Predominant Frequency in Near-Field Strong Ground Motion by Analysis of Displacement Response Spectra

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Reviewer comments:

 The paper will be ready for publication after some corrections that author have to accomplish.

 ·       On the end of the introduction section, a paragraph describing the main chapters of the work should be inserted so that the reader can form an idea about the most significant parts of the work;

·       Table 1 seems to exceed the page width limit and needs to be adjusted; to check the permitted page sizes in the journal's rules for authors;

·       Figures 2-20 contain large spaces and must be adjusted so that they can fit better on the page and avoid spaces especially on the end of the page;

·       In the discussion section it is stated that improved values were obtained, but this success cannot be highlighted from the results;

·       The work seems more like a review; It should be developed more on the side of methodology and tool used to obtain the presented results.

Comments for author File: Comments.pdf

Author Response

We do thank this reviewer for the 5 comments and suggestions for improvement; this is what we have done very accordingly:

1) At the end of the Introduction text was added on how the paper is divided, as suggested (yellow highlighting was used for these improvements, and other 3 colors for the other reviews).

2) We have adjusted or reduced the width of table 1; moreover, we have placed the table on one page (it was previously divided); this improvement is not highlighted (yellow) as the table has remained intact, it was only a shape change, as suggested by the reviewer. We would like to point out a) we originally did not submit in that form, and b) that it is expected that the editorial team (journal) will make the final editing of the pages that contain tables and figures.

3) This has already been done: there are now 3 figures per page, so there are no large spaces anymore; again, this improvement is not highlighted because they were mere shape adjustments, but it is an important enhancement

4) In Section 4 when referring to improved values (current second-to-last paragraph) an explanation has been added (highlighted in yellow) to clarify why the new results are not only an adjustment but a positive one, or an improvement.

5) The method section or section 2 has been extended; aspects of the procedure have been added or improved. These enhancements and extensions are highlighted not only in yellow but also in green in the revised paper because a similar comment was given by reviewer 2.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear author,

the paper addresses a topic of relevance. In particular, the importance of the development of innovative approaches for the seismic analysis based on displacement response spectra, instead of the common acceleration one, is well addressed.

This strategy – in my opinion, not a substitute for existing methods but to be used to complement them and for comparative purposes – can orient choices and corrective to increase the safety of important assets (both in terms of design of new buildings and retrofitting of heritage structures).

The paper is worthy of publication after minor revisions; however, the author should keep in mind that while the research is well set up and there are no unbridgeable gaps - concerning both language and scientific content – many aspects as well as bibliographic research deserve to be better cared for.

Please, find attached a detailed list of suggestions that should be followed point by point.

Best Regards.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

A review of the English is needed and more attention to detail is required since some sentences must be entirely revised and few typos are observable in the manuscript. All these issues are reported in detail in the file attached.

Author Response

First of all, we thank the reviewer for considering that the topic is relevant and innovative. Next, we explain the changes and improvements associated to his(her) 4 points or suggestions:

1) Language, template and errors. The paper has been fully reread and its English has been improved and corrected, according to the comments by all 4 reviewers and to own language enhancements after reading again (just a couple of examples of these own enhancements are highlighted in lines 223 and 271, new version). Also, it has been checked that the size of the text outside and inside tables is the same: 10; regarding the table, its general size has been reduced and it is now on one page. Also, the reviewer gave us, of which we are thankful, a list of subpoints or errors, starting at line 15, we have changed or corrected all, which is shown by the green highlighting in the revised paper.

2) Method. The method section or section 2 has been extended; aspects of the procedure have been added or improved. In particular and as suggested, our consideration of site condition was explained more; this enhancement is in the fourth paragraph. Moreover, applications in professional practice were included, also as suggested. These enhancements and extensions are highlighted not only in green but also in yellow because a similar comment was given by reviewer 1.

3) Figures. The figures have been edited and rearranged, and considering also that the text or explanations have been extended, now the count is more text pages than figure pages.

4) Introduction and state of the art. We have truly studied several papers of this research team from Italy, not only the two indicated in the review. From all these research papers of this group, the one closest to Earthquake Engineering or to our paper is “Enhancement of thermographic images as tool for structural analysis in earthquake engineering”; as a matter of fact, we have referred to it when discussing that fixed or common structures do not reach more than 5 s in natural period, as it is shown in this paper published in the journal NDT&E International (2015) for real buildings.

5) Results, discussion and conclusion. We thank the reviewer for considering that more credit should be given to the work outcomes. We have added more information to Sections 3 and 4, as suggested, and this is clear from the revised paper by noting the changes highlighted in green. Just as example of improvement in this sense, in Section 3, are lines 171-174 where it has been stressed the contribution. And as just examples, from Section 4, are lines 312 and 315 where more detail has been given and the language has been changed to emphasize the contribution in comparison to previous negative results. Two additional enhancements in the sense of giving more credit to the work are highlighted in other two colors because reviewers 1 and 4 also indicated improvements in these 2 sections; these are in the last paragraph of Section 3 (blue) and lines 358-360 (yellow).

Reviewer 3 Report

Comments and Suggestions for Authors

(1) I made some correction suggestions in the manuscript (see attachment). The author or authors either take these suggestions into consideration or explain why did not take them into consideration,

(2) It would be more elegant for author or authors th show the figures in the manuscript as Figure both in the text and in figure captions and

(3) The references in the manuscript must be written both in the text and in the references section strictly following the rules of the journal

Comments for author File: Comments.rar

Comments on the Quality of English Language

English language is in a good quality

Author Response

We thank the reviewer for attaching the manuscript with corrections and for considering that the English is of good quality. All the corrections suggested were done, and these are highlighted in purple for transparency in our revised manuscript. Every “Fig” instance was changed for Figure, and the References were listed according to the journal guidelines.

Reviewer 4 Report

Comments and Suggestions for Authors

First, I would like to thank the author for his valuable efforts to advance our knowledge of seismology. In this study, by analysis of displacement response spectra, has been tried to estimate predominant frequency of near-field strong ground motion , the methodology previously explained by author  ( Ref.[10]), and  present study further demonstrates its application for near field ground motions. Therefore, I think the technical merit and originality of the paper is somewhat low. 

Comments :

1-      The number of selected earthquakes is not adequate to develop a general conclusion about the mean predominant frequency of Near-Field earthquakes and site effects .

2-       What is the criteria to recognize and consequently develop near-field ground motion records set? Whether distance is only criterion ( this is inferred from the text, Line 136-137)  or other phenomenon such as forward directivity, fling step, large rupture , --- are considered when records are selected ?

3-      the author concluded that  the mean predominant frequency of near-field earthquake is a bout 0.15 Hz which is much far from fundamental frequency of common structures. this means that such records are not considered  a serious concern for engineering structures ,which is some what amazing   

4-      text English is not fluent and require to be rewritten 

Comments on the Quality of English Language

4-      text English is not fluent and require to be rewritten 

Author Response

We thank the reviewer for considering that this effort on Seismology is valuable, even though he(she) considers that originality or the difference with our previous work is not very high. We try to clarify the contribution of this work with answers to the 3 comments in the review, and by highlighting associated changes and enhancements with light blue in the new manuscript (which is the fourth color used as there were 4 reviewers):

1) In regards to the number of earthquakes, we have rewritten and explained more in the last paragraph of Section 3, about the notability and nonrandom nature of the selected set of twenty events (please note the blue highlighting of enhancements). That is, the set is composed by 20 events but these are not just any set. Moreover, a new paragraph was added at the end of Section 4 to transmit that in future work more seisms will be analyzed. The point is that in this work the idea was to present both the shape of the spectra (plots) and the respective predominant frequencies (table). As Kramer indicates in his well-known book (Geotech. Earthq. Eng., p. 76) one thing is the shape of the spectrum and another the predominant period. First, we wanted to study both but this takes space because of the plots; that is, once the content or shape has been studied (here) in further projects we will analyze many more events, but concentrating only on the predominant frequency, and in that second stage a table suffices. In other words, a paper with 30 or 40 plots (spectra) may not be elegant, or even acceptable by journals.

2) This question is answered in the first paragraph of Section 3; the addition is highlighted in light blue and a new reference is included regarding fault rupture directivity.

3) Since a predominant frequency of 0.15 Hz (or period of 7 s) was a surprise, and discovery, to us as well, we had already commented over this in the Discussion section. It is or was in the last paragraph of that section (now second to last because of changes). That paragraph starts: “It can also be argued that the predominant period obtained of ~ 7 s may not be very useful in Earthquake Engineering or in design codes, because there are basically no standard buildings that have that level of natural period [18]; however, newer isolated structures…” Still, there are additions and improvements in that paragraph that discusses the application to isolated buildings.

4) The paper has been fully reread and its English has been improved and corrected, according to the comments by all 4 reviewers and to own language enhancements after reading again; just a couple of examples of these own enhancements are highlighted in lines 223 and 271, new version.