Performance and strength analysis of concrete-encased steel plate walls under tensile-flexural-shear load

Abstract

When located at the base of a building experiencing high-intensity earthquakes or bi-directional earthquakes, shear walls may be tensile, resulting in tensile-flexural-shear (TFS) stress states after lateral load coupling. The Chinese code proposes the embedded steel to counteract such issues, but there are few relevant studies. Six concrete-encased steel plate (CES) walls were tested under the TFS load to investigate the effects of axial tensile ratio and steel content on seismic behavior. The results showed that TFS specimens failed in tensile flexural-shear mode. Compared to the tension-free specimen, TFS specimens with an axial tensile ratio of 2.5 had 21%, 56%, and 40% lower shear strength, initial lateral stiffness, and ductility. Comparatively, increasing the steel content in the boundary elements effectively reduced the strengthening effect of steel and the brittle fracture potential of boundary elements induced by TFS load, thus enhancing the overall behavior by 15–19%. Furthermore, the failure mechanism was proposed based on the development of deformation and strain. It demonstrated that the maximum principal tensile stress in the web caused severe shear strength degradation and highlighted the importance of the dowel action through the crack interface, depending on the variables. Through the comparative analysis of the shear strength design formulas for eccentric tensile CES walls, the steel proportion was proposed as a modified factor in Chinese code for better estimation.