Force Identification and Response Prediction of an Offshore Platform Using Admittance Function and Incomplete Response Measurements

In several existing structures and infrastructure systems, the loads and responses are hard to be accurately measured especially when the structural systems are partly or wholly inaccessible or located in harsh conditions (e.g., offshore structures). The chapter proposes a frequency-domain technique to estimate the force and response of vibrating structures using limited response signals. The frequency response function of a structure can be reconstructed either based on an updated finite element model’s properties or identified modal parameters by a data-driven approach. Next, the components of the frequency response function corresponding to a few degrees of freedom, whose response measurements are available, can be selected to create the admittance function and, consequently, to estimate the applied loads and predict the response of any degree of freedom. The technique is implemented on the finite element model of an offshore platform exposed to wave loads. The estimated wave loads and response of the submerged elements indicate the proposed technique’s competence in simplicity and efficiency compared with other methods.