Zhuojin Pipe Fitting Co., LtdAxial Compression Performance of Concrete Columns Confined by Horizontal-Ribbed Corrugated Plate and Square Steel Tube
Research Context and Objectives
Published in the "China Journal of Highway and Transport" in 2022, this study by Zou Yun and colleagues from Jiangnan University and Shanghai Ouben Steel Structure Co. examines the axial compression behavior of a novel composite column system known as CPST (Corrugated Plate and Square Steel Tube). The column is constructed by welding horizontal-ribbed corrugated plates to four square steel tubes at the corners, with concrete poured into the enclosed cavity. The research was funded by the Jiangsu Provincial Science and Technology Department and the National Natural Science Foundation.
Specimen Configuration and Test Results
Three full-scale CPST short column specimens were tested under axial compression. The failure sequence was observed as follows: local buckling of the square steel tubes occurred first, followed by outward bulging of the corrugated plates, and finally crushing of both the internal and core concrete. The corrugated plates provided effective lateral confinement to the core concrete but contributed minimally to axial load resistance.
| Parameter | Effect on Axial Capacity | Effect on Ductility |
|---|---|---|
| Concrete strength increase | Increases capacity | Decreases ductility |
| Square tube wall thickness increase | Increases capacity | Increases ductility |
| Square tube strength increase | Increases capacity | Minimal effect |
| Corrugated plate thickness increase | Increases capacity | Increases ductility |
| Corrugated plate strength increase | Minimal effect on capacity | Slight improvement in ductility |
| Square tube outer section size increase | Increases capacity | Not explicitly quantified |
Analytical Model Development
Based on the Mander et al. confined concrete compressive strength formula, the authors introduced a comprehensive influence variable to propose a calculation equation for the axial compressive strength of CPST short columns. This approach provides a practical design tool for engineers, extending the well-established Mander model to accommodate the unique confinement geometry provided by the combination of corrugated plates and corner steel tubes.
Welding and Fabrication Considerations
From a fabrication standpoint, the CPST column system requires precise welding of the corrugated plates to the square steel tubes at the corners. The quality of these welds is critical because they must maintain structural integrity under cyclic or sustained axial loading. Common welding processes for such connections include GMAW (gas metal arc welding) and SAW (submerged arc welding), with attention required to control residual stresses and ensure full penetration at the tube-to-plate junctions. Welding-induced distortion in the corrugated plates could compromise the uniformity of concrete confinement, making pre-weld alignment and post-weld straightening important fabrication steps.
Study Insights and Practical Value
The research demonstrates that the CPST system offers a viable alternative to conventional CFST columns, particularly where the corrugated plate provides efficient lateral confinement without significantly increasing material weight. The finding that corrugated plate strength has minimal influence on axial capacity suggests that thinner, lower-grade corrugated plates could be used economically, with the primary design focus placed on plate thickness and tube geometry. For highway bridge applications, where this column type may be particularly relevant, the proposed analytical model offers a straightforward path to design verification.