Abstract: Coupled steel plate shear wall is a new type of lateral force resisting system which is formed by connecting two steel plate shear walls with coupling beams. Through the interaction of coupling beam and wall limb, the capacity of resisting overturning moment and lateral stiffness of the coupled steel plate wall are improved. Coupling beam is the key component that affects the seismic performance of coupled steel plate shear wall, and coupling ratio is an important parameter to measure the wall limb interaction. Therefore, a design method with coupling ratio as control index is proposed. Three 20-story steel frame-coupled steel plate wall structures are designed with coupling ratios of 20%, 40% and 60%, respectively. The finite element model of the structure is established by using ABAQUS software, and the results of mode-decomposition response spectrum analysis show that the difference of each structural performance index of the three models is less than 5%, which indicates that the steel frame-coupled steel plate wall structure can be designed to meet the expected structural performance by using the design method with coupling ratio as the control index under the same design seismic shear force. The coupling ratio will affect the steel consumption of steel plate wall.
In the coupled steel plate shear wall, the steel consumption of frame column is much larger than that of other components. When the design seismic shear force is the same, with the increase of the design target coupling ratio, the design section of coupling beam increases, and the interaction between coupling beam and wall limb is strengthened, which can reduce the thickness of embedded steel plate and reduce the section size of frame column. On the other hand, the shear force and bending moment of coupling beam will increase with the increase of coupling ratio. The increase of coupling beam shear force will reduce the axial force of the frame inner column connected with it, but the increase of coupling beam bending moment will increase the bending moment of the frame inner column. Therefore, when the coupling ratio increases to a certain extent, the cross-section size of the inner column may increase instead of decreasing. Among the three models, the 40% coupling ratio model has the least steel consumption and the best economy.
Seven seismic waves are selected for time-history analysis of the three models. Under frequent earthquakes, the average values of base shear of the three models are basically the same. Under rare earthquake, the average value of base shear of 40% coupling ratio model is the largest, but the average value of interstory drift angle is the smallest, which indicates that the degree of plasticity of the structure is small, and the stiffness degradation is not obvious as the other two models. The smaller the coupling ratio is, the deeper the plastic development of coupling beam is. The larger the coupling ratio is, the deeper the plastic development of steel plate is. However, the maximum equivalent plastic strain of the steel plate is much larger than that of the other two models, while the coupling beam remains elastic. Therefore, the 20% and 40% coupling models are more reasonable than the models.
The horizontal load of inverted triangle distribution mode is applied to the model, and the static elastic-plastic analysis is carried out to obtain the base shear-top drift angle curve and the stiffness-top drift angle curve. According to the yield order of the members, the whole process of pushover curve is divided into eight stages. The failure order of the three models is:steel plate yield→ coupling beam yield→ frame beam end yield → frame column base yield, which indicates that the three steel frame-coupling steel plate wall models have good ductility and meet the structural design performance objectives.