This paper discussed the mechanical properties of hybrid structures, which composed of a reinforced concrete beam and steel columns. Analytical methods and loading tests were carried out. A Concentrated load was applied to four-types of specimens. Under the state of serviceability limit, it was made clear that moment distribution of hybrid portal frame could be calculated in consideration of decease of flexural rigidity. After the steel yielding of the reinforced concrete beam, moment redistribution were ocurred and portal frame was finally collapsed in flexure. It was found adequate to apply the design method of flexural rigidities and moment redistribution proposed in JSCE code.
