| Steel hollow sections are commonly used as supporting structures in onshore and offshore engineering. And tubular Y joint is the simplest joint of all. In the structures, the members are jointed together by welding the profiled ends of the brace onto the circumference of the chord. The stiffness around the intersections is ununiform and it will lead to the stress concentration. The present method to predict the fatigue life of tubular joint is the S-N (Stress-Number of the cyclic loads) curves. It can only predict the life from the time when it begins to use to the time when crack initiates. However, it ignores the residual life from the time of crack initiation to the time when through thickness crack forms. It is too conservative for the estimation of its whole life.In this study , VISUAL FORTRAN is used to get the nodes and elements of tubular Y joint without crack and with surface crack. And then ABAQUS is adopted to compute and analyze the models. It provides a good tool to analyze and estimate the residual life of tubular joint. In the study , a new method of modeling is presented to simulate tubular Y joints with any surface crack along the weld toe. Hence, two models can be obtained by this new method. One is the model of tubular Y joint without any crack simulated with 3D solid element. The other is the model of tubular Y joint with surface crack simulated with different kinds of solid elements.A scheme of doubling the mesh density is adopted to verify the convergence of the value of SIF. So the reliability of the finite element mesh can be verified.In the study, a convenient tool is provided to model the tubular joint for the coming researchers .And the model can be used to deduce a better formulation of SIF to make a more rational estimation of the fatigue life.
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