Crane runway beam with channel cap on W-beam 2

[tnteng]

I am trying to select an appropriate W-beam and channel cap for a runway beam that is to support an under running bridge crane. The channel cap is to be on top of the W-beam. I am using the AISC ASD code and I am having problems with what value to use for "bf" in formula F1-2. Would "bf" be the width of the channel flange or the width of the W-beam flange? Am I correct in assuming that "Af" in that formula would be the sum of the area of one flange of the W-beam and the area of the web of the channel.

Also in section B.5.1, on the check for compact or non-compact section, b/t is compared to 65/sqrt(Fy). What value of "b" & "t" should be used in this case with the composite section?

Thanks in advance for any help with this problem.

Tony Billeaud
Mechanical Engineer

 

[271828]

Can you switch to the 13th Edition Spec.? Section F4 is more applicable than the old 89 ASD stuff.

As for flange compactness, the compression (top) flange is a stiffened element in this case because it's connected to the channel. Using 65/Sqrt() is very conservative. The bottom line is that standard W-shapes are almost always compact using 65/Sqrt(), so are waaay compact when stiffened.

 

[dik]

Check the AISC site for an excel spreadsheet to use as a guide for this...

Dik