A Revised Ice Pressure-Area Curve

An existing pressure vs. area curve for determining local ice pressures on offshore structures and ship hulls was included in the CSA S-471 and API RP 2N standards for offshore structure design. The data comprising the original curve was based on multi-year ice obtained from medium scale impact tests, ship ramming tests, and ice load panels on the Molikpaq structure. The curve subsequently has been adapted to warmer climates where multi-year ice is absent. In adapting the pressure vs. area curve to new requirements for application in other codes and practices, it was observed that the ship impact tests may be too conservative for the local ice pressure curve. Also, further analysis of relevant data from the Molikpaq measurements in the Beaufort Sea has been obtained. Thus the pressure-area curve has been updated to reflect the new data, and the ship impact data removed. The local ice pressures that were used in the original Molikpaq design have been included and there is very good agreement between the design pressures and those derived from a database not available at the time. The new relationships that have been developed for local ice pressure versus area are presented.