Fatigue life prognosis study of welded tubular joints in signal support structures

Welded tubular joints have exhibited vulnerability to fatigue cracks. This paper presents the research on fatigue life prognosis study of steel welded tubular joints from traffic signal support structures. Fatigue testing results of six full-scale steel welded tubular joint specimens of signal support structures are first discussed. In order to predict the fatigue behavior for welded tubular structure and estimate its fatigue life, a fatigue life prognosis procedure based on Bayesian updating of the stochastic coefficients of the fatigue growth model is employed. Bayesian updating allows the use of dynamic diagnostic information with prior knowledge for improved prognosis. Surface fatigue crack growth data are recorded during fatigue tests of three specimens and the experimental data is used to demonstrate the fatigue life prognosis procedure for welded tubular structures. The prognosis results of this study provide insight into how fatigue hazard evolves in welded tubular joints of signal support structures.