Experience of building and operating ice vessels, icebreakers and offshore structures in ice conditions demonstrated the necessity of monitoring actual strength and life parameters. Monitoring data permit to solve questions related to estimation of external forces, evaluation of hull structural stressed-deformed state, check of strength, reliability and specific features of hull structures operation.
A strength monitoring system for hull structures of ice vessels, icebreakers and offshore structures developed by Krylov State Research Centre is considered. Evaluation of the general stressed-deformed state picture is based on complex analysis of results of computer simulating, laboratory and full scale testing of hull structures. The monitoring system has passed tests in full scale conditions during Arctic voyages and could be used as a basis for taking operative measures providing safe operation and creating a database on loads and deformation of hull structures.
Modern trends of developing ice vessels, icebreakers and offshore structures are characterized by optimizing hull structures in order to decrease weight characteristics and ensuring the required strength level at ever-increasing service loads (convoying speed growth, transport loading increase in the Northern Sea Route (Mihaylichenko, 2013)). Increased requirements to structural strength (including strength of ice strengthening structures) are caused by safety requirements and economical reasons, such as building costs and operational expenses. All mentioned factors determine the necessity to develop methods and methodologies for monitoring loading of offshore structure hulls during operation.
To improve the quality of engineering new types of offshore structures designed for operation in severe ice conditions, reliable information on external force values, for which structural strength is calculated, is required. So to calculate ice loads, a function of contact pressure values versus the contact area is used; this function is generated by results of processing data of a multitude of full scale tests and model experimental studies. The experimental data scatter relatively the accepted approximation of design pressure is rather considerable that introduces large uncertainty in ice loading values (Aleksandrov, Platonov, Matantsev, 2014). At the same time, design estimations of structural strength and service life, as well as requirements to the used materials depend on the accuracy of acting loading evaluation. Reliable information of external forces and strength properties will permit to specify strength margins, reduce material consumption reasonably at required reliability assurance.
