Modelling of the dynamic behaviour of in situ concrete railway sleepers

• An analytical Solution to the problem of a vibrating beam on an elastic foundation is presented. An application example of a concrete railway sleeper embedded in an elastic medium (the ballast) is provided. The sleeper is also elastically connected to the rails. The Rayleigh-Timoshenko (R-T) beam theory for a beam on an elastic foundation is used and eigenfrequencies are calculated. The beam (sleeper) is divided into three sections that have piecewise constant properties. The central portion of the beam is slightly thinner than the outer parts, and each one of the three parts may or may not be supported by the elastic foundation. The elastic connections to the rails are situated at the two joinings of the three sleeper sections. Conclusions drawn are that the Euler-Bernoulli beam theory can be used to calculate two, or maximum three, eigenfrequencies of the sleeper. For higher frequencies, the R-T beam theory should be used. The foundation stiffness influences the lowest bending-mode eigenfrequency the most; higher eigenfrequencies are practically unaffected by the foundation stiffness. The influence of railpad (and rail) stiffness on the sleeper eigenfrequencies is negligible.

Nyckelord

railway sleeper

concrete sleeper

Rayleigh-Timoshenko beam theory

elastic foundation

eigenfrequencies

TECHNOLOGY

TEKNIKVETENSKAP

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