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Keywords: underpass, railway, high-speed.

Summary

Bridge design rules in accordance with Eurocodes involves checks on stresses according to dynamic loading. These checks are often performed based on the impact factor. There are bridge typologies for which the Eurocode provides simplified expressions, depending on a few basic parameters. In other cases, there is not such a guidance and, if train speeds exceed 220 km/h, a comprehensive set of dynamic analysis is necessary. Culverts fall into this category. Thus, their design to Eurocodes in high speed lines (HSL) may require a design effort which is not consistent with their reduced cost.

This paper contains work on the development of simplified expressions for the impact factor suitable for culverts. The response parameter of interest is the maximum roof slab deflection at mid span. First, a complete three-dimensional model is presented. The model is based on sub-structuring and consists of a set of two finite element models, that will be referred to as the emission and the transmission models.

The model is checked against measurements on a 3x3m frame box culvert. The three-dimensional model permits the assessment of a range of frequencies of interest, as well as the deformed shape of the vibration modes that influence the response.

The study of the three-dimensional model suggests that a simplified two-dimensional model may be used since a beam type is the most important one. Once such a two-dimensional model is developed. The thicknesses of the plane elements allow the model to be tuned. The difficulty arises when neither measurements or a complete three-dimensional model are available for this purpose. In order to overcome this difficulty, the fitting procedure is performed for a set of six culverts of variable spans, and a simplified rule based on geometry and material properties is proposed.

The last part of the paper explores the potential of the simplified model. Since they are much less time consuming, they enable performing parametric studies. With reference to a square shaped box frame, with an inner opening of 2x2m, the influence of train type and speed, the depth of cover and soil properties are assessed.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 98 PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE Edited by: J. Pombo Paper 10 A Parametric Study of the Dynamic Effects of Underpasses of High-Speed Railway Lines L. Hermanns¹, J. Vega², E. Alarcon¹ and A. Fraile¹ ¹ETSII, Universidad Politecnica de Madrid, Spain ²CEMIM-F2I2, Madrid, Spain doi:10.4203/ccp.98.10 purchase the full-text of this paper Full Bibliographic Reference for this paper L. Hermanns, J. Vega, E. Alarcon, A. Fraile, "A Parametric Study of the Dynamic Effects of Underpasses of High-Speed Railway Lines", in J. Pombo, (Editor), "Proceedings of the First International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 10, 2012. doi:10.4203/ccp.98.10 Keywords: underpass, railway, high-speed. Summary Bridge design rules in accordance with Eurocodes involves checks on stresses according to dynamic loading. These checks are often performed based on the impact factor. There are bridge typologies for which the Eurocode provides simplified expressions, depending on a few basic parameters. In other cases, there is not such a guidance and, if train speeds exceed 220 km/h, a comprehensive set of dynamic analysis is necessary. Culverts fall into this category. Thus, their design to Eurocodes in high speed lines (HSL) may require a design effort which is not consistent with their reduced cost. This paper contains work on the development of simplified expressions for the impact factor suitable for culverts. The response parameter of interest is the maximum roof slab deflection at mid span. First, a complete three-dimensional model is presented. The model is based on sub-structuring and consists of a set of two finite element models, that will be referred to as the emission and the transmission models. The model is checked against measurements on a 3x3m frame box culvert. The three-dimensional model permits the assessment of a range of frequencies of interest, as well as the deformed shape of the vibration modes that influence the response. The study of the three-dimensional model suggests that a simplified two-dimensional model may be used since a beam type is the most important one. Once such a two-dimensional model is developed. The thicknesses of the plane elements allow the model to be tuned. The difficulty arises when neither measurements or a complete three-dimensional model are available for this purpose. In order to overcome this difficulty, the fitting procedure is performed for a set of six culverts of variable spans, and a simplified rule based on geometry and material properties is proposed. The last part of the paper explores the potential of the simplified model. Since they are much less time consuming, they enable performing parametric studies. With reference to a square shaped box frame, with an inner opening of 2x2m, the influence of train type and speed, the depth of cover and soil properties are assessed. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £110 +P&P)
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