This study focuses on mixing steel fiber in the concrete to improve the ductility and toughness of the columns. The
purpose of the study is to evaluate the load capacity and deformation capacity associated with the amount of steel fiber and
loading condition and to analyze the interplay between the steel fiber reinforced concrete and the welding built-up square tube in
terms of structure and fire resistance performance. Reinforcement of concrete with steel fiber(Vf=0.375%), when cross-section
shape and boundary condition (load ratio) remained unchanged, improved fire resistance performance by 1.1~1.3 times. It is
deemed that the area resisting thermal load increased and fire resistance performance was improved since the concrete reinforced
with steel fiber restrained cracking. In addition, the fact that the cross-sections of the concrete were barely damaged indicates that
load share capacity was greatly improved.