Mechanical performance of high-strength steel tube confined self-stressing concrete short columns

In this paper, eleven high-strength steel tube confined self-stressing concrete (HSTCSC) short columns were tested to study their strengthening mechanism and axial compression performance. The effects of different material strengths, cross-section types, and hollow ratios on the axial mechanical properties of the HSTCSC short columns were investigated using the finite element analysis method. Experimental results highlighted that the HSTCSC short columns presented the waist drum-type failure mode significantly, with a higher axial load-bearing capacity and deformation performance, and possess a large safety reserve. It was also found that the axial compression property of the HSTCSC short column could be improved significantly due to the joint action of the micro-expansion of the self-stressing concrete and the hoop constraint of the high-strength steel tube. Moreover, the circular cross-section HSTCSC short columns were found to result in better mechanical performance after yielding of the high-strength steel tubes, especially entering the strengthening section. Under the condition of equal steel content ratio and cross-section area, the single-layer circular HSTCSC short columns were found to have the largest load-bearing capacities after yielding the high-strength steel tubes, followed by the double-layer circular HSTCSC short columns, and then the double-layer square HSTCSC short columns. The hollow rate of the cross-section could also decrease the load-bearing capacity of the HSTCSC short column with both circular and square sections, although increasing the hollow rate could save material and reduce the weight of the structure. The finite element analysis results showed that the proposed finite element model could be employed to simulate the compressive behavior of HSTCSC short columns with high calculation accuracy.