Fatigue Strength of Weathered A588 Steel Beams

Abstract

This paper presents the fatigue behavior of 39 welded and 12 cover-plated beams fabricated from A588 weathering steel. One set of beams was boldly exposed to the environment; the other was exposed under a metal deck that simulated the shelter provided by highway bridge decks and was lightly sprayed with a salt solution during the winter months. The test data showed that the boldly exposed, welded and cover-plated beams had Categories B and D fatigue strengths, respectively, after 45 and 74 months of weathering. The cover-plated beams had initially high fatigue strength because of their high weld quality. The fatigue strength will continue to degrade with exposure time. All sheltered beams had Category E fatigue strength after 62–72 months of weathering as a result of very severe corrosion and pitting. Such losses are unacceptable. To stop the degradation of fatigue strength, severely corroding weathering steel bridges should be painted without delay.