Experimental and numerical investigation of prefabricated spiral reinforcement engineered cementitious composites confined recycled aggregate concrete columns subjected to axial compression

This study investigates the axial compression behavior of prefabricated spiral reinforcement engineered cementitious composite (ECC) confined recycled aggregate concrete (RAC) columns through experimental and finite element analysis. A composite confinement system combining an ECC shell and spiral steel reinforcement is proposed to improve the brittleness and durability deficiencies of RAC. Axial compression tests were conducted on specimens with varying RAC strength, core diameter, and spiral reinforcement configuration. The results show that the ECC shell provides effective passive confinement through multiple cracking and fiber bridging, while spiral reinforcement further enhances confinement efficiency, leading to significant improvements in strength, ductility, and post‐peak behavior. The composite confinement increases axial compressive capacity by up to 23.8% compared with the superposition method. A finite element model validated against experimental results accurately reproduces the structural response. Based on the test and numerical results, a simplified calculation method for axial bearing capacity is proposed, providing a practical basis for engineering design.