Ein “Overall‐Konzept” für die Querschnittstragfähigkeit im elasto‐plastischen Bereich

Es wird die bereits für andere Tragfähigkeitsprobleme von Bauteilen (Knicken, Beulen) entwickelte “Overall‐Methode” auf die Berechnung der Querschnittstragfähigkeit von Stahlprofilen angewendet. Dies führt zu einer neuen Berechnungsmethode, die den gesamten elasto‐plastischen Bereich ohne die Notwendigkeit einer Klasseneinteilung umfasst. Basierend auf zahlreichen Versuchen und Querschnittsberechnungen mittels geometrisch, materiell nichtlinearer Analysen mit Imperfektionen werden (analog den Knicklinien) Bemessungskurven für die Abminderungsfaktoren vorgeschlagen, die für bestimmte Querschnittstypen wie I‐beziehungsweise H‐Profile oder Rechteck‐Hohlprofile, einen einheitlichen Verlauf im elasto‐plastischen Bereich aufweisen. An overall concept for the cross‐section resistance in the elasto‐plastic range. The “overall method” which has been developed for other load carrying problems of steel members (e.g. lateral member buckling or buckling of shells) is applied to the calculation of the cross‐section resistance of steel members. This leads to a new procedure that covers the whole elasto‐plastic range without the need of cross‐section classification. Based on numerous experimental tests and numerical calculations (GMNIA) design curves for the reduction factors of I‐ and H‐shaped sections and RHS‐sections are proposed that show a consistent transition in the elasto‐plastic range.     

Experimentelle Validierung von Bemessungsregeln für Stahltrapezprofile mit Öffnungen

Experimental validation of design rules for trapezoidal profiles with openings. Structural design and detailing of trapezoidal steel sheets in Germany currently follows the rules provided by the still valid National Standard DIN 18807‐3 (1987). This Standard is based on the old design concept using one global safety factor and contains references to outdated codes which had been long since withdrawn. Within the framework of transition of design rules from DIN 18807‐3 to the European Standard EN 1090‐4 available provisions for openings in trapezoidal profiles, which exist since 30 years, were brought into question. The investigations regarding background information on these rules revealed a number of open questions concerning their application in practice as well as the mechanical performance of the cover plates. The basic concept for consideration of openings consists of the application of increased loads and verification using the complete cross‐section of trapezoidal profiles. On the one head, several details regarding the application of this method are, however, not clearly specified leaving space for interpretations which may lead to non‐economic results in case of over‐conservative interpretation. On the other hand, non‐safe results may be obtained if neglecting the increased loads while relying on the (non‐existing) strengthening effect of the cover plates.     

Regelwerke für die Werkstoffauswahl und Dauerhaftigkeit von nichtrostenden Stählen für Stahlbauten – Entwicklung und aktueller Stand

Technical regulations for the selection of materials and dura bility for steel structures – Development and current status. One of the most important changes of the revised DIN EN 1993‐1‐4 released in October 2015 can be found in the annex section A ”Selection of materials and durability“. Contrary to the previous version this annex is now normative. By means of a point system considering different key variables that influence the selection of stainless steel alloys and combines values for each to give a total corrosion resistance factor suitable alloys can be selected. The annex aims to provide a methodology for use by designers with no specialist knowledge of either corrosion or stainless steels. The paper also discusses differences and similarities with the previous valid German national technical approval Z‐30.3.6.