Axial compressive performance of thin-walled square steel tube concrete short column with built-in steel slag block

Abstract

In the process of iron and steel production, steel slag is produced as waste. The steel slag processing method generally produces steel slag cement as a substitute for gravel and fine aggregates. Steel slag aggregates replace natural aggregate concrete used in concrete components. In addition, steel slag expansion can compensate for the shrinkage characteristics of concrete and steel pipes inside closed wet environments, and the outer steel tube hoop constraint can avoid late hydration expansion structure cracking. Through orthogonal testing, the wall thickness of the steel pipe (3 mm, 3.75 mm, 4.5 mm), content of the steel slag blocks (10 %, 15 %, 20 %) and particle size of the steel slag blocks (40–60 mm, 60–80 mm) were used as experimental variables to conduct axial compression tests on 9 groups of short columns made of slag aggregate concrete-filled thin-walled square steel tubes. Based on the analysis of the test process and displacement, strain, ductility and ultimate bearing capacity results, the failure pattern and mechanism of the short column specimens under axial compression were obtained, and a bearing capacity calculation formula was obtained according to the existing theoretical methods. The results indicate three failure patterns: local convexity, shearing and circumferential bulging. The factors influencing the bearing capacity, from most influential to least influential, are the particle size of the steel slag, the wall thickness of the steel pipe and the amount of steel slag. The Poisson's ratio of core concrete has an important effect on its passive binding force, which affects the longitudinal displacement and load-bearing capacity of the component. The deduced formula can be used to accurately calculate the ultimate bearing capacity of the square steel tube and steel slag concrete. This article transforms the drawbacks of steel slag concrete into advantages and, by combining the characteristics of steel tube concrete, proposes a new type of composite component that has a certain degree of innovation and application value.