Axial compression performance of circular UHPC-filled stainless-steel tubular columns

Abstract

Whether the high ductility of stainless-steel tubes can impede the brittle failure of ultrahigh-performance concrete (UHPC) and improve their cooperative load-carrying efficiency is a research direction worth exploring. Twenty-seven circular UHPC-filled stainless-steel tubular (UHPCFSST) columns were designed and tested under axial compression. The variables were the outside diameter and wall thickness of the stainless-steel tube. The axial compression performance and cooperative load-carrying efficiency of the UHPCFSST columns, such as the failure mode, stress–strain relationship, and ductility, were quantitatively evaluated. The experimental results show that the stress–axial strain curves can be divided into two forms based on hoop confinement coefficient (ξs). The ductility of the UHPCFSST columns is considerably better than that of UHPC-filled steel tubular (UHPCFST) columns, and there is an obvious strain-hardening phenomenon after the peak. A database of UHPCFST columns containing 272 specimens was constructed. The relationships between parameters and enhancement coefficients such as the strength index were quantitatively investigated. Through regression analysis, a prediction model for the axial compression load-carrying capacity of UHPCFSST and UHPCFST columns was established. Using the database, the rationality and accuracy of the proposed model were verified.