Seismic Response Analysis of Concrete Box-Type Subgrade in High-Speed Railways

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

- The state of the art should be improved – the current version is really poor and unacceptable in this Journal.

- what is the novelty of this paper? – please add in the text

- has any sensitivity analysis or other test been performed to check the validity of the simulation?

- how do you validate your models? What was validated, and how was it validated in detail? – please add in the text

- please show your full numerical model with boundary condition – please add in the text

- what is new in your paper? – please add in the text

- please compare your results to other results or research – please add in the text

- The references are really poor. Please add a few papers about numerical modeling bridges, tunnels, civil structures, etc.

•           https://doi.org/10.1061/JGGEFK.GTENG-12674

•           https://doi.org/10.1016/j.jcsr.2024.108743

•           https://doi.org/10.1016/j.engfailanal.2024.108993

•           https://doi.org/10.1016/j.tws.2024.112479

•           https://doi.org/10.1016/j.engstruct.2021.112333

 

 

Comments on the Quality of English Language

This text should check by Native Speakers

Author Response

Dear reviewer:

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The work is interesting, even if it does not appear to be fully suitable for a journal entitled 'Applied Sciences', but it appears to be more suitable for 'Infrastructures'. The work needs to be better described, in particular, the geometric characteristics of the model together with its relationships with the external environment (soil) need to be better explained, with additional figures, if possible.

The following specific comments should be also taken into consideration for manuscript improvement:

- lines 35-36 and 46-47: even if no studies exist dedicated to the vibration response of box-type subgrade, at least a few references on this structure should exist and have to be added to the manuscript introduction.

- lines 71-79: the introduction end should contain a detailed description of the manuscript organization (sections dedicated to..)

- figure 2 is not fully clear: the thickness of the different elements of railway track, box subgrade, and foundation should be declared (at least with a letter and then indicating the ranges of variation of each thickness value). In particular, it is not clear where the soil level is, and if the foundation element is given by piles in soil or by free-standing columns. Furthermore, the caption of the figure is not in agreement with the content, since the 'nonlinear interaction' is not represented.

- lines 126-128: please reformulate the sentence, since the software ABAQUS is already introduced at lines 123-125.

- figure 4 (lines 151-152) is defined as a schematic of the case study considered, but it appears to be already a 3d (finite element?) model of the structure. If it is already a detail of the FEM, authors have to specify how the rebars are connected to the 3d FEs. If it is not true and the figure is a simple schematic of the case study, additional details should be added (with another figure, if possible), by highlighting the geometry of the case study, focusing also on model restraints, in order to allow the future readers to reproduce it.

- figure 4 (page 7): first of all, the figure should be renumbered to figure 5, then considering sub-figures b and c, a clear separation between the inner and the outer box elements is evident. Does this mean that the model is characterized by three box elements simply placed one next to the other one without connections?

- table 6 collects a comparison between box-type subgrade and simply supported beams having different lengths. The overall length of the box-type subgrade is not declared and, more generally, it is not clear a comparison with a bridge-type structure if the box-type structure is standing on the ground.

- figure 12: since displacements appear to be not uniform along top and bottom slabs and side walls, a detail on the specific points chosen for determining the displacement variation along time should be added.

Comments on the Quality of English Language

English is sufficiently clear, a general grammar check is suggested.

Author Response

Dear reviewer:

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Seismic Response Analysis of Box-Type Subgrade in High-Speed Railways

applsci-3325769

The manuscript presents a numerical study of reinforced concrete box structures to be used for ballastless railway substructures. This type of substructure aims at replacing traditional filler-substructures for high speed railways and the advantages includes reduced land occupation and high structural stability. This study focused on the seismic response of box structures and the nonlinear numerical modelling was conducted in Abaqus. The analysis showed that the structure meets the Chinese requirements regarding seismic performance and that the deformations can primarily be considered as a rigid body motion. The analysis showed a concentration of tensile stress in the conjunction between the top slab and side walls, however well below the tensile capacity. The analysis also showed a threshold at about 0.2g and the degree of damage seemed to accelerate above this level.

The topic of the manuscript is interesting and relevant for the readers of Applied Sciences. The study seems well executed and the structure is generally good. However, there are a few recommendations that the authors should consider before the paper can be accepted for publication.

The type of paper seems to be considered as an essay, which can not be correct. See line 1.

The title could be more specific, for example “Seismic Response Analysis of Concrete Box Subgrade Structures for High-Speed Railways“.

The second sentence of the abstract is a bit unclear to me and could perhaps be rephrased for clarity.

The introduction starting on line 25 should have a heading “1. Introduction”.

Many of the references include the full name of the first author, which is not appropriate. The references in the main text should be written in the style “Chen et al. (2024)”.

The second paragraph of the introduction is missing references. The following addition on line 38 is therefore suggested: “It may also be considered as a sustainable option to traditional filler subgrades as it reduces the need for natural aggregates [x]” [x] https://doi.org/10.1016/j.dibe.2023.100177

The chapter headings on line 80 and forward should be renumbered as the introduction becomes chapter 1.

In the chapter describing the models, there is no information regarding the cross-section of the box structure. A figure including the dimensions of the structure would be appreciated.

It is also not completely obvious regarding how (or if) the model includes any soil around the side walls. This should be clarified.

Professor Nadakatti seems to appear twice in the credit authorship statement (Line 375 and 376).

The topic of the manuscript is very interesting, generally well presented and it is also suitable for publishing in Applied Sciences. I congratulate the authors to a very interesting study. By incorporating the suggestions above, the paper will become a good contribution to the journal.

Author Response

Dear reviewer:

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The paper proposes a spatial dynamic model of a track and a box-shaped earthwork to investigate vibrations under multidimensional seismic effects. The study is of great practical significance. The title and abstract fully disclose the purpose of the study.

However, there are some questions.

1. What method is used to convert seismic waves into equivalent load?

2. Are the seismic excitations non-uniform or uniform?

3. The authors have constructed a finite element model of a box-shaped earthwork. Has the convergence of the finite element solution been investigated.

How do the results obtained using this model (Figures 10 and 11) correlate with in-situ test data?

The paper can be accepted for publication with minor corrections.

Comments for author File: Comments.pdf

Author Response

Dear reviewer:

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Please add more papers from the last five to ten years. No of 32 references is not enough. You can cite other papers of Authors, which you cited in the text before.

Author Response

Dear Reviewer,

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The work was effectively improved by the authors. Several aspects still need to be detailed to increase manuscript clearness and readability:

- lines 85, 87, 91, 151: please correct "Tab.TableX" (and check the entire manuscript for similar mistakes)

- end of page 3: modify manuscript organization in order to avoid a short sentence at lines 90-91 that is difficult to be found between two tables, furthermore, try to place table 3 entirely in page 4.

- lines 109, 142, 176: please correct "Fig.FigureX" (and check the entire manuscript for similar mistakes).

- table 5 should be corrected, the titles of the first and second columns do not agree with the corresponding information, frequencies appear to be in the 2nd column, whereas the 1st one appears to be just the frequency number.

- the correction applied to table 6 is good. However, a further detailed description of the comparison done with this table should be added to the text, since the citation [25] is not sufficient. Authors should better describe the bridge type, in particular its beam sections. Are the beams of this bridge made with box culverts similar to those of the manuscript?

- even if box-type subgrade is a novel structure proposed by Chinese engineers, analysis of box culverts on soil is not a new topic (even if it is not specifically related to railway design). Authors can consider the analyses performed by Tullini and co-workers (Stability of slender beams and frames resting on 2D elastic half-space, Static analysis of shear flexible beams and frames in adhesive contact with an isotropic elastic half-plane using a coupled FE-BIE model, Incremental analysis of elastoplastic beams and frames resting on an elastic half-plane) where after simple foundation beams, rectangular box culverts on elastic half-plane were considered.

Author Response

Dear Reviewer,

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for addressing all my previous comments and suggestions. The clarity of the manuscript has improved and it is a good contribution to Applied Sciences. My recommendation is to accept it in present form. 

Author Response

Dear Reviewer,

Thank you very much for your positive feedback and for the time and effort you have invested in reviewing our manuscript. We are delighted to hear that you found the revisions satisfactory and that the clarity of the manuscript has improved.

We appreciate your recommendation to accept the manuscript in its current form for publication in Applied Sciences. We are excited about the prospect of contributing to your esteemed journal and look forward to the next steps in the publication process.

Please feel free to reach out if there is any further information we can provide or any additional changes that need to be made.

Best regards,

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for your improvement.

Author Response

Dear Reviewer,

Thank you very much for your positive feedback and for the time and effort you have invested in reviewing our manuscript. We are delighted to hear that you found the revisions satisfactory and that the clarity of the manuscript has improved.

We appreciate your recommendation to accept the manuscript in its current form for publication in Applied Sciences. We are excited about the prospect of contributing to your esteemed journal and look forward to the next steps in the publication process.

Please feel free to reach out if there is any further information we can provide or any additional changes that need to be made.

Best regards,

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have successfully improved the manuscript. Several minor corrections are still suggested in order to increase manuscript quality.

Among the new references added to the final list, ref. 16 should be checked and corrected (authors are Tullini, Tralli, Baraldi, and the year of pubblication is 2013). Furthermore, refs. 16, 22, 23 should be placed in manuscript introduction instead of their current position, for instance by highlighting that box culverts were also studied focusing on buckling and considering a support given by and elastic half-space, instead of a simple Winkler support.

Author Response

Dear Reviewer,

Please see the attachment.

Author Response File: Author Response.pdf