Dear Dick,

I used your 300 lbs / sq ft figure today in my model and got really alarming results - 20" deep beams.

I then did a quick check assuming that a hay bale is 2 x 2 x 4 and weighs 50 lbs and I got a remarkably good comparison with your code figure loadings.

This led me to question why the typical 8 x 8 scantlings is so common in North American mid west barn frames.

The answer might be simple. I guess that the hay bale is probably a fairly recent invention and I would surmise that most barns were built to be loaded from the ground floor to the roof and did not necessarily have a fixed mow floor. I have seen many pictures of round poles which are simply laid across the mow beams and this might explain how the old barns did not need to be built to such a demanding standard since most of the weight must have been bearing on the ground floor and of course there would also have been an internal wall pressure as well.

I managed to solve my problem using cleverly positioned bracing and also narrowing the main mow beam span which helped reduce horizontal shear from 120 to 60 psi and also depth of beam from 20" to 12".

Now I know why those Dutch barns have such deep swing beams. It does not appear to be overdesign.

I will weigh a hay bale tomorrow at my friends farm.

Does anybody have any thoughts on these observations.

Regards

Ken Hume