Define Structural connection loosening - Deterioration in Steel?

Structural connections joined together by rivets or bolts have a tendency to work loose over an extended period of time.  Connection loosening can result from impact loading of the type imparted by a vessel striking substructure.  Wave action is another source of possible connection loosening.  Corrosion of bolts, rivets, nuts, washers, and holes can also contribute to connection loosening.  Loosening of connections will tend to produce misalignment in mating surfaces, which in turn can result in distortion and stress concentrations in framing members.