The paper presents the finite element method model (FEM) which allows the forecasting of the evolution of damage in a concrete cover together with experimental verification of the model. The objective of the model is to define the corrosive volume strain tensor rate effected by corrosion, which comprises the accumulation of corrosion products in pore spaces as well as in micro-cracks which develop at the initial stage of cover degradation. The propagation of damage in the contact zone was captured by taking into account the function describing the degradation of the interface transition zone depending on the cover tightening time–critical time. The method of determining the critical time along with the method of taking into account the effective electrochemical equivalent of iron was also analyzed in this paper. The work presents the experimental verification of the model using an accelerated corrosion test of reinforcement in concrete and strain measurements with optical methods. The conducted tests demonstrate satisfactory compliance of the model with the test results.

Przedstawiona praca ma charakter przeglądowy. Obejmuje charakterystykę okresowych kontroli obiektów budowlanych wraz z podaniem ich rodzaju, zakresu i częstotliwości przeprowadzania zgodnie z obecnie obowiązującymi aktami prawnymi. W pracy krótko opisano rodzaje posiadania kwalifikacji osób przeprowadzających kontrole okresowe. Scharakteryzowano wymogi stawiane właścicielom oraz zarządcom obiektów budowlanych w zakresie bezpiecznego ich użytkowania. Następnie przedstawiono szereg błędów powszechnie popełnianych przez osoby wykonujące przeglądy wraz ze wskazaniem możliwych negatywnych skutków.

The work is theoretical with the use of analytical calculations, subsequently confirmed by a numerical method, in which an attempt was made to verify the method of estimating the corrosion current density based on the deflection of reinforced concrete (RC) elements affected by reinforcement corrosion. The focus was on the possibility of estimating the corrosion current intensity on the basis of external measurements of deflections of RC elements subjected to reinforcement corrosion. The method can be used as an element supporting the diagnosis of RC structures. The article presents an example of analytical and numerical deflection calculations, on the basis of which an attempt was made to estimate the corrosion current density. The obtained results were considered satisfactory, which is sent for further considerations, and above all for experimental verification of the proposed method. The analysis was based on the theoretical work of a simply supported beam, whose analytical results were verified using the finite element method. For the purposes of theoretical considerations, the impact of corrosion of the beam reinforcement was assumed in the form of a history of changes in the intensity of the corrosion current obtained in another research work. Finally, the obtained results confirmed the assumptions regarding the possibility of estimating the corrosion current density on the basis of the deflection of the analyzed beam.

STRESZCZENIEW pracy podjęto problematykę ugięcia elementów żelbetowych, podlegających wpływom korozji zbrojenia. Praca ma charakter w pełni teoretyczny. Skupiono się na wyprowadzeniu zależności, wiążącej gęstość natężenia prądu korozyjnego z krzywizną ugięcia. W zamyśle przedstawionej metody jest to nowy element, umożliwiający wstępne oszacowanie gęstości prądu korozyjnego w oparciu o bezinwazyjne pomiary ugięć konstrukcji. SŁOWA KLUCZOWE korozja stali zbrojeniowej, ugięcie elementów żelbetowych, prąd korozyjny

This paper is focused on the problem of forecasting damage in reinforced concrete specimens as the consequence of chloride corrosion. The performed numerical calculations included time necessary for filling empty pore space and tightening corrosion products in the interfacial transition zone (ITZ) . In those calculations we assumed the formation of distortional strains in the ITZ layer caused by mass increase of corrosion products dependent on corrosion current intensity.