Prying Action 2

[wale01]

I have a situation where I have a typical beam that rests on top of a steel tube column. The column has a 1" plate and connects to the beam by 4 bolts (the old typical connection). I have a significant uplift on this connection. About 33 kips worth. I'm well aware the of the effects of the prying on the bolts. Is there any way I can avoid prying by increasing stiffness and lowering deformation? If so, how can this be determined? Also, do these bolts need to be pretensionsed or is snug tight sufficient? It will not be cyclic loading. Thanks for your help.

 

[samdamon]

Wale- If this is a new conn that hasn't been fabricated yet, you can eliminate prying forces by adjusting the top plate thickness. Solve for "tc" per formula on AISC ninth ed page 4-90, setting B=(uplift tension force per bolt)=33k/4. Also, imho snug tight bolts are sufficient. Regards

 

[WillisV]

In this case where the uplift appears to be coming from the beam which I assume is bolted through the flanges to the column cap plate, it is actually the beam flanges that are the controlling elements for prying action. Putting half-depth stiffeners on the lower half of the beam at the connection (web and flange welded) would most likely eliminate the prying action concern by stiffening the lower flanges against deforming.

 

[wale01]

Thanks for the help. That's exactly what I needed.

Willisv: I have full height stiffeners in the connection for what you just stated and for some other things I have going on. Thanks again.