PSI - Issue 5

Lars Sieber et al. / Procedia Structural Integrity 5 (2017) 1019–1026 Sieber, Stroetmann / Structural Integrity Procedia 00 (2017) 000 – 000

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4. Summary and Outlook

In this paper examinations of brittle fracture of riveted structures made of old mild steels were presented. An integral part was the extensive material analyses carried out to identify the fracture toughness in the brittle-ductile transition zone using the Master-Curve concept. The evaluations confirmed that different material grades can be defined depending on the manufacturing process. To be able to assess the influence of the punching of holes on the brittle fracture characteristics of old mild steels, structural examinations and micro hardness measurements were carried out. Based on these results a procedure for the assessment of brittle fracture in riveted components has been derived by Sieber (2016) for typical construction details of existing steel structures within a fracture mechanical safety analysis. In accordance with the width of the hardened peripheral zone of punched holes a crack with a straight crack front and a depth of 3 mm is assumed at the most stressed hole edges. Equations for stress intensity factor approaches from specialized literature are used to determine the toughness requirements for components with rivet holes. Based on fracture mechanical FE calculations a modification of these approaches has been carried out for joints with angle profiles. The assessment procedure has been transferred to a semi-probabilistic verification concept verified by component tests using statistic methods to consider the variation of strength and toughness values of the mild steels. Acknowledgment The presented material examinations were mainly carried out within the research project “Assessment o f the risk of brittle fracture at punched steel structures - further development of analytical methods” (Stroetmann et al. (2015)) and were supported with funding from the research initiative “Zukunft Bau des BBSR” (AZ: II 3 -F20-12-1-054). The authors sincerely thanks for this. Bannister, A.C., Webster, S.E., 1999. SINTAP Procedure - Final Version. FITNET - European Fitness-for-Service Network. EN 1993-1-10:2010 “ Material toughness and through-thickness properties “ German Version, Berlin: Beuth Verlag GmbH. Helmerich, R., 2005. Alte Stähle und Stahlkonstruktionen: Materialuntersuchungen, Ermüdungsversuche an originalen Brückenträgern und Messungen von 1990 bis 2003. Bundesanst. für Materialforschung und -prüfung, Berlin. Hensen, W., 1992. Grundlagen für die Beurteilung der Weiterverwendung alter Stahlbrücken. Doctoral thesis. RWTH Aachen. Huhn, H., 2004. Ermüdungsfestigkeit von Schraubenverbindungen aus feuerverzinkten Stahlbauteilen mit gestanzten Löchern. Doctoral thesis. VDI-Verlag, Düsseldorf. Klinger, C., Mehdianpour, M., Klingbeil, D., Bettge, D., Häcker, R., Baer, W., 2011. Failure analysis on collapsed towers of overhead electrical lines in the region Münsterland (Germany) 2005. Engineering Failure Analysis Journal 18 (7), 1873 – 1883. Landes, D., Shaffer, D.H., 1980. Statistical Characterization of Fracture in the Transition Region, in: ASTM International (Ed.), ASTM STP 700, West Conshohocken, PA, pp. 368 – 382. Langenberg, P., 1996. Bruchmechanische Sicherheitsanalyse anrissgefährdeter Bauteile im Stahlbau. Zugl.: Aachen, Techn. Hochsch., Doctoral thesis. Shaker Verlag, Aachen. Phaal, R., Macdonald, K.A., 1991. Critical examination of correlations between fracture toughness and charpy impact energy: Report - OTO 96 710, Cambridge. Reiche, A., 2000. Zustandsbewertung von metallischen Tragwerkskomponenten. Fraunhofer-IRB-Verlag, Stuttgart. Sanz, G., 1980. Essai de mise au point dune method quantitative de choix des qualities d’aciers vis -à-vis du risqué de rupture fragile. Revue de Métallurgie, 621 – 642. Sieber, L., 2016. Zur Beurteilung der Sprödbruchgefährdung gelochter Stahltragwerke aus Flussstahl. Doctoral thesis at the Institute of Steel and Timber Construction, Technische Universität Dresden. Stroetmann, R., Sieber, L., Viehrig, H.-W., Houska, M., Vetter, B., Schubert, V., 2015. Beurteilung der Sprödbruchgefährdung gelochter Stahltragwerke: Weiterentwicklung der Analysemethoden. (Aktenzeichen: II 3- F20-12-1-054). Fraunhofer-IRB-Verlag, Stuttgart. Wallin, K., 1998. Master Curve Analysis of Ductile to Brittle Transition Region Fracture Toughness Round Robin Data - The ‘Euro’ Fracture Toughness Curve. Technical Research Centre of Finland, Espoo. Wallin, K., Nevasmaa, P., Laukkanen, A., Planman, T., 2004. Master Curve analysis of inhomogeneous ferritic steels. Engineering Fracture Mechanics 71 (16-17), 2329 – 2346. References ASTM E1921:2013 “Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range”, United States.