Ridge beam end to end connection..sagging?
A lot of times the bowed 2x4 was used as an aide to installation of the rafters. What happens is all of the rafters are cut at the same time down on the ground to the same dimension. If, during installation, the framers notice the seat cuts are not fitting for whatever reason, they will cut a 2x4 1/2" longer than the height of the bottom of the LVL. They will put a massive bow in it and place it under the ridge. When the 2x4 attempts to straighten out, it extends, pushing the ridge upward with amazing force, enabling the next precut rafter to fit more snugly. Sometimes, all of the bow they put on this 2x4 doesn't get straightened out. Once the roof system is complete, the "jack" can be removed, and everything will stay in place.