Effects of input direction of ground motion and column overdesign factor on seismic response of 3D steel moment frames with square tube columns

This paper presents a numerical study on 3D steel moment frames with square tube columns. The major parameters are column overdesign factor, shapes of the frames and input direction of ground motion. From the analysis, it is revealed that the relationships between cumulative plastic deformation of columns and column overdesign factor are not affected by the shapes of frames but influenced by amplitude and input direction of ground motion and width-thickness ratio of columns. The required column overdesign factor to keep the damage of columns below the limit of plastic deformation is proposed under the reliability index of 2.0.