Numerical investigation of stress intensity and geometry correction factors in welded cover plate details

The cover plate is a common structural detail in railway bridges, and its welds are particularly susceptible to fatigue cracking. This study investigates the fracture mechanics of cover plate welds, focusing on the stress intensity factor and geometry correction factor through numerical simulations. A simple plate model with a semi-elliptical surface crack is first used for validation, with a maximum deviation of about 4%, confirming the accuracy of the finite element analysis. A comprehensive parametric study is then performed for two configurations: a cover plate detail without a web and a cover plate detail with a web. Key geometric parameters are systematically analyzed. The results show that smaller width and thickness ratios increase the stress intensity factors, making these configurations more critical for fatigue. Additionally, steeper weld slopes (1:2) result in higher stress intensities than shallower slopes (1:3), which are more favorable. The inclusion of a web significantly increases the geometry correction factor, resulting in higher crack propagation rates. The web restricts base plate bending and compressive stress relief at the weld toe, resulting in stress intensity increases of up to 63% (1:2 slope) and 40% (1:3 slope). Comparison with literature formulas shows that the FEA-based results of this study yield lower correction factors, suggesting that current design formulas may be conservative. To support practical applications, regression formulas for the geometry correction factor are developed that achieve high accuracy (R 2 ≥ 0.9774) and provide a more accurate basis for fatigue assessment in welded cover plate details. • Stress intensity factors for welded cover plate details are determined by FEA. • Analytical regressions are developed for deepest and surface points of the crack. • Weld toe crack is analyzed in cover plate detail with and without web. • Parametric study includes plate width, thickness ratios, and weld slope. • Web presence significantly increases stress intensity at crack tip. • Regression formulas support practical design and fatigue assessment.