Seismic behaviour and strength prediction of corroded RC columns subjected to cyclic loading

In this paper, the performance degradation of reinforced-concrete (RC) columns with corroded longitudinal steel bars was experimentally investigated. Ten large-scale RC column specimens were constructed, and the longitudinal steel bars were corroded, to simulate the real severe environmental condition that concrete structures may encounter during their long-term service life, using a hybrid method. All specimens were tested under lateral cyclic loadings up to failure with the aim of revealing the effects of rebar corrosion level and axial compression ratio on the seismic behaviour of corroded RC columns. Test results indicate that an increase in the rebar corrosion level and axial compression ratio causes a marked degradation in the seismic performance of corroded RC columns, especially a reduction in the strength, ductility and energy dissipation capacity. To study the effect of the rebar corrosion level, the seismic damage indices of the corroded RC columns were also assessed using the damage model proposed by Park-Ang. In addition, a strength prediction method for corroded RC columns was proposed based on the modified compression field theory coupled with the conventional sectional analysis method. The proposed prediction method was then verified with the experimental results.