Experimental, theoretical and numerical analysis of K-joint made of CHS aluminium profiles

Abstract K-joints of welded aluminium lattice structure made of circular hollow section (CHS) profiles are analysed. Aluminium alloy EN AW 6082 T6 was used. The paper topic is determination of design resistance of K-joint in aluminium lattice structure. Change of mechanical properties of material in welding zones due to high temperatures is important characteristic of aluminium. Level and manner of influence of aluminium softening in zone of welded joint on design joint resistance have been analysed in paper. Theoretical, experimental and numerical analysis by means of finite elements method (FEM) with 12 specimens of K-joint have been done. European Standard for aluminium structures EN 1999 does not define design resistance of joint in welded aluminium lattice structures. Therefore expressions from standard for steel structures were used. The aim of the paper was to investigate up to which level expressions from EN 1993-1-8 for design resistance of K-joints in welded steel lattice structure may be used for aluminium alloys structures, having in mind change of material properties in welded joints. After comparative analysis, correction and upgrade of expressions from steel structures standard have been proposed, in order to enable their implementation for determination of design resistance of K-joints in aluminium lattice structures.