Development of hybrid column member combining wood and steel

In response to Japan promoting the use of domestic wood in construction, the hybrid member which combined wood and steel was developed as a technology which effectively utilized wood for steel structures. The member is a hybrid member with a square steel pipe core, covered and stiffened by laminated lumber. This paper confirms the effect of wood stiffening for square steel pipe with a structural performance testing in which some full-size test specimens are loaded by compression. In addition, it proposes an evaluation method of compressive strength of the hybrid member by extending the existing buckling-strength evaluation formula. The fire-resistance testing, in which two test specimens of different lengths are heated under load, confirmed that the hybrid member has a fire-resistance performance of one hour. Furthermore, the hybrid member used as columns of a new public building, and the effectiveness of the technology was verified through design and construction of this building.