Numerical analysis of square concrete-filled double skin steel tubular columns with rubberized concrete

Structural engineers have assessed the possibility of replacing part of natural aggregates with rubber particles in concrete in recent years to obtain sustainable structural members. It has been confirmed that the use of rubber particles can enhance ductility and energy absorption capacity of concrete. By contrast, the compressive capacity of rubberized concrete (RuC) is usually lower than the normal concrete (NC). Confining RuC with steel tubes can be considered as an appropriate solution for reaching to a ductile member with adequate strength. This paper, therefore, investigates the behavior of rubberized concrete-filled double skin steel tubular (RuCFDST) short columns by performing a series of nonlinear finite element (FE) analyses. The developed FE models were verified against the experimental test results by comparing the axial load–displacement curves, ultimate axial strength, and failure mechanism of specimens. The validated FE model was used to investigate the effects of geometric and material properties on the behavior of RuCFDST columns with 5%, 15%, and 30% rubber contents, and to compare the performance of RuCFDST and concrete-filled double skin steel tubular (CFDST) columns. The results showed that using RuC for filling square CFDST columns could significantly enhance the ductility. By contrast, CFDSTs presented greater axial strengths than RuCFDSTs. Reduced confining stresses between the outer tube and the concrete core were displayed when RuC was applied compared to CFDST