Bridging Law Application to Fracture of Fiber Concrete Containing Oil Shale Ash

Round 1

Reviewer 1 Report

Please read the attachment. Thank you.

Comments for author File: Comments.pdf

Minor changes are needed. 

Author Response

Thank you for your helpful questions and comments. Detailed answers are in the attached file and the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study investigated crack propagation in eco-friendly concrete with OSA and BF using a 2D FE model and experimental testing. The results showed that the bilinear and nonlinear bridging law functions best describe the crack development in the analyzed material. The length of the composite BF strongly affects the accuracy of the numerical models. However, before further consideration of the manuscript, the authors must “fully” address the comments listed below:

 

1.      What are the limitations of the FE model in predicting the crack propagation behavior of BF concrete samples? What are the future research directions to improve the accuracy of the FE model?

 

2.      Further discuss on trends of changes in the mechanical properties of BF concrete samples depending on the parameters such as the fiber content, OSA content, and the notch depth. What is the purpose of the notch in the 3PBT model? How does the notch affect the crack propagation behavior of the concrete in the model?

 

3.      What is the purpose of the condition that the bridging law is not applied to point B in the fiber concrete models? How does this condition affect the crack propagation behavior of the concrete in the model?

 

4.      Why is it necessary to model only half of the prism sample in the FE model? How does this simplification affect the accuracy of the model predictions? What are the limitations of the linear elastic 2D problem in the FE model? How does this approximation affect the accuracy of the model predictions?

 

5.      Which bridging law function is the most appropriate for samples with a higher BF dose? Please provide a detailed justification for your answer, including a discussion of the properties of the bridging law functions and the characteristics of the concrete mixes.

 

6.      What is the leave-k-out cross-validation approach? How is it used to evaluate the accuracy of a surrogate model? What is the range of possible values for the cross-validation percentage error? What does a high or low cross-validation percentage error indicate?

 

7.      Please fully introduce the elastic properties of all the structural components explained in your manuscript. You can summarize them in a table.

 

8.      Did you do any sensitivity analysis for the numerical results obtained? Please create an “Appendix” at the end of your manuscript and provide the core “Subroutine code” of your numerical simulations in ~10-15 lines such that the readers of your paper can better understand your work.

 

9.      You may mention in the Introduction of your paper that apart from finite element analysis, fracture analysis of concrete specimens can "also" be done using many other strong numerical modeling methods such as Finite Difference Method (https://doi.org/10.1016/j.tafmec.2021.102942), Bezier Multi-Step Method (https://doi.org/10.1016/j.tws.2021.108484), and Differential Quadrature Method (https://doi.org/10.1016/S0263-8223(97)00112-8). You can briefly introduce these methods and reference the referred papers.

 

10.    It is still unclear how the coordinates of the kink point (expressed in equations 7 and 8) were derived. Please add more explanation. 

 

11.    Conclusion: Can authors highlight future research directions and recommendations? Also, highlight the assumptions and limitations (e.g., shortcomings of the present study). Besides, recheck your manuscript and polish it for grammatical mistakes (you can use “Grammarly” or similar software to quickly edit your document).

Minor language editing is required. 

Author Response

Thank you for your helpful questions and comments. Detailed answers are in the attached file and the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments are addressed