Study of recycled aggregate concrete-filled circular steel columns with H-shaped steel reinforcement

In this study, the prediction formula of the axial compressive bearing capacity of recycled aggregate concretefilled (RAC) circular steel columns with H-shaped steel reinforcement was theoretically studied with the limit analysis method. To differentiate the restraining effect due to H-shaped steel and steel tube, the bearing capacity of the concrete is divided into two parts, i.e., recycled aggregate concrete in the H-shaped steel confined area and the recycled aggregate concrete in the steel-tube confined area. Second, the effect of inner diameter-thickness ratio of steel tube, H-shaped steel and recycled coarse aggregate replacement rate on the axial compressive bearing capacity of the column is studied. Finally, a set of calculation formulas for the axial load bearing capacity of recycled aggregate concrete stub columns with steel tubes with H-shaped steel reinforcement is proposed. The validity and accuracy of the calculation formula of the bearing capacity was assessed by comparing with test results. The error between the theoretically formula and test results was within 10%. It demonstrates the feasibility of the proposed formula and accuracy of the limit analysis method.

Automated summary

In this study, the prediction formula for the axial compressive bearing capacity of recycled aggregate concrete-filled circular steel columns with H-shaped steel reinforcement was theoretically studied using the limit analysis method. The bearing capacity of the concrete was divided into two parts, namely the recycled aggregate concrete in the H-shaped steel confined area and the recycled aggregate concrete in the steel-tube confined area, to differentiate the restraining effect due to H-shaped steel and steel tube. The study also investigated the effects of inner diameter-thickness ratio of steel tube, H-shaped steel, and recycled coarse aggregate replacement rate on the column's axial compressive bearing capacity. Eventually, a set of calculation formulas for the axial load bearing capacity of recycled aggregate concrete stub columns with steel tubes and H-shaped steel reinforcement was proposed and validated against test results with an error within 10%, demonstrating the feasibility and accuracy of the proposed formula and the limit analysis method.