
orientation
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Lumber
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Width
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b
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=
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in
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mm
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Depth
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d
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=
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in
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mm
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Cross section
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A
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=
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in2
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mm2
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Section modulus
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S
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=
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in3
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mm3
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Moment of inertia
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I
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=
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in4
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mm4
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Wood properties
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Wood species and grade
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Bearing resistance
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Fcp
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=
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psi
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MPa
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Planar shear
resistance
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Fv
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=
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psi
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MPa
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Bending resistance
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Fb
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=
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psi
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MPa
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Modulus of
elasticity
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E
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=
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psi
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MPa
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Deflection
criteria
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Allowable relative deflection
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Allowable absolute
deflection
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Δmax
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=
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in
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mm
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Size of supports
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Support width
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Lcp
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=
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in
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mm
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Support area
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Acp
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=
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in2
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mm2
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Factors
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Load factor
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α
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=
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Resistance factor
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φ
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=
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Resistance factor
(bearing)
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φb
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=
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Load-duration
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KD
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=
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System
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KH
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=
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Service-condition
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Shear
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KSv
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=
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Bending
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KSb
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=
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Bearing
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KScp
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=
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Deflection
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KSE
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=
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Treatment
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KT
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=
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Size factor
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KZv, KZb
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=
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Size factor
(bearing)
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KZcp
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=
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Lateral stability
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KL
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=
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Bearing length
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KB
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=
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Allowable
capacities
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Allowable bearing
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(KD, KScp, KT, KB, KZcp,α,φb)
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B
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=
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lbf
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kN
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Allowable
shear
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(KD, KH, KSv, KT, KZv,α,φ)
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V
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=
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lbf
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kN
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Allowable
moment
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(KD, KH, KSB, KT, KZB, KL,α,φ)
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M
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=
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lbf•ft
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kN•m
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Modulus of
elasticity
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(KSE, KT)
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Ef
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=
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psi
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Mpa
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Bending
stiffness
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(Ef x I)
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EI
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=
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lbf•ft2
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kN•m2
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Allowable loads
(imperial)
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UDL ( PLF )
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Point load (
lbf )
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Span ( ft )
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Criteria
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Single span
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Double span
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Triple span
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Single span
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R
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V
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M
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Δmax
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Allowable loads
(metric)
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UDL ( kN/m )
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Point load (
kN )
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Span ( m )
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Criteria
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Single span
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Double span
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Triple span
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Single span
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R
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V
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M
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Δmax
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Version:
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20260319
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