A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Essential modelling details in dynamic FE-analyses of railway bridges
The increased need to reduce the use of fossil fuels imposes higher demands on the efficiency of rail transportation. Therefore, an improved knowledge regarding the dynamic properties of railway bridges and infrastructure for railway traffic in general is required. Typically, increased train speed, longer trains and increased axle loads increase the dynamic response in railway bridges. Modelling details for bridge structures such as the flexibility of the foundations, radiation damping in the subsoil and the embankments as well as hysteretic effects in bridge bearings and the track superstructure are typically neglected. The reason for this is that suitable models which consider the influence of such effects in engineering calculations have not yet been implemented in the effectual design codes. This thesis is mainly based on a case study of a ballasted, simply supported steel-concrete composite bridge, which shows a considerable variation in the natural frequencies and damping ratios depending on the amplitude of vibration. Furthermore, the natural frequencies were found to increase significantly during the winter. It is well known that the dynamic properties of typical civil engineering structures are dependent on the amplitude of vibration. However, the fact that certain railway bridges exhibit such non-linear behaviour also for very small amplitudes of vibration has been shown only during later years. This has been verified by means of measurements of the free vibrations after train passages on three typical Swedish beam bridges for railway traffic. Possible sources to this amplitude dependency have been identified primarily in the bridge bearings and the track superstructure. Models of these structural components, based on the so called Bouc-Wen model, have been implemented in a commercial finite element program and was used in a preliminary study. The results indicate that roller bearings and pot bearings can give rise to a non-linear mode of vibration, characterised by two different states. At very small ...
Essential modelling details in dynamic FE-analyses of railway bridges
The increased need to reduce the use of fossil fuels imposes higher demands on the efficiency of rail transportation. Therefore, an improved knowledge regarding the dynamic properties of railway bridges and infrastructure for railway traffic in general is required. Typically, increased train speed, longer trains and increased axle loads increase the dynamic response in railway bridges. Modelling details for bridge structures such as the flexibility of the foundations, radiation damping in the subsoil and the embankments as well as hysteretic effects in bridge bearings and the track superstructure are typically neglected. The reason for this is that suitable models which consider the influence of such effects in engineering calculations have not yet been implemented in the effectual design codes. This thesis is mainly based on a case study of a ballasted, simply supported steel-concrete composite bridge, which shows a considerable variation in the natural frequencies and damping ratios depending on the amplitude of vibration. Furthermore, the natural frequencies were found to increase significantly during the winter. It is well known that the dynamic properties of typical civil engineering structures are dependent on the amplitude of vibration. However, the fact that certain railway bridges exhibit such non-linear behaviour also for very small amplitudes of vibration has been shown only during later years. This has been verified by means of measurements of the free vibrations after train passages on three typical Swedish beam bridges for railway traffic. Possible sources to this amplitude dependency have been identified primarily in the bridge bearings and the track superstructure. Models of these structural components, based on the so called Bouc-Wen model, have been implemented in a commercial finite element program and was used in a preliminary study. The results indicate that roller bearings and pot bearings can give rise to a non-linear mode of vibration, characterised by two different states. At very small ...
Essential modelling details in dynamic FE-analyses of railway bridges
Ülker-Kaustell, Mahir (author)
2013-01-01
120
Theses
Electronic Resource
English
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