Duct trapeze Support
Duct trapeze Support
(OP)
I'm analyzing some trapeze hanger supports for a 72" diameter duct and I'm not sure about the load distribution from the ducting to the hangers.
The hangers are semi-circular straps, unreinforced, attached to 3/8" hanger rods while the ducting is 12 ga. thick.
Would the duct self-weight be uniformly distributed to the strap, (i.e. combination of cases 12 and 20 from Table 9.2 of Roark, or would the distribution be localized to a few locations on the strap. Is anyone aware of a design guide for these types of supports?
The hangers are semi-circular straps, unreinforced, attached to 3/8" hanger rods while the ducting is 12 ga. thick.
Would the duct self-weight be uniformly distributed to the strap, (i.e. combination of cases 12 and 20 from Table 9.2 of Roark, or would the distribution be localized to a few locations on the strap. Is anyone aware of a design guide for these types of supports?






RE: Duct trapeze Support
Do you need lateral loads as well?
RE: Duct trapeze Support
RE: Duct trapeze Support
cosine dist'n is another ... peak at the bttm of the arc, zero at the diameter) ... possibly a little more real.
yes there would be bending in the duct ... a continuous beam at a support ... you could simplify to two 1/2 bays, cantilevered at the ends with a support.
RE: Duct trapeze Support
RE: Duct trapeze Support
When I mentioned circumferential bending I was referring to the transverse direction (i.e. bending around the duct circumference). I'm not really concerned about longitudinal bending.
RE: Duct trapeze Support
However, the duct will deflect laterally under the load from the strap, so there will bed a point of equilibrium of forces and deflections that determine the actual force pattern.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com