Damage Diagnosis of a Structure in Time-Frequency Domain
This work proposes a simple and efficient approach to locating the storeys whose stiffness change in the life cycle of a structure. The storeys that may be damaged are determined by comparing the unitary stiffness matrix in different stages in the life cycle of a building. An appropriate ARX (autoregressive with exogenous input) model of structure in established from the structural dynamic responses in terms of acceleration or velocity. The parameters in an ARX model are identified through the short time Fourier transform, and the natural frequency and damping ratio of structure are estimated directly through these identified parameters. The effectiveness of the proposed procedure is verified using the numerically simulated earthquake acceleration responses of a six-storey structure that is damaged at one or two storeys. The proposed scheme is compared to the DLV approach (flexibility-based damage locating vector approach) in identifying damage storeys.