Zhuojin Pipe Fitting Co., LtdMechanical Behavior of Hollow Sandwich Steel Tube Recycled Ceramic Concrete Compression-Bending Members
Literature Overview
The paper by Zuo Yong, Huang Hong, Wang Yi, and Wang Kai (East China Jiaotong University and China Railway Nanchang Group, 2023) presents experimental and numerical investigations on hollow sandwich steel tube recycled ceramic concrete compression-bending members. Funded by the National Natural Science Foundation of China (51868020), the Jiangxi Provincial Youth Science Fund (20192ACBL21002), and the Jiangxi Provincial Department of Education Science and Technology Research (GJJ210649), the study was published in the Journal of the China Railway Society (Vol. 45, No. 9, pp. 185–194).
Core Technical Content
The research investigates the mechanical behavior of a novel composite system: hollow sandwich steel tube members filled with recycled ceramic concrete (RCC). The sandwich configuration incorporates both an inner and outer steel tube, creating a hollow core that partially reduces material consumption while maintaining structural integrity. The study examines the effects of four parametric variables: hollow ratio, concrete type, slenderness ratio, and eccentricity ratio.
Experimental Program
| Parameter | Variables | Test Count |
|---|---|---|
| Total specimens | 16 | — |
| RCC specimens | 12 | Varying hollow ratio, slenderness ratio, eccentricity ratio |
| Normal concrete specimens | 4 | Control group for comparison |
| Test type | Eccentric compression (compression-bending) | — |
Key Experimental Findings
All specimens exhibited overall buckling failure. For medium-long columns, outer steel tube buckling occurred near the end and mid-span sections. Larger eccentricity ratios led to faster deflection development, reduced bearing capacity and stiffness, but increased ductility. Long columns did not exhibit buckling; compared to medium-long columns, their bearing capacity and stiffness were lower, while ductility showed no significant change. The hollow ratio had minimal influence on stiffness and ductility.
Recycled Ceramic Concrete vs. Normal Concrete
| Performance Indicator | RCC Specimens | Normal Concrete Specimens |
|---|---|---|
| Elastic-plastic stiffness | Slightly lower | Higher |
| Post-peak ductility | Comparable, slightly increased | Baseline |
| Bearing capacity | Slightly reduced | Baseline |
| Peak load prediction error | Within 5% of test values | — |
Finite Element Modeling
The authors proposed a constitutive relationship for recycled ceramic concrete confined by steel tubes. The finite element model accurately simulated the failure mode, with load-deflection curves closely matching experimental results. The ratio of calculated peak loads to experimental values showed deviations within 5%.
Load Distribution Analysis
At peak load, the proportion of load carried by concrete increases with eccentricity ratio. Medium-long columns carry a larger proportion of load compared to long columns. Due to the inner tube carrying part of the load, the concrete in hollow specimens carries less load than in solid specimens.
Engineering Practice Implications
From a steel pipe manufacturing and welding standpoint, the sandwich configuration introduces several considerations:
- Inner tube installation and welding: The inner steel tube must be precisely positioned within the outer tube before concrete filling. Welding the inner tube to the outer tube at the ends requires careful control of heat input to avoid excessive distortion of the inner tube, which could compromise the hollow core geometry.
- Concrete placement: The hollow sandwich configuration requires special attention to concrete placement methods. Self-consolidating concrete or forced vibration methods must ensure complete filling of the annular space between the inner and outer tubes without voids.
- Material sourcing: Recycled ceramic concrete incorporates recycled ceramic waste as aggregate replacement. Engineers must verify that the recycled aggregate does not introduce adverse effects on weldability or corrosion resistance of the steel tubes.
Key Questions and Reflections
The finding that hollow ratio has minimal influence on stiffness and ductility is noteworthy. This suggests that material savings through hollowing can be achieved without significant structural performance penalty, which is economically attractive for large-scale infrastructure projects. However, the practical limit of hollow ratio should be further investigated, particularly under seismic or fatigue loading conditions not covered in this study.
The use of recycled ceramic concrete raises sustainability questions that are increasingly relevant in modern engineering practice. The slight reduction in stiffness and bearing capacity must be weighed against the environmental benefits of recycling construction waste. Engineers should consider whether the 5% peak load deviation in FEM predictions is acceptable for design purposes or whether additional safety factors are warranted.
Study Insights and Conclusions
This research demonstrates the viability of hollow sandwich steel tube recycled ceramic concrete members for compression-bending applications. The proposed constitutive model provides a reliable tool for numerical analysis, and the experimental results offer practical guidance for engineers designing sustainable composite columns. The work contributes to the growing field of green construction materials and composite structural systems, with direct relevance to railway infrastructure applications given the authors' institutional affiliations. Future research should extend to cyclic loading, fire resistance, and long-term durability of the sandwich configuration.