Yield line Analysis

[Sheila Rose]

I have been confused about the application of yield line on the web of a member. Please help me clear about this issue. Im working on a plan brace connected on a gusset which is directly welded on the beam web. But the brace drop is not located at the center of the beam. Example, on the W12X40 beam with a brace drop of 3in. Is yield line still applicable? Can you help me prove the proceedings with written manuals. Thank you so much.

 

[KootK]

You may find this document useful: Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JoshPlumSE]

There is another paper by Abolitz & Warner (Bending Under Seated Connections) that includes web yielding of a rectangular area subjected to a moment... in case the gusset carries moment as well as axial force.

If the gusset plate is attached to both the beam flange and the web, you might check out formula 4-17 in AISC Design Guide 29 on vertical brace connections.

Note:There is also a "punching shear" aspect to the failure rather than just a yield line aspect.

The next version of the AISC specification should have more information on both concepts.

 

[BAretired]

Yield line theory is applicable but there may be easier ways of dealing with the connection. A sketch might help.

BA

 

[Sheila Rose]

Please see attached file for reference.

 

[BAretired]

Your sketch is by no means clear. Which way is up? Why don't you label the various points a, b, c etc. so that we can refer to yield lines by name? Does the thin rectangle in the middle represent the dimensions of the gusset?

I'm guessing that your gusset runs parallel to the beam flanges. Have you considered running it normal to the flanges and considering its strength in bending rather than worrying about yield line theory? Or alternatively, have you considered using a channel or angle between flanges to connect your brace?

Are you intending to show yield lines with your sketch? If so, I am not at all sure that you have selected the most critical failure mode.

1) The lines along the flanges of the beam are probably closer to simple supports than yield lines because the only resistance to moment in the web would be torsion in the flange.

2) Yield lines running full height of the web do not necessarily occur at right angles to the flanges as you have shown.




BA