As per 6.5.4.3 for sawn lumber, 7.5.7.3 for glulam and 15.3.3.4 for SCL, Sizer compares the factored shear resistance resistance Vr to the applied shear force Vf at a distance equal to the member depth d from the inner edge of each side of each support, which is roughly equivalent to ignoring the effects of loads between that point and the support.
Modified equations at member supports with notches are given for sawn lumber and glulam in subsequent sections of the O86, with different equations for tension side notches and compression side notches, and for the latter, for different lengths of the unsupported length of the notch.
Sizer also identifies the unusual situation where the shear force is at its maximum interior to the span. It issues a screen warning and a note in the Shear Analysis diagram for this circumstances, and designs for the interior shear.
A different procedure using rolling shear resistance is used for CLT; refer to CLT Shear Resistance.
O86 15.3.2.4 is used for I-Joists, for which Vr comes directly from the database for each section.
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