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  1. JStephen

    Wind Load

    There's potentially a bunch of stuff vibrating up there, as well as the overall structure. Why the "half the wind load value"? At 15', if it blows over, that's a bit of hazard. Can an athletic person jump up and grab a hoop?
  2. JStephen

    Coaxiality tolerance for the welded structures

    Tolerance would depend on the application, I assume. You could assume an offset and check resulting moments and stresses in all members to find the effect of tolerance. Perhaps limited by cosmetics, by measuring and fit-up gear available, by tolerances in tube roundness.
  3. JStephen

    Stairway forces on Shell

    I think all of the above. Normally, when I put together a calculation package, I include major items, but there are a lot of little items that I either know don't really need checking or that I have design spreadsheets for but don't include them in the package. There are ways to check stresses...
  4. JStephen

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    A while back, I was checking this on a tank. I tried distributing loads proportional to the deflections and iterating to a solution. Result: A lot of extra work and almost exactly the same frequency. More clarity would definitely be helpful with the way it's presented there, though. For...
  5. JStephen

    Index for 12 page calculations?

    Make each separate line of the calculations a separate entry in the index, so you wind up with a 12-page index?
  6. JStephen

    Shaft Failure in Translation Gear Reducer of Bucket Wheel – Need Help Identifying Cause

    I would not expect them to put a student in charge of analyzing high-dollar failures in expensive equipment, so this sounds a lot like homework...
  7. JStephen

    Leaning Pedestal (Octagonal) Home

    It's a pedestal house, and the small base tilting and being amplified in the whole house makes sense to me. However, there seems to be an entire rectangular section built into it, and then there're posts from the house itself and from the deck. Is all of that stuff tilting uniformly to match...
  8. JStephen

    Convert Gas Oil Tank to unconverted oil product from hydrocracking unit

    Some general items- also see API-653. You are proposing a "change of service": Changes in specific gravity vs shell design, foundation design, seismic design, floating roof design, manway cover design Requirements for floating roofs, internal or external Requirements for venting, emergency...
  9. JStephen

    Machinery supports vs. structural steel

    The last time I checked, a "structure" was defined as "that which is built", so it includes houses, cars, televisions, and kazoos, so not an especially useful definition. In ASCE 7, tanks fall under "non-building structures" (as do silos, pressure vessels, etc) but are still not considered as...
  10. JStephen

    Machinery supports vs. structural steel

    We do tank work. In the AISC Code of Standard Practice, they define "Structural Steel" and that definition specifically excludes "tanks". Generally, as a contractual issue, we'll qualify that anything we furnish that is attached to the tank is defined as part of the tank and designed and welded...
  11. JStephen

    Regarding shell to curb angle welding category and NDT requirement

    r6155, see HTURKAK's quote above, which specifically excludes that weld from radiography.
  12. JStephen

    Regarding shell to curb angle welding category and NDT requirement

    I don't think it's the intention of API-650 to include either the roof plate, compression rings, or top angles in the "permanent attachments" in Section 5.8. IE, they are considered part of the shell or roof, not attachments to the shell or roof.
  13. JStephen

    Cabagan–Santa Maria Bridge collapse

    I ran across a live video of this bridge collapse (doesn't show much, though), and realized it seems to have escaped notice here. Information seems rather fragmentary. This article by surveyors ponders the surveying aspects, although that seems unrelated, but gives basic details...
  14. JStephen

    Weld on a UL tank

    I don't see any picture, so can't comment there. Generally, tanks are welded per ASME rules, not per AWS D1.1. Not that the welding is that not (edited!) much different. But there are some details required by one while prohibited by the other, etc. Where some of that comes from is that the...
  15. JStephen

    What's up with retaining wall footings and details

    Those designs may just come from the significant parts of the US that don't have frost issues.
  16. JStephen

    Flat Plate Bending Weld Stress

    To fit that specific model, you could use b as the full circumference and M as full circumference x moment/in. Or use b as 1" and M as moment/inch, should be the same. If it's a code-related question, refer to the code in question for weld requirements. That model assumes rigid support and...
  17. JStephen

    Shear Connection - Short Slotted Holes in the Connector or the Beam?

    It may depend on what equipment you have available to make those holes. Long ago, at a former employer, they had an ironworker (a machine) that could punch oval holes, but it wasn't set up to punch them in beams, so you'd always put the oval hole in a little clip and then drill any holes in the...
  18. JStephen

    Stamping plans for welded Ibeam building?

    That just sounds like an odd situation all the way around. My advice: Don't design it yourself, find somebody that does a lot of this, and it ought to be 10 times more efficient and avoid all kinds of little detailing/design issues that you'd never think about otherwise. One question to run by...
  19. JStephen

    Ladder Safety Systems

    I believe the system shown in the video is an older style. See the manufacturer's instructions here: .https://multimedia.3m.com/mws/media/1522189O/ifu-5908282-lad-saf-flexible-cable-system.pdf A single-user system applies a dynamic load of 2,700 lbs. This is applied 4.7" from the near edge of...
  20. JStephen

    Forcing function of falling mass

    Small gravel off a conveyor belt- just treat like a liquid impinging on a surface. Large rocks at uniform intervals- (sin(t)+1) to get rid of the negative, or square wave, etc. If you don't know the actual wave shape, go with the simplest.

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