Shear strength of steel-concrete composite walls (aspect ratio 2.0) with steel U-SECTION boundary element

A steel-concrete composite wall with steel U-section boundary elements was developed for enhanced structural performance and constructability. In the present study, cyclic lateral loading tests were performed to investigate the shear strength of the proposed walls. Test parameters were the type of boundary reinforcement (rebars or steel U-sections), sectional area of steel U-sections, and type (horizontal rebars, steel plate beams, or steel faceplates) and spacing of web reinforcement. The test results showed that the boundary steel U-sections restrained diagonal tension cracking and shear sliding in the web. Further, the steel U-sections restrained cracking and crushing of the boundary concrete, confining the boundary zone. For this reason, the shear strength of the composite wall was 35 % greater than that of the counterpart reinforced concrete wall with conventional boundary reinforcement. The use of steel plate beams and steel faceplates further increased shear strength. Existing reinforced concrete design methods underestimated the shear strength of the composite walls, neglecting the contribution of steel U-sections. The tested shear strengths exceeded the web crushing strengths of ACI 318, even though the horizontal web reinforcement ratio was less than the code-based maximum ratio.