Finite element modelling of cracked railway pre-stressed concrete sleepers

摘要

Loading conditions on railway tracks are the result of the sum of the static axle load of vehicles and augments caused by dynamic effects. Dynamic loads have several causes and can be quasi-static or impacts. Cracking in pre-stressed concrete sleepers is mainly due to these impact loads and vibrations, converting the central and the rail seat sections of the critical sections in sleepers. This paper presents the development of a finite element model of a cracked sleeper that may be adapted to every condition of damage related to cracking. Cracks have been modelled as volumes characterised by a lower stiffness in order to simulate the loss of inertia. The models have been updated in terms of the frequencies of the first three bending modes of vibration of cracked and uncracked sleepers, obtained using experimental modal analysis technique, as presented in previous author's work. The updating process led to the mechanical properties that define the whole model. Results point out that frequencies obtained with the numerical model agree experimental data obtained in laboratory. These models may be used in further investigations to predict the static influence of cracked sleepers in complete finite element models of ballasted railway tracks.