I Beam Reinforcing Question
I Beam Reinforcing Question
(OP)
We built a cart to handle a 35kip heat exchanger. Due to an interference, the construction crew want to modify the cart as shown below. The beam is a W10x30 and they need to remove 6" of the beam for a clearance issue. Obviously solution 1 is to just not do it, but I am seeing if it is feasible at all. Due to the geometry of the cart, the loads in this particular beam are not great, the max. moment is only 72 in-k. My question is about reinforcing the underside of this beam after we cut out most of it. I can take my reinforced section with the plates we intend to add and show that the section modulus of the reinforced section still greatly exceeds that required for the loads and I can take the eccentricity into account for the small axial loads, but my question relates more to how in general to be sure that my new beam section is fully developed and is sharing the load. Is there any guidance for something like this?
Thanks for the help
Thanks for the help






RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies
RE: I Beam Reinforcing Question
This cut is actually two cuts located at each end of the span where the moments are the highest. I don't have it detailed there, but my reinforced section will extend past the cut on each side by ~6" before the taper begins back to the original bottom flange.
Here is the section view I should have included at first
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
If you can make it work, I'd hang another W10 on the bottom flange (along with the stiffeners around the opening). You'd probably have to bolt it because a field weld would probably bring the whole thing down.
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
I don't see any load path for your compression force.
Away from the cut, you have compression in your top flange and tension in your bottom flange.
At your cut, you have compression in your original bottom flange and tension in your reinforcing.
Adjacent to the cut, the tension can "flow" into the reinforcing, but how does the compression "flow" into the bottom original flange? Through the web? That's taking the large area of steel in the original top flange and significantly reducing it / concentrating it through the web.
Why not add a second pair of diagonals, mirroring the geometry of the reinforcing to create this load path. Essentially it would be a kinked beam.
I`m not sure I'd love this approach for heavy loads or where deflection is critical, but for your structure it might be appropriate.
Keep in mind with this "kinked beam" approach, any axial force will create p-delta moments, possibly increasing your 72inkip significantly (or maybe not)
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
* you said the moment is the highest at ends where the cuts would be located - is the beam a fixed end beam? How is it supported??
* if the above is true them you do have a moment at the cut section and you need some continuity of the (tensile) flange that what you propose to add does not provide.
* if the beam is in fact simply supported then you don't have much moment at ends and your concern should be shear which is carried mostly by the web.
I think some more information is needed to see the whole picture of the problem.
A plan view would be helpful also..
RE: I Beam Reinforcing Question
I do indeed have a moment at the cut section, which depending on the direction of travel of the cart could be compression or tensile. My rational currently for my design is that the scab plates I use to frame the opening will be bent about their strong axes as the section tries to open up. Their stiffness will help carry the load into the reinforcing provided on the underside of the beam.
I do not have much concern for shear, I am overlapping my spliced section with the W10 for a sufficient length to take the small shear loads. We can take the "steel is cheap" approach for sure, but I would like to try to put numbers to whatever I end up doing.
RE: I Beam Reinforcing Question
If you don’t fix your sketch..., you don’t deserve another second of our time or our guesses at what you really have and are doing. Either the W10 is about 3' long, as JAE suggests, and your sketch proportions show; or it’s 14' long as you suggest and your sketch is all messed up, and you can’t have it both ways. You would be surprised at what meaningful first impressions an experienced engineer can draw from a well proportioned sketch with a few dimensions, sizes, thicknesses and some loads and their directions, etc. etc. We have no idea how you got your 72 "k moment, how and where it’s applied, how the beam is supported, etc. We can’t see it from here. You want our help, and you are perfectly happy to have us waste our time guessing what you have, all becuase you are to damn lazy to provide a good/meaningful sketch and explanation of your problem. I’m really tired of this kinda crap here on E-Tips. E-Tips is supposed to be about engineers talking to engineers in a meaningful way, not 20 questions for people who can’t define an engineering/technical problem.
RE: I Beam Reinforcing Question
As far as the length, I have answered that question that it is indeed 14' long.
As for the loading, I developed that on my own and did not ask for a second check regarding the loading.
As for the support, I stated above that due to the configuration of the cart this beam is simply supported with an applied moment of 72k-in at each end. They need to cut the beam in two locations and want to reinforce as I have shown.
RE: I Beam Reinforcing Question
Regardless,if there is a flexural moment at the reduced/cut out section then you need to provide some flange continuity. Reinforcing the web is not enough in my opinion.
I know that you have everything else figured out when you're only asking about the reinforcing of the cut out part but if you provided us more detail of your whole set up you would've gotten a much better response. Good luck.
RE: I Beam Reinforcing Question
RE: I Beam Reinforcing Question
A simpler idea is to offset the 14'-0" long W10x30 and add 90 degree jogs at each end as required to meet the supports, but this may introduce more clearance problems of which I am not aware.
BA
RE: I Beam Reinforcing Question
BA
RE: I Beam Reinforcing Question