INFLUENCE OF LONG WELDED RAILWAY TRACK ON FATIGUE OF STEEL RAILWAY BRIDGES

Abstract

The increase of the population and the need for the quick transportation of the men and material in the modernized world has le-d to the requirement of man to deal with high velocities with greater comfort at low cost. In the rail transportation system, the use of the long welded railway track is one of the method which has grabbed the attention of the engineers for attaining higher speeds, with smooth riding experience and cost efficiency. The existing infrastructure should be checked and analyzed for the effects with this replacement and should be assured for its safety. Since, with the replacement of the long welded railway track on the bridge, the length of the track extends beyond the length of the bridge. As a result, the frequency characteristics and the response of the bridge changes when subjected to dynamic loading such as a train passing on it. Hence study should be made before the replacement of the long welded track is done. A complete study on the variation of the thtigue life has been done for 30.5meter and 76.2 meter truss bridges for all the routes and all the trains with a speed of 300Kinph. A comparison of the dynamic analysis and the static analysis with the dynamic augmentation factor has also been made in the report. Also the dynamic response of the bridge with the variation of velocity has been done for a train. From the analytical results obtained in the study, it can be justified that the the bridges are safe from fatigue point of view along with a little increase in life of the bridge. Itis also found that the dynamic augmentation factors given are not adequate for all the spans