The bridge on Km 461+500 of Iranian railway network is an old stone masonry arch bridge, which has been in service for about 75 years. The bridge consists of two long spans of 25m, seven spans of 8m, and two smaller spans of 3.5m, totaling a length of 147 meters. The bridge accomodates a single track with an allowable axle load and speed of 20 tons and 60 Km/h, respectively. The bridge is situated in a curved section of the track with a radius of 250 meters. Track's superstructure consists of U33 rails, steel sleepers, and fixed fasteners.
Summary of results:
The aim of this project was to study the effect of rehabilitation procedures (Ballast cleaning and installing ballast mats) on strcutural response of the bridge. To do so, the bridge is instrumented with 22 sensors and dynamic load tests are carried out in three phases. First one, before any rehabilitation procedures take place, second one, after ballast cleaning, and the last one after installing ballast mats. A total of 76 test runs are carried out through three phases. Results suggest that mid-span deflection remains constant, while acceleration values are reduced significantly.
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