Unistrut Connection Capacity for General Fittings

[MMinGRB]

I am putting together some drawings for a multi-discipline utility rack and I'm using Unistrut tracks and fittings. Their engineering catalog shows beam and column capacities for their tracks and a handful of fitting capacities, but I'm finding a lot of gaps in their published load tables. So, I have the following questions:
- There are no tabulated load capacities for a P1000/P1001 in tension. Would it be accurate to use the area of the section and 42ksi steel to calculate it myself? Or, is it generally known that the tension capacity of the track is far greater than the "Resistance to Slip" capacity of 1- or 2-bolts so it's common to assume the connection capacity will govern?
- There are no tabulated load capacities for any of the flat plate fittings like P2325/P1066/P1941. Similar to the tension capacities of the track, is it common to calculate the capacity of the fitting or simply assume the "Resistance to Slip" values govern?
- There are no tabulated load capacities for "Tetris" shaped fittings like P1821/P1823/P1034. Can I assume that they have the same capacity as the P1026 shown in the "Design Load Data for Typical Unistrut Channel Connections" table?
- The tabulated values for a P1026 (seat) @ 1,500# vs P1026 (hanger) @ 1,000# vs P1068 (seat) @ 500# are all very different even though they have a similar "Force at distance X". I understand that these capacities are directly from testing with a safety factor of 2.5, but this leaves me with no established path forward for determining the capacity of other 90deg angle fittings or wing shape fittings. Do I review my assemblies on a case-by-case basis and determine which tabulated condition best matches my situation? My assumption here is that the simple fittings in the table would be conservative since they have less steel and fewer strain-hardened bends.

I'm certain I will have more questions as I go through this process, but I think these will cover the general design strategy.

Thanks!

Michael

 

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At the risk of an 'unhelpful' answer, speak to the Unistrut supplier re. capacities for their items.

 

[Teguci]

- For tension use AISI. Ag x Fy / Omega-y or An x Fu / Omega-r. Omega-y = 1.67 and Omega-r = 2.0. Rupture for P1000/1 will always control since Fy due to cold working on the section = Fu (45 ksi). Of course you should never come anywhere close to this since tension on the full section will never control under a good design.
- For 1/4" A36 fittings, consider your loads and directions and calculate the plate capacities accordingly. I recommend not using catalog numbers for these since you have no documentation for how the elements were loaded under the tests (simple, partial/full moment, laterally braced, ...). Do consider bolt capacities though (especially with any prying action) and torsion resistance from a bolt = 0. You are a structural engineer therefore you've designed 1/4" plate steel before.

Do use the catalog for beam clamps. For back to back welded strut, the welds should be good for an allowable 745 lbs/in at the interface (working backwards from the catalog numbers).