Axial Compressive Performance of L-Shaped Columns Composed of RAC-Filled Steel Tubes

This paper discusses the application of recycled aggregate concrete (RAC) in novel special-shaped concrete-filled steel tube (CFST) columns and presents an axial compressive test of the L-shaped column composed of recycled aggregate concrete-filled steel tubes (RACFST). The replacement ratio of recycled coarse aggregate (RCA) was changed to explore the axial compression performance of the columns in comparison with the L-shaped hollow section columns. The results show that with the increase in the replacement ratio of RCA, the bearing capacity and stiffness of the special-shaped CFST column decrease, but are better than those of the hollow section columns. As the replacement ratio increases from 0 to 100%, the compressive strength of RAC is reduced by 73.1%, while the resistance of the column is reduced by 18.0%. The poor performance of RAC can be alleviated by this special cross-section of columns. The FEMs simulated using the software ABAQUS are in good agreement with the experimental results and provide a reference for the modeling method. The calculation method for the axial bearing capacity of the L-shaped column was established considering the effect of constrained concrete and RCA replacement ratio. The deviation between the calculation and the test results is within 7%.