There are many century-old plain-concrete-arch railway bridges in Iran in need of seismic assessment. Given the logistical difficulties of conducting field tests, the use of computer models is being investigated as an alternative. Three-dimensional finite-element models were created for two bridges that had already been physically tested. After calibration with the test results, the modelled bridges were then subjected to a modelled earthquake to evaluate their behaviour under seismic loading. The results demonstrate that seismic response depends entirely on the geometrical and material properties, and that bridges perform better in a transverse direction
