Composite floor plan 2

[shin25]

Attached is a part of a composite floor plan. The particular span is about 27' long. I am trying to evaluate the load carrying capacity of this span.

Reading the plans, I see, beside beam designations few more numbers- (14) and V25 (I have clouded the numbers). I presume, 14 is the total number of studs and V25 is the end reaction. but, seems that the total number of studs is awefully less for a full composite action. Can anyone confirm?

thanks in advance.

 

[civilperson]

See sheet S2.G1 for plan notes. Hopefully a legend will also be there.

 

[shin25]

I do not have access to this drawing. Any other thoughts?

 

[COEngineeer]

It must be the number of studs. How many inches of concrete is it?

Never, but never question engineer's judgement

 

[shin25]

its, 3 1/2" LWC over 2"-18 gage metal deck. That is total 5 1/2" thick floor.

 

[lkjh345]

What is the deck composed of? (Deck height, concrete thhickness)?

Composite beams are routinely designed for less than 100% composite action. 25% is the minimum, but there is no requirement to go to 100% of composite action.

Assuming the 'V' number is the shear, you have approximately 1.85 kip/ft of load (50k total reaction/27 long).

For kicks I ran the problem assuming 3" deck with 3" concrete (6" total thhickness) and 850 PLF dead load and 1 K/ft LL, and lo and behold, I get a W16x26 with 14 - 3/4 dia x 5" studs. This assumes 50 ksi steel in the beam.

So, it may be fairly reasonably depending on the deck size and concrete cover.

May have made a mistake, as I went threough this fairly quickly, but off the top, it does not seem unreasonable.

 

[lkjh345]

Your post with the deck section came through as I was typing my response above.

If the concrete fill is lightweight, then yes, the stud # does look suspiciously low. I would get 22 studs with the deck configuration you list above, and the rest of my assumptions shown above.

 

[shin25]

Thanks Ikj. I think, the number of studs are even less to resist the uplift of the deck. The ribs are perpendicular to span.

 

[jike]

I roughed some numbers out and it appears that it was designed for partial composite action which is not at all unusual for commercial construction. We do this all the time.