Effect of corrosion degree on different steel ductility parameters, based on “Equivalent Steel” criterion

Purpose – One of the meaningful effects of concrete reinforcement steel corrosion on concrete structures is the decrease of mechanical properties, specifically the ductility of steel. The term ductility of steel refers to a group of properties which determine the reinforced concrete structures (RCS) and it is necessary to take this property into account for the recalculation of structures that have been already corroded until the point to condition in many occasions the analysis methodology. The paper aims to discuss these issues. Design/methodology/approach – This research studies the variation on ductility of concrete embedded steels bars after going through an accelerated corrosion process. Tensile strength of high ductility reinforcements with different corrosion levels has been tested. Ductility was studied in terms of ultimate tensile strength, yield strength, ultimate strain, energy density of deformation and “equivalent steel” criterion. It also makes some considerations about what is the best methodology of structural analysis according to the obtained results. Findings – Based on the obtained results, conclusions are established that determine whether the corroded steel satisfy the requirements of different codes in order to identify them as “steels with special characteristics of ductility” assessing in each case the possibility of reallocating solicitations in structures which might need to be repaired. Originality/value – The analysis of existing RC structures should address moment redistribution to be able to compare ultimate strength values, rather than to a single value obtained with elastic linear models to a range of values centered on the elastic and linear values obtained and defining an interval equal to double the value of the maximum redistribution capacity. This greatly enhances the possibility of “saving” a standing structure. In ductile structures the effect of actions can be distributed. The ascertainment of corroded reinforcement ductility variation is of key importance in structural re-engineering and recalculation of structures. The research developed in this paper is motivated by the need to contribute to knowledge of the behavior of RCS with reinforcement damaged.