Experimental and numerical study on self-compacting alkali-activated slag concrete-filled steel tubes

Abstract

This study presents a comprehensive experimental and numerical investigation of axially loaded self-compacting alkali-activated slag concrete-filled steel tubular (ACFST) stub columns. Integrating alkali-activated slag concrete (AASC) with concrete-filled steel tubes (CFST) can yield a novel construction composite material that offers advantageous outcomes for both AASC and steel tube. AASC, an environmentally friendly alternative to traditional concrete, offers improved sustainability, while CFST can provide enhanced structural capabilities. To investigate the performance of ACFST columns, nine different AASC mixtures were designed, each varying in binder content, water-to-binder ratio, Na2O %, and activation modulus. In this study, eighteen ACFST specimens were tested under axial compression, evenly divided into nine circular and nine square CFST sections. A numerical model is developed to evaluate the stress-strain behaviour of confined AASC filled in circular and square steel tubes. The proposed numerical model is first applied to analyse ACFST specimens tested in this study and then used to analyse ACFST specimens tested by another researcher to verify its accuracy. The results, including ultimate load capacity, axial load-displacement graphs, and failure modes obtained from the proposed numerical model, have shown strong agreement with the test results. This suggests that the proposed model can be effectively utilized to predict the axial compressive behaviour of both circular and square ACFST columns.