Time Series Based Damage Detection and Localization in an Offshore Platform Using Wireless Sensor Networks

Continuous structural integrity monitoring (SIM) can be a valuable complementary tool to the current practice of periodic inspections in detecting damage in jacket platforms.  This paper demonstrates the technical feasibility of adopting the recent advances in onshore SIM technology for offshore jacket platforms. Both the analysis method and hardware technology are investigated.  To demonstrate the feasibility of the analysis method, a time series based damage detection and localization algorithm is evaluated.  Nodal acceleration and brace strain responses from a jacket platform computer model are simulated and used to determine the Autoregressive (AR) model coefficients. Mahalonobis distance calculated from the first 10 AR coefficients is used as the damage feature (DF).  The DF’s from three different damage cases comprising of missing member, dented member (stiffness reduction), and cracked member (nonlinear behavior), respectively are compared with those from the healthy baseline case to detect and localize damage.  To demonstrate the feasibility of hardware technology, a survey of the state of the art in wireless sensor network technology is conducted.  The survey shows that wireless accelerometers and strain gauges packaged for underwater use can be fitted in a wireless sensor network throughout the jacket using the electromagnetic communication approach. A conceptual configuration of underwater damage detection wireless sensor network for offshore jacket platforms is presented.