چكيده به لاتين
Although, the application of tire derived aggregates (TDA) as the sub-ballast layer has been investigated by different researchers in light ballasted rail track, but its influence on the dynamic behavior of railway bridges has not been studied up to now. In the current study, a 6 m span railway concrete slab bridge was chosen to be evaluated under the effects of GT26 diesel in static and different moving speeds. In this regard, the selected bridge was instrumented, and its behavior was studied in presence and absence of the TDA layer. As a part of the study, the dynamic characteristics of TDA material was examined using ballast box test apparatuses in the laboratory and its elastic module and damping were obtained as 4.7 N/mm2 and 0. 23, respectively.
Overall, by frequency analysis of free vibrations, it was found that natural frequency of the whole bridge and track system has changed from 20 to 23 Hz whereas the natural frequency of the track superstructure has decreased from 33 to 24 due to the presence of TDA layer. Furthermore, by analyzing the results in the time domain, it was understood that the percentage the maximum sleeper acceleration, the maximum bridge deck acceleration and its maximum flexural strain have been decreased 63, 33 and 58 %, respectively for diesel running speed 50 km/h. On the other hand, the mentioned values have been modified to 71, 40 and 58 % for moving speed 32 Km/hr. Also, in static loading, deflection of the deck, the strain of rail and deck 14, 82 and 55 % has decreased. Finally, numerical model was established to verify the field achieved data.
