Monorail attachment

[tebodm]

I am designing a replacement monorail at a papermill, the rail will support a trolley on the bottom flange and will be a multi-span beam. I have the rail sized at S24x90 for a 15T capacity. My question is, should the rail be bolted directly to the bottom flange of the roof beams which are at 6' o.c. or hung with a bracket from the bottom flange of the roof steel? Existing rail has a bracket hanger style connection. The existing monorail is only 10T so we are reinforcing the existing roof steel to achieve the higher rating on the new rail.

 

[TehMightyEngineer]

I personally prefer connecting them directly but only if the roof beams bottom flanges are all the same height.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[Ron]

If I understand your terminology correctly, the current 10T rail is hanging from the "roof steel" (presumably purlins or open web joists). The roof beams that support the roof steel are likely better to take the additional load than the "roof steel". Further, the roof beams obtain additional lateral bracing by the rail. Spend your time reinforcing the roof beams, not the roof steel.

I would also attach to the roof beams with the same caveat. If not at the same level, then weld supplementary adjustments for height differences to the roof beam (can take on a variety of configurations, depending on load and weld orientation for fatigue).