The structural Bolts following EN 14399-4 and DIN 6914 is to use thinner nuts and shorter thread lengths to obtain the required ductility by plastic deformation of the threads within the nut. The structural bolt assembly is used in both preloaded and non-preloaded applications and it can be argued that in the event of failure by thread plastic deformation the assembly still acts as a ... https://www.bigboltnut.com/product/structural-bolts.html