TY - CONF A1 - Mehdianpour, Milad A1 - Herter, Jürgen A1 - Hille, Falk T1 - Service life extension of a railway viaduct in Berlin N2 - Bridge retrofitting of a section of the Berlin subway which is designed as railway on steel viaduct is presented. Fatigue damage in the superstructure of the over 70-years-old viaduct made an investigation of the damage causes necessary prior to the planning of retrofitting measures. The damage specifically occurred at the inverted arched steel plates of the ballast support elements. Those plates were provided for carrying the track ballast as well as the traffic load. For the retrofitting, the inverted arched plates were unloaded. The superstructure was redesigned into a fixed track system, which is able to transfer the traffic load directly into the substructure. The new rail fastening system made it necessary to verify the structural integrity of single elements as well as of the main system of the existing viaduct. The verification was based on several experimental investigations at BAM laboratory and on-site. Based on the evaluation of all test results the operation license could be issued. T2 - Munich Bridge Assessment Conference (MBAC 2009) CY - Munich, Germany DA - 2009-05-27 KW - Life time extension KW - Fatigue KW - Load test KW - Experimental investigations KW - On-site tests PY - 2009 IS - Paper # T13 SP - 1 EP - 18 CY - Munich, Germany AN - OPUS4-19483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehdianpour, Milad T1 - SERVICE LIFE EXTENSION OF A RAILWAY VIADUCT IN BERLIN T2 - Munich Bridge Assessment Conference CY - Munich, Germany DA - 2009-05-27 PY - 2009 AN - OPUS4-19540 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehdianpour, Milad A1 - Herter, Jürgen A1 - Hille, Falk ED - Steffen Marx, ED - Heinz Opitz, ED - Manfred Curbach, T1 - Experimentelle Ermittlung des Lastabtrages von Bremskräften an einem Stahlviadukt der Berliner U-Bahn T2 - 5. Symposium "Experimentelle Untersuchungen von Baukonstruktionen" CY - Dresden, Deutschland DA - 2009-09-11 KW - Belastungsversuch KW - Bremsversuch KW - Experimentelle Untersuchung KW - On-Site Test PY - 2009 SN - 1613-6934 N1 - Serientitel: Schriftenreihe Konstruktiver Ingenieurbau Dresden – Series title: Schriftenreihe Konstruktiver Ingenieurbau Dresden IS - 18 SP - 183 EP - 196 AN - OPUS4-19958 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mehdianpour, Milad T1 - Experimentelle Ermittlung des Lastabtrages von Bremskräften an einem Stahlviadukt der Berliner U-Bahn T2 - 5. Symposium "Experimentelle Untersuchungen von Baukonstruktionen" CY - Dresden, Germany DA - 2009-09-11 PY - 2009 AN - OPUS4-19877 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 - Stengel, Dominik A1 - Mehdianpour, Milad T1 - Finite element modelling of electrical overhead line cables under turbulent wind load N2 - This paper presents a finite element model of an overhead transmission line using so called cable elements which allow reproducing the cable's nonlinear characteristics accurately employing only a few elements. Aerodynamic damping is considered in the equation of motion by taking into account the relative velocity between the flow of the wind and the moving structure. The wind flow itself is simulated by wave superposition making necessary assumptions on the lateral correlation between the wind velocities along the cable length. As result from the simulation, the following conclusions can be drawn. The first natural frequency of generally used wide spanning cables lies well below 1 Hz where also most of the energy content of the wind excitation is to be expected. Aerodynamic damping is significant for the moving cables holding very low structural damping which leads to a suppression of resonant amplification. This is particularly of interest regarding the support reaction which is dominated by the mean value and the so called background response. The latter is mostly influenced by the randomness of the wind flow, especially lateral to the main wind direction. KW - Nonlinear Finite Element Formulations KW - Nonlinear Equation of Motion KW - Turbulent Wind Excitation PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-304567 DO - https://doi.org/10.1155/2014/421587 SN - 2314-6494 SN - 2356-766X VL - 2014 IS - Article ID 421587 SP - 1 EP - 8 PB - Hindawi Publ. CY - New York, NY ; Cairo AN - OPUS4-30456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klinger, Christian A1 - Mehdianpour, Milad A1 - Klingbeil, Dietmar A1 - Bettge, Dirk A1 - Häcker, Ralf A1 - Baer, Wolfram T1 - Failure analysis on collapsed towers of overhead electrical lines in the region Münsterland (Germany) 2005 N2 - End of November 2005 strong south-west wind and heavy snowfall were predominant in the region Münsterland, north-western part of Germany. This led to accretion of a considerable quantity of wet snow to overhead electrical lines in form of snow rolls on the conductors. Eighty-two transmission towers failed catastrophically, most of them by buckling, however some by brittle fracture. As a consequence nearly 250,000 people have been cut off from electrical power supply for several days with major media attention. This paper describes the forensic analysis in order to investigate the failure cause. Therefore extensive materials investigations, mechanical testing of original components and specimens thereof, estimations for the real wind and snow loads and their combinations, structural analyses as well as detailed evaluations on the basis of previous investigations, literature and regulations were conducted. It was revealed that some of the examined components were manufactured from Thomas steel which was partially in embrittled condition. The investigated towers fulfilled the design codes valid at the time of erection. However the present line loads of the wet snow rolls on the conductors exceeded by far the ones given in the design codes valid at that time. The load case leading to failure was reconstructed by the derived positions of loads mainly caused by unequal and asymmetric distribution of snow rolls on left and right electrical system. The loads and corresponding stresses acting on the structure before failure were estimated. By comparison with the fracture forces from mechanical testing of original members of the collapsed tower the component that primarily failed was localised. The primary fracture occurred on a diagonal member under tension made of Thomas steel which was weakened by embrittlement. The failure cause was a combination of heavy weather conditions (storm, approx. 0 °C and wet snowfall leading to heavy snow rolls on conductors), asymmetric loading conditions and the usage of Thomas steel which was partially embrittled. Finally, recommendations for avoiding future failures are given. KW - Transmission towers KW - Thomas steel KW - Embrittlement KW - Snow loads KW - Ice loads PY - 2011 DO - https://doi.org/10.1016/j.engfailanal.2011.07.004 SN - 1350-6307 SN - 1873-1961 VL - 18 IS - 7 SP - 1873 EP - 1883 PB - Elsevier Science Publ. CY - Oxford AN - OPUS4-24517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -