Structural damage identification based on short-time temporal coherence using free-vibration response signals

•A linear/nonlinear damage identification method is proposed based on STC.•Two STC-based indices are constructed for damage detection and localization.•The indices have high sensitivity to linear/nonlinear structural damage.•The STC-based method can identify loose connections in steel structure effectively. This paper proposes a short-time temporal coherence (STC)-based approach for linear and nonlinear structural damage identification. Two novel damage indices (damage detection index, DDI and damage localization index, DLI) are constructed based on the peak coherence function of the STC, which aims at detecting and localizing the damage using the measured free-vibration responses. Detailed numerical investigation was performed on a spring-damping-mass system. The results show that the two indices are sensitive to linear and nonlinear structural damage, and they can accurately identify the damage even with severely noise-polluted signals. An experimental study was conducted on a steel cantilever column to further validate the proposed approach. A typical nonlinear structural damage was simulated by loosening the bolts in the flange connection, which was successfully identified by the two indices. The results demonstrate that the proposed STC-based damage identification approach is effective to identify the bolt-loosening of structure with free-vibration response signals.