Engineering critical assessment of steel shell structure elements welded joints under high cycle fatigue

Abstract

Existing flaws in critical parts of structural elements may lead to failures of subassemblies and, in case of lack of redundancy, even to the entire structure collapse. Considering the case of cyclic loading - wind load (including extreme phenomena as storms or blizzards), in which some of these type of structures have failed/collapsed, the post factum assessment, indicated the principal damage causes, i.e. existing welding flaws in combination with corrosion (surface flaws). The paper presents the fitness-for-purpose analysis, i.e. Engineering Critical Assessment, applied during design, in order to assist in the choice of welding procedure and/or inspection techniques. The evaluation is made with BS7910/2013 standard using level 2 failure assessment diagrams for possible discovered flaws, considering a real case assessment - a new designed steel monopole type antenna tower structure.