How Do I Design And Calculate The Stress Of My C-Channel

Master, if your reasoning was correct your slings would have to weigh at least 3000 kg in order to lift the 6000 kg weight.

Logically the C Channel has to be designed for the set load and not having the same weight. If it was you would need a crane for 12000 kg lift.

You need to design a channel FOR 6000 kg load.

Look at your vectors and forces and I am sure you can come up with some ideas how to calculate the loads on your channel!

My thoughts exactly. I voted/rated your post good.

Please do not try to do this yourself. You don't know how.

Simply call a metals supplier and ask their engineer, or hire an engineer to SELECT, not design, a channel for you.

Kudos for knowing your limitations but filling in what you do not know by asking a public forum is wrong. On the other hand, we do clearly explain your assumption and we could then correct those assumptions. So you do have the potential to eventually get it right but not now.

Safely moving things with a crane requires proper training and certification. Your two dimensional drawing does not take at all into account that we exist in a three dimensional world. The mass of all parts including the spreader bar and the lifting base must be included in the analysis. There is also no identification of the center of mass of any part, let alone the entire body to be lifted.

Oh, since when is kilograms a unit of force? With the sparse information provided, I calculate that each strap will be under tension of 60.8 N to just be in stasis. The lifting acceleration will add additional loads.

Exactly!

It's a spreader, and unless that load is a 6T 2 dimensional object then you will need at least 2 of them and they will need to be spread as well.

Quite. The drawing shows a 6000kg object held up by only two lifting points. Unless it is infinitesimably thin, and therefore unknowingly dense, it will only be metastable as drawn and the slightest breath of wind will cause it to flip over. Also, the tensile stresses in the members between the spreader beam and the hook point are incorrect.

One hopes that all other CR4 readers are standing well back when the lift begins...

Why you want to use 'C' Channel?. There are many alternatives readily available in market:-

1. Link Chain sling with 4 legs and 'O' ring at top.

2. Wire Rope Sling.

3. Nylon Web slings.

4. Lifting Beams. etc.

A simple job for a structural engineer, if you aren't one, get one.

allowable stress= Mc/I + TR/J + P/A

for lifting devices I use a factor of safety of 5:1

Rather than risk injuring(or worse) anyone, hire a consultant to design your spreader beam, or leave it to the crane rental company who will be doing the lift. They usually have quite a selection of spreader beams in their arsenal to choose from and good ones have engineers or technical people on staff who can do the calc's for you. If you aren't hiring an outside crane, refer to my first sentence.

And I forget that the same goes for calculating deflections, etc., of the structural section the will be used.