Masonry on W section
Masonry on W section
(OP)
Hi guys, I am currently working on a old building where the owner had some issues with a W beam supporting one storey of masonry (mortar joint start to cracks), the masonry can’t sat directly on the beam so I add some stiffeners at each 16’’ c/c with a L section welded on them, but that will create a moment due to the eccentricity (around 4 kN*m), my W section is a W200x42. From the web to the middle of the brick I have 6 inches, when I evaluate the total stresses in compression I got 560 Mpa which is way above 350MPa (fy) and it seems overkill to increase my W section. One of my colleague suggests to ignore the eccentricity I would like to have your opinion on that.
Thanks
Thanks
RE: Masonry on W section
The beam web stiffener plates will reduce the bending of the beam flange, but do not increase the beams torsional strength.
Not sure what check you ran, it isn't clear to me where there is compression due to this? I would look at the beam shear including the torsion, as well as beam bending stresses. AISC (pardon my americanness) provides equations for member strength for combined bending and torsion. (AISC 360-10 Section H1.2)
Now if the beam is locked into a concrete deck there might be a good load path for the torque to be taken out directly.
We spent a bunch of conversation on this a few months ago. Very similar condition. If I can find it I will post it back here.
RE: Masonry on W section
RE: Masonry on W section
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RE: Masonry on W section
Can't say I agree with you. Draw a section through the beam and then create a free body diagram. See what the beam is resisting and how.
RE: Masonry on W section
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Pay attention to Hokie’s suggestions, they are right on the money. Additionally, you have to unload, untwist, the beam (reduce the stresses) by jacking it up on the loaded side before you do the additional work on it, in place. You shouldn’t normally be welding on a highly stressed beam, because it will just yield even more, due to the heat.
RE: Masonry on W section
W section (or to me, UBs) are often used with a plate on the underside but I can rarely ever justify them except for on very short spans (so brick arching very much in effect) and with the plate itself also bearing onto the support (so some torsion is taken out).
Edit - missed Jed's post above me
RE: Masonry on W section
That will only work if there is enough torsional resistance at the ends of the beam. Hard to calculate that IMHO.
RE: Masonry on W section
To analyze, resolve the torsion into a couple.