Dynamic load testing of a railway masonry arch bridge: A case study of Babak Bridge

Health monitoring of masonry bridges is vital due to their long life in service and an increasing need for higher axle loads. Results of feasibility study of applying an increased axle load of 25 tons to an old masonry bridge are presented in this paper. Babak Bridge is located in north western zone of Iranian railway network and has been in service for more than 70 years. It consists of stone masonry blocks, has three long spans of 21.5 m, 7 spans of 10 m, and a total length of 270 m. Response of the bridge subjected to prede ned train loading by 15 sensors, including deflection meters, accelerometers, and strain gauges, is recorded. A total of 37 tests are carried out on Babak Bridge, and the results are used to calibrate the nite-element model of the bridge, which is developed by Abaqus software. The numerical model is then used to determine the weak spots of bridge due to subjection of higher axle loads for a possible strengthening procedure. Ultimate load-carrying capacity of the bridge is also assessed by Ring software, which suggests a minimum adequacy factor of 1.25 for an axle load of 25 tons.