Modelling of the flexural behaviour of RC beams subjected to localised and uniform corrosion

Abstract

This paper presents a finite element study of corroded concrete beam flexural behaviour in which the influence of the percentage of corrosion on the load–deflection curve was studied. CASTEM 2000 computation software was used and the output compared with two experimental studies, the first on uniformly corroded beams, and the second based on a long-term experimental program inducing heterogeneously localised corrosion of beams. For the computation special elements were used to represent the interface between steel and concrete, named rust elements. A sensitivity analysis was carried out using different sizes of rust elements, in order to study their influence on analysis accuracy. The element sizes used were 1, 2, 3, 5, 10 mm. An analysis with only steel cross section reduction (PS, in French “perte de section”) was also made and two concrete behaviour models were used. Comparison of the results showed good correlation between the finite element computation and the experimental studies, and highlighted the efficiency of the rust elements for the flexural behaviour study. In particular, the ultimate load and the deterioration in the stiffness with corrosion were accurately modelled. The prediction of the ultimate deflection required the use of an appropriate damage model for the concrete behaviour.