Weight distribution

[gee]

I have a square truss rig with lights, projectors and speakers hanging at different points around it, if there is 1 point on each corner of the truss then each point is not an even load, how do I calculate the load at each point?

[Seano]

I have a square truss rig with lights, projectors and speakers hanging at different points around it, if there is 1 point on each corner of the truss then each point is not an even load, how do I calculate the load at each point?

 

You can get an approximation by treating each of the 4 sides as a 'simple beam' and 'taking moments'.

(I've put those in inverted commas because they're good scroogle search terms to use to look stuff up on this.)

 

So, if a point load (projector etc.) is 10% of the distance between points A and B, 10% of the weight will be transferred to point B and 90% to point A.

 

But you need to be aware that if the corners are rigid this is just an approximation. Especially if its hanging from motors, hoists, winches etc., and may not be perfectly level. If one corner is a bit high or a bit low a disproportionate amount of the load will be referred to one or other pair of diagonally opposite corners. (In the same way that a 4-legged table will rock if any one leg is a touch too long or too short - all the weight rests on only two feet.)

 

Clear as mud.

[gee]

Hi Seano,

 

Thanks for the reply.