| Abstract: | The non-linear response of planar moment-resistant steel frames is investigated with regard to P-Δ-type collapses under severe earthquake ground motions. The frame model employs configuration updating, fibre-type beam-column members with geometric stiffness, panel zone elements at the beam-to-column junctions, and realistic hysteretic relations which are used for both the fibres and panel zones. Frame design follows the 1991 Uniform Building Code, and three panel zone designs are considered. It is found that P-Δ collapse of the 20-storey frame examined results from the formation of a collapse mechanism involving the lowest few stories. Column hinging occurs even though the code requirement that column strength exceed beam strength is satisfied. Among the different panel zone designs, the weakest one proved most resistant to developing a collapse mechanism in the frame. |
