Identification of Damage in Reinforced Concrete Columns under Progressive Seismic Excitation Stages

Prompt and accurate detection of realistic damage in constructed facilities is critical for effective condition assessment and structural health monitoring. This paper reports the experimental investigations of eccentric reinforced concrete columns mounted onto a shaking table and subject to progressively increasing seismic excitations. The investigation was aimed at studying the changes in the dynamic parameters in order to assess the structural conditions of the concrete columns after each post-seismic stage. The dynamic response of the structure was measured using accelerometers, traditional foilstrain gauges, and long-gauge fiber Bragg grating (FBG) sensors. The post-seismic conditions of the columns were evaluated via vibration-based damage identification methods. Results from this study demonstrate the applicability of specially packaged surfacemounted long-gauge FBG sensors for detecting the initiation and the progression of cracks due to reverse dynamic loads. The concept of modal macrostrain analysis was also introduced to identify and localize mild damage due to the applied seismic excitations of increasing intensities. The performance of the sensors for structural identification is also discussed.