MODAL ANALYSIS FOR DAMAGE DETECTION OF REINFORCED CONCRETE COLUMNS AFTER FIRE

摘要

Many civil structures are subjected to damage due to overloading, and natural disasters or man-made hazards. Detection of damage in these structures as well as the prediction of their remaining life is of great economic and social value with respect to the safety of people's asset and life. In this paper, vibration based damage detection techniques were employed to detect damage in reinforced concrete (RC) columns exposed to different levels of fire. Modal test and analysis was carried out for the RC columns in original condition at first. Then, the RC columns were put in fire. Finally, dynamic test on the damaged RC columns was carried out and changes in the dynamic characteristics of the columns before and after fire were examined. Two different methods including Eigen-System Realization Algorithm (ERA) and PolyMax method were employed to extract modal parameters of the columns before and after fire. The performance of the proposed methods is discussed. Lastly, the location of the damage is detected by employing the Co-Ordinate Modal Assurance Criterion (COMAC) method. Results show that the presence and the location of the damage of the RC columns after fire can be identified correctly.