Optimization and fatigue assessment of girders with large-dimension corrugated steel webs

In recent years, large-dimension Corrugated Steel Webs (CSW) has increasingly become an available solution for long-span bridges to reduce deadweight and improve prestressing efficiency. Compared to conventional CSW used in small-span bridge girders, girders with large-dimension CSW in long-span bridges are more susceptible to fatigue cracking under repetitive traffic loads. However, the specifications aimed for small-dimension CSW may resulted in unsafe fatigue detail categories. This paper investigated the fatigue performance of large-dimension CSW girders for bridges. The reasonable corrugation angles of girders with CSW were obtained using Grey Relational analysis. The fatigue detail category corresponding to optimized corrugation angles was suggested based on the Theory of Critical Distance (TCD). The Finite Element Analysis (FEA) results indicate that the hot spot stress concentration factor (Ks) on the web-flange weld toe increases with the corrugation angle and decreases with the bend radius. When the corrugation angle and the bend radius are fixed, Ks increases with the corrugation wavelength. By developing a balanced fatigue and shear buckling performance scheme, the optimized corrugation angles of wavelength 1000 ∼ 2000 mm are between 30° and 45°. There is a negative correlation between the fatigue detail categories of CSW girders and corrugation wavelengths. In general, the fatigue detail category of wavelength 1600 ∼ 2000 mm under four-point bending can be classified into a range between 50 and 71 for Eurocode 3, Category D and Category E′ design curves for AASHTO, FAT 50 and FAT 71 for IIW respectively.