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Comparison of ballasted and ballastless bridges for high speed trains
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The purpose of the project is to investigate the difference in performance between

ballasted and ballastless railway bridges dedicated to high speed trains by taking into

account both static and dynamic requirements. The main questions are:

a) whether choosing a ballastless bridge results in a more slender section due to

the lower self-weight

b) if the design of bridges for high speed trains is governed by the static or by the

dynamic requirements.

The method followed was to first make a complete static design of a ballasted and a

ballastless bridge, and then subject them to a 2D dynamic analyses in order to see if

the cross section dimensions must be changed. Some of the bridges required a more

thorough dynamic analyses, and for these, a 3D model was developed.

The analysed bridge is a simply supported beam with a T section carrying one track.

Some variations were also considered, namely a simply supported bridge with a

double T section carrying two tracks, as well as a single track bridge in two spans.

It was found that all of the analysed bridges are somewhat more slender for the

ballastless alternative, and require a 10 -30% less reinforcement. Simply supported

bridges carrying one track are governed by the dynamic requirements; the bridges

in two spans are for shorter spans governed by the statics and for longer spans by

the dynamics. Bridges in double T fulfilled all the requirements according to the 2D

analyses, but were found to be greatly affected by the 3 dimensional effects and failed

to satisfy the criteria when these were taken into account.

Finally, the optimal design according to these analyses is a ballastless bridge in a

simple T section. If the bridge constructed should carry two tracks, then it should be

constructed as two T beams that are not connected to one another in order to avoid

the unfavourable 3D effects.

Place, publisher, year, edition, pages
TRITA-BKN-Examensarbete, ISSN 1103-4297 ; 481
Keyword [en]
High-speed train, concrete bridge, beam bridge, dynamic, 3D dynamic
National Category
Civil Engineering
URN: urn:nbn:se:kth:diva-188524ISRN: KTH/BKN/EX--481--SEOAI: diva2:935876
Educational program
Degree of Master - Civil and Architectural Engineering
Available from: 2016-06-17 Created: 2016-06-13 Last updated: 2016-06-17Bibliographically approved

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