Abstract
A lot of alternate load tests have been performed mainly in the architectural research field in order to examine the bearing capacity and ductility of concrete encased steel column members. However, in the field of civil engineering, the research focusing on the ductility is still few. Then, the alternate load tests under the constant axial compressive force and bending moment were performed by using the test pieces taken into consideration the loading condition and section parameters for railway structures. In this paper, based on the above-mentioned experimental results, a method of quantitatively evaluating the ductility of concrete encased steel column members was developed.