Beam splice not 90 degrees to flange

[WestLevel]

I have a beam that has a welded center section with a thinner web. The beams are on a 7% slope. The fabricator spliced the beams perpendicular to the horizontal.

Euler-Bernoulli beam theory states plane sections remain plane etc. Perpendicular to neutral axis.

Wondering some opinions on how much you all think this matters for analysis of the beam capacity.

 

[driftLimiter]

What kind of splice are we talking about here?

Is this a plate girder that has welded splices?

 

[WestLevel]

Yes correct.

 

[JoshPlumSE]

Euler-Bernoulli beam theory states plane sections remain plane etc. Perpendicular to neutral axis.

This is an assumption used in the DERIVATION of standard beam theory. There are many cases where this isn't 100% accurate in reality, but where we just accept the results anyway. The question is whether this is significant enough of a difference that it will be unconservative enough to cause issues with the design. I doubt that this would be the case.

I don't have any proof of that. If this really concerned me, I might choose to do an FEM model of the beam using meshed plate elements. Then compare that to what I get if I use just a simple beam.

If I remember correctly, some of the "verification" problems I helped put together for RISA's plate elements, we ran into a problem. I'm talking about concrete shear walls where the plan sections weren't remaining plane. So, the results didn't match the text book hand calculations. More realistically they didn't match close enough for the verification to be a "slam dunk" comparison (like withing less than .2% or so). I believe we put in some "rigid link" members at some locations to force the sections to remain plane at those link locations.... Then voila the results matched the hand calcs perfectly.

 

[WestLevel]

Thanks Josh. My thought was also to mesh it but I dont think I am there yet.

I was going to just take the dimension perp to the flange and call it all the thinner section.

 

[JoshPlumSE]

Yeah, that's totally reasonable The deviation from beam theory should be minimal, IMO.