Prediction of Seismic Performance Levels of Corroded Reinforced Concrete Columns as a Function of Crack Width

An experimental study was conducted for the prediction of the seismic performance levels of corroded reinforced concrete (RC) columns as a function of the initial corrosion crack widths. A full-scale accelerated-corrosion pool was used to corrode 25 full-scale RC columns. The initial crack widths at different levels of corrosion were measured for three different concrete strength levels: 9, 27, and 37 MPa. The seismic performance levels of corroded RC columns under combined cyclic lateral-displacement excursions at two different axial-load ratios (0.20 and 0.40) were measured. The corrosion levels obtained for the initially measured corrosion crack widths were used for establishing a correlation with the lateral-displacement capacities of the RC columns according to an energy-based method. Three empirical models were developed. The first was for predicting the cross-sectional area reduction of reinforcement bars according to the initial corrosion crack widths. The second model was for predicting the percentage of energy capacity of RC columns as a function of the drift ratio and corrosion levels. The third model was for predicting the seismic performance levels of RC columns as a function of the initial corrosion crack widths and was used for an in situ structural assessment. The experimental test results showed that above a 2% drift ratio, all uncorroded RC columns (regardless of the concrete strength levels) exhibited a sudden reduction in energy capacity, and their total energy capacity was consumed. In the case of corrosion, the energy capacity of concrete with high strength levels was prematurely exhausted above a 1.4% drift ratio because of the effects of the corrosion products under the high strength levels of the concrete.