| Title |
Improving IMD Indicators through Multivariate Data Analysis |
| Authors |
이재훈(Lee, Jae Hoon);허광희(Heo, Gwang Hee);전승곤(Jeon, Seung Gon);방건혁(Bang, Geonhyeok) |
| DOI |
https://doi.org/10.12652/Ksce.2026.46.1.0021 |
| Keywords |
통계적 패턴인식; IMD; 공분산 행렬; SHM SPR; IMD; Covariance matrix; SHM |
| Abstract |
Under non-stationary dynamic excitations whose characteristics vary with time, such as seismic loads, the variability of structural responses increases significantly, which limits the ability to determine the presence or absence of damage using only raw measured signals. In this study, to address this limitation, an IMD-based damage indicator enhancement method grounded in multivariate statistical analysis is proposed, and the effect of changes in the covariance-matrix dimension on damage discrimination performance is experimentally investigated. To this end, a shake-table excitation test was conducted on a scaled cable-stayed bridge model using input motions simulating the El-centro earthquake
record, and vertical acceleration responses were measured under an undamaged condition as well as under single- and combined-cable damage conditions. Based on the measured signals, IMD was computed by progressively expanding the covariance-matrix dimension, and the damage discrimination characteristics associated with the dimensional variation were comparatively analyzed. The results show that, as the covariance dimension increased, the increase in IMD values within the damaged intervals became more pronounced, and the separability between the undamaged and damaged states improved progressively. This indicates that expanding the scope of multivariate information enables more effective representation of response characteristics induced by damage. In addition, considering that IMD is a point-wise metric that may be sensitive to transient disturbances, the IMD time series was summarized using the RMS value; consequently, consistently larger RMS values were observed at sensors located near the damage. These findings confirm that the proposed indicator is applicable not only to damage detection but also as an auxiliary quantitative measure for damage localization. |