STRUCTURAL RESPONSE COMPARISON USING DIFFERENT APPROACHES TO ACCOUNT FOR ICE LOADING

摘要

Ships operating in ice-covered waters need to comply with the route-specific ice-induced loads. Compliance with classification societies' rules is achieved through the introduction of a uniform pressure patch applied to the hull surface. As this approach aims to capture the average force acting over the specified panel area, it does not directly account for the high degree of spatial and temporal variations observed in ice load measurements, which are inherent to the ice failure process. Furthermore, the current formulations of ice class rules do not fully account for the probabilistic nature of ice loads, i.e. scale effects for local ice pressures captured in full-scale measurements. Finally, ice class rules do not consider route-specific ice conditions when estimating the design load, i.e. the exposure of the vessel to ice crushing as determined by the number and duration of rams. The current paper addresses those discrepancies, previously studied by Erceg et al. (2014, 2015), through the response comparison of a stiffened panel subjected to ice loads using different approaches to account for ice loading. Full-scale pressure distributions obtained from Japanese Ocean Industries Association (JOIA) field indentation programme are used to investigate the effects of spatially localized loads on the local plastic deformation of the hull. The results obtained using the Finite Element Method (FEM) are compared to the rule-based method as well as the rational approach for design load estimation developed by Jordaan and co-workers.