Prying with stiffeners??

[cjkelly83]

I have a connection design which is effectively a beam with welded end plate connecting to a column column by a 4 bolt group which is set within the beam flanges.

I have two questions relating to prying in this connection.

1 - Do I have to consider prying of the end plate?
2 - If I add full depth web stiffeners to the column do i still check it for prying and if so how?

From the literature I've read it only takes account of unstiffened flanges and makes no comment on stiffened flanges.

 

[DaveAtkins]

If you follow the AISC Steel Construction Manual guidelines for designing end plate connections, it will be considered a pinned connection, and prying will not occur. This is for shear.

If you have an axial tension in the beam, then you would need to do a prying check.

Column web stiffeners will not help with prying of the beam end connection.

DaveAtkins

 

[Leftwow]

Best thing is to refer to AISC Design Guide 16 -Flush and extended multiple Row Moment End Plate Connections and see if you meet the criteria needed for prying. After going through this, they do check for prying, but just check to make sure you meet the criteria, because I don't understand how your stiffener plates are placed.

 

[DaveAtkins]

With only four bolts in the connection, I assumed it is not a moment connection.

DaveAtkins

 

[DCBII]

There's a 2011 2nd Quarter AISC Engineering Journal article that addresses this exact subject. It's titled "A Yield Line Component Method for Bolted Flange Connections". The "Proposed Design Method" on page 102 of the article is pretty straightforward. Essentially you draw 45 degree yield lines from the bolt outward until you intersect the edge of the plate or the stiffener. Based on whether or not the yield lines are obstructed by the stiffener you adjust the value of "p" in the prying equations. Also, the author recommends using Fy instead of Fu in the prying equations unless large deformations are acceptable. It sounds complicated, but it's actually pretty simple. There are several examples in the article. This procedure works well for instances where the arrangement or loading doesn't fit the standard end plate moment connections.

 

[cjkelly83]

Thankyou very much from the responses, I will get hold of the DG and the journal if i can and see what they say.

I have subsequently found some literature in Butterworths Structural Steelwork Connections under the local out of plane bending of plates supported on more than one side (Sect 7.7.4). It breaks the plate into overlaid cantilevers (2 sides) or a cantilever and an encased beam (3 sides). In it it suggests to check prying for each individual 'virtual' cantilever and use the maximum force calculated. It proposes to neglect the encased beam. Is this a fair enough consideration.

The arrangement is a 'Goalpost' pipe support sitting on top of 2 beams that span existing steelwork. This connection is actually between the foot of the goalpost and the top of the supporting beams. It is a moment connection but only very small, I'd rather consider it as a moment connection than to brace the frame for two reasons. 1 to simplify fabrication and 2 to make it look "right". The frame is only 600mm tall and made out of 203UC. a brace on this will frankly look stupid.

Thanks again for the help.