Seismic response assessment of ductile and non-ductile reinforced concrete columns affected by corrosion and axial load variations

Abstract

This research delves into the combined impacts of reinforcement corrosion and axial compression ratio (ACR) on the seismic performance of large-scale ductile and non-ductile reinforced concrete (RC) columns. The study employed quasi-static cyclic lateral loading tests with progressively increasing magnitudes to simulate seismic conditions. Initially, the seismic behaviour of control ductile and non-ductile RC columns was examined. The theoretical axial load capacity (P0) under concentric axial loading was calculated, and an axial load equivalent to 0.35P0 was applied consistently during seismic testing. The construction of the columns featured distinct lateral reinforcement ratios—1.31% for ductile columns and 0.33% for non ductile columns—to highlight the performance differences. A detailed parametric study was conducted using three-dimensional (3D) simulation models in ABAQUS, which were calibrated and validated against experimental data to ensure reliability. To investigate the influence of ACR on column performance, a comprehensive analysis was performed by varying the ACR from 0.35P0 to 0.7P0. Results demonstrated that ductile columns exhibited a modest increase in peak strength up to an ACR of 0.5P0, accompanied by a consistent reduction in ductility. In contrast, non-ductile columns experienced a pronounced decline in peak strength, deformability, and overall ductility with increasing ACR levels. Further, to evaluate the combined effects of varying corrosion levels and ACR on column behaviour, advanced 3D numerical models of corroded RC columns were developed and rigorously validated through experimental testing to evaluate the combined effects of varying corrosion levels and ACR on column behaviour. Key performance parameters such as hysteresis and backbone curves, stiffness degradation, ductility, equivalent viscous damping, and energy dissipation were meticulously calculated and compared across different conditions. The findings revealed that both ductile and non-ductile columns subjected to corrosion showed significant reductions in strength, deformability, stiffness, and ductility at higher ACR levels. The increased ACR led to diminished pre-peak and post-peak response characteristics and resulted in peak response reaching lower drift levels, indicating reduced seismic resilience. This condition precipitated various deterioration phenomena, including longitudinal cracking, spalling of the concrete cover, and the weakening of the bond between reinforcing steel and concrete. These observations underscore the critical importance of factoring in ACR and corrosion impacts in the design and maintenance of RC columns to enhance their seismic performance and structural reliability.