EXPERIMENTAL STUDY AND THEORETICAL ANALYSIS ON AXIAL COMPRESS CAPACITY OF ERCYCLED AGGREGATE CONCRETE-FILLED CIRCLE STEEL TUBE SHORT COLUMN

In order to study the axial compress capacity of recycled aggregate concrete-filled steel tube short-columns, 22 specimens were designed to test, and the recycled coarse aggregate replacement percentage and confinement index were regarded as major variable parameters. By the experiment, the whole mechanical process and failure mode of all specimens were observed, and stress-strain curves of the specimens were obtained. The influence of the aggregate replacement rate and confinement index on the bearing behaviour of the specimens was analyzed. The test results indicate that the failure mode of the columns is similar to that of an ordinary concrete-filled steel tube, and recycled coarse aggregate replacement rate has little effect on a recycled aggregate concrete-filled steel tube, but confinement index has a significant effect on the bearing behaviour and deformation performance. The bearing capacity of the specimens was calculated and analyzed according to the theories of Unified Strengthen, Confinement and Superposition Calculation. Compared with the experimental values, the results show that calculated values are low on the basis of the first and the third calculation theories, but the calculated values are slightly high based on the second calculation theory. Finally, stress-strain curves were fitted and analyzed according to experimental data. Stress-strain whole curve equations of specimens were put forward. The research conclusions could be a reference for the scientific study and engineering application of recycled aggregate concrete-filled steel tubes.