TY - JOUR A1 - Helmerich, Rosemarie A1 - Herter, Jürgen T1 - Root cause analysis of cracks in old steel viaducts and retrofitting T2 - Engineering failure analysis N2 - Following the long tradition of the Federal Institute for Materials Research and Testing (BAM) since Adolf Martens has created first routines in failure analysis (Ruske, 1971), BAM has been frequently called-in by the Berlin Traffic Association (BVG) to carry out root-cause analyses of the Berlin suburban train line (Frahm, 1902), reported in Helmerich and Herter (1999), Helmerich (2000), Nega and Winkler (1998), Helmerich et al. (2002) and Herter et al. (2002). This was also the case in the 1990s, when BVG-inspectors found cracks in hanging, barrel-like shaped ballast plates of the Berlin underground steel viaducts during regularly scheduled inspections. Cracks were located parallel to the riveted connection between the ballast plates and the upper chord of the viaduct cross girder steel profiles. For safety reasons, the operator BVG immediately stopped the cracks by means of drilling stop holes at the crack tips. As intermediate measures, longitudinal steel profiles were spanned below the rail axes between the cross girders affected to stabilize the track in longitudinal direction. The inspection period was shortened from years to few weeks. BAM was mandated to measure strains under regular train traffic to analyze the cause of the cracks. Strains were measured in identical connections as the damaged details, which did not suffer from cracks at the time of the measurement. The traffic-induced strain cycles and thus the resulting strain differences in the questionable cross sections were higher than expected and resulted in stresses of max. 85.8 MPa. Calculations showed that the credible remaining fatigue life for this particular structural detail was exceeded after 68 years according to nowadays standards. Extensive discussions, further field and laboratory tests followed to develop a rehabilitation plan for retrofitting the structure with minimum interference of the traffic. Finally, a method with minimum intervention to the structure was elaborated by a consortium of the operator BVG, BAM and producers based on further laboratory and field tests at BAM. Now, the viaduct is saved for the future. PB - Elsevier Science Publ. CY - Oxford KW - Riveted viaducts KW - Fatigue cracks KW - Strain measurement KW - Rehabilitation KW - Non-ballasted track PY - 2014 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/30897 AN - OPUS4-30897 SN - 1350-6307 SN - 1873-1961 VL - 43 IS - Special Issue 'A Tribute to Prof. A. Martens' SP - 150 EP - 170 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany