Notching on Beams

NSCP 2001
When rectangular shaped girders, beams or joists are notched at points of supports on the tension side, the horizontal shear stress at such point shall not exceed:
 

$F_v = \dfrac{3V}{2bd'}\left( \dfrac{d}{d'} \right)$

Where

$d$ = total depth of beam
$d'$ = actual depth of beam at notch