Experimental Study on the Behavior of Steel–Concrete Composite Decks with Different Shear Span-to-Depth Ratios

Round 1

Reviewer 1 Report

Four composite beams were tested to investigate the effect of shear-span to depth ratio. However, the paper is more like a technical not than a research paper. Theoretical analysis should be carried out to investigate the test results. 

Author Response

Authors' response to comments from reviewers

The authors would like to thank the reviewer for your constructive comments. Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewers’ comments are provided through point-by-point as follows:

 

(1) Four composite beams were tested to investigate the effect of shear-span to depth ratio. However, the paper is more like a technical not than a research paper. Theoretical analysis should be carried out to investigate the test results.

 

Response: Thanks for your overall comments. The authors agree with the reviewer that this paper seems to be like a technical work. However, we have substantially revised the paper to improve the paper content by considering all comments of the reviewers. The research novelty of this paper is expressed as follows: In this study the results of an experimental program of four steel‒concrete composite slabs were reported. The main factor of the experiment is the effect of different shear span-to-depth ratios (a/h) on the behaviors of composite slabs. The results with respect to the capacity, displacement, crack mechanism, and failure mode were studied. In addition, the conventional bending analysis to calculate the bending moment was provided to compare with the experimental data base. This study also aims to draw initial steps to select the considerable shear span-to-depth ratio for the design of the composite slabs. Further investigation on the structural responses of composite slabs under different a/h ratios is needed.

 

Please see Table 1 for the results of moment capacity produced by tests and theoretical calculations. The text regarding Table can be found in Lines…, as presented below:

“Conversely, Table 2 presents the results of the nominal moments of composite decks derived by section analysis. The section analysis was carried out using conventional bending theory, which is commonly used to analyze the flexural behavior of conventional steel reinforced concrete members. The following assumptions were considered in the calculation. The linear strain distribution through the deck depth was examined. The perfect bond between steel and concrete was assumed. No tensile strength in concrete was included in the calculation. The equivalent concrete stress block for estimating the concrete internal force in compression was considered. Only the case with a neutral axis located beyond the steel profile sheeting was assumed. The formulation of the moment capacity after taking a force equilibrium in the section can be generally express as below:

Mn=F_a(d-a/2) + F_d(d'-a/2)                                                                                   (1)

where Mn is the moment capacity (kNm); Fa and Fd denote the internal forces in steel sheet and reinforcement (kN), respectively; a is the height of equivalent block of concrete compressive stress distributed in the section (mm); d and d’ are the distance from top fiber to centroid of steel sheet and reinforcement (mm), respectively.

Apparently, the predicted results made by section analysis generally overestimated the experimental results. This is possibly because the effect of shear span-to-depth was not considered in the analysis and the perfect bond between the steel and concrete were assumed. This implies that further study on the model for prediction of the flexural capacity of the steel‒concrete composite decks is needed.”

Reviewer 2 Report

The presented research may be interesting from an engineering and practical point of view. Unfortunately, they concern a very small number of research elements, so they can only be treated as a contribution to the discussion of the issues raised. The analysis of the bahavior of tested models is presented in a rather laconic way. The descriptions are quite modest, as if the authors lack adequate knowledge and experience in conducting experimental research. In their conclusions, the authors refer to computational analyzes, which are not included in the article. One gets the impression that the article is part of a larger whole. In the case of articles with scientific aspirations, additionally published in such a prestigious journal, this approach is unacceptable.

In my opinion, this article should be rejected.

Only some of the detailed comments are given below.

1. Page 3. Line #108. What kind of steel were the steel plates made of? At least the type of steel and the yield strength value should be given. This information may be useful in the analysis of the state of failure of research models.
2. Page 3. Lines #117-118. When examining only three cylindrical samples, the smallest value should also be given in addition to the mean value. It is advisable when it is not possible to perform a statistical evaluation of the results. In addition, more information concerning the concrete should be provided, e.g. type of cement and water/cement ratio. It would be good to indicate the standard according to which the test was conducted. Were all the test models made of the same concrete mix?
3. Page 3. Line #128. In Fig. 3, the roller supports is not showed. This figure should be corrected. In addition, it should be presented which support allowed for horizontal travel, and which was only articulated.
4. Pages 6-7. Lines #176-178. The reviewer cannot agree with this statement. The arch action depends on the thickness of the element and the distance between supports, not the distribution of aggregate. The authors should conduct a proper discussion of the obtained results. The presented explanations are unacceptable.
5. Page 9. Figs. 7 and 8. Why authors did not present the cracking modes of all four tested models? Taking into account the differences in the behavior of models with the same shape and overall dimensions (S1 and S2 and S3 and S4, respectively), showing the crack modes of all models is necessary. Only on this basis, a deeper analysis of the reasons for the difference in the behavior and obtained tests results of these elements should be carried out.
6. Page 10. Lines #267-281. The presented conclusions are unacceptable. Due to the small number of research models, no generalizations are valid. Moreover, the first conclusion is correct though obvious. The second conclusion is completely unauthorized because the authors did not include any computational analyzes in the article. Therefore, there is no basis for its formulation. The third conclusion is indeed based on the results of the research carried out. Whereas, the last conclusion is obvious and it can be formulated without conducting such research.

Author Response

The authors would like to thank the reviewer for your constructive comments. Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewers’ comments are provided through point-by-point as follows:

(1)  Page 3. Line #108. What kind of steel were the steel plates made of? At least the type of steel and the yield strength value should be given. This information may be useful in the analysis of the state of failure of research models.

 

Response: The details have been added in the revised version of manuscript. We also show below for your quick reading:

“A composite deck consists of cold-formed steel sheet, shear connectors, and concrete. The steel sheet with an embossed trapezoidal profile had a thickness of 1.2 mm. Its yield strength and tensile strength were 312 MPa and 436 MPa, respectively. The dead weight of the steel sheet was about 12 kg/m²…”

 

 

(2) Page 3. Lines #117-118. When examining only three cylindrical samples, the smallest value should also be given in addition to the mean value. It is advisable when it is not possible to perform a statistical evaluation of the results. In addition, more information concerning the concrete should be provided, e.g. type of cement and water/cement ratio. It would be good to indicate the standard according to which the test was conducted. Were all the test models made of the same concrete mix?

 

Response: Section 2.1 has been substantially revised.

 

(3) Page 3. Line #128. In Fig. 3, the roller supports is not showed. This figure should be corrected. In addition, it should be presented which support allowed for horizontal travel, and which was only articulated.

 

Response: Thanks for the comments. Fig. 3 has been revised.

 

(4) Pages 6-7. Lines #176-178. The reviewer cannot agree with this statement. The arch action depends on the thickness of the element and the distance between supports, not the distribution of aggregate. The authors should conduct a proper discussion of the obtained results. The presented explanations are unacceptable.

 

 

Response: The authors thank the reviewer for raising this point. We have revised the text for clearer. In this context, we are discussing on the difference on the load and cracking behaviors between composite slabs S1 and S2, which have the same properties and configurations. It is clear that the slabs S1 and S2 had the same a/h ratio (2.5) and thickness. This may induce the arch action in both slabs. The concrete arch would be partially carried the shear force transfer. However, during the casting process, the distribution of aggregate in concrete might be different among S1 and S2. If the coarse aggregate mainly distributed at the concrete arch area, the shear resistance and stiffness of the arch would be high. However, if the coarse aggregate distributed far away the concrete arch zone, the shear resistance of concrete arch would be low. This phenomenon has been reported by Higuchi et al. [33].

Please see the in the revised manuscript. We also draw our revision below:

“This could be due to that the arch action might be dominant in the specimens S1 and S2 with shear span-to-depth ratio by 2.5, ensuring that the force transfer could be partially carried by concrete arch. The performance of the concrete arch may depend on the aggregate distribution and aggregate interlocking mechanism, which could be different between the specimens S1 and S2. The similar phenomenon has reported in the study by Higuchi et al. [33]….”

 

(5) Page 9. Figs. 7 and 8. Why authors did not present the cracking modes of all four tested models? Taking into account the differences in the behavior of models with the same shape and overall dimensions (S1 and S2 and S3 and S4, respectively), showing the crack modes of all models is necessary. Only on this basis, a deeper analysis of the reasons for the difference in the behavior and obtained tests results of these elements should be carried out.

 

Response: Thank you for your comments. In Figs. 7 and 8, we show the development of cracks under load increases of two specimens with different shear span-to-depth ratios. The failure modes of all specimens have been shown in Table 2 and have been clearly discussed where applicable.

 

(6) Page 10. Lines #267-281. The presented conclusions are unacceptable. Due to the small number of research models, no generalizations are valid. Moreover, the first conclusion is correct though obvious. The second conclusion is completely unauthorized because the authors did not include any computational analyzes in the article. Therefore, there is no basis for its formulation. The third conclusion is indeed based on the results of the research carried out. Whereas, the last conclusion is obvious and it can be formulated without conducting such research.

 

Response: Thanks for the comments. In the conclusions, we summarized the experimental results in the scope of this study. We have included the calculation of moment capacity of composite slabs, thereby we have second conclusion. We have revised the conclusions for providing the findings achieved in this study and indicating the necessity of future works. Please read all conclusions in the revised manuscript.

 

 

 

Reviewer# 3

This manuscript present results of an experimental study on the mechanical behaviors of steel‒concrete composite decks with different shear span-to-depth ratios. It is interesting paper and fits in the field of an international journal of Buildings.

 

(1) The first paragraph of the introduction lacks literature references.

 

Response: Literature references have been added.

“First, the cold-formed profiled sheet can be used as formwork during the casting of concrete [3]. Second, at the working stage, the profiled sheet acts as the main steel tension reinforcement that can withstand high tensile forces [4].”

 

(2) The novelty and originality of the research should be emphasized in the article. How important are the results of this study and stand out from other works?

 

Response: Thanks for the comments. The novelty and originality of this study are to furnish the understanding on the mechanical behaviors of steel‒concrete composite slabs considering different shear span-to-depth ratios, which have had little information in past studies. The study aims to complement the documented experimental data base in the composite structures. The new findings attained in this study are revealed in the conclusions. We have revised the conclusion section to emphasize the novelty and originality of the paper.

 

(3) The text is clear and easy to read.

 

Response: Thank you very much.

 

(4) In Chapter 2 should be rearranged sub-sections material: concrete composition, steel sheets, and then other sub-section specimens.

 

Response: Revised as suggested. Please see section 2.1.

 

(5) Tables and figures must be marked immediately after the text is first marked. Therefore, for example, Table 1 can be divided into two parts geometric data and research results.

 

Response: Revised as suggested. Dimensions of composite decks are shown in Table 1.

 

(6) Figure 6 missed in the text and not present.

 

Response: Revised as suggested. Please see section 3.2.

 

(7) The manuscript does not provide a methodology for processing the results.

 

Response: We thank for your observation. In this study, we mainly report the test data measured via the devices. Therefore, the process of results is made using a data logger. The monitored results will be discussed and analyzed. Based on the comments of all reviewers, we have significantly revised the paper to properly present the results of this study.

 

(8) Are the results of the experimental tests performed reliable?

 

Response: Thank you very much for your question. We have investigated two values of a/h ratios. At each ratio, we have made two similar beams to have a reliable data of the tests. We have also made the discussion on all test results.

 

(9) The experimental results of the research could be compared with the results of computer simulation. A more detailed analysis of the results would be welcome.

 

Response: We thank for your comments. In this work, we have made the calculation of moment capacity of the composite slabs using conventional section analysis. We have presented the assumptions for calculation. The analysis and comparison between calculation and experiment are also made. Please see in the revised manuscript, as summarized below:

“Conversely, Table 2 presents the results of the nominal moments of composite decks derived by section analysis. The section analysis was carried out using conven-tional bending theory, which is commonly used to analyze the flexural behavior of conventional steel reinforced concrete members. The following assumptions were con-sidered in the calculation. The linear strain distribution through the deck depth was examined. The perfect bond between steel and concrete was assumed. No tensile strength in concrete was included in the calculation. The equivalent concrete stress block for estimating the concrete internal force in compression was considered. Only the case with a neutral axis located beyond the steel profile sheeting was assumed. The formulation of the moment capacity after taking a force equilibrium in the section can be generally express as below:
Mn=F_a(d-a/2) + F_d(d'-a/2)                                    (1)

where Mn is the moment capacity (kNm); Fa and Fd denote the internal forces in steel sheet and reinforcement (kN), respectively; a is the height of equivalent block of concrete compressive stress distributed in the section (mm); d and d’ are the distance from top fiber to centroid of steel sheet and reinforcement (mm), respectively.

Apparently, the predicted results made by section analysis generally overestimated the experimental results. This is possibly because the effect of shear span-to-depth was not considered in the analysis and the perfect bond between the steel and concrete were assumed. This implies that further study on the model for prediction of the flexural capacity of the steel‒concrete composite decks is needed.”

For computer simulation, the future study of our group will be concerned.

 

Conclusions:

This is an interesting manuscript. Such a paper could certainly interest readers of MDPI Buildings journal. Therefore, this paper is recommended for publication in MDPI Buildings journal with the suggested corrections in the review.

 Response: Thank you for your positive comments.

Reviewer 3 Report

Comments to the Author

Review of the manuscript „ Experimental Study on Behaviour of Steel–Concrete Composite Decks with Different Shear Span-to-depth Ratios“

This manuscript present results of an experimental study on the mechanical behaviors of steel‒concrete composite decks with different shear span-to-depth ratios. It is interesting paper and fits in the field of an international journal of Buildings.

Remarks:

The first paragraph of the introduction lacks literature references.

The novelty and originality of the research should be emphasized in the article.

How important are the results of this study and stand out from other works?

The text is clear and easy to read.

In Chapter 2 should be rearranged sub-sections material: concrete composition, steel sheets, and then other sub-section specimens.

Tables and figures must be marked immediately after the text is first marked.

Therefore, for example, Table 1 can be divided into two parts geometric data and research results.

Figure 6 missed in the text and not present.

The manuscript does not provide a methodology for processing the results.

Are the results of the experimental tests performed reliable?

The experimental results of the research could be compared with the results of computer simulation. A more detailed analysis of the results would be welcome.

Conclusions:

This is an interesting manuscript. Such a paper could certainly interest readers of MDPI Buildings journal. Therefore, this paper is recommend for publication in MDPI Buildings journal with the suggested corrections in the review.

Author Response

This manuscript present results of an experimental study on the mechanical behaviors of steel‒concrete composite decks with different shear span-to-depth ratios. It is interesting paper and fits in the field of an international journal of Buildings.

 

(1) The first paragraph of the introduction lacks literature references.

 

Response: Literature references have been added.

“First, the cold-formed profiled sheet can be used as formwork during the casting of concrete [3]. Second, at the working stage, the profiled sheet acts as the main steel tension reinforcement that can withstand high tensile forces [4].”

 

(2) The novelty and originality of the research should be emphasized in the article. How important are the results of this study and stand out from other works?

 

Response: Thanks for the comments. The novelty and originality of this study are to furnish the understanding on the mechanical behaviors of steel‒concrete composite slabs considering different shear span-to-depth ratios, which have had little information in past studies. The study aims to complement the documented experimental data base in the composite structures. The new findings attained in this study are revealed in the conclusions. We have revised the conclusion section to emphasize the novelty and originality of the paper.

 

(3) The text is clear and easy to read.

 

Response: Thank you very much.

 

(4) In Chapter 2 should be rearranged sub-sections material: concrete composition, steel sheets, and then other sub-section specimens.

 

Response: Revised as suggested. Please see section 2.1.

 

(5) Tables and figures must be marked immediately after the text is first marked. Therefore, for example, Table 1 can be divided into two parts geometric data and research results.

 

Response: Revised as suggested. Dimensions of composite decks are shown in Table 1.

 

(6) Figure 6 missed in the text and not present.

 

Response: Revised as suggested. Please see section 3.2.

 

(7) The manuscript does not provide a methodology for processing the results.

 

Response: We thank for your observation. In this study, we mainly report the test data measured via the devices. Therefore, the process of results is made using a data logger. The monitored results will be discussed and analyzed. Based on the comments of all reviewers, we have significantly revised the paper to properly present the results of this study.

 

(8) Are the results of the experimental tests performed reliable?

 

Response: Thank you very much for your question. We have investigated two values of a/h ratios. At each ratio, we have made two similar beams to have a reliable data of the tests. We have also made the discussion on all test results.

 

(9) The experimental results of the research could be compared with the results of computer simulation. A more detailed analysis of the results would be welcome.

 

Response: We thank for your comments. In this work, we have made the calculation of moment capacity of the composite slabs using conventional section analysis. We have presented the assumptions for calculation. The analysis and comparison between calculation and experiment are also made. Please see in the revised manuscript, as summarized below:

“Conversely, Table 2 presents the results of the nominal moments of composite decks derived by section analysis. The section analysis was carried out using conven-tional bending theory, which is commonly used to analyze the flexural behavior of conventional steel reinforced concrete members. The following assumptions were con-sidered in the calculation. The linear strain distribution through the deck depth was examined. The perfect bond between steel and concrete was assumed. No tensile strength in concrete was included in the calculation. The equivalent concrete stress block for estimating the concrete internal force in compression was considered. Only the case with a neutral axis located beyond the steel profile sheeting was assumed. The formulation of the moment capacity after taking a force equilibrium in the section can be generally express as below:

Mn=F_a(d-a/2) + F_d(d'-a/2)                                    (1)

 

 

where Mn is the moment capacity (kNm); Fa and Fd denote the internal forces in steel sheet and reinforcement (kN), respectively; a is the height of equivalent block of concrete compressive stress distributed in the section (mm); d and d’ are the distance from top fiber to centroid of steel sheet and reinforcement (mm), respectively.

Apparently, the predicted results made by section analysis generally overestimated the experimental results. This is possibly because the effect of shear span-to-depth was not considered in the analysis and the perfect bond between the steel and concrete were assumed. This implies that further study on the model for prediction of the flexural capacity of the steel‒concrete composite decks is needed.”

For computer simulation, the future study of our group will be concerned.

 Conclusions:

This is an interesting manuscript. Such a paper could certainly interest readers of MDPI Buildings journal. Therefore, this paper is recommended for publication in MDPI Buildings journal with the suggested corrections in the review.

 Response: Thank you for your positive comments.

Reviewer 4 Report

The manuscript entitled "Experimental Study on Behaviour of Steel-Concrete Composite Decks with Different Shear Span-to-depth Ratios” presented the results of an experimental study on the mechanical behaviors of steel-concrete composite decks with different shear span-to-depth ratios. Four composite decks were designed for the experimental program. The decks are then undergone the four-point bending tests until failure.

This reviewer recommends major editing and resubmitted for re-review because of the following comments.

Technical comments:

• Moderate English changes required
• Line 14: The expression "provide are" should be corrected.
• Lines 23-24: The grammar of this sentence should be corrected. I think the authors should add "is" before "made" or the structure of the sentence should be corrected.
• Lines 31-32: I think this statement is not accurate because the composite metal deck should have a thinner thickness in comparison to the conventional RC slab.
• Lines 50-52: What are the modes of failure reported by these studies?
• Lines 71-72: What do you mean by "two way composite slabs"? Clarifications should be provided about this system to create a two-way slab.
• The authors should highlight how their study is providing a different approach or adding significantly to what has been done.
• Line 105: How did the authors determine that these samples are full-scale or not?
• Lines 106-107: Steel rebars should be added as a component of the composite deck.
• Section 2.1: Detailed dimensions of the steel sheet should be provided in Figure 1. Also, details about the used stud bolts and H-beam should be highlighted in the text and their function. Moreover, the used steel reinforcement should be discussed.
• Line 113: "and" should be added between S3 and S4.
• Section 2.1: The mechanical properties for the steel sheet, stud bolts, steel bars, and H-beams should be provided like the yield stress and ultimate strength.
• Line 167: What was the type of this first crack? Was it shear cracks in the ribs, flexural crack, or what? More information should be provided about the initiation of the first crack.
• Line 177: Can the authors explain the meaning of "arch action" by providing a sketch to explain this behavior?
• Figure 5: How did the authors recognize yielding in the steel sheet? However, no strain gages were used during the tests.
• The "section analysis" section should be improved in the revised manuscript. Sketches and illustrations on how to calculate the nominal moments should be provided with references. I think it should be in a separate section after providing the experimental results. Also, comparisons between the experimental results and the theoretical analysis should be included in a chart or Table 1 by showing how much the difference.
• No need to repeat these statements after calling the tested specimens "shorter shear span-to-depth ratio" or "longer shear span-to-depth ratio".
• Line 224: This reviewer cannot see any propagation of the mid-span cracks. I think you mean new crack formation at the loading points.
• Line 228-229: How did the authors measure the crack width? The crack width for each specimen should be provided.
• Line 235-237: The separation mode of failure between the steel sheet and concrete occurred because these specimens are lack continuity. The width of these specimens was only 1000 mm which is very small and cannot represent the continuity in a real composite deck. This behavior is against what the authors mentioned about using full-scale specimens in Line 105.
• Line 238: Measuring slippage in this kind of test is required and it is a shortage in the current manuscript.

Author Response

The authors would like to thank the reviewer for your constructive comments. Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewers’ comments are provided through point-by-point as follows:

The manuscript entitled "Experimental Study on Behaviour of Steel-Concrete Composite Decks with Different Shear Span-to-depth Ratios” presented the results of an experimental study on the mechanical behaviors of steel-concrete composite decks with different shear span-to-depth ratios. Four composite decks were designed for the experimental program. The decks are then undergone the four-point bending tests until failure. The reviewer recommends major editing and resubmits for re-review because of the following comments.

 

(1) Line 14: The expression "provide are" should be corrected.

 

Response: In the revised version of manuscript, the revised sentence was mentioned below.

“The analysis results demonstrated that the stiffness and capacity of the composite deck increased with the decrease in the shear span length. However, the displacement ductility of the composite slabs increased with the shear span length.”

 

(2) Lines 23-24: The grammar of this sentence should be corrected. I think the authors should add "is" before "made" or the structure of the sentence should be corrected.

 

Response: In the revised version of manuscript. The revised sentence was mentioned below.

“A novel composite metal decking system with innovative technology is made from cold-formed steel [1].”

 

(3) Lines 31-32: I think this statement is not accurate because the composite metal deck should have a thinner thickness in comparison to the conventional RC slab.

 

Response: We thank for your comments. We have removed the sentence making the discussion on the benefits of composite slabs to be shortened. Please see in the revised manuscript, as presented below:

“There are two key reasons for the use of the cold-formed profiled sheet for producing composite slab systems. First, the cold-formed profiled sheet can be used as formwork during the casting of concrete [3]. Second, at the working stage, the profiled sheet acts as the main steel tension reinforcement that can withstand high tensile forces [4].”

 

(4) Lines 50-52: What are the modes of failure reported by these studies?

 

Response: The authors would like to apologize for this issue. We carefully checked in their papers; however, the details of modes of failure from those studies were unclear. So, we decided to not mention this in the paper.

 

(5) Lines 71-72: What do you mean by "two-way composite slabs"? Clarifications should be provided about this system to create a two-way slab. The authors should highlight how their study is providing a different approach or adding significantly to what has been done.

 

Response: We thank for your useful comments. The two-way composite slabs mean that the slabs can carry the loads along with both directions. The length ratio between two edges of the slabs is usually used to determine the slab characteristic. Slabs with the length ratio by longer edge to shorter edge less than 2 can be considered two-way slabs. We have revised the text for clearer. Also, we have highlighted that this study consider one-way composite slabs, which have length ratio greater than 2. Please see in the revised manuscript.

 

(6) Line 105: How did the authors determine that these samples are full-scale or not?

 

Response: Thank you so much for your question. We have revised the text to clarify the meaning of sentence. The term “full-scale” has been removed. Please see in the revised manuscript, as shown below:

“The aim of this research is to assess the flexural strength and behavior of one-way steel‒concrete composite decks, which have the length ratios of longer edge to shorter edge greater than two…”

 

(7) Lines 106-107: Steel rebars should be added as a component of the composite deck.

 

Response: In the revised manuscript, the revised sentence was mentioned below.

“The transverse steels used in the investigation were made of conventional round bars of 9 mm in diameter with a spacing of 200 mm.”

 

(8) Section 2.1: Detailed dimensions of the steel sheet should be provided in Figure 1. Also, details about the used stud bolts and H-beam should be highlighted in the text and their function. Moreover, the used steel reinforcement should be discussed.

 

Response: Revised as suggested. The sentences have been added to elaborate the information you suggested.

“The details of specimens are presented in Figure. 1. A composite deck consists of cold-formed steel sheet, shear connectors, and concrete. The steel sheet with an embossed trapezoidal profile had a thickness of 1.2 mm. Its yield strength and tensile strength were 312 MPa and 436 MPa, respectively. The dead weight of the steel sheet was about 12 kg/m². Stud bolts were used as shear connectors to overcome the longitudinal shear stress (i.e, prevent the slippage between steel sheet and concrete). To avoid the cracks in negative bending zone, the transverse steels used in the investigation were made of conventional round bars of 9 mm in diameter with a horizontal spacing of 200 mm. The composite decks were tested on simple supports made from steel H-beam to reasonably reflect the actual composite systems of deck‒beam joints. The H-shaped beam dimensions are shown in Figure 1.”

 

(9) Line 113: "and" should be added between S3 and S4.

 

Response: Revised as suggested. Please see section 2.1.

 “Figure. 1(b) illustrates the specimen details for the decks S3 S4.” The sentence has been deleted.

 

(10) Section 2.1: The mechanical properties for the steel sheet, stud bolts, steel bars, and H-beams should be provided like the yield stress and ultimate strength.

 

Response: The mechanical properties of the materials have been added. Please see section 2.1

 

(11) Line 167: What was the type of this first crack? Was it shear cracks in the ribs, flexural crack, or what? More information should be provided about the initiation of the first crack.

 

Response: We thank for your useful comments. We have added the text for making the argument clearer. Please see Lines…:

“…In other words, the deflection no longer remains proportional to the applied load after initiation of the first crack, which was taken place in the flexure…”

 

(12) Line 177: Can the authors explain the meaning of "arch action" by providing a sketch to explain this behavior?

 

Response: Thank you so much for your suggestion. We have added a sketch to explain the arch action in both sections 3.1 and 3.2. Please see those sections and Fig. 6(b).

 

(13) Figure 5: How did the authors recognize yielding in the steel sheet? However, no strain gages were used during the tests.

 

Response: Thank you for the comments. We have added the explanation in Lines… Please also see below:

“As shown in Figure. 5, the ductility index is defined by the ratio between the displacement at peak load (u_u) to the displacement at yielding (u_y). It is important to note that the yielding point is given by a point on the curve corresponding to a change in stiffness of the composite, where the slope of the curve is distinct, since it is not possibly to directly determine the strain of the composite [33, 34]…”

(14) The "section analysis" section should be improved in the revised manuscript. Sketches and illustrations on how to calculate the nominal moments should be provided with references. I think it should be in a separate section after providing the experimental results. Also, comparisons between the experimental results and the theoretical analysis should be included in a chart or Table 1 by showing how much the difference.

 

Response: We thank for your suggestion. The section analysis using bending theory is very basic and available in the textbooks. By taking your suggestion, we have improved the part of “section analysis” by providing the force equilibrium equation and discussion. We have also added the difference between results made by section analysis and produced by tests in Table 1. Please see in the revised manuscript.

“Conversely, Table 1 presents the results of the nominal moments of composite decks derived by section analysis. The section analysis was carried out using conventional bending theory, which is commonly used to analyze the flexural behavior of conventional steel reinforced concrete members. The following assumptions were considered in the calculation. The linear strain distribution through the deck depth was examined. The perfect bond between steel and concrete was assumed. No tensile strength in concrete was included in the calculation. The equivalent concrete stress block for estimating the concrete internal force in compression was considered. Only the case with a neutral axis located beyond the steel profile sheeting was assumed. The formulation of the moment capacity after taking a force equilibrium in the section can be generally express as below:

Mn=F_a(d-a/2) + F_d(d'-a/2)                                    (1)

where M_n is the moment capacity (kNm); F_a and F_d denote the internal forces in steel sheet and reinforcement (kN), respectively; a is the height of equivalent block of concrete compressive stress distributed in the section (mm).

Apparently, the predicted results made by section analysis generally overestimated the experimental results. This is possibly because the effect of shear span-to-depth was not considered in the analysis and the perfect bond between the steel and concrete were assumed. This implies that further study on the model for prediction of the flexural capacity of the steel‒concrete composite decks is needed.”

 

(15) No need to repeat these statements after calling the tested specimens "shorter shear span-to-depth ratio" or "longer shear span-to-depth ratio".

 

Response:

15.1) “The analysis results demonstrated that the stiffness and capacity of the composite decks with shorter shear span length are higher than those with larger shear span.”

The sentence mentioned above has been revised to “The analysis results demonstrated that the stiffness and capacity of the composite deck increased with decrease in the shear span length.”

15.2) “The composite decks with longer shear span lengths are more ductile than those with shorter shear span lengths.”

The sentence mentioned above has been revised to “However, increasing the shear span length produced a more ductile member.”

15.3) “The maximum moments and deflections at peak loads of the specimens S1 and S2 with the shorter shear span-to-depth ratio increased by 21% and 40%, respectively, compared to those produced by the specimens S3 and S4 with the longer shear span-to-depth ratio.”

The sentence mentioned above has been revised to “The maximum moments and deflections at peak loads of the series I specimens increased by 21% and 40%, respectively, compared to those produced by the series II specimens.”

15.4) “The ductility indices of the specimens S1 (u_u/u_y = 3.0) and S2 (u_u/u_y = 3.16) with shorter shear span-to-depth ratio are lower than those of the specimens S3 (u_u/u_y = 5.28) and S4 (u_u/u_y = 3.57) with longer shear span-to-depth ratio.”

The sentence mentioned above has been revised to “The ductility indices of the specimens S1 (u_u/u_y = 3.0) and S2 (u_u/u_y = 3.16) are lower than those of the specimens S3 (u_u/u_y = 5.28) and S4 (u_u/u_y = 3.57).”

15.5) “The deck S1 with shorter shear span-to-depth ratio started cracking at load by 100 kN, while the deck S3 with longer shear span-to-depth begun fracturing at load by 130 kN.”

The sentence mentioned above has been revised to “The deck S1 started cracking at load by 100 kN, while the deck S3 begun fracturing at load by 130 kN.”

15.6) “The failure crack width in the specimen S3 with longer shear span-to-depth ratio was larger than those in the deck S1 with shorter shear span-to-depth ratio.”

The sentence mentioned above has been revised to “The failure crack width in the specimen S3 was larger than that in the deck S1.”

15.7) “However, the composite decks with larger shear span length could provide greater displacement ductility compared to the decks with shorter shear span.”

The sentence mentioned above has been revised to “However, the composite decks with larger shear span length could provide greater displacement ductility.”

15.8) “The flexural cracks of the deck with a longer shear span were larger than those of the deck with a shorter shear span.”

            The sentence mentioned above has been revised to “It should be noted that the longer shear span length, the larger the flexural cracks observed in the composite deck.”

(16) Line 224: This reviewer cannot see any propagation of the mid-span cracks. I think you mean new crack formation at the loading points.

Response: Thanks for the comments. We have revised in the revised version of the manuscript. Please also see below for your quick consideration:

“…Generally, the specimens started cracking at the central; then, the cracks tended to open. Following, the new crack formation under the loading points was observed…”

(17) Line 228-229: How did the authors measure the crack width? The crack width for each specimen should be provided.

Response: Thank you for your comments. We did not measure the crack width. The discussion regarding the crack width has been made based on the observation from the tests. We have slightly revised the text for clearer. Please see in the revised manuscript or below:

“…As observed from the tests, the failure crack width in the specimen S3 was larger than that in the deck S1…”

 

(18) Line 235-237: The separation mode of failure between the steel sheet and concrete occurred because these specimens are lack continuity. The width of these specimens was only 1000 mm which is very small and cannot represent the continuity in a real composite deck. This behavior is against what the authors mentioned about using full-scale specimens in Line 105.

 

Response: Thank you for raising the insightful point. We agree that the lack of continuity induced the separation of steel sheet to concrete. We have made revision considering your suggestion. In addition, we have removed term “full-scale” throughout the manuscript for identification of the test specimens. Please see in the revised manuscript. Also please see below:

“…The primary failure mode observed in the experiments was the debonding of the sheeting profile steel and the detachment of the steel sheet from concrete followed by concrete fracture. The separation mode of failure between the steel sheet and concrete occurred because these test specimens are lack continuity. This failure mode reveals that the slippage of steel sheet to concrete would govern the structural efficiency of the steel‒concrete composite decks…”

(19) Line 238: Measuring slippage in this kind of test is required and it is a shortage in the current manuscript.

Response: Thank you very much for indicating the weakness of the current manuscript regarding the measurement of slippage. We have raised this point in the conclusions for future study. Please see the conclusions no. 4 in section 4, as presented below:

“At failure completion, the detachment of profile sheeting steel to concrete was observed. The measurement of the bond‒slip profile between the steel sheet and concrete is needed. On-going study on innovative anchorage and friction systems to prevent the slippage between steel and concrete in the composite slabs is planned by the authors.”

 

Reviewer 5 Report

This paper presents an experimental study on the behavior of steel–concrete composite decks with different shear span-to-depth ratios (2.5 and 4.6). The topic is interesting, and the results are solid. The following issues need to be addressed.

• 5. How the yielding point on the load-deflection curves was identified? No strain measuring devices were introduced. Please explain.
• How about the interfacial slip between steel deck and concrete?
• Authors are encouraged to compare the value of stiffness obtained in tests with the predictions using models in design codes.
• The flexural strengths predicted by section analysis overestimate the 15 actual test results. Authors are encouraged to provide the material properties, material constitutive laws, assumptions, and theoretical framework for the section analysis.
• In the introduction part, the presentation and understanding in terms of the effect of shear span-to-depth ratios on the structural behavior of concrete members need to be enhanced. Authors are encouraged to read more papers on this topic (e.g., Engineering Structures 168, 770-783) and enrich this part.

Author Response

The authors would like to thank the reviewer for your constructive comments. Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewers’ comments are provided through point-by-point as follows:

This paper presents an experimental study on the behavior of steel–concrete composite decks with different shear span-to-depth ratios (2.5 and 4.6). The topic is interesting, and the results are solid. The following issues need to be addressed.

(1) How the yielding point on the load-deflection curves was identified? No strain measuring devices were introduced. Please explain.

Response: The sentence mentioned below has been added.

“It is important to note that the yielding point is given by a point on the curve corresponding to a change in stiffness of the composite [33, 34], where the slope of the curve is distinct, since it is not possibly to directly determine the strain of the composite.”

(2) How about the interfacial slip between steel deck and concrete?

Response: Thank you very much for a good question. As we discussed, the failure mode by the separation of steel sheet to concrete was observed from the tests. However, we did not measure the slip between steel deck and concrete in the study. We suggested that the interfacial slip should be considered in future study. On-going research of our group is planned to provide the new anchorage system to restrict the slippage or separation of the steel sheet to concrete.

(3) Authors are encouraged to compare the value of stiffness obtained in tests with the predictions using models in design codes.

Response: We thank for your interesting suggestion. We totally agree with you that the comparison in stiffness between experiments and models in codes has significance. However, we think that the comparison should be more noticeable when we have extended the data. Therefore, as we suggested in the conclusions, the future study on the composite slabs should be carried out by experimental, numerical, and analytical programs.

(4) The flexural strengths predicted by section analysis overestimate the 15 actual test results. Authors are encouraged to provide the material properties, material constitutive laws, assumptions, and theoretical framework for the section analysis.

Response: Thank you so much for your comments. We have added more information about the section analysis. Please see Lines…in the revised manuscript. The section analysis is a basic technique to compute the section capacity using force equilibrium equations with specified assumptions. We show whole part regarding section analysis below:

“Conversely, Table 1 presents the results of the nominal moments of composite decks derived by section analysis. The section analysis was carried out using conventional bending theory, which is commonly used to analyze the flexural behavior of conventional steel reinforced concrete members. The following assumptions were considered in the calculation. The linear strain distribution through the deck depth was examined. The perfect bond between steel and concrete was assumed. No tensile strength in concrete was included in the calculation. The equivalent concrete stress block for estimating the concrete internal force in compression was considered Only the case with a neutral axis located beyond the steel profile sheeting was assumed. The formulation of the moment capacity after taking a force equilibrium in the section can be generally express as below:

Mn=F_a(d-a/2) + F_d(d'-a/2)                                    (1)

where Mn is the moment capacity (kNm); Fa and Fd denote the internal forces in steel sheet and reinforcement (kN), respectively; a is the height of equivalent block of concrete compressive stress distributed in the section (mm); d and d’ are the distance from top fiber to centroid of steel sheet and reinforcement (mm), respectively.

Apparently, the predicted results made by section analysis generally overestimated the experimental results. This is possibly because the effect of shear span-to-depth was not considered in the analysis and the perfect bond between the steel and concrete were assumed. This implies that further study on the model for prediction of the flexural capacity of the steel‒concrete composite decks is needed.”

(5) In the introduction part, the presentation and understanding in terms of the effect of shear span-to-depth ratios on the structural behavior of concrete members need to be enhanced. Authors are encouraged to read more papers on this topic (e.g., Engineering Structures 168, 770-783) and enrich this part.

Response: Thank you for your suggestion. The literature suggested has been added. The sentences mentioned below have been added in the revised manuscript.

“One of the most important factors influencing strengths of RC members is shear span-to-depth ratio [27]. This factor plays a major role in determining the performance and failure behavior of slender RC beams used for tall building construction [28]. For example, the shear strength of the RC beams increased with decreasing the shear span-to-depth ratio due to the mechanism, commonly refer to as the “strut and tie action” [29, 30]. The RC beams with low shear span-to-depth ratio are prone to suffer shear-compression failure mode [31]. Despite extensive research on this subject, very few experimental studies on the influence of shear span-to-depth ratio on behaviors of slender composite metal decks have been reported in the literature. Therefore, the understanding of failure mechanism and bonding resistance in the composite metal decks under bending needs to be enhanced.”

Round 2

Reviewer 1 Report

Authors have addressed all problems and the paper could be accepted. 

Author Response

Thank you very much.

Reviewer 2 Report

Comments:

1. Page 3. Line #108. What kind of steel were the steel plates made of? At least the type of steel and the yield strength value should be given. This information may be useful in the analysis of the state of failure of research models.
2. Page 3. Lines #117-118. When examining only three cylindrical samples, the smallest value should also be given in addition to the mean value. It is advisable when it is not possible to perform a statistical evaluation of the results. In addition, more information concerning the concrete should be provided, e.g. type of cement and water/cement ratio. It would be good to indicate the standard according to which the test was conducted. Were all the test models made of the same concrete mix?
3. Page 6. Line #187. In Fig. 3, the roller supports are still not showed despite the authors' claim that Fig. 3 has been corrected. This is unacceptable.
4. Page 8. Table 2 and Page 9. Eq. (1). Including only the formula together with a general description of the size without the equilibrium of forces scheme in the cross-section of the calculated element (an appropriate drawing is required) with the indication of all sizes in formula (1)) is insufficient. It is also necessary to provide (specify) the values of all quantities appearing in Eq. (1). For example, how were the forces of Fa and Fd received? Only as the product of the tensile strength and the cross-sectional area of these steel elements (reinforcement and steel-sheet? How was value "a" defined, i.e. the height of equivalent block of concrete compressive stress? What shape was adopted for the compressive stress distribution in compressed concrete: parabolic or equivalent, rectangular? Without this information, the correctness of the calculation of the maximum bending moments cannot be verified.

In scientific articles, it is not allowed to provide only the formulas themselves and the values calculated on their basis, without precisely specifying the quantities appearing in these formulas. This is the basic principle of writing and publishing research papers.

3. Page 10. Fig. 6. The vertical bending cracks are clearly visible in Fig. 6a, while the authors claim that the failure was due to exceeding the shear forces, as shown in Fig. 6b. What the authors call and mark in this figure as a compressive arch section is in fact a typical compression diagonal truss in truss-tie analysis.
4. Page 10. Fig.7. Only vertical cracks typical of bending are visible in this drawing, not those typical of shear failure.
5. Page 11. Fig.11. What part of the test item does the detail shown in this drawing cover? Due to the oblique photograph, it is difficult to say exactly what the actual direction of the shown main crack is. The work lacks a precise sketch (drawings) of the layout of scratches for individual research models. It is standard in scientific work to include such crack patterns, regardless of the possible showing of the photograph.
6. Page 11. Conclusions. In my opinion, the conclusions are still unacceptable. Due to the small number of research models, no generalizations are valid. It should be made clear that the conclusions only apply to these studies. The second conclusion is very important from the point of view of design practice. If the values of the bearing capacity obtained from the analytical calculations exceed those determined in the tests, it is a very dangerous situation, which proves the inadequacy of the calculation model (no safety margin). When discussing the data from Table 2, this issue should be thoroughly discussed, because it is very important. The authors did not do this, which is disqualifying.

Author Response

Thank you for your comments and suggestion on our first revised manuscript. 
Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewer’ comments are provided through point-by-point as follows:

(1)  Page 3. Line #108. What kind of steel were the steel plates made of? At least the type of steel and the yield strength value should be given. This information may be useful in the analysis of the state of failure of research models.

 

Response: The details have been clearly added in the revised version of manuscript at R1. Please see Lines #139-142. We also repeat below for your quick reading:

“A composite deck consists of cold-formed steel sheet, shear connectors, and concrete. The steel sheet with an embossed trapezoidal profile had a thickness of 1.2 mm. Its yield strength and tensile strength were 312 MPa and 436 MPa, respectively. The dead weight of the steel sheet was about 12 kg/m²…”

 

 

(2) Page 3. Lines #117-118. When examining only three cylindrical samples, the smallest value should also be given in addition to the mean value. It is advisable when it is not possible to perform a statistical evaluation of the results. In addition, more information concerning the concrete should be provided, e.g. type of cement and water/cement ratio. It would be good to indicate the standard according to which the test was conducted. Were all the test models made of the same concrete mix?

 

Response: We have substantially revised Section 2.1 to show the concrete properties used in this study. The information regarding the concrete presented in Section 2.1 are recorded from our material testing. Please see Section 2.1 in the revised manuscript.

 

(3) Page 6. Line #187. In Fig. 3, the roller supports are still not showed despite the authors' claim that Fig. 3 has been corrected. This is unacceptable.

 

Response: Thanks for repeating the comments. As we can see in Fig. 3, the supports for the decks are the I-shape steel beams. In this study, we want to reflect the actual composite deck‒beam joints, thereby the I steel beams connected to the decks via the studs are used. Please see for our description of the support. We also show below for your quick consideration:.

“…To reflect the actual composite deck‒beam joints, the supports of the decks are I-shape section steel beams. The profile steel sheets are connected to the I steel beams via the studs, as demonstrated in Figs. 3(a) and (b)…”

 

(4) Page 8. Table 2 and Page 9. Eq. (1). Including only the formula together with a general description of the size without the equilibrium of forces scheme in the cross-section of the calculated element (an appropriate drawing is required) with the indication of all sizes in formula (1)) is insufficient. It is also necessary to provide (specify) the values of all quantities appearing in Eq. (1). For example, how were the forces of Fa and Fd received? Only as the product of the tensile strength and the cross-sectional area of these steel elements (reinforcement and steel-sheet? How was value "a" defined, i.e. the height of equivalent block of concrete compressive stress? What shape was adopted for the compressive stress distribution in compressed concrete: parabolic or equivalent, rectangular? Without this information, the correctness of the calculation of the maximum bending moments cannot be verified.

Response: Revised as suggested. Please see Lines #249-254. We have added equations to show Fa and Fd. The revised sentences were mentioned below for your quick reading.

“…a (= B₁ × c) is the height of equivalent block of concrete compressive stress distributed in the section (mm); B₁ is the factor relating the depth of equivalent rectangular compressive stress block to the depth of neutral axis; c is the distance from extreme compression fiber to the neutral axis (mm)…”

 

(5) Page 10. Fig. 6. The vertical bending cracks are clearly visible in Fig. 6a, while the authors claim that the failure was due to exceeding the shear forces, as shown in Fig. 6b. What the authors call and mark in this figure as a compressive arch section is in fact a typical compression diagonal truss in truss-tie analysis.

Response: Thank you for your comments. We do not think that we claimed that the failure was due to exceeding the shear forces. Fig. 6(b) is to demonstrate the compressive arch mechanism, which would depend on the shear span-to-depth (a/d) ratio. For deck S1, with smaller a/d ratio, the arch mechanism might be stronger than the deck S3 with larger a/d ratio. This is not meant that the failure was due to exceeding the shear forces. Please see our discussion on the crack patterns of the decks in Lines… We also present the discussion below for your consideration:

“Figures 6(a) and 7 show the crack patterns of the specimens under the load increments. The deck S1 started cracking at load by 100 kN, while the deck S3 begun fracturing at load by 130 kN. Generally, the specimens started cracking at the central; then, the cracks tended to open. Following, the new crack formation under the loading points was observed. In specimen S1 with a short shear span length, the cracks were occurred in the pure bending region, while the cracks under the loading points were observed in the deck S3 with a larger shear span length. In addition, at high loads, the number of cracks in the composite deck S3 are fewer than those in the deck S1. As observed from the tests, the failure crack width in the specimen S3 was larger than that in the deck S1. The possible reason is due to that besides the flexural capacity, the concrete arch (as illustrated in Figure 6(b)) in the shear span of the deck S1 contributed to resisting the applied forces. Meanwhile, the arch action in the deck S3 could be neglected and it behaved only as a bending member; therefore, the flexural cracks were wide. These findings indicate that the shear span-to-depth ratio affected the failure mechanisms of the composite decks.”

 

 

(6) Page 10. Fig.7. Only vertical cracks typical of bending are visible in this drawing, not those typical of shear failure.

Response: Thank you for your comment. The authors indicated the crack in the pure bending region in Section 3.2 lines # 275-277. However, for your quick reading, please see the highlighted sentence mentioned below.

“Figures 6(a) and 7 show the crack patterns of the specimens under the load increments. The deck S1 started cracking at load by 100 kN, while the deck S3 begun fracturing at load by 130 kN. Generally, the specimens started cracking at the central; then, the cracks tended to open. Following, the new crack formation under the loading points was observed. In specimen S1 with a short shear span length, the cracks were occurred in the pure bending region, while the cracks under the loading points were observed in the deck S3 with a larger shear span length…..”

 

(7) Page 11. Fig.11. What part of the test item does the detail shown in this drawing cover? Due to the oblique photograph, it is difficult to say exactly what the actual direction of the shown main crack is. The work lacks a precise sketch (drawings) of the layout of scratches for individual research models. It is standard in scientific work to include such crack patterns, regardless of the possible showing of the photograph.

Response: Thank you for your comments. We do not have Fig. 11 in our article. We suppose that you are talking about Fig. 8. We have revised Fig. 8 showing the loading and support points to understand the failure patterns easily.

 

(8) Page 11. Conclusions. In my opinion, the conclusions are still unacceptable. Due to the small number of research models, no generalizations are valid. It should be made clear that the conclusions only apply to these studies. The second conclusion is very important from the point of view of design practice. If the values of the bearing capacity obtained from the analytical calculations exceed those determined in the tests, it is a very dangerous situation, which proves the inadequacy of the calculation model (no safety margin). When discussing the data from Table 2, this issue should be thoroughly discussed, because it is very important. The authors did not do this, which is disqualifying.

Response: The authors would like to thank Reviewer #2 for this comment. Based on the experimental results, the conclusion mentioned in the revised manuscript can be drawn. It is suitable for the experimental based research. The conclusions are made based on the results obtained from this study only. For the results regarding second conclusion, we have clearly discussed about the comparison between test and model. We also discuss on the reason why we have overestimation by using the model for prediction of the moment capacity of the composite decks. We have also indicated the weakness of the section analysis and we have also concluded the necessity of model improvement. Please see Lines 240-261. We think that our discussion is very clear and understandable to the readers. Your comment is very basic knowledge, which we have already covered in our submission. We have revised the second conclusion for clearer. Please see Lines 320-324. The revised sentences were mentioned below for your quick reading.

 

“2. The current research found that the flexural strength of the composite decks predicted by conventional section analysis overestimates the experimental values, which is critical for safety. Therefore, in future, experimental, numerical, and analytical investigations should be studied to comprehensively develop the strength model for composite decks.”

Reviewer 3 Report

The authors took note of the reviewer's comments and revised the manuscript of the article. 

Author Response

Thank you very much.

Reviewer 4 Report

The authors have addressed most of the reviewer's comments.

Author Response

Thank you very much.

Reviewer 5 Report

Can be accepted as it is.

Author Response

Thank you very much.

Round 3

Reviewer 2 Report

Most of the explanations and supplements provided by the authors can be considered appropriate and sufficient.

However, I still have some comments regarding the explanation of the quantities appearing in formula (1). It is clear from the authors' responses that for the distribution of compressive stresses in compressed concrete, a rectangular equivalent shape was adopted. This is of course evidenced by the information that a = (β₁ × c). In Line #244 this formula includes a spelling error a (= β₁ × c).

Unfortunately, the authors do not provide the value of the β₁ coefficient used. Probably according to some standard. The number of standard according to which it was adopted and the β₁ value should be specified. This will allow for a possible verification of the correctness of calculations. In addition, another thing. For what shape of the cross-section was the position of the neutral axis determined in the analytical calculations? Such information is essential in a scientific article.

I am wondering, however, why the authors do not include in the article an appropriate computational drawing of the cross-section with all the quantities that occur there? This attitude of the authors is completely incomprehensible.

Author Response

The authors would like to thank the editor and the reviewer for their constructive comments. Revisions have been made to the manuscript to address all of the recommendations. Responses to the reviewer’ comments are provided through point-by-point as follows:

 

Reviewer# 2

Most of the explanations and supplements provided by the authors can be considered appropriate and sufficient.

Response: Thank you very much.

 

However, I still have some comments regarding the explanation of the quantities appearing in formula (1). It is clear from the authors' responses that for the distribution of compressive stresses in compressed concrete, a rectangular equivalent shape was adopted. This is of course evidenced by the information that a = (β1 × c). In Line #244 this formula includes a spelling error a (= β1 × c).

Unfortunately, the authors do not provide the value of the β1 coefficient used. Probably according to some standard. The number of standard according to which it was adopted and the β1 value should be specified. This will allow for a possible verification of the correctness of calculations. In addition, another thing. For what shape of the cross-section was the position of the neutral axis determined in the analytical calculations? Such information is essential in a scientific article.

Response: Thank you for your comments. The details have been clearly added in the revised version of manuscript at R3. Also, the standard ACI318-19 is added in our reference.

 

I am wondering, however, why the authors do not include in the article an appropriate computational drawing of the cross-section with all the quantities that occur there? This attitude of the authors is completely incomprehensible.

Response: Thank you for your comments and suggestions. The details of computational drawing of the cross-section have been clearly added in the revised version of manuscript at R3. Please see in the revised version of our manuscript.