Behavior of square geopolymer recycled brick aggregate concrete filled steel tubular stub columns under axial compression

Abstract

Geopolymer recycled brick aggregate concrete filled steel tubes (GRBACFST) have the advantages of waste utilization, reducing carbon dioxide emission and overcoming concrete defects, which have broad potential applications in engineering structures. However, there is little relative research and regulations for this kind of structure with the innovative material. In this paper, 20 square GRBACFST stub columns were tested under axial compression to investigate the effects of concrete reference strength, replacement ratio of recycled brick aggregate (RBA) and thickness of steel tube. The failure mode, load–strain curve, ultimate strength, compressive stiffness and ductility were analyzed. Based on the material characteristics of geopolymer RBA concrete, the existing constitutive model of traditional core concrete confined by steel tube for finite element method was modified. Numerical data of 192 GRBACFST stub columns with different parameters under axial compression were generated and compared with the design methods for traditional concrete filled steel tubes. It can be found using the actual strength and elastic modulus of geopolymer RBA concrete, the existing formulas are capable of predicting the axial compressive ultimate strength and stiffness of square GRBACFST stub columns.