The Investigation To Behavior Of Diagonal Stiffened Steel Plate Shear Walls

As a new type of lateral resisting element in medium and high-rise buildings, steel plate shear wall (SPSW) has exhibited many desirable characteristics in high seismic risk regions, such as high initial stiffness, high load-carrying capacity, good ductility, excellent energy absorption capacity, and stable hystersis loops. Unstiffened thin steel plate shear walls will buckle at very low shear load and develop rather considerable out-of-plane deformation at service load. At the post-buckling phase, the tension field arises along the diagonal orientation, and the wall can carry much higher load than the theoretical buckling load. Based on the characteristics of unstiffened SPSW, if stiffener is located along the diagonal orientation, then forms a new kind of SPSW, namely diagonal stiffened steel plate shear wall, which can restrain out-of-plane deformation, enhance initial stiffness and shear load-carrying capacity.In this dissertation, diagonal stiffened SPSW with moment-resisting frame has been comprehensive investigated theoretically and experimentally. The purposes of this research are to reveal the ultimate load-carrying capacity and hysteretic behavior of diagonal stiffened SPSW structure under monotonic and cyclic loads. The numerical and experimental results provide the bases for the elastic-plastic design criteria of diagonal stiffened SPSW. Main research contents and corresponding results are listed as follow:Four one-story single-bay unstiffened and diagonal stiffened SPSW of roughly one-third of full scale were tested under a combination of constant gravity load and cyclic lateral loads in a quastic-static condition in order to investigate the failure mechanism and overall performance. The diagonal stiffened SPSW showed high lateral stiffness and load-carrying capacity, excellent displacement ductility and energy dissipation characteristics. The hystersis loops of diagonal stiffened SPSW were stable and eliminated the pinch phenomena at the point of zero displacement. The experimental results showed that diagonal stiffened SPSW was an effective lateral load resisting element.A nonlinear finite element model for unstiffened and diagonal stiffened SPSW was developed using the as-built dimensions and measured material properities of the test specimen, respectively. In the finite element model, a non-planar initial gemotry was included. The effectiveness and validity of the model were demonstrated by comparing its monotonic and cyclic load condition with experimental results. The results showed that finite element method can predict the unstiffened and diagonal stiffened SPSW accurately. The system performances were utilized fully on the base of tension field development and interaction of infill panel and moment resisting frame. In order to fully utilize the diagonal tension field action, boundary columns should be reinforced at the ends. The finite element analysis of the specimens provided a sound foundation for further research of SPSW.Elastic buckling analyses have been carried out to reveal the inherent properities of diagonal stiffened SPSW. A set of non-dimensional parameters that affect the behavior of SPSW under shear and gravity load was investigated such as panel slenderness ratio, column flexibility, stiffness ratio of stiffener to panel, slenderness ratio of stiffener and aspect ratio of panel etc. the obtained results showed that thin and thick SPSW had different elastic buckling limits which should be stiffened by different criterias. The buckling analyses provided the foundation for elastic design of diagonal stiffened SPSW.The influences of initial geometric imperfection, panel slenderness ratio, column flexibility, stiffness ratio of stiffener to panel, slenderness ratio of stiffener, aspect ratio of panel and normalized axial force etc. on ultimate load-carrying capacity of diagonal stiffened SPSW were investigated. Based on the research of one story diagonal stiffened SPSW, the post-buckling behavior of multistories SPSW was still studied accounting for the effect of overturning moment. It was concluded that column flexibility has a significant effect on the behavior of SPSW. The boundary column was dominated by bending stiffness or axial stiffness mainly deponded on column flexibility. For the notable effect of overturning moment, steel tube filled with concrete was proposed for boundary columns in multistories SPSW.The hysteretic behavior of diagonal stiffened SPSW was influenced by many factors, such as panel slenderness ratio, column flexibility, stiffness ratio of stiffener to panel, slenderness ratio of stiffener, aspect ratio of panel and normalized axial force etc. The research of load-displacement relationship, energy dissipation characteristics, out-panel deformation, internal force and deformation of boundary columns showed that diagonal stiffened SPSW was an excellent lateral resisting element.