Structural Damage Alarming of Offshore Platform Based on AR Model and PCA in Changing Environment Conditions

摘要

It is well known that the results of vibration based damage detectionmethod do not depend only on damage but also on environmentalconditions (temperature, humidity, mass loading, running speed). In thispaper, a new damage alarming method in changing environmentalconditions is proposed. Firstly, the autoregressive (AR) model is usedto fit the structural acceleration response pre and post damage.Secondly, the principal component analysis (PCA) is employed toremove the influences of environmental conditions on the coefficientsof AR model. Mahalanobis norm calculated from the AR coefficients isused as the damage-sensitive novelty index. Finally, the statisticalcontrol chart is used to alarm damage. A numerical model of a fourfloorsteel offshore platform excited with white noise is used to test themethod, the results show that the proposed method can accomplish thedamage alarming in changing environmental conditions.