Calculate load on pipe supported on multiple points

[vccoffey]

I am planning to use a steel SCH 40 pipe (using this material for cost and availability) to distribute a load across a ceiling. I will attach a 21' stick of pipe to each joist (16" on center; 15 joists). I'm trying to figure out what size pipe I need to buy, and to do this I want to calculate how good of a job the pipe will do distributing the load. So, I want to calculate:

If a load (say, 2000 lb) is placed exactly between two load points ( for symmetry to keep the math simpler we can assume 7 support points on each side of load, at 8" from load, 24", 40", etc.), how much of that load will be applied to the two nearest support points?

Thanks

Vernon

[jboggs]

All of it. Support points beyond the closest one on either side of the load contribute nothing to the support of that load.

[PinkertonD]

7 support points on each side of load, at 8" from load, 24", 40", etc.), how much of that load will be applied to the two nearest support points?

Hi Vernon, welcome to the forum.

Exactly as JB says, the two supports at 8" will be carrying all of the 2000-lb load when using pipe. Pipe is not structural support system and cannot transfer load beyond the first supports.

If you want to distribute the load over multiple support points, then you need to calculate for a beam that will carry the entire 2000-lbs when supported ONLY at the ends and with a very small amount of deflection in the center. Then the load will be distributed over the multiple supports! Albeit, not exactly evenly, but near enough. The inner supports will bow down slightly loading the next outer and so on.

If you only have pipe, then you will need to design and build a truss structure as a stiff support for the 2000-lbs, again, designed to be supported only at the ends. Physics will get ya every time.