A reliability-based methodology for considering corrosion effects on fatigue deterioration in steel bridges - Part I: Methodology -

It is known that the effects of corrosion on fatigue originate from two major sources: stress concentration due to corrosion discontinuities (CNF factor) and stress amplification due to loosing net section (NAF factor). In order to account for these effects, a performance function is developed which takes CNF and NAF factors into account and considers both random and time-dependent nature of the involved parameters. In order to consider real fatigue and environmental conditions, the available CNF-y and y-t functions are extended employing α and φ factors, respectively. In addition, some recommendations have been made to establish corrosion pattern of different steel sections. The final output of the methodology is development of a reliability-based procedure to establish time-dependent deterioration profile of a structural member, which assists in decision-making with regard to maintenance activities. The proposed methodology has been applied to Neka Bridge, a railway bridge in northern Iran, which is presented in Part II.