Enhancing Flexural Strength of RC Beams with Different Steel–Glass Fiber-Reinforced Polymer Composite Laminate Configurations: Experimental and Analytical Approach

Round 1

Reviewer 1 Report

The authors' research is relevant and presented at a fairly high level. However, to improve the work, it is necessary to make additions:

-  The further work should be mentioned at the end of the article. Have the authors planned to extend the use of Steel-GFRP Composite Laminates for strengthening concrete girder-bridges ? This argument will surely be a very interesting topic for further research.

-  An “appendix” section, containing names and elaboration of the symbols and acronyms used, should be inserted within the article.

Author Response

RESPONSES TO Reviewer #1’s COMMENTS:

The authors would like to express their great appreciation for your thorough and detailed review of our manuscript. Without a doubt, the presented ideas and the additional recommended actions have strengthened the article. Almost all of your comments have been included in the paper. The places in the text where these suggestions are considered are marked by Red. The answers to all of your valuable comments are given in the following lines.

1. COMMENT: Further work should be mentioned at the end of the article. Have the authors planned to extend the use of Steel-GFRP Composite Laminates for strengthening concrete girder-bridges? This argument will surely be a very interesting topic for further research.

RESPONSE: Thank you. Your interesting comment has been performed in the revised file and new suggestions have been added for further investigations in the future after the conclusion section. About the second part of your comment, the authors would like to explain the main reason for this study. The main aim of this study was to measure the effect of strengthening concrete beams in buildings but this could cover the strengthening of concrete girder-bridges which needs more investigation. Authors will keep your valuable comment in their mind for their future studies. Also, your interesting comment has been presented as a suggestion for future studies.

2. COMMENT: An “appendix” section, containing names and elaboration of the symbols and acronyms used, should be inserted within the article.

RESPONSE: Excellent point. A new section of “Acronyms and symbols” has been added after the conclusion section.

Again, we appreciate all of your insightful comments. We worked hard to be responsive to them. Thank you for taking the time and energy to help us improve the paper.

Reviewer 2 Report

Accept in the present form

Minor editing is mandatory.

Author Response

Dear Reviewer, thank you so much for your positive feedback about our paper. The whole paper has been reviewed and modified

Reviewer 3 Report

The manuscript is more like an experimental report than a technical article. The importance, discussion, and figures drawing all need significant modifications, including extensive deletion of some insignificant contents. The Abstract is too long and must be shortened with only key contents. How many duplicates did you produce to assess the mechanical strengths? The error bar in the figures? The conclusion is too long, I would suggest only list the really meaningful results.  

The English expression is fine.

Author Response

RESPONSES TO Reviewer #3’s COMMENTS:

The authors would like to express their great appreciation for your thorough and detailed review of our manuscript. Without a doubt, the presented ideas and the additional recommended actions have strengthened the article. Almost all of your comments have been included in the paper. The places in the text where these suggestions are considered are marked by Green. The answers to all of your valuable comments are given in the following lines.

1. COMMENT: The manuscript is more like an experimental report than a technical article. The importance, discussion, and figures drawing all need significant modifications, including extensive deletion of some insignificant contents. The Abstract is too long and must be shortened with only key contents. How many duplicates did you produce to assess the mechanical strengths? The error bar in the figures? The conclusion is too long, I would suggest only listing the really meaningful results.

RESPONSE: Thank you for your time and your technical comments. Please find the following responses to your interesting comments:

• The experimental report is just a part of this study. In addition to experimental results, the authors compared their results with standards and well-known existing models and provided an analytical section which is about 50% of this paper
• In terms of the compressive strength of concrete. in the paper, it was mentioned that “The specimens' compressive strength was determined by averaging the values of three samples”
• For beams, just one specimen was tested for each technique. Due to the size of the beam samples, in terms of financial efficiency, it is not possible to produce three samples for each beam and average between the results. Also, most published studies have examined only one beam sample from any sample.
• Because only one beam has been examined from each method, it is not possible to provide an error bar. The error bar becomes meaningful when more than one sample is made from each technique.
• The abstract has been shortened.
• Modification of the text has been performed and the conclusion section has been shortened, as well.

Again, we appreciate all of your insightful comments. We worked hard to be responsive to them. Thank you for taking the time and energy to help us improve the paper.  

Reviewer 4 Report

Review for Infrastructures MDPI

Manuscript ID: infrastructures-2916996

Title: Enhancing Flexural Strength of RC Beams with Different Steel-GFRP Composite Laminate Configurations: Experimental and Analytical Approach

This study investigates the effectiveness of different techniques for strengthening reinforced concrete (RC) beams using glass fiber-reinforced polymer (GFRP) laminates. Techniques include externally bonded reinforcement (EBR), EBR on grooves (EBROG), EBR in grooves (EBRIG), and near-surface mounted (NSM) systems, with a new NSM method using anchorage rebar introduced. Twelve RC beams were tested under bending, with one serving as a control. Both steel and GFRP rebars were used in the NSM method. Experimental results, including load-bearing capacity, deformation, and ductileness, were compared to existing standards. A regression was developed to predict final resistance. NSM significantly enhanced load-bearing capacity and ductileness compared to EBR techniques. EBROG and EBRIG slightly improved ductility but combining GFRP rebar and laminates notably enhanced both flexural resistance and ductility. The subject addressed in this article is worthy of investigation and the review paper is of sufficient technical quality.

The article is well-presented, with clear figures, and the results obtained from the analytical model are consistent with the experimental findings. However, some typos are present; for instance, in Figure 21, I would recommend adding a legend to differentiate between the experimental results and the line representing the analytical model.

Furthermore, while the authors provide a comprehensive review of experiments and analytical models based on standards to investigate the behavior of reinforced concrete structures with these types of reinforcements, they should also incorporate a brief discussion on numerical models that examine collapse phenomena in structural concrete beams with different fracture approaches, such as those referenced in [“A combined ALE-cohesive fracture approach for the arbitrary crack growth analysis” Engineering Fracture Mechanics, 109996, https://doi.org/10.1016/j.engfracmech.2024.1099 and “Uncertainty of the smeared crack model applied to RC beams, Engineering Fracture Mechanics 233 (2020) 107088, https://doi.org/10.1016/j.engfracmech.2020.107088.

In my opinion, the paper is acceptable for publication in the journal “Infrastructures MDPI”. However, the author is encouraged to take into account the above-mentioned comments in order to make the paper clearer and more appreciable.

Author Response

RESPONSES TO Reviewer #4’s COMMENTS:

The authors would like to express their great appreciation for your thorough and detailed review of our manuscript. Without a doubt, the presented ideas and the additional recommended actions have strengthened the article. Almost all of your comments have been included in the paper. The places in the text where these suggestions are considered are marked by Blue. The answers to all of your valuable comments are given in the following lines.

1. COMMENT: The article is well-presented, with clear figures, and the results obtained from the analytical model are consistent with the experimental findings. However, some typos are present; for instance, in Figure 21, I would recommend adding a legend to differentiate between the experimental results and the line representing the analytical model.

RESPONSE: Thank you so much for your technical comment. Your comment has been performed and the legend has been provided. Also, the whole paper has been controlled in terms of English and typos. 

2. COMMENT: Furthermore, while the authors provide a comprehensive review of experiments and analytical models based on standards to investigate the behavior of reinforced concrete structures with these types of reinforcements, they should also incorporate a brief discussion on numerical models that examine collapse phenomena in structural concrete beams with different fracture approaches, such as those referenced in [“A combined ALE-cohesive fracture approach for the arbitrary crack growth analysis” Engineering Fracture Mechanics, 109996, https://doi.org/10.1016/j.engfracmech.2024.1099 and “Uncertainty of the smeared crack model applied to RC beams, Engineering Fracture Mechanics 233 (2020) 107088, https://doi.org/10.1016/j.engfracmech.2020.107088.

RESPONSE: Excellent comment. A brief discussion on numerical models that examine collapse phenomena in structural concrete beams with different fracture approaches has been provided considering the mentioned interesting references

Again, we appreciate all of your insightful comments. We worked hard to be responsive to them. Thank you for taking the time and energy to help us improve the paper.  

Round 2

Reviewer 3 Report

The manuscript can be accepted in this version, because the comments from reviewers have been replied properly. 

The English expression is fine.

Reviewer 4 Report

All the comments provided by the Reviewer have been properly addressed. Now the manuscript can be accepted for publication.