Design of platforms in an industrial building.
Design of platforms in an industrial building.
(OP)
I'm looking into designing a several steel platforms in an industrial building. Since it's not part of the superstructure it should be considered a non-building structure, correct? The platforms support hoppers and have monorails on them to transfer one ton bags of a powder chemical. Chapter 15 of AISC has it's own requirements for non-building structures, so seismic detailing will still be required and satisfied.






RE: Design of platforms in an industrial building.
I'm more familiar with the Canadian code but the seismic forces for non-structural components tend to be higher than those derived from the equivalent static shear method (energy dissipation due to ductility etc is not accounted for). You will be designing for higher forces if you assume them to be non structural.
RE: Design of platforms in an industrial building.
Mike McCann, PE, SE (WA)
RE: Design of platforms in an industrial building.
Depending on what they're connected to, I'd likely just attack this as ordinary frames. A little bit of extra steel in an industrial setting isn't a bad thing, plus usually you'll have a lot of extra lateral capacity in platform structures just from the necessity of hitting slenderness on braces and minimum number of bolts. As long as your connections don't get stupid, it's normally fine.
In your instance, though, this may not be applicable given that you have material storage and a crane. Your seismic load is significantly higher than in the usual industrial access platform. It's worth having a think about the R factors, though, to see if you're actually saving steel or labour with the extra detailing requirements.
Naggud, in ASCE 7 they have separated things into building structures, non-building structures similar to buildings (for non-buildings that are basically framed structures) and non-building structures not similar to buildings (big tanks, stacks, things like that). Then on top of that they have the non-structural component section. They're all reasonably big. The non-building structures sections basically reference the building structures section with a bunch of different assumptions, R factors and other requirements.
That's in comparison to the NBCC, which basically has one section that tells you how to do it for buildings, a couple of clauses that say you should come up with something similar if you've got a structure mostly analogous to a building, and then a couple of clauses about non-structural components.
They've both got their own quirks.
RE: Design of platforms in an industrial building.
http://www.structurearchives.org/article.aspx?arti...
RE: Design of platforms in an industrial building.
RE: Design of platforms in an industrial building.
RE: Design of platforms in an industrial building.
Thanks
RE: Design of platforms in an industrial building.
The AISC Code of Standard practice section 2.2 list "other steel" that is exempted from being classified as "structural steel". Catwalks, stairs, ladders, etc. are "other steel".
Faith is taking the first step even when you can't see the whole staircase. -MLK
RE: Design of platforms in an industrial building.
Maine EIT, Civil/Structural.
RE: Design of platforms in an industrial building.
In your case, use chapter 15 for your design. If you have a braced frame system, use R=1 to exempt yourself from using the seismic design manual (AISC 341). Similarly, for a moment frame, use R=1.5 for this exemption. This is similar to the R=3 exemption for normal buildings. The main benefit from this is not having to design the connections for the capacity of the members. With industrial applications, you want everything to be oversized (you can imagine how everything is a target for someone on a forklift). So, you oversize the members, but now you don't have to design a huge, expensive connection to correspond. Talk to any millwright and they will tell you the bigger the better. That is the mill mentality.
The live load to use as a seismic component is up to your judgment. You may find that the member sizes you are specifying are large enough that it won't make much difference. Good luck.
RE: Design of platforms in an industrial building.