Relaxation of Lag Bolt in Wood Connection
I am a structural engineer looking at lag bolt connections between a roof top solar panel support system (racking) and typical residential construction (2x joists or trusses). I have been trying to find information on the long term withdrawal capacity of a single lag bolt. I am interested in determining if over the long term the lag bolt might lose some of the clamping force it exerts on metal foot that connects the rack to the roof. Given the various cycles of temperature swings, wind downforce and uplift, and snow loading and unloading does the lag bolt tend to “relax” its grip on the wood grain?