Fluctuations of prestressed reinforced concrete railway bridge span during oscillator motion

This paper considers the peculiarities of strength calculation of reinforced concrete railway bridges under moving load and moving oscillator. Finite element and finite difference methods are used.One span girder is considered, which is modelled by a Timoshenko girder with regard to prestressing. The point of contact between the beam and the support and the fixed and movable joints at the points of contact with the support are taken into account.The 23.6 m long spans were taken as an example for the study of a railway bridge. In the numerical solution of the problem of oscillations of a system with distributed parameters under the action of a moving concentrated force and mass, parasitic oscillations were established by selecting the time step depending on the speed of load movement. Calculations were performed using an implicit Newmark scheme for a moving concentrated force at a velocity of 25 m/s with a time step of 0.008 s; at 50 m/s with 0.004 s; at 75 m/s with 0.00267 s; at 100 m/s with 0.002 s; and at 200 m/s with 0.001 s.Vibrations of the system bridge – mobile load were investigated. The study was carried out on the example of a Talgo locomotive as a moving load or mass. The velocity of the moving load below which the travelling force model can be used was determined. With increasing horizontal speed of the oscillator the deflection of the girder increases, also the vertical oscillation of the mass increases.

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