As part of the ongoing revision of the Eurocodes, design provisions in EN 1999-1-1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. Numerical investigations were conducted because a need for improvement was identified. This part 1 of the paper describes the individual steps of the revision and the modifications discussed, which include the introduction of longitudinally welded members. Before going into the numerical investigations in more detail, previous observations are presented regarding buckling classes and plateau lengths. In part 1 of the paper, explanations of the numerical investigations are limited to presenting the modelling of the geometry, the mechanical properties and the imperfections as well as their respective variation in the context of the parametric studies. The results of the numerical investigations and the proposed design approaches will be presented in detail in parts 2 and 3.

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 of the paper, the main observations are presented in qualitative terms. Those observations are: the influence of the allocation of the materials to buckling classes, the influence of the imperfections plus the cross‐section geometry including the position and size of the HAZ within the cross‐section. Part 3 will conclude this paper by discussing the proposed design approaches in detail.

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Sowohl die Bemessung von Aluminiumtragwerken nach DIN EN 1999‐1‐1 [1] im Allgemeinen als auch die der Schweißverbindungen im Besonderen unterscheidet sich von der nach DIN 4113 in vielerlei Grundsätzen. Bestehende deutsche Regelungen und aus der Anwendung der EN 1999‐1‐1 deutlich gewordene Lücken erforderten, dass durch ergänzende, nicht widersprechende Angaben, die so genannten NCI‐Regelungen, im Nationalen Anhang und seinen Änderungen Bemessungsregeln und Erläuterungen ergänzt wurden. Bei NCI‐Regelungen ist zu beachten, dass diese nur für Tragwerke und tragende Bauteile angewendet werden dürfen, die im betreffenden Land – das heißt also hier in Deutschland – zum Einsatz kommen. Da der Umfang der zerstörungsfreien Prüfung der Schweißnähte gemäß DIN EN 1090‐3 [5] vom Ausnutzungsgrad (Ausnutzungsklasse) und der Art des Bauwerks (Ausführungsklasse) abhängt und so indirekt die Beanspruchbarkeit bestimmt, werden nach der Behandlung der Bemessungsregeln für Schweißverbindungen abschließend die Regelungen der DIN EN 1090‐3 zur Ausführung und Prüfung von Schweißnähten beschrieben, die auch der Tragwerksplaner kennen muss.Design of predominantly statically loaded welded connections of aluminium structures according to DIN EN 1999‐1‐1. The design of aluminium structures according to DIN EN 1999‐1‐1 is different with respect to many design principles of DIN 4113 in general as well as especially for welded connections. Non‐contradicting existing German design rules and deficiencies (missing design provisions) which became obvious with the application of DIN EN 1999‐1‐1 in daily practice required and will require NCI‐regulations with supplemental design rules and comments in the National Annex and its amendments. The regulations of DIN EN 1090‐3 [5] for execution and testing of welds are discussed in connection with the design rules. This is important since the degree of nondestructive testing of welds according to DIN EN 1090‐3 [5] depends on the utilization factor (utilization range) and the nature of structure (execution class). Thus it indirectly determines the design resistance which is needed by the designing engineer.

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