suspended unit 2

[hello12345hello]

I have one mechanical unit which is suspended from steel roof framing. how to support unit with steel framing. unit weight is 500 lb.
Thank you

 

[JAE]

Not enough detail to help.

 

[hello12345hello]

Mechanical unit is 2ft high and that will fit between ceiling and roof framing. So mechanical unit is suspended from steel framing. do i have use steel hanger at four corners to support this unit.
what is best way to support.

 

[MiketheEngineer]

Are you really an SE. This is easy IF you have ALL the details!!!

Don't forget - two fat boys weigh about 500 lbs.....Not usually a big problem UNLESS it wasn't designed very well or is quite old??

 

[JAE]

Here's a few aspects to this:

1. Yes - mechanical units are usually suspended from roof framing with four threaded rods (size depends on the unit's weight).

2. We typically run a steel angle spanning between the rods. Two angles at either end of the unit to support the unit.

3. The rods can be connected to the roof framing in various ways - depends on the type of roof.

4. Your design checks:
a) Angle size required to span between rods.
b) Rod diameter required to support the load.
c) Rod fastening system at the roof members.
d) Check roof members for overall loading of the unit (shear, flexure, connection to other supports).
e) Check local problems with the rod concentrated load on the roof members (i.e. steel joist bottom chord bending)
f) Design required lateral braces if required due to seismic area.
g) Check deflection of roof under new load - ponding/drainage now an issue?

 

[wannabeSE]

Also, braces are required when there are any seismic loads. If spring hangers are needed for vibration isolation (often specified for fan coil units), splayed cable braces are typically used because rigid braces defeat the vibration isolation. With braces, the hangers can see compression and threaded rod hangers typically need stiifenrs to reduce the unbraced length. The stiffener may be an angle or strut (unistrut, powerstrut, etc.) with clamps made specifically for this purpose.

Hanging small mechanical equipment is similar to trapezes for pipes. There are a number of companies that provide information and details for trapezes (Unistrut, Powerstrut, B-Line, Tolco, Mason Industiries, etc.).