Abstract
In multi-story braced frame, axial forces of columns vary significantly in the earthquake excitation, and the hysteretic behavior of the system much depends on the column behavior. In this study, the hysteretic characteristics of columns in a multi-story braced frame is investigated experimentally and theoretically. Eight specimens are tested under the alternately repeated loading, which correspond to the base story of 6 story braced frame. Axial force variation and the hysteretic behavior of columns are investigated by analysing the column strain gage output. Theoretical consideration is also conducted to analyse the relationship between the column axial force and the load carrying capacity of the system. The major conclusions of this study are as follows : (1) Axial force variation of columns is almost proportional to the horizontal force carried by the system. (2) The maximum ratio of the column compression force to the limt axial force is little dependent on the column cross-sectional area, because the increase of the column cross-sectional area causes the increase of the load carrying capacity of the system. (3) The effect of the column axial force variation to the load carrying capacity of the system depends on the aspect ratio of the system and on the cross-sectional shape and the slenderness of the column.
