The impact forces produced by ice floes can be a significant factor in the design considerations for structures off the East Coast of Canada. A test program was carried out in an ice tank to investigate the force levels due to impact of isolated floes with a structure. In the tests, large floes of sea ice with a surface area of up to 60 m 2 and thickness over 200 mm were grown. These floes represented actual sea ice floes, since there was no scaling of ice strength properties. These floes, with a mass up to 14 tonnes, were then accelerated to a desired speed (up 0.2 m/s) and allowed to impact against an instrumented test structure. The impact force and local pressures were measured for each impact. Impact velocity, floe mass and floe edge geometry were varied. The highest force levels measured were of the order of 50 kN at a speed of 0.2m/s. A simple analytical impact model was developed and validated with test results. It indicates that the maximum impact force was a function of the kinetic energy of the impacting floe raised to some power less than 1. The exponent and coefficient of the power relation were a function of ice floe edge geometry and the ice crushing pressure relation.
In parts of the Grand Banks off the east coast of Canada, floating pack ice can be present for several weeks of the year (Wright, 1998). Offshore structures in these waters have to be designed to withstand the forces generated by the ice. Operational procedures of offshore production systems also have to take into account ice conditions. Ice forces on any fixed or floating offshore structure are generated by the interaction of loose ice floes colliding with the structure.
