Hello,
My question is whether NEC or other standards prohibit this design choice:
We have an industrial electrical cabinet that receives 480V power from an electrical drop. There is a knife switch disconnect that kills power to the whole cabinet. We would like to be able to disconnect just the...
Hello, I am working on a small to medium-sized automation system, and I am currently writing the commissioning procedures, particularly ones related to functional safety. I am somewhat new to it.
The procedure I have written out is based on some examples I found while searching the internet...
@BrianE22 Thanks for the input. Good to know that it helped. We will be much lower in amplitude than a shaker table, so it might be a solution.
@IRstuff That is an interesting point, didn't think about that at all. This is something we are going to have to access.
Hi, I am working on a project with thin-walled aluminum extrusions (4" x 4" x 1/8" x 6' LG) that are bolted to a large machine that produces a lot of vibration. The concern (not yet proven, but suspected) is that the tubes will act as an acoustic chamber and produce a lot of nuisance noise...
Ingenuity - thanks again for the detailed response. For "option 1", could you confirm how you calculated the 18,000 lbf dead load? I assume it is the beam weight + slab weight, using a typical concrete density. I've included a quick sketch of the beam geometry - would the tributary area be the...
Tomfh/STrctPono, thank you, I appreciate the advice. I seem to have found myself slightly out of my depth with this one. I will try to see if the building plans are available, although the building is quite old - at least part of the building was built in 1903.
I did a global analysis on the overall concrete beam for simple bending. I got a tensile bending stress value of 117 psi. I have to admit my own ignorance (my career so far has mostly involved metal...), I am not sure what to do with that. Based on Ingenuity's post, a conservative assumption for...
Thank you STrctPono for the input. I agree with your concern. When I did my nominal stress analysis on the bolt, I assumed a cantilever length of 2" to be conservative, which I think is about 0.75" longer than the apparent length.
The steel strap is definitely an interesting idea.
One more question - there are two lifting points that have been set up. The concrete condition in the first is very good, no indications. In the second, near the form ties, there is some missing material (much of which has been painted, so it has been that way for some time). This is more of a...
Thank you Ingenuity for the helpful post (your diagram does represent our situation), I appreciate your time, and everyone else for your advice. This helps a lot with our assessment.
Hello, I work in a small R&D lab. Our CTO had our technician set up a lifting point using a concrete beam in the ceiling of our lab (a week when I was out). I would like to validate the strength of this setup to make sure it is safe, since it was done very ad-hoc.
The setup is a 3/4"-10 double...
drbrainsol, thanks for the source.
Does anyone have experience with vacuum drying? I am wondering if ice formation will slow us down. I am also somewhat concerned about the ice expanding in any crevices in the beam.
Thanks for the additional input! A corrosion inhibitor sounds like a good idea, but we have very little access to the beam interior (without being destructive!), which is also divided by a baffle. I will probably seek the advice of a corrosion engineer moving forward.
I wish I could share more...
Thanks all for your replies. This forum is a lifesaver, 10 heads are better than 1.
For our application, a vacuum pump is going to be the best solution, being non-invasive and relatively quick. This is not a road vehicle, and we need very high reliability, so removing all of the moisture will...
Hello,
I am dealing with a sealed, welded box beam (~8" x 8" x 36", 8mm wall thickness, low carbon structural steel) which acts as the backbone of a chassis frame. At some point, some small #6 tapped holes were drilled through the beam to mount a bracket. We have discovered, during a repair...
Hello,
I am dealing with a sealed, welded box beam (~8" x 8" x 36", 8mm wall thickness, low carbon structural steel) which acts as the backbone of a chassis frame. At some point, some small #6 tapped holes were drilled through the beam to mount a bracket. We have discovered, during a repair...
KootK:
What do you mean by "assuming that plane section remains plane". Are you referring to the cross section relative to the NA? Why would it be out-of-plane? Also, where does shear lag come into play? At the released ends of the tubes?
This is now beyond the scope of my analysis, but it is...
JAE,
Thanks for your reply. My hangup is this - a shape with an equivalent moment of inertia is just the same two tubes, considered as a solid cross section (unlike a stack of rectangular layers, where the MOI of the composite beam is larger than the sum of the layers). Is it possible that the...
