Developing Fracture-Based Fragility Curves for Steel Components in Corrosive Environments

Abstract

Under excessive plastic deformations, pitting corrosion accelerates ductile fracture initiation in steel components. Because of the stochastic and time-dependent nature of corrosion in steel material, the integrity of the steel components must be evaluated through a rational procedure in which corrosion uncertainties are considered to estimate the probability of failure for future events. Previous studies developed fragility curves to predict the capacity of global structures under uniform corrosion. However, for steel structures subjected to pitting corrosion, the local effect of corrosion is substantial and is also challenging to implement in the global model of structures. In this study, the concept of fracture-based fragility curves was developed at the component level by micromechanical modeling of different random pitting morphologies at a given intensity level of pitting corrosion. For this purpose, a unique meshing technique was employed to implement random pitting morphologies in numerical models. A demonstration study on a single-sided corroded plate revealed that random morphologies at an identical corrosion intensity level led to a notable dispersion in the failure elongations. The proposed fragility curves could address this effect on the probability of failure of the specimen. Therefore, decision makers can reliably utilize such curves in a comprehensive risk-based corrosion management framework to evaluate the risk of failures and determine proper treatment strategies.