Deflection of RC beams under simultaneous load and steel corrosion

Abstract

This paper presents the results of a series of tests aimed at characterising the serviceability and ultimate limit state deflection of reinforced concrete beams subjected to steel corrosion while under load. Reinforcement corrosion was accelerated by impressing a DC current on the main tension steel while the load was applied through a static, spring-loaded support frame. Central deflections of beams subjected to 23% and 34% of the design ultimate load, under 4-point loading over a span of 1050 mm and accelerated corrosion, were monitored over a period of approximately 30 days. These beams were then tested to failure to assess the effects of reinforcement corrosion on performance at the ultimate limit state. Uncorroded beams were used as control samples and tested in parallel with the corroded samples. The results show the importance of assessing the structural effects of reinforcement corrosion under simultaneous load and corrosion conditions, as would occur in situ. In this situation, when 6% of the mass of steel is corroded, beam deflections are increased by between 40% and 70% relative to the deflection of the control samples. Furthermore, depending on the extent of corrosion and the mode of failure, the ultimate bending strength of the beams can be reduced by up to 30%.