Mechanical behavior of hybrid steel I-girder assembled by high manganese non-magnetic steel (Hi-Mn) and SM490YA steel (SM) under uniform vertical loading was investigated based on the results of elastic-plastic large deformation analysis. In the case of hybrid girder, vertical displacement was larger than that of Hi-Mn girder and smaller than that of SM girder. The maximum load was same as that of Hi-Mn girder. Out-of-plane displacement in the web was larger than those of Hi-Mn and SM girders. When the horizontal stiffener of hybrid girder was moved 10% down, or thickness of the web was increased 10%, out-of-plane displacement could be controlled.
