# Axial Compression Behavior of Steel Angle-Corrugated Steel Plate-Confined Concrete Columns
## 6 Conclusions  
Three SA-CS columns and one CFST column were tested under axial compression and compared with respect to their mechanical behavior. The FE model of the SA-CS column was established, and a parametric analysis was conducted. The calculation methods of some existing codes were assessed by comparing the calculated and numerical results and proposing a new calculation method for the SA-CS column. The results demonstrated herein show that:  
1. All the SA-CS columns failed with the severe local buckling of the steel angle and the spalling of the crest of the core concrete. The CFST column failed with the steel tube's buckling and the internal concrete's shear failure. The strength index (\(I_{s}\)) and ductility index (\(\mu\)) of the SA-CS column were better than those of the CFST column with a similar steel ratio, indicating that the SA-CS column provided more excellent confinement effects on the core concrete than the CFST column.
2. The increase in the section width (decrease of the steel ratio) of the SA-CS column improved the ultimate bearing capacity but reduced \(I_{s}\) and \(\mu\). However, the degree of decline of \(I_{s}\) and \(\mu\) was slight, indicating that the SA-CS column's mechanical properties were only slightly affected by the steel ratio in a particular range. In practical engineering, reducing the steel ratio of the SA-CS column can be considered to improve economic benefits.
3. The FE models were in good agreement with the experimental results. The parametric analysis results have shown that the corrugated steel plate primarily confined the core concrete, and the steel angle bore a part of the axial load.
4. Increasing the compression strength of concrete can effectively improve the ultimate bearing capacity of the specimens but \(I_{s}\) and \(\mu\) will decrease. Increasing the yield strength and thickness of the corrugated steel plate will improve the confinement effect on the core concrete to enhance the axial compression behavior of the specimen. The yield strength and the thickness of the steel angle had little influence on the mechanical properties of the specimens. The variation trend of \(I_{s}\) was not monotonous with the increase in the wave height of the corrugated steel plate (\(h\)), and the confinement of the corrugated steel plate to the core concrete was the strongest when \(h\) was taken as 24 mm.
5. A comparison of the ultimate bearing capacities between the FE results and calculated results by some current codes was conducted, and it was found that the existing codes always underrated or overrated the ultimate bearing capacity of the SA-CS column. The fundamental reason is that the current codes cannot accurately calculate the effective confining stress on the core concrete provided by the corrugated steel  
Figure 18: Comparison of \(N_{\text{u-FEM}}/N_{\text{u-Cal}}\) between existing codes and proposed design method.  
plate. Thus, a new design model for the SA-CS column was proposed, which provided reasonably good predictions with FE-simulated results.  
Conceptualization, Y.Z.; data curation, Z.S; formal analysis, Z.S.; funding acquisition, Y.Z.; investigation, L.W.; methodology, C.W.; project administration, Y.Z.; software, Z.S.; supervision, C.W.; validation, J.P.; visualization, Z.S.; writing-original draft, Z.S.; writing-review and editing, Z.S. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Jiangsu Province Department of Science and Technology (BE2018625) and National Natural Science Foundation of China (51873240). The financial supports are gratefully acknowledged.  
Not applicable.  
All data, models, or codes that support the findings of this study are available from the corresponding author upon reasonable request.  
The authors declare that they have no conflict of interest regarding this work, the work described is original research that has not been published previously, and that it is not under consideration for publication elsewhere, in whole or in part.