The engineering society is in trouble when they have to design structures for ice covered waters, because the various world wide available predictions of ice forces on structures scatter by a good factor of 10.

Scattering of ice load and force predictions by
twenty different predictors for typical Baltic Sea ice.

For several years research groups in Japan, Canada, USA and Europe are working on this problem in order to elucidate the controversies. Under the Marine Science and Technology Programme of the previous EU RTD Framework Programme the project LOLEIF - Low Level Ice Forces was conducted by the research groups also active in STRICE. The results achieved in LOLEIF were highly promising and highly justified supplementary research work. This in particular as the evaluation of such complex processes in the nature with all its variability requires extended measurements.

So far the various groups of researchers have different opinions on the mechanisms and failure processes of ice interacting with structures and on the question which kind of failure leads to the most critical load conditions. This insufficient understanding results from difficult combinations of ice effects and impacts on the structure. Model tests which have been used to develop empircal ice force prediction formulae may also mislead due to incomplete similarity of the mechanical properties of the model ice.

In this situation, facing the wide scatter of ice force prediction, the STRICE researchers intend to go out into nature and study the phenomena of the various ice failure modes and measure the force and its effecting parameters under real conditions and in full scale.

The most severe ice loads against offshore structures and ships are caused by pressure ridges. Indeed, the ridges are still today the only ice feature that can stop ships or icebreakers proceeding in the Baltic Sea. Ice rubble together with the consolidated ice layer is a complicated structure and its mechanical behaviour is not well understood. The ridge loads cannot be predicted reliably because general constitutive laws are unknown. Existing ridge load models are based on soil mechanics limit load analysis with simple simultaneous failure planes. In reality the failure will be progressive along complicated three-dimensional failure surfaces. Thus, traditional models predict too high ridge loads.

The STRICE Consortium - a group of scientists from six countries in Europe - has evidence, that the ice forces are indeed smaller than being used world wide for design of marine structures placed in ice. This means that these structures are most likely over designed and more expensive than necessary.

This evidence comes from full scale measurements in China and in the northern part of the Baltic Sea. On the other hand one has to make sure that the structures are safe and will withstand the hazard of ice impact of different ice scenarios. An unsafe offshore structure is certainly hazardous both to mankind and the environment.

The STRICE project was initiated to significantly contribute to the solution of the aforementioned problems and to provide within three years of intensive, trans-European and multi-disciplinary research reliable data, information and results for optimised and safe design of structures in ice.