Calculation Model for Estimation of Residual Bearing Capacity of Damaged Reinforced Concrete Slender Columns

Round 1

Reviewer 1 Report

In this manuscript, a calculation method is proposed to estimate the residual bearing capacity of pre damaged reinforced concrete slender columns. The subject of the manuscript is novel and interesting and it is well written. Some questions and suggestions are provided below for the presented manuscript before its publication:

 

-       Two words of “Calculation” in the title is not proper. It is suggested to change the second “Calculation” to “Estimation”.

-       The final sentences of the abstract can be designated to more quantitively results.

-       Most of the previous research review is moved to “Materials and Methods” section. They should be transferred to “Introduction” section.

-       There are various new research works that studied the different compressive behavior of concrete columns that could be added to the introduction. Here are some suggestions to review:

·      Huang, H., Guo, M., Zhang, W., & Huang, M. (2022). Seismic Behavior of Strengthened RC Columns under Combined Loadings. Journal of Bridge Engineering, 27(6), 05022005.

·      Bagheri, M., Chahkandi, A., & Jahangir, H. (2019). Seismic reliability analysis of RC frames rehabilitated by glass fiber-reinforced polymers. International Journal of Civil Engineering, 17(11), 1785-1797.

·      Xu, J. G., Hong, W., Zhang, J., Hou, S. T., & Wu, G. (2022). Seismic performance assessment of corroded RC columns based on data-driven machine-learning approach. Engineering Structures, 255, 113936.

-       It is suggested to improve the quality of Figure 1.

-       Please remove the grids from Figures 3 to 5. These grids make them hard to read.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Review for Applied Sciences (MDPI)

Manuscript ID: applsci-1822249

Title: Calculation model for calculation of residual bearing capacity of damaged reinforced concrete slender columns

In this work, an analytical model for assessing the residual bearing capacity of damaged compressed reinforced concrete elements with different flexibility, based on the basic prerequisites of the current standards and extends their effect to the case of oblique off-center compression caused by damage to a part of the cross section, has been proposed. Several experimental tests of pilot samples were carried out, and the influence of the angle and depth of damage on behavior and the nature of the destruction of experimental samples have been investigated. The results obtained by the proposed analytical model showed a satisfactory convergence with the experimental values.

The subject addressed in this article is worthy of investigation and the paper is of sufficient technical quality. The proposed approach is not a new addition. However, the work pertains to its novel application to the mentioned class of problem. The chosen topic has a good potential for contributing to the knowledge domain and could benefit the readers remarkably, as the paper is well written with good result discussions. Despite this, there are some important concerns related to the following points that need to be taken into account by the authors before the manuscript can be accepted for publication.

Comments:

1.      In the title of the manuscript “Calculation model for calculation of residual bearing capacity of damaged reinforced concrete slender columns” appear too many time the word “Calculation”. In my opinion, the authors could add the word “assessing” in this way: “Calculation model for assessing of the residual bearing capacity of damaged reinforced concrete slender columns”.

2.      In the Abstract, the sentence at line 18 could be rewritten in a clear way, for example: “Analyzing the influence of the angle and depth of damage on behavior and the nature of the destruction of experimental samples, 3 main destruction patterns were identified.”

3.      Section 2 and Section 3 have the same title. Please, rewrite the titles making them different.

4.      Please remove the word “you” in the sentence at line 57: “Systematization, classification, and study of certain types of damage allows you to give accurate quantitative estimates of the bearing capacity of damaged”

5.      In Section 2 the authors explain the importance of suitable methods for assessing and detecting the damage phenomena in building and civil construction due to tensile and compressive loading conditions. This is very important because the appearance of the cracks, mainly due to the corrosion, chemical deterioration, and the application of adverse loading, is a sign of stress and weakness, of the structure leading to possible failure. In the technical literature, several theoretical and numerical methods have been proposed to predict the onset and evolution of damage phenomena with sufficient accuracy. Moreover, for a better understanding of the above-mentioned problem, in this section, the authors are encouraged to discuss in a critical manner, the existing numerical methods able to predict and detect the damage phenomena in reinforced concrete structures. The bibliographic context of the paper could be properly enlarged by improving the literature review of the most models to detect the onset and evolution of damage phenomena recommending, thus, to discuss these works:

-        A cohesive fracture model for predicting crack spacing and crack width in reinforced concrete structures. Engineering Failure Analysis, Volume 139, September 2022, 106452. https://doi.org/10.1016/j.engfailanal.2022.106452

-        FE analysis of failure behaviour of reinforced concrete columns under eccentric compression, Engineering Structures, Volume 30, Issue 2, February 2008, Pages 300-317, https://doi.org/10.1016/j.engstruct.2007.03.024

6.      Please add a reference to better explain the adopted Box-Behnken plan. For example:

-        George Box, Donald Behnken, "Some new three level designs for the study of quantitative variables", Technometrics, Volume 2, pages 455–475, 1960.

7.      At line 115 different units of measurement (mm and pcs) have been employed to describe the height of the reinforced concrete element. It is recommended to adopt only “mm” or “pcs”. In my opinion, since in the rest of the manuscript the unit of measurement “mm” has been adopted, the unit of measurement “pcs” should be removed from the sentence.

8.      Please, at line 117, the authors should better explain the state “The mode of the experiment”. Maybe the authors refer to the SETUP of the experiment?

9.      In the sentence at line 125, the authors should specify that the length of the damage zone (400 mm) is the same for each tested reinforced concrete element.

10.   At line 128, the word “Concreting” could be easily rewritten with “The concrete”, for example: “The concrete was performed with ready-made industrial concrete class C 25/30 at the…”

11.   In Figure 1, specifically in the Cross-Section 1-1, the authors should indicate the angle of damage q and the depth of damage.

12.   In the caption of Figure 2, seems that the pictures, representing the damage patterns, are not obtained by the performed experiment. It is correct? Moreover, The description of Figure 2c is missing. Please add it. Finally, the authors must remove the sentence: “Figures should be placed in the main text near to the first time they are cited. A caption on a single line should be centered”

13.   Please, at line 159, the height of the columns should be expressed in “mm” or “m” as reported in Table 1.

14.   At line 179, as well as in other parts of the manuscript, the authors write a new unit of measurement of the Force, i.e. Nu. I think such a word “Nu” indicate the ultimate load level. Please clarify this Symbol (Nu) in the text.

15.   At line 227, the authors should avoid the abbreviation ES for the cited model and rewrite it in extended form also adding a scientific reference of such model.

16.   At line 263, the initial part of the sentence is wrong. Please rewrite it in this form: “Figure 7 shows the calculated scheme of…”

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The Authors introduce the required clarifications and modification. The paper benefits for it. The revised paper is adequate for publication.