Influence of the Second Flexural Mode on the Response of High-Speed Bridges

Museros Romero, Pedro and Alarcón Álvarez, Enrique (2003). Influence of the Second Flexural Mode on the Response of High-Speed Bridges. In: "9th International Conference on Civil and Structural Engineering Computing", 02/09/2003-04/09/2003, Egmond-aan-Zee, The Netherlands. ISBN 0-9487749-89-X.

Description

Title: Influence of the Second Flexural Mode on the Response of High-Speed Bridges
Author/s:
  • Museros Romero, Pedro
  • Alarcón Álvarez, Enrique
Item Type: Presentation at Congress or Conference (Article)
Event Title: 9th International Conference on Civil and Structural Engineering Computing
Event Dates: 02/09/2003-04/09/2003
Event Location: Egmond-aan-Zee, The Netherlands
Title of Book: Proceedings of the Ninth International Conference on Civil and Structural Engineering Computing
Date: 2003
ISBN: 0-9487749-89-X
Subjects:
Faculty: E.T.S.I. Industriales (UPM)
Department: Mecánica Estructural y Construcciones Industriales [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

This paper deals with the assessment of the contribution of the second flexural mode to the dynamic behaviour of simply supported railway bridges. Alluding to the works of other authors, it is suggested in some references that the dynamic behaviour of simply supported bridges could be adequately represented taking into account only the contribution of the fundamental flexural mode. On the other hand, the European Rail Research Institute (ERRI) proposes that the second mode should also be included whenever the associated natural frequency is lower than 30 Hz]. This investigation endeavours to clarify the question as much as possible by establishing whether the maximum response of the bridge, in terms of displacements, accelerations and bending moments, can be computed accurately not taking account of the contribution of the second mode. To this end, a dimensionless formulation of the equations of motion of a simply supported beam traversed by a series of equally spaced moving loads is presented. This formulation brings to light the fundamental parameters governing the behaviour of the beam: damping ratio, dimensionless speed $ \alpha$=VT/L, and L/d ratio (L stands for the span of the beam, V for the speed of the train, T represents the fundamental period of the bridge and d symbolises the distance between consecutive loads). Assuming a damping ratio equal to 1%, which is a usual value for prestressed high-speed bridges, a parametric analysis is conducted over realistic ranges of values of $ \alpha$ and L/d. The results can be extended to any simply supported bridge subjected to a train of equally spaced loads in virtue of the so-called Similarity Formulae. The validity of these formulae can be derived from the dimensionless formulation mentioned above. In the parametric analysis the maximum response of the bridge is obtained for one thousand values of speed that cover the range from the fourth resonance of the first mode to the first resonance of the second mode. The response at twenty-one different locations along the span of the beam is compared in order to decide if the maximum can be accurately computed with the sole contribution of the fundamental mode.

More information

Item ID: 20130
DC Identifier: http://oa.upm.es/20130/
OAI Identifier: oai:oa.upm.es:20130
Official URL: http://www.ctresources.info/ccp/paper.html?id=3210
Deposited by: Biblioteca ETSI Industriales
Deposited on: 18 Sep 2013 09:42
Last Modified: 21 Apr 2016 22:33
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