Soil–Structure Interaction Effects on Seismic Responses of a Conventional and Isolated Bridge Subjected to Moderate Near-Fault and Far-Field Records

Round 1

Reviewer 1 Report

Major revision is suggested for this paper. In particular:

1) section 2.1: the first two paragraphs dealing with the bridge and its modeling have to be extended even if the authors have to convey information from other references.

2) The properties (period, damping, design displacement) of the isolation system seem to be randomly chosen. I do not understand why the authors refer to an optimum isolation system. Usually, optimum properties are derived from constrains in conjunction with a minimization of a function. This is not the case herein unless the authors mean something else.

3) Section 2.3.2: important phenomena such as uplift, spatial variation of seismic motion, incoherence of motion are not presented or discussed. This is crucial in view of the direct approach. 

4) Lines 200-203: the μ value was selected only by using references 47-48. You mention 'practical cases' but you do not present them. Moreover, is the 0.5 value in accordance to soil classes used in this study (lines 173-174)?

5) section 2.4: simplified approach seems to be oversimplified. Damping values (representing radiation and material damping) are totally absent in the analyses performed. The authors present only Table 5 that provides stiffness values. I am puzzled after reading that CSA S6-19 simplifies soil behavior by Winkler springs while American codes rely heavily on spring-dashpots system to simulate SSI. Please comment very carefully.

6) Predominant periods of motion have to be mentioned in lines 292-296.

7) Lines 339-340: No damping in the system, thus, problems in the results of the simplified method. Please explain by using also your response to the aforementioned comment 5.

8) Literature contains many old papers. Please replace them with more modern ones. Please make use of scientific work done at the last 15 years. 

Phrasing problems: please re-write lines 563-565 and 584-585 of conclusions.

Author Response

We would like to express our appreciation to the reviewers for their time, insight, and valuable comments. Please find in the attachment our responses to the comments. The changed sections or related parts are highlighted in yellow in the manuscript for the comments of reviewer No.1.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The paper entitled “Soil-Structure Interaction Effects on Seismic Responses of a Conventional and Isolated Bridge Subjected to Moderate Near-Fault and Far-Field Records” provides a very interesting research work about the possible effects of soil-structure interaction for bridges subjected to near field and far field events. The manuscript is well written, easy to read and provides very useful information. However, a number of revisions are suggested, in order to increase the value of the manuscript.

 

1.      Literature review is good for all the covered topics. However, Authors are encouraged to enrich the state of art about design and testing of both traditional and innovative isolation devices. Among the others, the following references are suggested:

 

http://doi.org/10.1016/j.engstruct.2022.115118

https://doi.org/10.1002/eqe.1039

https://doi.org/10.1080/13632469.2022.2036271

 

2.      It is not clear in the manuscript if the adopted NF and FF records are representative to one-directional earthquake simulations (single component) rather than bidirectional events. If one direction is considered, is it the longitudinal of the transversal direction of the bridge? Additional details are required.

 

3.      All records have been scaled in order to obtain the same PGA. Is this a requirement of the adopted standard code? All the adopted scale factors should be listed  in Table 7: did Authors consider upper and lower bounds for such scale factors? Additional details are needed.

 

4.      Further descriptions of the simplified model are needed, in order to better understand the level of simplification. A figure showing a sketch of the model could be useful.

Author Response

We would like to express our appreciation to the reviewers for their time, insight, and valuable comments. Please find in the attachement our responses to the comments. The changed sections or related parts are highlighted in blue in the manuscript for the comments of reviewer No.2.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments for author File: Comments.pdf

Author Response

We would like to express our appreciation to the reviewers for their time, insight, and valuable comments. Please find in the attachment our responses to the comments. The changed sections or related parts are highlighted in green in the manuscript for the comments of reviewer No.3.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Please make sure that you have incorporated your answers to my comments in the text in order to help casual readers who may have similar doubts or questions. After doing that, the paper is ready for publication. However, before publication, I insist on the following point: 

Original comments 5 and 7 in conjunction with the answer given: the approach using dashpots-springs-masses is the exact one (not of course in front of direct finite-element modeling of the soil). Thus, the conclusion of the cited paper '…that the substructure method is not accurate enough to capture all the records and soil properties' is not correct. Please revise and address the issue more carefully and if needed remove this paper. Or explain what you mean by saying 'substructure method'. Winkler model is a substructure method too as far as I understand. 

Author Response

We would like to express our gratitude for your time, insight, and valuable comments. The changed sections or related parts are highlighted in yellow in the manuscript.

The paragraph related to the mentioned journal paper was deleted, and also one adjustment (Highlighted in yellow) in the text was made as follows:

The conclusion part, number 7:

7. Using the simplified method in this study should be alongside careful attention to the validity of using the equivalent linear method instead of the nonlinear method. Because all the records on Soil-C and Soil-D were not eligible based on the limitation of the shear strain index (generally under 0.03%), and the responses were very scattered, especially in the conventional method. Therefore, the simplified method of using springs to represent the soil stratum is rather a simple approach to capture all the major mechanisms involved in soil, SSI, and characteristics of each earthquake ground motion.

Author Response File: Author Response.docx

Reviewer 2 Report

Authors have significantly increased the overall quality of the manuscript. Therefore, the article can be accepted for publication, in its revised form.

Author Response

We are delighted that you found the revised version of the manuscript satisfying and qualified for publication. We would like to express our gratefulness for your time, insight, and valuable comments.

Author Response File: Author Response.docx

Reviewer 3 Report

I recommend to accept this paper after minor revision. Small issues still exist. For example, the figure numbers need to be carefully corrected because they are very disordered. For instance, two different figures are numbered as Figure 3. Please check the table and figure numbers to ensure they're numbered right and cited right in the text.

Author Response

We would like to express our gratitude for your time, insight, and valuable comment. 

The numbers of the tables and figures were checked and corrected.

Author Response File: Author Response.docx