How to safely hang a punchbag in garage?

[peca27]

I've just bought a punch bag to use in my garage, it's a flat roofed prefab bolted together detached garage approx 40 yrs old. The old (+ much lighter) punch bag I had was just hung off a 4' x 8' roof timber. I had a bolt + hook thru the middle of this roof timber, it seemed to work well.

Well now I've got a much heavier bag + i'm concerned that this 4' x 8' roof timber isn't going to hold. So I was thinking if I could span the weight across 2, or maybe 3, of these roof timbers I would have a better chance of my garage still standing in 5 years time.

Question is how could I span the weight? I've been thinking about putting in a nogging, but how could I fix it between the roof timbers? I've been trying to make sense of this.........

http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101228&ts=30477

My idea is once the noggings have been fixed in, drill thru + bolt in the hook on one the roof timbers. And then if the roof timbers either side take some weight thru the noggings I should be ok.

Is my theory pie in the sky or am I on the right tracks? any help is much appreciated

 

[Deluks]

Are all the timbers 4"x8" ? What is the span of the timbers and what are they resting on at the supporting ends?? How far apart are they (distance from beam to beam)

You are on the right track , but I'd fix a noggin between 2 of these joists using jiffy hangers and a doubled up 6x2 (to make a 6x4), and hang the punchbag from the middle of this noggin, that way the load is spread evenly between 2 of the joists.