TY - CONF A1 - Mehdianpour, Milad A1 - Eisenkolb, Tino ED - Jasienko, J. T1 - Experimental investigations on sliding friction of historic bridge bearings N2 - The necessity to reassess historic bridges has yielded the recurrent insight in recent years that the bearings made from iron or sleel implemented in those structures have not received any scientific attention for nearly a Century. This paper presents results, some of them surprising indeed, from a series of experimental investigations performed on sliding bearings from past generation. The Undings show that these types of bearings require further investigation not only for economic reasons, but also for safety issues. These examinations were to yield realistic coefficients of sliding friction. 1t could be demonstratedthat the coeffecients at the upper margin (95%-quantile) were unexpectedly high and almost linear depending on the existing contact stress, whereas some of the coefficients at the lower margin (5%-quantile) were seen to diminish to zero, once a local maximum friction was exceeded. In addition the data measured proved that the lower coefficients do not only result from the naturally operant materials combination of the bearing parts, but furthermore are determined in differing degrees by factors such as topography of the surfaces, corrosion, dirt, contact stress and loading order. The upper coefficients mainly depend on the theoretical contact stress and the materials combined. T2 - SAHC 2012 - 8th International conference on structural analysis of historical constructions CY - Wroclaw, Poland DA - 15.10.2012 KW - Bridge bearings KW - Historic bearings KW - Cast steel KW - Sliding friction KW - Friction coefficient PY - 2012 SN - 978-83-7125-216-7 SN - 0860-2395 SP - 1 EP - 9 PB - DWE CY - Wroclaw, Poland AN - OPUS4-25793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eisenkolb, Tino A1 - Mehdianpour, Milad T1 - Bewertung historischer Brückenlager - Das Kontaktproblem - Teil 2 N2 - Der vorliegende Beitrag thematisiert die Spannungsberechnung im Kontaktbereich historischer Brückenlager. Speziell der Kontakt zwischen Kugelzapfen und Lagerpfanne steht im Fokus der Ausführungen. Es wird gezeigt, dass die auf Grundlage der Hertz'schen Theorie an der Ersatzgeometrie Kugel–Ebene berechneten Spannungszustände nennenswerte Fehler gegenüber den numerisch an der tatsächlichen Geometrie Kugelzapfen-Lagerpfanne ermittelten Spannungen aufweisen können. Nach Darstellung der Ursachen und Einflussparameter dieser Fehler wird eine Methodik aufgezeigt, diese Fehler signifikant zu korrigieren. ----------------------------------------------------------------------------------------------------------------- This paper addresses the calculation of stresses within the contact zone of historical bridge bearings. Special attention is paid to the contact between ball stud and bearing cup. It will be shown that the stresses calculated according to the Hertzian theory at the idealised analogous geometry of a ball on a plate present considerable differences to the stresses numerically calculated at the real geometry of a ball stud on a bearing cup. Afterwards the causes and influencing factors of these failures are discussed, and a method to improve them significantly is provided. KW - Brückenlager KW - Kontaktproblem KW - Hertzsche Pressung KW - Kontaktspannung KW - Vergleichsspannung KW - Bewertung KW - Historische Lager PY - 2012 DO - https://doi.org/10.1002/stab.201201576 SN - 0038-9145 SN - 1437-1049 SN - 0932-6375 VL - 81 IS - 7 SP - 510 EP - 518 PB - Ernst CY - Berlin AN - OPUS4-26294 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -