Stress intensity factors for structural steel I-beams

The finite element method was used to develop accurate stress intensity factor (SIF) solutions for two-tip web cracks and symmetric three-tip cracks in I-beams under tension or bending. Governing parameters for cracked I-beams were determined. For web cracks, the SIF is a function of applied stress, crack length, eccentricity, and flange-to-web area ratio of W shape. For three-tip cracks in web and flange, the SIF is a function of applied stress, web and flange crack lengths, and flange-to-web area ratio. The flange-to-web area ratio accounts for the constraining effect of the flange on two-tip web cracks and the interaction effect on three-tip cracks. A total of 2,106 combinations of type of crack, type of loading, crack length, eccentricity, and flanges-to-web area ratio were analyzed. Numerical results were fitted with polynomial equations for ready use by practicing engineers.