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Masonry on W section

Masonry on W section

Masonry on W section

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.


RE: Masonry on W section

Its a torsional loading to the WF beam. I guess some people might hand have that but I think its prudent to design for the eccentricity.

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

I would not ignore the eccentricity. Can you add another beam adjacent to it?

RE: Masonry on W section

What's above that vented soffit? If there's a diaphragm up there and the beam is adequately connected, then that could be used to resolve the torsion (driftLimiter mentioned this with the concrete reference, but it could be other materials with sufficient strength, stiffness, and connections as well).

RE: Masonry on W section

Well from the other side I can see half of the beam, so best case, only the top flange is bolted on the diaphragm, that doesn't seems enough to control the torsion..

RE: Masonry on W section

Quote (Simlac450)

only the top flange is bolted on the diaphragm, that doesn't seems enough to control the torsion..

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

alright, I'll check that, thank you y'all, I appreciate

RE: Masonry on W section

Can you close up the section? Add side plates so that there is a box section? It doesn't have to be on both sides.

RE: Masonry on W section

Yes I could do that, and it could be pretty straightforward to evaluate !

RE: Masonry on W section

Creating a box section would probably resolve the beam torsion issue, but in addition, the end connections must be able to resist that torsion.

RE: Masonry on W section

What about something like this...?

RE: Masonry on W section

I think it will change the look too much but if I put the hss somewhere between the flanges I think it could be good solution

RE: Masonry on W section

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

Weld a plate on the side of the W beam to turn it into a fabricated box.

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

Quote (GTCE)

Weld a plate on the side of the W beam to turn it into a fabricated box.

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 get rid of the torsion at the ends, I'd unload the beam (you might need to use some jacks) put on the side plate(s) to make it into a box, then add a new clip angle at the ends to the side plate and brick (using epoxy to anchor to the brick). Carefully unload the jacks, looking for distress.
To analyze, resolve the torsion into a couple.

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