Beam Deflection w/ Web Opening 1

[SteveGregory]

I have a simple span W21x50 beam with a 20x14 web opening centered between the top and bottom flanges and it is loaded with a uniform load. The AISC Design Guide 2 equations tell me that the beam is fine without any reinforcement.

However, I wanted to check the deflection using STAAD Pro. So modeled the beam with nodes at each end of the opening and one at midspan for the deflection. I used a "prismatic" section for the reduced I and A at the hole:
PRISMATIC
Hole20x14
9.38 897.1 24.9 0 9.38 9.38 20.83 6.53

Does this approach make sense or am I missing something?

 

[SethGuthrie]

So long as the opening is in the center of the beam depth (and we are not talking about composite beam design) then I think using a reduced I (and A) over the width of the opening represents a realistic approach to analyzing the beam for deflection.