Steve:
There are beam analysis programs out there, some of them you can download a sample version and you can use them (if you know how to) to check out beam loads.
Most of the demo versions are limited by only allowing you to do short lengths and you can't print your results.
If you do a search here on this forum for info about beam analysis you'll find quite a bit of info about it.
One message by Ed Levin lists web sites where you can go and find these demo versions. It's title is "Engineering software".
I recently found a program called BeamChek and it has a demo version and it has a button for round timbers. You can find it at
www.BeamChek.com I'm not sure if it has a setting for cm's or not you'll have to see.
Good luck with your research.
Jim