Behavior of corrosion damaged non-seismically and seismically detailed reinforced concrete beam-column sub-assemblages under cyclic loading

Abstract

Corrosion of reinforcement requires immediate redressal as it poses a severe threat to the serviceability and seismic performance of the existing reinforced concrete structure. Taking this into consideration, the current study presents an experimental assessment of the seismic behavior of corroded exterior beam-column joint sub-assemblage under quasi-static reverse-cyclic loading. A total of eight exterior beam-column joint specimens i.e., four having traditional non-ductile transverse reinforcement detailing as per IS 456:2000 and the remaining specimens ductile detailed according to IS 13920:2016 were cast. One specimen from each detailing regime was tested uncorroded and acted as a control specimen while the remaining six specimens were subjected to varying levels of accelerated corrosion. The experimental results illustrated that the sliding phenomenon in the hysteresis curve gradually increases and a drastic fall in energy dissipation, stiffness, and post-yield displacement were seen as the corrosion progresses within reinforcing bars. The failure mode shifted from diagonal joint shear failure observed in control specimens to longitudinal and major flexural cracking failure along the beam reinforcement. First-level corroded specimens showed a slightly increased ductility factor, indicating that low levels of corrosion may improve ductility. However, after 10% corrosion, all corroded specimens showed poor seismic performance and the cumulative energy dissipation curve tends to go flat at approximately half the displacement as compared to control specimens. The cumulative energy dissipation of non-ductile and ductile specimens damaged to the most severe level of corrosion in this study was only 0.3 and 0.4 times that of respective control specimens. In general, the ductile detailed specimens showed better seismic performance than the corresponding non-ductile detailed specimens owing to the closer arrangement of stirrups.