Axial compressive behavior of high-strength steel-UHPC-clad steel composite walls

This paper proposed a novel high-strength steel-UHPC-clad steel composite wall (HS-UHPC-CS composite wall) and investigated its axial compressive behavior through experimental and numerical methods. A total of 18 axial compressive tests and finite element (FE) analyses, including parametric studies of 120 cases, were conducted. It was shown that the stud spacing-to-plate thickness ratio and the normalized slenderness ratio notably affected the strength and local buckling, while their influence on the initial stiffness was minor. The strength and initial stiffness were improved, while the ductility was compromised by the presence of ultra-high-performance concrete (UHPC). Steel fiber was critical to the HS-UHPC-CS composite wall, while the lack of steel fiber could trigger premature brittle failure. The influence of the strength of concrete was higher compared to steel plate. The critical buckling stress of the steel plate was calculated using Euler's buckling formula for the clad steel plate of the HS-UHPC-CS composite wall. The results were compared with the ordinary composite wall database. In addition, strength from test results, FE results, and the database were compared were compared with strength calculated by design provisions. It was found that the calculated strength was close but not safe. It was recommended that different concrete contribution coefficients should be applied for HS-UHPC-CS composite walls with different normalized slenderness ratios.