Lifetime lateral resistance of steel frames subjected to atmospheric corrosion

During its lifetime, an engineering system is exposed to various potentially damaging factors, which arise due to common everyday or frequent environmental effects, as well as infrequent severe/accidental actions. Despite its exposure to such degradation causes and the accumulation of damage with time, the system is required to be operational and safe for a certain period of time. Therefore, the estimation of the remaining carrying capacity of the damaged system is a crucial aspect in its assessment with respect to the safety level provided and the frequency of repair/retrofit measures required.

The present work focuses on steel structures subjected to atmospheric corrosion, which results in progressive deterioration of steel members and affects structural system performance with time. The corrosivity of the atmospheric environment is taken into account by applying the provisions of ISO standards, which define corrosivity categories and specify corrosion rates for metals. This enables the identification of the magnitude of corrosion attack after extended atmospheric exposure of steel components.

This methodology for atmospheric corrosion evolution is applied to the members of elastoplastic steel frames using various deterioration scenarios. The scenarios are defined through the progressive notional thickness reduction of the exposed member sections, which simulates the progressive deterioration effect of atmospheric corrosion on the steel members of a structure. Such local damage affects the overall load carrying capacity and causes a drop in the safety level of the structural system. Hence, limit elastoplastic analyses are performed to compute the remaining structural resistance of the deteriorated structure due to the evolution of atmospheric corrosion.

Such information on the lifetime structural performance of a steel frame subjected to atmospheric corrosion is essential in specifying an effective monitoring and maintenance strategy aiming at preserving an acceptable safety level for the structure while optimally dealing with respective present and future costs.