Behavior of columns of steel plate shear walls with beam-connected web plates

Steel plate shear walls with beam-connected web plates (B-SPSWs) are an alternative configuration of steel plate shear walls (SPSWs) where web plates are connected to the beams only. Detaching web plates from columns and introducing simple beam-column connections in B-SPSWs eliminate flexural demands in the columns resulting from web plate tension field action; consequently, the columns of B-SPSWs are designed primarily for axial loads. A recent study, however, showed that the columns of B-SPSWs resist significant flexural demands during earthquake shaking due to differential interstory drifts that result in significant column rotations at floor levels. Typical design methods (i.e., the Equivalent Lateral Force method and Modal Response Spectrum analysis) do not capture these rotations associated with differential drifts that might lead to column instability. A two-phase numerical study is conducted to evaluate the behavior and stability of B-SPSW columns. In the first phase, three-dimensional nonlinear response-history analyses are conducted to investigate the column stability for eighteen B-SPSWs with different geometric characteristics designed following two design approaches. The results suggest that column buckling is a possible mode of failure for one of the design approaches. In the second phase, a parametric study is undertaken to further investigate potential column buckling failure modes in B-SPSW columns and to establish an upper-bound estimate for the column buckling strength reduction due to column rotations at floor levels that are not considered in traditional design approaches.