Wood Bending Member Shear (fv and the NDS Tension-Side End-Notch Reduction)
The end shear a wood beam carries, and how much a tension-side notch at the support takes away: the un-notched allowable Vr = (2/3) Fv' b d, the notched allowable V' = (2/3) Fv' b dn (dn/d)^2, and the actual stress fv = 3V / (2 b dn) on the net section. A single 2 in notch in a 4x12 cuts the allowable end reaction nearly in half - the reason the NDS penalizes notches on the tension side so hard. A design aid, not a substitute for the engineer of record.
Formula and source
Vr = (2/3) Fv' b d; ratio = dn/d; Vr' = (2/3) Fv' b dn (dn/d)^2; fv = 3V / (2 b dn); dcr = V / Vr'.
NDS 3.4.2 rectangular-section shear stress and the NDS 3.4.3.2 tension-side end-notch reduction, by name; the adjusted shear value comes from the NDS Supplement.
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