Since the column layer is closed, the problem appears at the junction of the beams. In general, there seems to be no problem with the connections. (Except if your K49 beam is not started on the bottom column). I don't think it makes much sense to make the beams bow. The result is that the arc angle in a single beam is negligibly small. I reintroduced the same system using spring axles and without springing the beams. Check it out. You can use it if you see fit.