Effect of Inertial and Kinetic Forces of a Soil–Pile–Structure System on the Behavior of a Superstructure Under Earthquake

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a comprehensive study on the seismic behavior of pile-supported structures, focusing on the interplay between inertial and kinematic forces. The research employs three-dimensional numerical simulations using FLAC3D to evaluate the dynamic response of pile foundations under various seismic conditions. The study is well-structured, with a clear methodology, robust data analysis, and meaningful conclusions. The findings provide valuable insights into the seismic response of pile-supported structures and highlight the importance of considering both inertial and kinematic effects in seismic design. With the implementation of the following suggestions, the manuscript will be better positioned for publication in the Applied Sciences.

1. While the study uses FLAC3D, a widely accepted tool in geotechnical engineering, it would be beneficial to include a validation section where the numerical results are compared with experimental data or field observations. This would enhance the credibility of the findings.
2. The study acknowledges the limitations of numerical modeling, such as the inability to fully capture the complexity of soil-structure interactions. A more detailed discussion of these limitations and potential future work to address them would strengthen the manuscript.
3. The quality of figures in the paper should be improved.
4. The sections of Supplementary Materials, Author Contributions, Funding, Institutional Review Board Statement, Informed Consent Statement, Data Availability Statement, Acknowledgments, Conflicts of Interest should be completed.
5. The manuscript is well-written overall, but some sections could benefit from minor language edits to improve clarity. Ensuring consistency in formatting (e.g., table and figure captions) would enhance the overall presentation.
6. The study provides valuable insights for seismic design, but a dedicated section on practical implications and recommendations for engineers and designers would enhance the manuscript's applicability.

Author Response

I have attached a file with the response to the reviewer's valuable comments. Please check it. Thank you.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript, a three-dimensional numerical simulation was conducted using FLAC3D to develop an analysis case by changing the input seismic motion level based on the substructure model of the bridge, soil relative density, and pile cap mass. The aim of this study is to investigate the comprehensive influence of the interaction between inertia and motion on the dynamic response of pile foundations under seismic loads. It is a very valuable research. There are several minor questions for the authors to consider.

(1) To simplify the calculation, the actual steel pipe pile is simplified as a solid pipe pile. Although the diameter is adjusted to ensure that it is equivalent to the bending stiffness of the real steel pipe pile, this simplification may ignore some special mechanical properties of the steel pipe pile. The impact of this simplification on the research results should be further verified.

(2) Why choose the North South (NS) component of the 2017 Pohang earthquake as the basis for designing the response spectrum? Suggest providing additional explanation on the "correction" of the original seismic waves, and what technical means were used for the modification?

(3) It is suggested to supplement the comparison of similar experimental data. Only numerical simulations are used in the manuscript to demonstrate the reliability of the simulation results.

(4) In the Results and Discussion section (Section 3), quantitative analysis should be conducted, such as providing specific percentages of differences in maximum lateral displacement and maximum peak velocity along the depth direction under different operating conditions.

Author Response

I have attached a file with the response to the reviewer's valuable comments. Please check it. Thank you.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, the authors investigate the combined effects of inertial and kinematic interaction on the dynamic response of pile foundations under seismic loading. The commercial software, FLAC3D, was used for numerical simulation. overall, the manuscript is well structured and presented. It provides some interesting results. In my opinion, the manuscript need major revision before further consideration.

Major weakness of the manuscript are summarised here:

• Lack of new scientific contribution: Although the authors used the commercial software for numerical simulation, it is still necessary to point out the new scientific contribution of this work. Otherwise, it becomes a pure numerical exercise.
• Lack of validation of the work: It is necessary to validate the model even it is a commercial software. The authors need to compare with field data or laboratory tests.
• Need to have mesh convergence analysis: It is a general practice to have mesh convergence analysis of the numerical model. This is to ensure the mesh used in numerical examples are converged numerically.

I provide the following specific comments for the authors consider in the revision.

• Input data In Table 1: It is confuse about two different silty sand. One with Dr=30% and another with Dr=80%. Both are within the depth of 0-9 m. I guess that one is 0-3 and another is 4-9 (for example). As shown in Figure 3, The soil should be three layers not two layers. Could you please check or clarify.
• Table 4: Is Dr the relative depth for silty sand?
• Validation of the numerical model is required.
• Limitation of the model need to be clearly stated.

I hope the above comments will help the authors further improve the quality of the manuscript.

Author Response

I have attached a file with the response to the reviewer's valuable comments. Please check it. Thank you.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author have revised the manuscript carefully. The manuscript have been improved and can be accepted.

Reviewer 3 Report

Comments and Suggestions for Authors

The author have tried to addressed my comments. Although I am not satisfied with their response  for the "lack of validation". I think the authors have tried their best. In my opinion, this manuscript can be accepted in the present form.