Fatigue Life Extension of Riveted Connections

The paper describes a fatigue test program that studied the effectiveness of rehabilitation by replacement of rivets with high-strength structural bolts in critical or fatigue-damaged locations as a more economical alternative to replacement of entire members. Constant amplitude fatigue tests and variable amplitude service simulation tests of full-scale model ore bridge joints and constant amplitude tests of joints removed from an ore bridge showed that rehabilitation of fatigue-damaged members by fastener replacement increases fatigue life two to six times. It was found that cumulative damage analysis of the constant amplitude tests conservatively predicts the variable amplitude test phenomena. The effect on fatigue life extension of increasing bolt tension above the minimum value accepted in present specifications and the effect of crack length up to l in. (25 mm) long or both, at rehabilitation were found to be of secondary importance.