Evaluation of Ice loads on Beitstadsundet bridge by deterministic and probabilistic approaches

Abstract

Ice loads on the bridge piers can be one of the major components for the Extreme Limit State (ELS) combinations, specified in the Euro Code. In arctic and sub-arctic regions, the ice action on infrastructures such as platforms, lighthouses, sub-sea pipelines, or wind turbines may exceed the total forces of wind, waves and currents and may, therefore, determine the design. For example, in regions such as Beitstad in Norway, ice loads can be the predominant lateral force in the design of bridge sub-structures. Therefore, accurate estimation of ice forces that can act on bridge piers in northern climates is critical in both cases – the design of new bridges and the structural evaluation of existing bridges. Different design codes provide empirical formulae to calculate the design ice forces, based on the effective ice strength, thickness and other important empirical environmental or climatic coefficients. Ice forces must be considered in the design of the coastal and hydraulic structures. Both the ice conditions and the environmental factors are combined in a formula to calculate the magnitude of ice forces that a structure is expected to withstand in the future and over its lifetime. The existing standards for estimation of the ice loads on vertical and sloping structures adopt different analysis methods, and to determine the global ice loads on these structures, the ice-structure interaction scenarios must be identified. In this study, most of the focus will be on fjord and lake ice conditions and their loading on a bridge pier will be assessed and compared by using different shapes of structure and standards of different countries, followed by the deterministic extreme value analysis , probabilistic assessment and uncertainty analysis of the ice loading during the design lifetime of the bridge sub-structure.