Fatigue Strength of Steel Beams with Corrugated Webs - Fatigue Assessment, Parametric Analysis and SCF Predictive Equation Development Using Effective Notch Stress Method

Abstract

Corrugated web girders (CWGs) have gained increasing attention in bridge engineering due to their high structural efficiency and favorable weight-to-strength ratio. However, fatigue assessment remains challenging because the corrugated geometry induces local stress concentrations that cannot be adequately captured using conventional nominal stress approaches. Moreover, no generalized formulation currently exists to relate nominal stresses to local fatigue-critical stresses while accounting for key corrugation parameters. This thesis investigates the fatigue behavior of trapezoidal corrugated web girders (TCWGs) using the effective notch stress (ENS) approach. A detailed finite element (FE) model of a full corrugated web girder was developed and validated against four experimental tests. The validated model is subsequently simplified to a corrugated web beam representation (CWT: flange with corrugated web subjected to tension) while preserving an equivalent stress concentration factor (SCF). A comparison between the Hot Spot Stress and Effective Notch Stress methods was performed to identify the most suitable approach for further analyses. Based on this selection, an extensive parametric study covering a wide range of geometrical parameters was conducted, and the resulting numerical database was used to develop an equation for predicting SCFENS. The results showed that the corrugation angle, θ, and the bend radius-to-web thickness ratio, R/tw, are the governing parameters influencing SCFENS. Increasing R/tw reduced stress concentrations, with a more pronounced effect at larger corrugation angles. Regres sion equations developed from the FE results showed good agreement with the numerical database, achieving R2 values above 0.94. The proposed equations provide a practical tool for estimating effective notch stresses without refined FE analyses, supporting fatigue assessment and design optimization of trapezoidal corrugated web girders.