Prying Action 1

[ben3929]

I am working on a project to design a bolt connection for wide flange beam seating on HSS column (cap plate). While checking the prying action on the beam flange I got a result that the minimum required thickness is twice greater than beam flange thickness. There is no room to put in additional bolts to my connection. Would it be okay if I weld a plate to the beam bottom flange to increase the thickness. Plate weld will be only at the connection area not through out the beam length.

 

[ToadJones]

post a sketch

 

[ben3929]

for reference see attached sketch

 

[StrPE]

Bill Thornton developed a method of reinforcing connection thickness' for prying action by adding reinforcing plates. Go to the link below and download the paper. Then go to page 167 where you'll find his procedure.

http://www.scribd.com/doc/42305267/Structural-Connections-Thornton-Kane

 

[hokie66]

The doubler plate may solve the prying problem, but would not help in developing significant moment into the beam. Vertical stiffeners in the beam would tend to address both issues.

 

[ToadJones]

can I ask what this connection is on?

It looks like a crane runway girder.

Anyway, I agree with hokie.

This connection should have a pair of stiffeners. It looks to be an "unframed end" of beam in which case I believe AISC requires stiffeners for rotation anyway.


Rotational Restraint at Support

AISC Specification Section J10.7 requires full-depth stiffeners at the “unframed ends of beams and girders.” What does this mean? Would an example be a girder bearing on a column with no beam framing into it at the column?
Answer

Yes, this section addresses situations such as the end of a beam that bears on column cap plate. Unless the column top is restrained, the beam might twist or the web might distort, allowing the bottom flange to move transversely. This creates a dangerous situation, because the column below was designed assuming a pinned-pinned condition with its top is restrained against lateral displacement. If a brace is provided to restrain the top of the column, the beam end is framed. If not, stiffeners can be used as required in Section J10.7. Note that the concern for column stability also exists when girders frame continuously over the top of the column. See Section 2 of the 13th edition AISC Steel Construction Manual for further information.

Brad Davis, Ph.D., S.E.

http://www.modernsteel.com/steelinterchange_details.php?id=819

 

[ben3929]

Thanks for the responds.
Perhaps I didn't show the stiffeners on my sketch. Per my calculation web crippling exist at support locations and I added a pair of transverse stiffeners to support the web.