| Abstract: | Fatigue behaviour of X‐joints made of rectangular hollow sections. In 1984 Mang and Bucak ([8], [9]) presented their first detailed proposal for FAT‐classes for welded X‐sections made of rectangular hollow sections (RHS) to the committee of regulations for the DIN EN 1993‐1‐9 [1]. The proposal was based on experimental investigations of welded X‐joints of RHS with different width (b/bo) and thickness (to/t) ratios, but were not accepted because the scope of the Eurocode 3 regulation should not be enlarged at that time. There are no FAT‐classes for welded X‐sections made of RHS in the current version of DIN EN 1993‐1‐9 [1], the IIW document [2] and the FKM guideline [4] for a nominal stress approach. There are specifications in the crane construction code DIN EN 13001‐3‐1 [3] but they are very conservative. CIDECT Design Guide No. 8 [12] also does not contain information referring this issue based on the nominal stress concept, but it gives detailed specifications like assessment formulas and graphs for the determination of the stresses (SCF) and strains (SCNF) for welded rectangular and hollow sections on the base of the structural stress concept. At the university of applied sciences Munich and the Labor für Stahl und Leichtmetallbau GmbH, Kissing, further investigations in the research project [13] were executed upon request of several industrial partners with focus on the fatigue behaviour of welded X‐sections made of RHS. Based on the results, a verification and extension of the code proposal of Mang and Bucak ([8], [9]) has been prepared. The main focus of this new investigation was the fatigue behaviour of bigger thickness ratios (to/t ≥ 2,0) as well as actual tube grades and welding procedures with high process reliability. This article summarizes the results and the #new code proposal. |
