THE MEASURED LINE LOAD AS A FUNCTION OF THE LOAD LENGTH IN THE ANTARCTIC WATERS

摘要

The sea ice in the Antarctic waters consists of first and multi-year ice. In order to secure the safety at sea, knowledge on the ice-induced loads on the ship hull is required. From the structural point of view, the knowledge on the load length and magnitude is needed. Earlier measurements have shown that the magnitude of the ice-induced line load is decreasing as a function of the loading length. However, only a few full-scale measurement campaigns have been conducted in the Antarctic waters. In order to increase the knowledge on ice-induced loads on the ship hull, PSRV S.A. Agulhas Ⅱ was instrumented with strain sensors when she was under construction. Two full-scale expeditions were conducted on board S.A. Agulhas Ⅱ in the Antarctic waters during the austral summers 2012/2013 and 2013/2014. During these campaigns, the ice-induced loading on the ship hull was recorded continuously at three hull areas. This paper studies the measured maximum line load as a function of the loading length. The results are compared to the earlier studies that have employed the data gathered in the Baltic Sea. The study shows that the Gumbel I asymptotic distribution gives a good representation of the measured 1-hour maxima for the bow and 12-hour maxima for the stern. Furthermore, it is shown that the magnitude of the expected maximum line load is significantly greater in the Antarctic waters in comparison to the Baltic Sea.