鋼構造物疲労き裂発生・進展による応力振幅比の変動に関する解析的検討

抄録

Fatigue cracks in steel structures often occur near welds where stress concentration is high. Fatigue cracks are inspected by visual inspection, and if necessary, non-destructive testing such as magnetic particle testing, and penetrant testing are used to confirm the presence of cracks. However, visual inspection has the disadvantage that it depends on inspectors’ experience and skills, and non-destructive testing may not be able to deal with fatigue cracks inside steel plates, so cracks may be overlooked. We are trying to develop auxiliary means to solve these problems. In this study, we attached strain gauges near the suspected fatigue damage position, and we confirmed stress amplitude ratio in two directions around the fatigue cracks, examined fluctuations around fatigue cracks occurrence and progress. We investigated whether cracks can be detected quantitatively by comparing and examining the results of vibration fatigue test and FEM analysis for out-of-plane gusset weld joint and the welding lines of U-rib in orthotropic steel decks. As a result, fluctuations in the stress amplitude ratio are confirmed due to the occurrence and progress of cracks. This method isn’t dependent on inspectors’ experience and skills, may be able to deal with damage inside the structure, so it can be an auxiliary mean of the existing inspection method.