Großversuche zur Ermüdung von Litzenseilen auf Umlenksätteln für Schrägseilbrücken

Abstract

Large scale fatigue tests of strands on saddle systems for cable-stayed bridges Stay cables made of parallel strands for cable-stayed or extradosed bridges are usually anchored in the pylon or the mast of the bridge. New saddle systems provide the opportunity to support them by saddles that guide the strands continuously from one side of the pylon to the other. While cables made of strands have been tested for fatigue extensively, saddle systems were not yet tested much although the fatigue mechanism occurring inside a saddle is particularly complex. The need to perform such a test and the facilities that exist at the Berlin Institute of Technology (TU Berlin), Department of Civil and Structural Engineering provided the unique opportunity to perform large scale fatigue test on cable saddle systems with 55 and with 37 strands. These tests were performed in accordance to fib recommendations, bulletin 30, January 2005. This paper describes the saddle systems used today as well as the test rig and tests conducted in Berlin.

Assessment of critical parameters affecting fretting fatigue life of bridge stay cables at saddle supports

“…A series of fatigue tests were done on steel cables over saddles at TU Berlin (Schlaich et al, 2016). This paper studies the TU Berlin test rig as a saddle system example.…”

“…A team of researchers at TU Berlin has been progressively working on this problem in the last few years. A series of fatigue tests done at TU Berlin to evaluate the fretting fatigue life of steel cables in saddle systems found that the cables usually fail at the contact points where the cables first meet the saddle (Schlaich et al, 2010(Schlaich et al, , 2016; Mohareb et al (2016) stated that this phenomenon occurs because of the irregular contact stress distribution at the zone where the cables first contact the saddle, and compared the analytical solutions and the results of a 2D Finite Element (FE) model of a band bent over a saddle. Mohareb et al (2017) developed a 3D FE model for the contact points between a cable and a saddle to evaluate the fretting fatigue life of the cables.…”

30‐MN‐Prüfmaschine für quasistatische und zyklische Druck‐ und Zugprüfungen

“…Dieser Versuchsaufbau ist sehr komplex (Sattel mit zyklischer Verschiebung etc.) und erfordert bei großen Seilen neben hohen Prüflasten einen sehr hohen Platzbedarf . Aufgrund dieser Problematik wurde für die 30‐MN‐Prüfmaschine ein modifizierter Satteltest (Halbsatteltest) am iBMB/MPA entwickelt.…”

Fretting fatigue tests and microstructure analysis of bridge stay cable wires

“…These tests were costly and time‐consuming. Therefore, an alternative smaller version of this setup was designed and used also at TU Berlin 4 . The new setup enabled tests to be done at three saddle radii of 500, 1000, and 1500 mm.…”