Determining the crack acceptability in the welded joints of a wind loaded cylindrical steel shell structure

Abstract

Engineering critical assessment can be considered as a mandatory request in the civil engineering designing and manufacturing process. The paper is presenting the procedure for determination of crack acceptability based on fracture toughness with failure assessment methods (FAD-1 and FAD-2) which is applied to a cylindrical steel shell structure with welded joints which is having the wind as the main load [7]. The stresses in the structure were determined based on a structural analysis. According to [3] an in depth finite element analysis was applied to the segment joint of the steel shell element (pillar), thus revealing the stresses in the joint (as well in the welded joints). There were assessed common types of flaws met at steel shell cylindrical structure elements using failure assessment diagrams - level 1 - FAD-1. The results are presenting the acceptability level for each type of flaw with comparative graphs, determining also the critical dimension of the flaw. For each flaw was calculated the failure assessment diagram level 2 (FAD-2). Comparisons between groups of flaws were done, revealing the critical crack like flaw. Also the critical values of flaw dimensions were calculated for each flaw type [7]. The methodology establishes clear rules for assessment of structural elements with cracks, determining the initial flaws, assessed flaws and critical values of the cracks. The conclusion of the research reveals the fracture resistance failure susceptibility of different parts of the segment joint given an existing discovered flaw. Based on the detailed procedures described in the paper, on conclusions to the assessment done on each type of flaw, the method can be applied from the design phase on these types of structure elements.