## analysis of calculations

student2 Member
Join Date: Mar 2006
Posts: 15 analysis of calculations

My homework:

Deck size = 16' x 8'
Number of columns = 6, evenly spaced @ 8'
Max Span of beams = 96"
Beams = C4x5.4, A36 steel channel
Permitted Deflection L/360

C4x5.4 Data:

Area = 1.59
Depth = 4"
Web thickness = 0.184
Flange width = 1.584
Support = simple
Moment of Inertia [in(4)] = 3.83
Section Modulus [in(3)] = 1.915
Modulus of Elasticity = 30,000,000psi

Deflection @ center = 0.235 = 96/408 =< L/360

Is this correct?

Thank you
Student2

lefty Member
Join Date: Mar 2000
Location: Arlington, WA
Posts: 8,670
Received 1 Upvote on 1 Post
student2,

I build decks for a living. I don't go through all that!! I simply figure out what spans the building dept. in question will let me use and go from there!! They have handouts that tell you what the inspector is going to be looking for. GO WITH THEM!!

student2 Member
Join Date: Mar 2006
Posts: 15
Thanks, Lefty. I did. The chief building official said if it (C-Channels for beams) is not Code listed, then he wants proof (calculations or engineering approval [\$\$\$]) of equivalent compliance (in this case, with the limiting factor of L/360 deflection).

fredmorrison Member
Join Date: Feb 2005
Location: USA
Posts: 336
Deflection for a simple beam uniformly loaded is:

5/384 x WLLL/EI =
0.013 x 3520 x 96 x 96 x 96 / EI =
0.3523 inches or L/272

You need a stiffer beam. Show Printable Version Email this Page