Hot-spot stress evaluation of fatigue in welded structural connections supported by finite element analysis

Various welded joints from the floor structure of city buses have been examined numerically and experimentally under bending and tensional cyclic constant-amplitude loading. Hot-spot stresses at failure-critical locations were calculated by means of finite element analysis. The corresponding fatigue lives were determined experimentally. There was good overall agreement between calculated and experimentally determined critical locations. The recommendations within the IIW guideline concerning the Hot Spot Stress Approach were found to give accurate approximations for the probability of survival of fatigue-loaded welded joints. The restriction regarding the applicability of the Hot Spot Stress Approach to welds failing only from their transition zones could be relaxed, at least at least for welds similar to those investigated here.