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Characterization of track geometric imperfections leading to maximal dynamic amplification of internal forces in railway bridges

Author(s):

Medium: journal article
Language(s): en 
Published in: Revista IBRACON de Estruturas e Materiais, , n. 4, v. 10
Page(s): 937-956
DOI: 10.1590/s1983-41952017000400010
Abstract:

This paper resorts to a simplified dynamic analysis methodology for the study of vibrations in railway bridges produced by the passage of a typical passenger train, or EUT (Electric Unit Train). It starts from a model with fifteen degrees-of-freedom, namely vertical (bounce) and horizontal displacements (sway) and rotations about the longitudinal (roll), transverse (pitch) and vertical (yaw) axes. In this methodology, dynamic models of the train and the bridge are assumed to be initially uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads are evaluated for the train running on a rigid and fixed deck, considering geometric irregularities, different for each rail line, in both the vertical and horizontal track planes, as well as in the wheels. The contact forces are statically condensed at the vehicle’s centre of gravity and applied on a simplified 3D beam model. To represent the train passage over the bridge, functions are used to describe the interaction forces at each node of the beam model, as time evolves. Thus, it is possible to identify the dynamic response caused by the geometric irregularities and also evaluate the dynamic amplification obtained for any internal force, which is compared to the impact coefficient proposed by the Brazilian standards for the design of railway bridges (NBR 7187), used in quasi-static analysis. For the sake of an illustration, a thirty-six-metre-span concrete bridge with box girder section was considered. A study was carried out to find out the parameters of the irregularity functions that could potentially lead to maximal amplification of internal forces in the bridge.

Structurae cannot make the full text of this publication available at this time. The full text can be accessed through the publisher via the DOI: 10.1590/s1983-41952017000400010.
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  • Reference-ID
    10413328
  • Published on:
    12/02/2020
  • Last updated on:
    12/02/2020