ABSTRACT
ABSTRACT: The railway bridges are exposed to the dynamic effects of high speed trains.As they are composed by a long sequence of axle forces or their groups in regular distances, the bridges are brought into intensive vibration under certain conditions. Therefore, a simple theoretical model of a railway bridge was put together in the form of a Bernoulli-Euler beam subjected to a row of axle forces moving at constant speed. The solution of the governing differential equation results in the deflection-, bending moment-and vertical acceleration-time histories. Moreover, the stresses were classified using the rain flow counting method to receive the stress spectra. The numerical calculations were performed for both the concrete and steel bridges of spans 5 to 50m subjected to the three types of high speed trains (ICE, Eurostar/TGV andTalgo) running at speeds 5 to 500 km/h. The effect of several parameterswas studied in detail in particular the effect of speed, span, damping, material (concrete, steel), critical velocities, vertical acceleration, etc. The stress spectra show the statistical distribution of stress cycles which are important for the fatigue calculations and for the estimation of the bridge life. The simplified formulas for the design of bridges as well as a method for the interoperability calculations are also suggested.
