Bearing Capacity of UHPC-Filled High-Strength Elliptical Steel Tube Composite Columns with Encased High-Strength H-Shape Steel Subjected to Eccentrical Load

Round 1

Reviewer 1 Report

The FE models of 44 HUCFEST composite columns subjected to eccentrical load are established by ABAQUS software. The load-deflection curves of the specimens are obtained during the whole process. The effect of different parameters on ultimate eccentric compression bearing capacity is discussed. The calculation formula for the eccentric bearing capacity of the HUCFEST composite columns is deduced by statistical regression. These can lay a foundation for applying of HUCFEST columns in practical engineering.

The content of this article is full and the data are accurate. The existing problems are as follows:

1. The second sentence in introduction is too long with incorrect grammar, please modify it.

2. Please use the same tenses in your introduction.

3.In 2.1.1 "E is equal to 0.1Es In Equation (1)." Remove bold punctuation after Equation(1).

4.The title of Figure 3:Model of 44 specimens in Figure 3 is not accurate, it is suggested that it should be revised as” Figure 3. The FE Models for 44 HUCFEST specimens”.

5.The format for the titles of Table2 and Table3need to be revised.

6. The first paragraph In Parameter Analysis: ABAQUS software carries out FE analyses on 44 specimens subjected to eccentrical compression load. It is suggested that it should be revised as follows: FE analysis on 44 specimens subjected to eccentrical compression load are carries out by ABAQUS software.

7.The direction of element micro stress of H-shape steel in Figure 12 is incorrect, and please revise it.

8. In 9.2,the express of “and the three are all in a three-dimensional stress state”is incorrect, and please revise it.

Author Response

Dear Reviewer 1：

In your review comments, you noted that this paper needs extensive English editing needs.We have sent the revised manuscript to a professional retouching agency for retouching, and these changes have been marked in the manuscript.

Reviewer 1:

this article is full and the data are accurate. The existing problems are as follows:

1. The second sentence in introduction is too long with incorrect grammar, please modify it.

Response:

Thanks for the reviewers' kind suggestion. We have revised the second sentence of the introduction. This sentence has been marked in the manuscript.

2. Please use the same tenses in your introduction.

Response:

Thanks for the reviewers' kind suggestion. We have revised the tense in the introduction to be consistent and have marked it in the manuscript.

3. In 2.1.1 "E is equal to 0.1Es In Equation (1)." Remove bold punctuation after Equation(1).

Response:

Thanks for the reviewers' kind suggestion. We have made the changes you requested and marked them in the manuscript

4. The title of Figure 3:Model of 44 specimens in Figure 3 is not accurate, it is suggested that it should be revised as” Figure 3. The FE Models for 44 HUCFEST specimens”.

Response:

Thanks for the reviewers' kind suggestion. We have made the changes you requested. This sentence has been marked in the manuscript.

5. The format for the titles of Table2 and Table3 need to be revised.

Response:

Thanks for the reviewers' kind suggestion.We have modified the the format for the titles of Table2 and Table3. These titles have been marked in the manuscript.

6. The first paragraph In Parameter Analysis: ABAQUS software carries out FE analyses on 44 specimens subjected to eccentrical compression load. It is suggested that it should be revised as follows: FE analysis on 44 specimens subjected to eccentrical compression load are carries out by ABAQUS software.

Response:

Thanks for the reviewers' kind suggestion.We have revised it as you suggested. This sentence has been marked in the manuscript.

7. The direction of element micro stress of H-shape steel in Figure 12 is incorrect, and please revise it.

Response:

Thanks for the reviewers' kind suggestion.We have modified the direction of element micro stress of H-shape steel in Figure 12. This modification has been marked in the manuscript.

 

8. In 9.2,the express of “and the three are all in a three-dimensional stress state”is incorrect, and please revise it.

Response:

Thanks for the reviewers' kind suggestion.We have modified the sentence “and the three are all in a three-dimensional stress state”. This sentence has been marked in the manuscript.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments as in attached .pdf file

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

English needs substantial improvement. Just a few examples:

1. Abstract: “In order to study the eccentric mechanical properties….”. The mechanical properties are not eccentric. The paper intends to study the response to eccentric loading.
2. Introduction: “In recent years, domestic and foreign scholars have shown tremendous research interest…” should be rephrased, to a sentence such as “The study of ….has recently attracted a lot of interest internationally….
3. Introduction: “..excellent plasticity…” should be rephrased to “…excellent ductility…”

Response:

Thanks for the reviewers' kind suggestion.We have revised these sentences as you requested. These sentences have been marked in the manuscript. And we sent the revised manuscript to a professional retouching agency for comprehensive retouching, and the revised part has been marked in the manuscript.

2. “…….the eccentric ultimate bearing capacity gradually increases.” should be changed to ”…the bearing capacity to eccentric compression gradually increases”.

Response:

Thanks for the reviewers' kind suggestion.We have revised this sentence as you requested. This sentence have been marked in the manuscript.

3. “Based on the double line elastic-plastic constitutive model of steel…” should be changed to ”Based on a bi-linear elastic-plastic constitutive model of steel…”

Response:

Thanks for the reviewers' kind suggestion.We have revised this sentence as you requested. This sentence have been marked in the manuscript.

 

4. Eq. (1): Change mutually Es and E.

Response:

Thanks for the reviewers' kind suggestion.We have swapped Es and E in Equation 1. These changes have been marked in the manuscript.

 

5. Change “…pagoulatou et al. [28],…” to “Pagoulatou et al. [28],..”

Response:

Thanks for the reviewers' kind suggestion.We have changed  “…pagoulatou et al. [28],…” to “Pagoulatou et al. [28],..”.  This change has been marked in the manuscript.

6. 3: Show the direction of the axes x, y and z.

Response:

Thanks for the reviewers' kind suggestion.We have added the axes x, y and z to Figure 3.

7. 4: Shortening of the columns is assigned as Δ in Figs. a to e and j to l, while as μm in Figs f to I and m to o. Change all to Δ (or better to Uz).

Response:

Thanks for the reviewers' kind suggestion.We have changed all μm in Figure 4 to Δ.

8. Fig 6: Change μm to Δ (or better to Uz, if z is along the specimen’s longitudinal axis).

Response:

Thanks for the reviewers' kind suggestion.We have changed all μm in Figure 6 to Δ.

9. Fig 7: Change μm to Uym , or another index as appropriate).

Response:

Thanks for the reviewers' kind suggestion.We have changed all μm in Figure 7 to Uxm.

 

10. (4): Change μm to Δ (or U..m , as appropriate). Note that μ is not an appropriate notation for deflections.

Response:

Thanks for the reviewers' kind suggestion.We have changed μm in Eq.4 to Δ, and the μm  in Figure 8 is also modified to Δ.

11. (5): The sign ε with dot is unusual for strain. Please change the dot to an index.

Response:

Thanks for the reviewers' kind suggestion.We have removed the dots from Eq5 and these changes have been marked in the manuscript

12. As is multiplied by fy in eqs. (6) and (8) and by fs in eqs. (7) and (9). Please correct as appropriate

Response:

Thanks for the reviewers' kind suggestion.We have made changes to Eq.6, 7, 8 and 9 as you requested and these changes have been marked in the manuscript.

 

Author Response File: Author Response.docx

Reviewer 3 Report

1、 Extensive editing of English language and style is required.

2、 In section 4, more details of other specimens, the comparison of initial stiffness and failure mode will make your FE model more convincing.

3、 Pictures should be closely with corresponding words. It is better to divide the Figure 6 into 8 pieces by the corresponding sections.

4、 The line 361 “It can be seen from Figure 8b that with the thickness of the steel tube ...” is unclear. “With the increasing of thickness” or “With the decreasing of thickness”?

5、 It is better to make the section 6、section 7 and section 8 into one section.

6、 Is Figure 14 combined with two pictures? If it is, the sign “Concrete crushed” should be combined with both pictures, respectively.

Author Response

Response to Reviewer 3 Comments

1.Extensive editing of English language and style is required.

Response:

Thanks for the reviewers' kind suggestion.We have sent the manuscript to a professional retouching agency for retouching, of which the revised parts have been marked in the manuscript.

2. In section 4, more details of other specimens, the comparison of initial stiffness and failure mode will make your FE model more convincing.

Response:

Thanks for the reviewers' kind suggestion.We have added three sets of validation model curves. These curves have been annotated in the manuscript

3. Pictures should be closely with corresponding words. It is better to divide the Figure 6 into 8 pieces by the corresponding sections.

Response:

Thanks for the reviewers' kind suggestion.We have divided Figure 6 into eight parts. These modifications have been marked in the manuscript.

4.The line 361 “It can be seen from Figure 8b that with the thickness of the steel tube ...” is unclear. “With the increasing of thickness” or “With the decreasing of thickness”?

Response:

Thanks for the reviewers' kind suggestion.We have modified this sentence. The revised sentence has been marked in the manuscript.

5. It is better to make the section 6、section 7 and section 8 into one section.

Response:

Thanks for the reviewers' kind suggestion.We have modified sections 6, 7, and 8 to one section as you requested. These changes have been marked up in the manuscript.

6.Is Figure 14 combined with two pictures? If it is, the sign “Concrete crushed” should be combined with both pictures, respectively.

Response:

Thanks for the reviewers' kind suggestion.We have combined the sign “Concrete crushed” with both pictures. These modifications have been marked up in the manuscript

Author Response File: Author Response.docx

Reviewer 4 Report

This manuscript presents a numerical study on the mechanical properties of Ultra-high performance concrete-filled high-strength elliptical steel tube composite columns with encased high-strength H-shaped steel (HUCFEST). The influence of different parameters, namely the yield strength of steel tube, the yield strength of H-shape steel, the concrete cube compressive strength, the steel tube thickness, the eccentricity e, the slenderness ratio, section area of H-shape steel AHS and the long-short axis ratio (ψ) on the ultimate bearing capacity and the typical failure modes of HUCFEST composite columns is discussed. The topic is interesting, but the manuscript requires some supplement and improvement before publication. The following comments are listed for authors clarification and consideration:

1．The focus of the research background review should be to seek the significance of your study by comparing and analyzing the advantages and disadvantages of relevant studies, rather than a simple list of similar studies. It is suggested to reorganize the Introduction section, especially pay attention to the logic and relevance of the literature discussion, so as to highlight the novelty of the research.

2．There are too many duplicate data in Table 1. It is suggested to delete Table 1 and briefly describe the changed parameters in section 2

3．What is the basis for specimens design and parameter variation? How to simulate the parameters? The author should give a detailed explanation about this point.

4．Similarly, the basis and rationality of model constitutive selection also need to be illustrated in detail. The methods were not adequately described to be able to interpret the results.

5．3.1.2 Concrete: “The constitutive models of concrete considering restraint effect have been given by Han et al. [25], Mander et al. [26], Teng et al. [27], Tao et al. [24], pagoulatou et al. [28], ....” suggested to be changed to “The constitutive models of concrete considering restraint effect have been given in reference [25-28],...”

6．It is suggested to delete figures that do not provide useful information, such as Figure 2

7．How is the friction coefficient 0.6 determined?

8．I don't understand the contact conditions settings, and I do not know the equilibrium of the force acting on contact.

9．What is C3D8R? Refers to the mesh generation method of the model?

10．Why use reference points to set constraints instead of directly imposing constraints on columns surfaces.

11．How is the load of axial compression and eccentric compression applied to the model, and what is the value of the applied load?

12．The author indicated that 44 HUCFEST composite columns FE models were established, but the constitutive parameters such as the yield strength, steel tube thickness were changed. In fact, only one FT model was established, that is, the model shown in Figure 3.

13．Fig. 5 shows that the maximum error between the simulated value and the test value is 5.5%, but the value in Table 2 is 5.73%.

14．I don't understand that how stress is transferred and distributed at the interface each component.

15．Considering the influence of different parameters, under different eccentric loads, the failure modes of HUCFEST composite column are the outward expansion of steel, the buckling of H-shape steel, and the crushing of concrete in the middle of the column and inside the H-shaped steel. That is, the author shows that the change of parameters seems to have little effect on the performance of the structure, and under any working condition, the mechanical performance of the structure is reasonable. This is unreasonable and untrustworthy. The author should note that the structural design must be based on reasonable theoretical calculation and analysis

16．Please indicate the performance requirements as the required performance of the structure.

17．Please indicate the applicability limits of this analysis method.

18．The author a lot of literature are cited in the introduction, the author should discuss and compare the results with literature and emphasize the importance of the results.

19．The conclusion is not concise enough. Conclusions need to include and highlight the main contributions and findings of this study.

Author Response

This manuscript presents a numerical study on the mechanical properties of Ultra-high performance concrete-filled high-strength elliptical steel tube composite columns with encased high-strength H-shaped steel (HUCFEST). The influence of different parameters, namely the yield strength of steel tube, the yield strength of H-shape steel, the concrete cube compressive strength, the steel tube thickness, the eccentricity e, the slenderness ratio, section area of H-shape steel AHS and the long-short axis ratio (ψ) on the ultimate bearing capacity and the typical failure modes of HUCFEST composite columns is discussed. The topic is interesting, but the manuscript requires some supplement and improvement before publication. The following comments are listed for authors clarification and consideration:

• The focus of the research background review should be to seek the significance of your study by comparing and analyzing the advantages and disadvantages of relevant studies, rather than a simple list of similar studies. It is suggested to reorganize the Introduction section, especially pay attention to the logic and relevance of the literature discussion, so as to highlight the novelty of the research.

Response:

Thanks for the reviewers' kind suggestion.We have reworked the introductory section. These changes have been marked in the manuscript.

• There are too many duplicate data in Table 1. It is suggested to delete Table 1 and briefly describe the changed parameters in section 2.

Response:

Thanks for the reviewers' kind suggestion.We have removed Table 1 as you requested and explained the parameter changes in Section 2. These changes have been marked in the text.

• What is the basis for specimens design and parameter variation? How to simulate the parameters? The author should give a detailed explanation about this point.

Response:

There is no design specification for ultra-high-performance concrete-filled high-strength steel tube  for the time being, and we designed the specimens mainly by reviewing the references. In addition, ABAQUS is not a finite element software for simulation by programming, and we set up the parameters by in directly in ABAQUS, so we do not think it is appropriate to describe the process of parameter setting in detail in the manuscript.

4．Similarly, the basis and rationality of model constitutive selection also need to be illustrated in detail. The methods were not adequately described to be able to interpret the results.

Response:

Thanks for the reviewers' kind suggestion.We have added the basis for model selection in 3.1.2, and these additions have been marked in the manuscript.

5．3.1.2 Concrete: “The constitutive models of concrete considering restraint effect have been given by Han et al. [25], Mander et al. [26], Teng et al. [27], Tao et al. [24], pagoulatou et al. [28], ....” suggested to be changed to “The constitutive models of concrete considering restraint effect have been given in reference [25-28],...”

 

Response:

Thanks for the reviewers' kind suggestion.We have revised this sentence according to your request, and the revised sentence has been marked in the manuscript

• It is suggested to delete figures that do not provide useful information, such as Figure 2

Response:

Thanks for the reviewers' kind suggestion.We have removed Figure 2.

• How is the friction coefficient 0.6 determined?

Response:

The coefficient of friction was determined by consulting the literature[31].

• I don't understand the contact conditions settings, and I do not know the equilibrium of the force acting on contact.

Response:

In ABAQUS, the setting of the contact condition refers to the contact method between the concrete and the steel pipe after the structure is deformed. In order to make the simulation more consistent with the actual test, the normal contact between the concrete and the steel tube is set to hard contact. That is, there is complete contact between the concrete and the steel tube.

• What is C3D8R? Refers to the mesh generation method of the model?

Response:

C3D8R is a property defined after the model is meshed, usually used in mechanical analysis

• Why use reference points to set constraints instead of directly imposing constraints on columns surfaces.

Response:

Because this paper studies the mechanical behavior of composite columns under eccentric loads, it is impossible to simulate eccentric loads directly by applying displacement loads on the surface. Therefore, in this paper, by adding a reference point and coupling it with the surface, it can not only simulate the eccentric load, but also more convenient when changing the eccentric distance parameter.

• How is the load of axial compression and eccentric compression applied to the model, and what is the value of the applied load?

Response:

The loads we apply are displacement loads, not directly applying specific axial load values. In ABAQUS, the load-displacement curve of the specimen can be extracted only when the displacement load is applied. The applied displacement load is usually 0.1*height of the specimen.

• The author indicated that 44 HUCFEST composite columns FE models were established, but the constitutive parameters such as the yield strength, steel tube thickness were changed. In fact, only one FT model was established, that is, the model shown in Figure 3.

Response:

After establishing a basic model, we can realize the change of each parameter by modifying the material constitutive model, section size and eccentricity of the basic model. Because the parameters changed, all 44 models were independent.

13．Fig. 5 shows that the maximum error between the simulated value and the test value is 5.5%, but the value in Table 2 is 5.73%.

Response:

Thanks for the reviewers' kind suggestion.We have fixed this one error. This change has been marked in the manuscript

14.I don't understand that how stress is transferred and distributed at the interface each component.

Response:

Figures 12, 13, and 14 show the stress distribution in each component, and Section 10.2 illustrates the specifics of the stresses in each component.

15．Considering the influence of different parameters, under different eccentric loads, the failure modes of HUCFEST composite column are the outward expansion of steel, the buckling of H-shape steel, and the crushing of concrete in the middle of the column and inside the H-shaped steel. That is, the author shows that the change of parameters seems to have little effect on the performance of the structure, and under any working condition, the mechanical performance of the structure is reasonable. This is unreasonable and untrustworthy. The author should note that the structural design must be based on reasonable theoretical calculation and analysis

Response:

Thanks for the reviewers' kind suggestion.The failure mode we describe in the manuscript is that of the typical specimen HUCFEST-13. Different parameters have an effect on the degree of failure of the HUCFEST composite column, but we do not describe this effect in the manuscript. We have annotated the failure mode described in 10.2 in the manuscript as the failure mode of the typical specimen HUCFEST-13, and these modifications have been annotated in the manuscript.

16.Please indicate the performance requirements as the required performance of the structure.

Response:

Thanks for the reviewers' kind suggestion. We have indicated the performance requirements and these changes have been marked in the manuscript.

17．Please indicate the applicability limits of this analysis method.

Response:

Thanks for the reviewers' kind suggestion.We have indicated the applicability limits of this analysis method and these additions have been annotated in the manuscript.

• The author a lot of literature are cited in the introduction, the author should discuss and compare the results with literature and emphasize the importance of the results.

Response:

Thanks for the reviewers' kind suggestion.We have supplemented the conclusion with a comparison of the finite element results with the literature results. These supplements have been annotated in the manuscript.

• The conclusion is not concise enough. Conclusions need to include and highlight the main contributions and findings of this study.

Response:

Thanks for the reviewers' kind suggestion.We have made revisions to the conclusions and these revisions have been annotated in the manuscript.

Dear Reviewer4

We sent the revised manuscript to a professional retouching agency for a full retouching of the manuscript, of which the revised parts have been marked in the text.

 

Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

Accept in present form