XIAMUXI A L F J, SHAO J L , SHI L J. Axial compressive bearing capacity of short columns of reinforced recycled aggregate concrete-filled steel tubes [J]. Journal of Henan Polytechnic University (Natural Science) , 2025, 44(4): 179-187.

doi: 10.16186/j.cnki.1673-9787.2023120060

Received: 2023/12/20

Revised: 2024/03/01

Published: 2025/06/19

Axial compressive bearing capacity of short columns of reinforced recycled aggregate concrete-filled steel tubes

Xiamuxi Alifujiang1, Shao Jinlan1, Shi Lujiang2

1.College of Civil Engineering and Architecture， Xinjiang University， Urumqi  830017， Xinjiang， China；2.Changzhou Construction Science Research Institute Group Co.， Ltd.， Changzhou  213000， Jiangsu， China

Abstract: Objectives This study aims to mitigate the adverse effects caused by the inhomogeneity of recycled aggregate concrete and to promote full utilization of recycled coarse aggregate by developing a calculation method for the bearing capacity of reinforced recycled aggregate concrete-filled steel tubes （R-RACFST）. Methods Based on the unified theory approach， the study fully considered the dual restraining effects of the steel tubes and steel reinforcement on the core recycled concrete. It modified parameters such as the confinement coefficient in existing concrete constitutive models to derive a nonlinear numerical simulation model suitable for R-RACFST. After verifying the model’s reliability with existing experimental data， a parameterized analysis was conducted on 90 model specimens obtained through orthogonal design considering different steel tube wall thicknesses， longitudinal reinforcement diameters， and concrete strength grades， using the corrected hoop coefficient as a parameter. Results When other parameters remained unchanged， increasing the concrete strength and steel tube wall thickness led to increased ultimate compressive strength and enhanced post-peak plastic deformation capacity， whereas increasing the diameter of the longitudinal reinforcement had minimal effect. Based on these findings and considering the influence of the three parameters on bearing capacity， the study referenced the existing T/CECS625-2019 code’s formula for short-column bearing capacity of recycled aggregate concrete-filled steel tubes， and proposed a new formula for calculating R-RACFST short-column bearing capacity based on the unified theory. To validate the reliability of the proposed formula， a comparative analysis was performed between experimental and calculated values for 100 sets of existing tests and model specimens. Results showed that directly using the reinforced concrete-filled steel tube formula from CECS408-2015 yielded an average ratio of 0.95 with a standard deviation of 0.05 between experimental and calculated values. In contrast， the proposed R-RACFST formula resulted in an average ratio of 1.11 with a standard deviation of 0.06， indicating better agreement. Conclusions The formula proposed in this study for R-RACFST short-column bearing capacity is safe， reliable， and applicable to engineering practice. 

Key words: reinforced recycled aggregate concrete-filled steel tubes; confinement coefficient; bearing capacity; finite element analysis