Structural damage detection with statistical analysis from support excitation

The unit impulse response (UIR) functions obtained from a structure under support excitation are used to identify local structural damages. The extraction of the UIR with the aid of discrete wavelet transform from the measured acceleration is described. The sensitivity matrix of these UIRs is then obtained based on the finite element model and the time-stepping integration method. Based on the computed sensitivity matrix of the UIRs from several accelerometers, a two-step model updating method is adopted for identifying the local damages. Statistical analysis is included into the damage identification procedure with the measurement noise taken as an independent random variable in the measured UIRs. A new damage localization index is proposed and the mean values of the identified parameters are taken as the damage severity. Finally, a nine-bay three-dimensional frame structure is analyzed numerically and experimentally using the proposed technique. The damage scenarios of multiple damages with different levels of noise are considered. The identified results are shown satisfactory, indicating the feasibility and effectiveness of the proposed technique.