Abstract
This paper proposes a novel vibration-based damage identification method, named the probability distribution of decay-rate (PDDR). By introducing a statistical framework, the PDDR method estimates damage-induced changes in overall damping behaviour of a free-vibration dynamic system. Utilising free-vibration impulse-response (IR) data, a one-dimensional dataset of local maxima-minima points is constructed. A statistical analysis of this dataset is then performed to derive damage-sensitive parameters. It is demonstrated that through the use of a statistical analysis framework, a number of enhancements are attained in terms of both robustness and leniency in estimating the significantly nonlinear property of overall damping. An impact hammer test is conducted in the laboratory to verify the efficacy of the proposed PDDR method. The test was performed on a scale-model steel Warren truss bridge structure, subjected to bolt-connection failures. The comparison results between the PDDR method and the standard experimental modal analysis (EMA) method confirm that the former is effective for damage identification of complex structures, particularly with real experimental data and steel-frame structure assemblies.