DemDem bridge is an old stone masonry arch bridge located on Km 611+630 of Iranian railway network. The bridge consists of seven spans of 21.5m and two smaller spans of 10m, totaling a length of 164 meters. The bridge has moderately tall piers of 40 meters. Arch thickness varies between 0.20 and 1.00 meter. It has a width of 4.5 meters and accomodates a single track of 20 tons. Maximum operational speed of the bridge is 60 Km/h. Track's superstructure consists of U33 rails, steel sleepers, and rigid fasteners. 

Summary of results:

The bridge has been controlled in serviceability and ultimate limit states. Three various loading schemes are considered in analyses, including an increased axle load pattern. According to results, some of the spans would require strenghening for withstanding the increased axle load. ULS analyses results in a load factor of 2.52 for the structure. Moreover, seismic assessment shows that the bridge requires retrofitting methods to withstand earthquake forces.