Laboratory tests on a hybrid SDR approach for jacket platforms via improved dynamic-reduction system

Abstract

Abstract The improvement of robust skills for early defect recognition for fixed marine structures is crucial to avoid the possible catastrophe caused by structural degradation. This paper presents an approach for defect recognition based on vibration measurements that is capable of detecting the defect to individual members of offshore jacket platforms, when limited, spatially incomplete modal datum is available. Generally, model reduction is better than modal expansion. Hereof, this paper investigates the developed new defect recognition method using improved dynamic-reduction system. The approach needs only one mode shape. The approach first updates the modal datum. Then, an efficient technique is applied to create a transformation matrix. This matrix is utilized to correct / or refine the nominal eigenvectors so that the updated model is well-matched with the experimental modal data. In this regard and also to conquer the uncertainties between numerically and experimentally identified features, laboratory vibration tests are accompanied on a physical platform model. The efficiency of the approach is validated by different destruction scenarios foreseen on the physical model. The proposed defect recognition approach in conjunction with iterative dynamic reduction approach yields the best defect location and severity estimate. Proposed technique is considered because of practical considerations and expansion of such methodologies would be extremely useful for offshore jacket structure.