Stahlsortenwahl für Brückenlager zur Vermeidung von Sprödbruch

摘要

Die Bemessung von Eisenbahnbrückenlagern nach der Normenreihe DIN EN 1337 [4] in Verbindung mit Modul 5101 der Richtlinie 804 [2] sowie DIN-Fachbericht 103 [3] fuhrt bei Eisenbahnbrücken mit großen Stützweiten vermehrt zur Verwendung von Stahlblechen, deren Blechdicke oberhalb der Anwendungsgrenzen der Technischen Baubestimmungen - hier insbesondere DIN-Fachbericht 103 (Tab. 1) und DASt Richtlinie 009 [18] sowie DIN EN 1993-1-10 ([7], [8]) - liegen. In Fällen wie diesen waren bisher Ausnahmegenehmigungen, in der Regel Unternehmensinterne Genehmigung (UiG) sowie Zustimmung im Einzelfall (ZiE) erforderlich, im Rahmen derer gutachterliche Stellungnahmen hinsichtlich der Stahlsortenwahl zur Vermeidung von Sprödbruch für diese speziellen Bauteile erforderlich wurden.%The dimensioning of railway bridge bearings requires a careful selection of steel grades in order to avoid brittle fractures. The selection of steel grades is stipulated in Germany by the guideline DASt 009 and in future identically in DIN EN 1993-1-10. Due to the fact that bridge bearings are essentially composed of machined parts, the assumptions and fracture-mechanical calculation models which served as the basis for the DASt-guideline 009 and for DIN 1993-1-10 had to be adapted to the specific situation of each individual bearing. A number of relevant bearing-specific crack formation scenarios were introduced and evaluated under fracture-mechanical aspects. Based on this analysis and in function of the operating temperature, the level of tension under load and the material toughness, the maximum permitted sheet thickness was derived. Design details with and without welded joints were taken into consideration. Nevertheless, in all cases an additional residual stress profile was superposed to the load tensions. In addition the technical delivery conditions on the requirements to steel structural components with sheet thickness of over 100 mm had to be defined. As a result and after introductions into the construction supervision of the bearing-specific concept modified with respect to the DASt-guideline 009 and DIN EN 1993-1-10 for the area of railways of the German Federal Republic of 24th of February 2012, it is now possible to establish proof of steel components for up to 250 mm thick railway bridge bearings, not only against brittle fracture but also - of course respecting the aforementioned limits and requirements - to apply them without certificates of exemption (in-house approval as well as acceptance in individual cases).