Estimation of seismic performance levels depending on the primary crack width of full-scale reinforced concrete columns exposed to corrosion

Today's structural assessment techniques provide practical methods (e.g., rapid screening and scoring of buildings) for structural engineers to assess the seismic performance levels of reinforced concrete (RC) buildings. Because of unknown many parameters with complex structures of corrosion, prediction of seismic performance levels of corroded RC buildings is more complex compared to uncorroded ones. Therefore, it is important to develop a practical model to predict the seismic performance levels of corroded RC columns based on visual assessments on site. An experimental study was performed for the prediction of the seismic performance levels of corroded RC columns as a function of initial corrosion crack widths. A full scale of an accelerated corrosion pool was used to corrode the 25 full scale RC columns. Initial corrosion crack widths at different levels of corrosion were measured for three different concrete strength levels of 9, 27 and 37 MPa. Seismic performance levels of corroded RC columns under combined cyclic lateral displacement excursions at two different axial load ratios (i.e., 0.20 and 0.40) of columns capacities were measured. Actual corrosion levels were obtained by breaking the concrete and extracting the all reinforcement bars following cyclic loading tests. Obtained actual corrosion levels at the measured initial corrosion crack widths were used to be correlated with lateral displacement capacities of RC columns according to 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.