Local damage detection of flexible offshore platforms using ambient vibration measurement
- Sato-kogyo Corp., Atugi (Japan)
- Musashi Inst. of Tech., Tokyo (Japan)
An efficient method using ambient vibration measurement is presented for detecting the local damage of flexible offshore platforms. Modal properties, such as natural frequencies, damping ratios and mode shapes, are identified from time-series of structural response by a multivariate ARMA model. Making use of the identified modal properties, the local damage detection scheme is broken into two stages. First, the damage region containing a damaged member is isolated from the whole structural system in terms of the curvature change ratio which is defined by the change in the curvature of mode shapes between undamaged and damaged states. Then, the location of a damaged member is pinpointed and the extent of damage is quantitatively evaluated within the damage region by a modal perturbation method. The extent of damage is characterized in terms of the stiffness reduction ratio which is defined as the ratio of member stiffness between undamaged and damaged states. An incremental approach is introduced to deal with large magnitude of damage. Numerical results are presented to illustrate and validate the proposed method for an example structure.
- OSTI ID:
- 433647
- Report Number(s):
- CONF-940409--; ISBN 1-880653-10-9
- Country of Publication:
- United States
- Language:
- English
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