Numerous steel bridges were built during the construction boom between the late 1950s and late 1970s and are still in use. Fatigue cracking can be considered as one of the main sources of the deterioration of these bridges. It is reported that the largest category of observed fatigue cracks are those caused by out-of-plane distortion. Locations where transverse structural components are framed into longitudinal girders through web stiffeners not attached to the flanges (such as diaphragms or cross-frames) are most susceptible. In the current study, a web stiffener detail is fatigue tested under different cyclic loading conditions. As-welded specimens are tested, along with specimens retrofitted by post-weld treatment (needle peening). Direct strain and deflection measurements are compared with finite element analysis predictions. Local (hot-spot) stresses are also obtained experimentally and numerically and compared with a hot-spot stress design curve. Based on the results, conclusions are drawn regarding the effectiveness of the investigated retrofitting method and the suitability of the hot-spot stress method for predicting the distortion fatigue performance of the investigated web stiffener detail.
展开▼
