CYCLIC BEHAVIOR OF STEEL PLATE SHEAR WALL CONNECTED TO FRAME BEAMS ONLY

Many previous experimental and analytical studies have shown that the column demands, especially column axial force demands, in a traditional multi-story steel shear wall (SPSW) system are extremely large for typical systems. Such configuration, in turn, results in large column dimensions and prohibits the use of narrow walls, thereby reducing the system's economy. Further, most of the column axial forces, especially in multi-story cases, come from plate tension forces on interfaces with the columns at different stories of the system. Thus, releasing the infill wall from the columns can help the column axial force demands to be reduced significantly. In the present paper, the behavior of steel shear walls connected to frame beams only is investigated using the finite-element method and compared with that of the corresponding system with fully connected infill walls (typical SPSW), in terms of strength, initial stiffness, ductility and max of out-of-plane deformation. In this study, the effects of different system aspect ratios, various infill plate thicknesses and application of end plate stiffeners on the free edges of the infill plates are also considered. SPSWs are analyzed using the nonlinear pushover analyses. The adequacy of the finite element modeling approach to representing the pushover responses of SPSWs is verified through comparison with experimental results. Results show that releasing of the infill wall connection to the columns limits the widespread yielding of the infill plate. This, in turn, affects the strength, initial stiffness and ductility of the system. Notably, the behavior of SPSW frames is not affected much by such configuration. Increasing the infill plate thickness in proportion to the decrease of its strength, not only offsets the effect of this configuration on the system strength, but also improves the system behavior in terms of initial stiffness and ductility (compared to the corresponding system with infill plate connected to boundary columns and beams). Application of end-plate stiffeners on the free edge of the infill plates in semi-connected systems can effectively reduce the out-of-plane deformation of the infill wall, but it has no significant effect on the system strength.