Strain response estimation for the fatigue monitoring of an offshore truss structure

Fatigue damage accumulation is an outstanding issue in ocean engineering due to long-term cyclic mechanical behaviours resulting from wind, waves and currents. Fatigue monitoring of offshore truss structures has been limited by the costs and techniques of current strain sensors. Aiming to estimate the unmeasured response of structural members, for which there are no available sensors, this paper proposes a strain response estimation strategy using three types of state-space formulations and a Kalman Filtering (KF) process. A strain modal coordinate based state-space model was developed, especially for large engineering structures. The theoretical approaches were evaluated using the numerical simulations based on deterministic and stochastic excitations. The algorithm can be integrated with the existing fatigue monitoring system as an early warning tool.