Three-dimensional Modeling of an Old Masonry Bridge and Assessing Its Current Capacity

Masonry bridges are among the main structures built along the road and railway routes. These structures are generally old and have historical value. Considering the increased axial load and passing speed from these bridges, an in-depth study of these structures and their potential is of paramount importance. In the present study, an old masonry arch bridge located in 475 km of Western Iranian railway is investigated. For the detailed modeling of this structure, a three-dimensional finite element method (3DFEM) was implemented to take into account the details of the bridge and the train passing over it. The developed model was calibrated and validated using the dynamic field test results. The obtained results showed that the increase in the axial load and train speed over the bridge must be done carefully because exceeding the travel speed of 90 km/h and increasing the axial load from 20 to 30 ton makes serious problems in the bridge and interrupts its performance. Furthermore, it was found that the adequacy factor of the bridge under the standard load of LM71 is over 2.