Effects of the number of Concrete panel and Concrete strength on the behavior of Composite Shear Wall

Composite steel plate shear wall -or in short Composite shear wall- is a lateral load resisting system which was investigated widely during past decade. Steel plate is the most important component of the system in carrying shear, but it would buckle under relatively low levels of loading due to its instinct high slenderness. To avoid such a buckling and obtaining a suitable seismic performance, Concrete panel is attached to one or both sides of the plate. The composite performance of the system would be achieved by using shear connectors, usually in the form of bolts when pre-cast concrete is utilized. Surrounding beams and columns act as a framework for the infill composite panel. However, the behavior of theses boundary members together with their connection to shear wall is of main concern, especially in high-seismic design when a dual action is needed and the beam-to-column connection should be rigid. Furthermore, these members would also participate in resisting most of the overturning moments and depends on their stiffness, a portion of the shear. In this paper, the number of concrete panels (whether on one or both sides of steel plate) and Concrete strength are the parameters that their effects on the behavior of composite wall would be investigated numerically. For this purpose, a valid experimental specimen was modeled in the Finite Element Software ABAQUS, with the capability of considering different elements for different parts of the composite system, and after verifying the accuracy of the numerical model, new specimens were constructed and analyzed using push-over method in order to demonstrate the effect of the required parameters. Results show that specimen with concrete on both sides would have considerably less ductile behavior than specimen with one-sided concrete, although its shear strength is higher at lower levels of inelastic displacements. However, both specimens reach the same ultimate shear strength and as was expected, they have also same initial stiffness. Although steel plate is likely to buckle in specimen with concrete on one side of the plate at high levels of stress near yielding, but results of the present paper shows that not only this kind of buckling has no stability sequences and does not result in performance similar to thin steel plate shear walls due to prevention of early buckling, but also leads to a more ductile behavior than the specimen which reaches the full shear yielding without the possibility of such buckling. Furthermore, Concrete strength has little effects on overall behavior of the system, although can reduce the damage to concrete panel. Based on the obtained results, it can be concluded that using normal-strength concrete (such as 4000psi or 28Mpa) and just on one side of steel plate is sufficient for obtaining a desirable seismic performance of the system.