Eccentric Compression Behavior of RCFST Columns with Web Perforated T-Shaped Stiffeners

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Summary of the Article:

This study investigates the eccentric compression behavior of rectangular concrete-filled steel tubular (CFST) columns with web perforated T-shaped stiffeners. Finite element models were developed and validated against experimental data. A comprehensive parametric analysis was conducted, including the number, dimensions, and materials of the stiffeners. Results indicate that the stiffeners significantly enhance the ultimate bearing capacity. Additionally, the authors propose an improved method for calculating the N-M interaction curve.

Language and Structural Review:

1-Grammatical Errors: The manuscript contains minor grammatical inconsistencies. For example:

• Phrases like "further investigate the eccentric compression behavior" could be simplified to "investigate the eccentric compression behavior further" for better readability.
• Usage of plural forms, such as "methods significantly enhances" (should be "enhance").

2-Clarity: Some sentences are overly complex and could be simplified. For instance:

• "The results indicate that the stiffening method significantly enhances the rectangular CFST ultimate bearing capacity." This could be rephrased as:

·        "The stiffening method significantly improves the ultimate bearing capacity of rectangular CFST columns."

3-Technical Terms: Most technical terms are appropriate; however, less common terms like "N-M interaction curve" could be briefly explained for clarity to readers unfamiliar with the concept.

Scientific Questions:

1. In Section 2, could the authors include graphical representations of the concrete’s behavior under tension and compression?
2. In the same section, could the authors numerically illustrate the stress-strain behavior of both concrete and steel at the stress point? For this purpose, the following references could be utilized:

·        Zhang, Xueyan, et al. "A constitutive model of concrete based on Ottosen yield criterion." International Journal of Solids and Structures, 193 (2020): 79-89.

·        Akhaveissy, Amir H., et al. "Seismic Retrofit of Defective RC Beam-Column Joints." Periodica Polytechnica Civil Engineering, 62.3 (2018): 596-611.

Additional Scientific Questions:

 

1. Could the authors elaborate on how the interaction coefficients for the stiffeners were derived and validated in the finite element models?
2. How does the proposed N-M interaction curve compare quantitatively with existing standards like CECS 28 for similar CFST columns?
3. Were sensitivity analyses conducted to assess the impact of material property variations (e.g., steel and concrete strengths) on the model accuracy?
4. Could the inclusion of dynamic or seismic loading scenarios enhance the applicability of the study findings?

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

 

This study investigates the eccentric compression behavior of rectangular concrete-filled steel tubular (CFST) columns with web-perforated T-shaped stiffeners using finite element analysis. The models were validated against experimental results, showing good accuracy. Parametric analyses revealed that increasing the number, size, and material strength of stiffeners significantly enhances load-bearing capacity, while a higher slenderness ratio reduces it. A new N-M interaction curve calculation method was proposed for predicting the ultimate strength of these columns, offering higher accuracy than the CECS 28 standard while maintaining safety. The paper needs to be revised based on the following:

 

1.      The author should tell the importance of the study and its novelty in terms of filling the gap in the literature. That should be done in the last part of Introduction. What is proposed in the paper needs to be expanded and detailed (To further investigate the eccentric compression behavior of rectangular CFST columns with web perforated T-shaped stiffeners, this paper conducts a numerical simulation study based on the previous tests. Firstly, finite element models of rectangular CFST with web perforated T-shaped stiffeners were made and verified by the axial compression test results by the authors.).

2.      In comparison to non-stiffened columns, how do web-perforated T-shaped stiffeners affect the development of strain and the distribution of stress in rectangular CFST columns under eccentric compression?

3.      How about mesh convergence study? Any reference for the selection of friction coefficient?

4.      How does this relate to local buckling mechanisms and global stability, and why does an increase in the slenderness ratio lower the ultimate capacity of CFST columns?

5.      What aspects of the suggested N-M interaction curve calculation approach, and how do correction variables play a role in this improvement, make it less conservative and more accurate than the CECS 28 standard?

6.      How and why does the load-bearing capacity under strong-axis and weak-axis eccentric loading alter depending on stiffener dimensions?

7. How do the mechanical characteristics of steel (fy) and concrete (fcu) affect the ductility and load-bearing capacity of CFST columns, and how might this affect design optimization?

8.  What elements contribute to the increased reliability of the suggested N-M interaction curve calculation approach, and how does it improve accuracy when compared to the CECS 28 standard?

9.      How specifically do the size and quantity of stiffeners affect the rectangular CFST columns' ability to support loads along their strong and weak axes?

What are the limitations of the present study? That needs to be addressed.

The Ithenticate report shows 28% similarity. That needs to be lessened below 20%.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Eccentric Compression Behavior of Rectangular CFST Columns with Web Perforated T-shaped Stiffeners

This paper investigates the eccentric compression behavior of rectangular concrete-filled steel tubular (CFST) columns reinforced with web-perforated T-shaped stiffeners. The study employs a combination of experimental and numerical methods to evaluate the effect of stiffeners on the performance of these structural elements. The findings demonstrate that perforated stiffeners reduce the weight of the structure without significantly affecting its load-carrying capacity, making the design efficient and resource-conscious.

The paper is novel and relevant to the structural engineering community, particularly for the design of composite structures in high-rise buildings and bridges. While the paper provides significant insights, there are areas where improvements in presentation and detail could enhance its overall quality.

The following improvements are recommended for the authors if it is possible:

1. Expand the introduction with more references to similar studies for better contextualization.
2. Provide additional details in the methods section, particularly regarding the selection of perforation parameters.
3. Simplify and clarify complex sentences for improved readability.
4. Include a more detailed discussion on the influence of concrete material properties and potential limitations of the proposed design.

With minor revisions to address the points outlined above, this paper is well-suited for publication and will likely have a significant impact on the field of composite structural design.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

the paper is revised as requested.