A PARAMETRIC STUDY ON FATIGUE DESIGN CURVES FOR STEEL HIGHWAY BRIDGES

Fatigue design curves of steel highway bridges were analyzed parametrically under computer simulated variable amplitude stresses. Crack propagation life of 4 types of welded joints was estimated by applying the constant amplitude da/dN-ΔK relationship and the liner cumulative damage rule. The configuration of fatigue life curves under variable amplitude stresses varied with the traffic constitution and the beam span particularly in the longer life region. The fatigue limit under variable amplitude stresses for each joint could be defined by using estimated fatigue life curves and Miner's rule.