VERTICAL COUPLING EFFECT OF THE BALLASTED TRACK ON THE DYNAMIC BEHAVIOR OF MULTITRACK RAILWAY BRIDGES COMPOSED BY ADJACENT DECKS

In the present contribution the effect of the continuity of the ballasted track on the dynamic response of simply-supported railway bridges composed by structurally independent adjacent slabs at each span is addressed.Previous research works and experimental campaigns performed on simply-supported structures have shown that the presence of the ballast layer and other track components (rails, sleepers) may induce a dynamic coupling effect between the bridge spans or adjacent decks.In this study the influence of this effect on the train-induced vibrations is assessed.With this purpose a preliminary three-dimensional finite element (FE) model that includes the track components as a set of discrete mass, stiffness and damping elements has been implemented to numerically evaluate the influence of the continuity of the track components on the prediction of the bridge acceleration response under the passage of railway vehicles.The numerical model is calibrated with the load test results performed on a simply-supported railway bridge composed by several adjacent slabs.Finally the measured structural response of the bridge under train induced vibrations is compared with the numerical predictions.Preliminary conclusions regarding the importance of considering the continuity of the track components for the prediction and the assessment of the Serviceability Limit State of vertical acceleration in ballasted simply-supported railway bridges are presented.