Lennart Fransson

A Statistical Approach to Extreme Ice Loads on Lighthouse Norströmsgrund

Data from full-scale measurements of ice loads on lighthouse Norstromsgrund has been analyzed using basic statistical methods. Questions like scaling, duration of ice interaction and correlation of extreme ice loads on different segments of the structure are discussed. Typical ice conditions in the Baltic Sea are described in general and the region is divided into areas with similar ice and ice movements. Indications of strong influence of structure diameter on the effective ice pressure were confirmed by results obtained on other lighthouses in the area. The result can be used in simulations of ice load probabilities for fixed vertical structures with small diameters located in the Baltic Sea.Copyright

Nonlinear Finite Element Simulations of Ice Sheet Forces on Conical Structures

The present paper deals with interaction between an ice sheet and fixed, conical structures. The ice sheet as well as the structure is discretizied by finite elements. The interaction between the ice sheet and the conical structure is simulated using a special contact algorithm which makes it possible to follow the gradually developing contact between the ice sheet and structure. As the configuration of the ice sheet changes during the interaction process, the buoyancy forces changes accordingly. This process is traced by introducing a continuous nonlinear foundation model to include the effects of buoyancy forces and specific weight of the ice. The mechanical behavior of ice is approximated using two different constitutive models. In the first material model the ice is treated as an isotropic, brittle material, while in the second model the ice is considered being a transversal isotropic, brittle material. When the state of stress at a material point in the ice reaches the failure surface, cracking or crushing is said to occur. After cracking or crushing, the post peak behavior of the ice is approximated as a rigid plastic material. The results obtained during the finite element simulations are compared with analytical methods for calculation of ice sheet forces on conical structures.Copyright

Investigation of ice surface change during vehicle testing

Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is ...

Do Cracks Reduce Thermal Ice Stresses

Theoretical predictions of thermal ice loads often result in over estimations. The most important discrepancy between theory and practice is the idea of an ice sheet without cracks. Field measurements of in situ stresses have shown that the ability to build up thermal stresses may vary from 130 to 290 kPa/°C in the same effectively confined ice sheet.