Axial compression and load-carrying performance of rectangular UHPC-filled stainless-steel tubular short columns

Abstract

Fifteen rectangular ultra-high-performance concrete (UHPC)-filled stainless-steel tubular (UHPCFSST) columns were designed and tested under axial compression to explore the axial compression performance and load-carrying effect. The variables included the cross-sectional size and wall thickness t of the stainless-steel tubes. Failure modes can be categorized into two types: bulging and oblique shear failures. The stress–strain curves can be classified into two categories based on the hoop confinement coefficient (ξs). The test specimens exhibited significant compressive size effects and excellent post-peak ductility. A quantitative analysis was conducted on the sensitivity of the parameters affecting the load-carrying capacity. As the cross-sectional steel ratio α increases, the strength index SI exhibits a growing trend. The specimens with high ξs experience a greater increase in the axial load-carrying capacity of the stainless-steel tubes. A predictive model for the axial load-carrying capacity of rectangular UHPCFSST columns was established with high accuracy and rationality. A quantitative evaluation of the load-carrying effect was conducted using a multilevel extension evaluation model, the results indicated that with an increase in the cross-sectional size, the multilevel extension grades exhibited a decreasing trend.