Abstract
Overhead line equipment (OHLE) is the components for the electric train which supply the electric power to the train. For one or two tracks, OHLE is normally supported by cantilever mast. The cantilever mast, which is made of H-section steel, is slender and has a poor dynamic behaviour by nature. Nonetheless, the mast structures, which located alongside the railway track, have not been fully studied on the dynamic behaviour. This paper presents the effects of far-field excitations on cantilever mast and overhead contact wire. The five far-field earthquake records at various magnitudes between 6.5 and 8 Mw are considered. A three-dimensional mast structure with varying support stiffness is made using finite element modelling. It is interesting that support stiffness plays a role in the dynamic responses of OHLE during far-field earthquakes due to the change of its properties. Surprisingly, the earthquakes can cause damage to the overhead contact wire which lead to the failure of electric system. In this case, the train cannot run until the broken wire and electric system is cleared. This occurs when there are the losses of support stiffness due to the failure of support connection or soil degradation. Moreover, beating phenomenon, which normally occurs in the tall building, is obviously observed in OHLE during the occurrence of earthquake. This is the world first to demonstrate the effects of far-field earthquakes on the cantilever mast structure and the response of OHLE. The insight in this earthquake response of OHLE and its support has raised the awareness of engineers for better design of cantilever mast structure and its support condition. The outcome of this study will provide a new earthquake detection method using OHLE.
Highlights
At present, railway infrastructure experiences harsh environments and aggressive loading conditions from increased traffic and load demands
The present paper aims to present a new study into the effect of far-field earthquakes on mast structure and overhead line equipment (OHLE) taking into account its underlying soil properties
For one or two railway tracks, the support of OHLE is cantilever mast which is normally made of H-section steel column
Summary
Railway infrastructure experiences harsh environments and aggressive loading conditions from increased traffic and load demands. The overhead line equipment (OHLE) is an important asset of the railway infrastructure and is one of the most vulnerable ones. The support of OHLE is cantilever mast or portal frame depending on the number of track. Due to the extreme environmental events and severe periodic force, such as an earthquake, in surrounding area may cause damage to the track and OHLE structure especially mast structure, this can lead to the failure of the electrical system (Shing and Wong, 2008; Robinson and Bryan, 2009; Taylor, 2013). The dynamic behaviors of cantilever mast structure and its monitoring system are needed to take into account during train operation and the occurrence of extreme environmental events. The effects of ground borne vibration generated by passing train on cantilever mast have been studied (Kurzeil, 1979; Madshus et al, 1996; Jonsson, 2000; Kouroussis et al, 2013, 2014, 2015; Vogiatzis and Mouzakis, 2017), the effects of earthquake have not been introduced
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