Damage Detection of Offshore Platform Structures Using Time Domain Response Data

In the paper, a new method using time-domain response data under random loading is proposed for detecting damage of offshore platform structures. In the study, a time series model with a fitting order is first constructed using the time domain response data with measurement noise. A sensitivity matrix consisting of the first differential of the autoregressive coefficients of the time series models with respect to the stiffness of the structural elements is then obtained based on time domain response data. The locations and severities of the damage may be finally estimated by solving for the damage vector whose components are the damage degrees of the structural elements. The efficiency and capability of the proposed method is demonstrated by applying the method to a FEM model of a simplified offshore platform structure with damages at single or two elements. Numerical simulations show that the use of a few sensors´ acceleration history data with certain level measurement noises is capable of detecting damages efficiently and the increase in numbers of sensors helps for improving the diagnosis success rate.