Fatigue characterisation of concrete composite girder with steel bottom plate and corrugated web under uniform corrosion environment

The objective of this study was to elucidate the fatigue characteristics of a concrete composite girder with a steel bottom plate and a corrugated web (Hereinafter referred to as CGSBCW), and compute its bending moment of inertia under uniform corrosion conditions by incorporating the corrosion rate parameter in the calculations. The corrosion rate was, in turn, determined from the stress value measured in the test. The stress amplitude – fatigue life (S–N) equation of the CGSBCW under uniform corrosion conditions was derived using the Paris semi-empirical law and Lemaitre fatigue life calculation formula. The Lemaitre parameters of the CGSBCW were determined through theoretical calculations and numerical simulations. The relationship among the stress amplitude, fatigue life, and corrosion rate when the corrosion rate was less than 20% was numerically fitted. Curvatures for the stress amplitude, fatigue life, and corrosion rate were confirmed. The results demonstrated that salt-corrosive environment had a significant impact on the fatigue characteristics of composite girders. For the same level of loading, it increased the stress amplitude and decreased the fatigue life. At a corrosion rate of 9%, the stresses in the test girders increased by 10%, while the fatigue life decreased by 24.5%. When the corrosion rate was less than 20%, the stress amplitude and fatigue life, respectively, increased and decreased essentially linearly with the increase in corrosion rate.