THE TRANSFER FUNCTION APPROACH FOR A STRUCTURE SUBJECTED TO ICE CRUSHING

A test program has been performed to investigate the suitability and reliability of the transfer function approach in determining ice loads on flexible structures. A simple cylindrical structure was modelled with a compliant foundation and the loads on both the structure and its foundation were measured during ice/structure interaction events. The dynamics of the structure were determined by step-unloading experiments in ice-free water. Assuming that the structure behaved as a single-degree-of-freedom oscillator, foundation loads (which include the dynamics of the structure) were calculated using Fourier techniques. These were compared to experimentally measured values. The results of the test program indicate that this approach is useful only if the frequency of the loading events is not at all close to the natural frequency of the structure. At or near resonance conditions, this technique cannot be used to predict accurately the loads or the dynamic behaviour of the loading events.