Experimental investigation of the seismic performance of corroded reinforced GO-modified concrete bridge columns

Coastal bridges face reduced bearing capacity due to prolonged seawater erosion, a pressing safety concern. Chloride‑induced oxidation of reinforcing steel leads to material degradation and continuous ion exchange, significantly deteriorating bridge column performance. To investigate the effects of varying graphene oxide (GO) incorporation levels on the seismic performance of reinforced concrete bridge columns under chloride ion erosion, four specimens were designed in this study for quasi-static testing, including comparisons of GO content and degrees of chloride ion erosion. The specimens were designed in accordance with Chinese codes, incorporating two GO proportions and three corrosion levels (including a zero‑corrosion control), with the two non‑zero corrosion rates corresponding to 10% and 15% mass loss. Based on the experimental results, the failure process, displacement ductility, energy dissipation, the confined concrete strength and residual displacement of each specimen were analyzed. Furthermore, the ductility and residual displacement of the specimens without GO were discussed. The results indicated that as the corrosion degree increased, the energy dissipation capacity of the specimens gradually decreased, and the confinement strength of the core concrete was also reduced accordingly. Moreover, the average corrosion rate of spiral hoops was generally significantly higher than that of the longitudinal bars, and the corrosion of the reinforcement exhibited notable non-uniformity, leading to a substantial reduction in displacement ductility. Compared to the specimens without GO, those incorporating GO exhibited an improvement in load-bearing capacity, regardless of the occurrence of corrosion. However, after the incorporation of GO, the specimens developed larger residual displacements at the same drift ratio, accompanied by a slight decrease in ductility. As a preliminary reference, code‑based shear design equations and design recommendations were proposed, along with the limitations of this study and suggestions for future research.