AISC Hanger-Type Connection Interpretation

[designx1]

My question involves an interpretation of AISC’s hanger-type connections. When faced with a situation where one has a tee flange with only two bolt holes, what value would you use for the “p” variable as indicated on p4-90? AISC defines this variable as the “Length of flange, parallel to stem or leg, tributary to each bolt”. The tees we fabricate are comprised of two welded plates, and to date I’ve been sizing the bolting flange plate thickness using a simple beam analysis with a conservative factor of safety to account for prying forces. I know I’m covered, but I want to get a more optimized connection. So would this distance just be the overall length of the flange or the distance from the bolt hole to edge of plate (parallel to the stem)? When using the latter (half the flange length) for “p” with AISC equations to arrive at treq’d, I get a result somewhat consistent with my own figures. Any insight is appreciated.

 

[WillisV]

Full flange width.

 

[miecz]

WillisV

Do you mean that "p" is limited to the width of the flange (b_f)? It seems as though there should be some upper limit to the tributary length, but I've never seen one.

 

[jike]

We limit p to a maximum of g. This gives a 45 degree distribution.

 

[WillisV]

agree with jike, though it is not required by code, it is recommended to limit p to the gage of the bolts.

 

[miecz]

Example 31 on sheet 4-92 (AISC 9th Ed.) has "p" of 4.5 inches, and a bolt gage of 4 inches.

 

[WillisV]

again...not required..just recommended...AISC 13th ed. p9-11 "p=tributary length per pair of bolts for a teel or angle.....which should PREFERABLY not exceed the gage between the pair of bolts"