Abstract：T-welded component is one of the key structures of the shield machine cutterhead, and sub-critical crack in the weld extensions is a key factor in its fatigue faliure. A new structural fatigue reliability analysis method is proposed, considering load shedding, by the use of probablistic fracture mechinics based on FORM method. The method is applied to a T-welded shield structure, and results of structural fatigue reliability are gotten at the cases of with and without considering load shedding. The method’s validity is verified using Monte Carlo method. And a curve that load shedding impacts on the T-welded structure fatigue reliability is fitted via least square method, which is divided in three regions: the high, medium and low fatigue failure zone. The results showed that the fatigue failure probabilities were 8.2644e-05 and 3.4314e-04 when with and without considering load shedding, which load shedding improved the structure fatigue reliability was reputed. The thickness of T-welded structure was thought as a design variable in the practical
project design of fatigue reliability, in which low fatigue failure zone may be used as a reliability
constraint. The results have a certain theoretical guidance for the maintenance, inspection plan and design of shield machine cutterhead in the practical project.
2014, Vol. 35 
