Influence of recycled large-aggregate self-compacting concrete-filled steel tube mechanical properties under pure bending load

In this study, the influence of different factors on pure bending members of recycled large-aggregate self-compacting concrete-filled steel tubes (RLA-SCCFSTs) was analyzed. Seven RLA-SCCFST members and one SCCFST member were designed to study their failure under a pure bending load and the influence of the steel tube wall thickness, RLA strength, and RLA particle size. The flexural bearing capacity was calculated using various codes. Based on the test results, ABAQUS and MIDAS FEA NX finite element analysis software were used to simulate and verify the test conditions. The results showed that under a pure bending load, the failure process of the RLA-SCCFSTs was much the same as that of an ordinary concrete-filled steel tube. Moreover, changes in the influencing factors resulted in different degrees of improvement in the flexural bearing capacity of the RLA-SCCFSTs. The factors most affecting the flexural members of the RLA-SCCFSTs – from large to small – included the steel tube wall thickness, RLA strength, and RLA particle size. The finite element simulation shows that the model based on the modified constitutive relation of core concrete was in good agreement with the experimental results. Among the various calculation methods for the bearing capacity, the results using the DBJ13-51-2003 specification were in good agreement with the test results. This study provides a reference for the reuse of waste concrete.