Corrosion behavior of stirrups in corroded concrete beams exposed to chloride environment under sustained loading

•Corrosion of horizontal legs of stirrups was related to their locations.•Corrosion of vertical legs of stirrups was not affected by the load-induced cracks.•No correlation was found between stirrups and the main steel in terms of corrosion. This paper discusses the corrosion behavior of stirrups in two concrete beams under sustained loading, exposed to a chloride environment for 9 years. The cracking maps of concrete beams were recorded after 28 days and after 9 years, respectively. The corrosion maps of the stirrups were drawn and the cross-sectional losses of stirrups were measured after destroying the beams. The experimental results show that the horizontal legs of stirrups mainly corroded at the mid span of the tensile zone and at the ends of the compressive zone of the reinforced concrete beams regardless of the exposure conditions, while the opposite horizontal legs were protected. The corrosion of vertical legs of stirrups, which was slight, was not impacted by the load-induced cracks. In the present study, it is difficult to find the correlation of corrosion degree between stirrups and the main reinforcing steels in the reinforced concrete beams. The corrosion behavior of the intersection between stirrups and main bars was controlled by the interfacial conditions between them. Cathodic protection occurred at the ends of the top-cast side and the mid-span of bottom-cast side of reinforced concrete beams when the compressive rebars and tensile rebars were placed at the top- and bottom- cast sides, respectively.