Floor Deflection

[bannerd]

Working on a hay barn that is old timber frame, but have a weird weird issue going on.

The first level of the barn is solid and I see no issue there.  All the beams were ended up in a X style brace and have a lot of plates and lag bolts.  This one room upstairs is the issue that is rather odd.  If I have a buddy run towards the room you can feel the barn moving.. sort of feels like it's bouncing and then causes a side by side motion.  The room literally next to it.. no deflection.. a light feeling but literally nothing this extreme.  The room in question will make your coffee dance inside your cup.  Had a few PE's look at it and everything is over kill.. nothing that is spanning.. everything is just to short of a distance.

at the end of the structure I threw all I had (not a big guy) and tried to shake that side of the building and nothing.. but in that room.. moving like to where you feel un-easy.  The building has had no snow on it.. and it was pretty bad.  Now it has 5 ft of snow and the movement is minor so perhaps a compression issue.  when it gets filled with hay, it's very hard to get it to move but I also think there is just massive downward pressure on the subfloor so there is no bounce.  Would deflection in a floor bring the walls down in a minimal way?  All buildings move and have deflection but this is a bit much.

Anyways, if anyone has some mechanical ways to start testing things I'm all ears.

[beenthere]

I'm a bit slow understanding what you are experiencing. A few pics of the parts of the barn that you think are "moving" with a live load (buddy running) and pointing out where in the barn it seems to be moving.

Sounds like loose joints from wood shrinkage and those joints tighten up when under a hay load.

There are ways to stretch some tight strings to learn more about what is moving.

Likely is not a structural problem, but good to find out more. Flexing (deflection) is usually low modulus of elasticity in some members. Uncomfortable, but not unsafe.