Fatigue Strength of Riveted Bridge Members

Available experimental data frorm more than 1,200 previous fatigue tests and some fatigue and fracture tests on full‐scale members are compiled and examined in conjunction with the details and measured live load stresses in riveted bridges. It is found that the type of riveted detail does not significantly affect fatigue resistance, that AASHTO fatigue strength category D is a reasonable lower bound for the initial fatigue crack development, and that the fatigue strength of a riveted built‐up member effectively exceeds the category C resistance curve. It is also found that the primary members in riveted highway bridges seldom are subjected to stress ranges that exceed the category D fatigue limit, and thus are not likely to develop fatigue cracks. The riveted details most likely to develop cracks are those subjected to distortion or displacement‐induced stresses at connections. Corrosion can reduce the fatigue resistance, but the effect is not critical if the minimum remaining thickness is not less than one‐half of the original thickness. Recommendations are made for rating riveted highway bridges for fatigue damage.