Multiple Tests for Dynamic Identification of a Reinforced Concrete Multi-Span Arch Bridge
Round 1
Reviewer 1 Report
(1) The paper deals with dynamic identification of reinforced concrete (RC) bridges through ambient vibration tests. In particular, experimental tests were carried out on different spans of a RC multi-span arch bridge under bridge service conditions. Simplified finite element models of the bridge were developed and calibrated considering the experimental results, resulting in relatively reliable estimations. The study proves that the proposed monitoring approach could be efficiently implemented to continuously assess the dynamic properties of bridge structures, towards more reliable and efficient structural health monitoring processes.
(2) The research study presented in the paper would potentially contribute to both scientific literature and current monitoring practice. As a matter of fact, the proposed monitoring approach (with related FE model) was found to be potentially efficient, and the application presented in the paper provides technical guidance for implementation and further development of the monitoring processes. However, the manuscript should be revised since there are minor formal and substantial issues, including moderate English changes required. Therefore, the result of the review assessment is MINOR REVISIONS. The detailed review comments are reported as margin comments in the reviewed manuscript report document.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
The article addresses an important and very interesting topic of the recursive/multiple tests for dynamic identification on a reinforced concrete multi-span arch bridge, which is appreciated. The study includes the experimental and numerical research. In this paper shows the results of an experimental research related to the dynamic behavior of a reinforced concrete multi-span arch bridge. The paper aims to point out the critical aspects in the Structural Identification and manual model updating of a complex structure. The Reviewer has some concerns regarding the introduction, numerical analysis, results, conclusions and references. In addition, the English language is good but some sentence should be more clear. Please check the text of Native Speaker. In opinion of Reviewer this paper should be subjected to major revision.
Other comments:
- Please explain more clearly what differences are between your research and previous research cited in the text (more detailed)? In addition, please explain more clearly what is new of your research?
- The introduction should be more enriched with papers on the topic of non-destructive test e.g.:
- https://doi.org/10.1016/j.ndteint.2011.04.001,
- https://doi.org/10.1155/2013/504958
- https://doi.org/10.1080/15732471003645666
- https://doi.org/10.1016/j.engstruct.2016.08.060
- https://doi.org/10.3390/ma13081846
- Please show the boundary conditions in numerical models. This aspect is very important due to the correct updating numerical models with experiment.
- Please show the mode shape for first five frequency and in addition, please try to explain tendency and compare their behaviour.
- What is value of damping ratio for your numerical research in modal analysis?
- Line 243 – 244 – please shown the directions on the Figure.
- Line 388 – 389 – why are you analysing the elastic and linear behaviour if your load had a dynamic character.
- What is mean in the lines 134-136 (“Moreover, some peculiarities provided by recursive or multiple experimental dynamic tests will be also highlighted”), line 272 (“n°3”), line 387 (“n°3”) etc.?
- In the experimental research you shown the time history record (Figure 8 and 9). In numerical analysis you don’t used any dynamic excitations, thus please explain the time history records of figures 13. This is true?
- Table 5 – please explain in detail the differences of these results.
- In the discussion, please compare your results with similar research, which were cited in the text. In addition, please explain the tendency and what have impact of your research.
- What is the density of FE in numerical program?
- Please improve the conclusions, because of in current version are poor, simple and obvious. Please show the most important tendency/mechanism of your research.
- References are really poor. Please add a few papers about similar research (look on the point 2). This is good journal of your research? The Reviewer cannot see paper from Buildings Journal.
And the end I hope that my comments will be helpful for the Authors.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The paper presents an experimental dynamic campaign on a 5-span reinforced concrete arch bridge over the river Tevere in Rome. Modal parameters have been identified through the Enhanced
Frequency Domain Decomposition (EFDD) procedure. In parallel a finite element numerical model has been implemented through a commercial software. By varying the E-module of concrete close relation between experimental-numerical vibration frequencies and modes has been achieved.
Comments:
- Affiliation No 3 is missing
- A sketch of the bridge cross section(s) should be added.
- 5: The no. of spans should be given in that figure too.
- Line 196: Change the phrase: “Ambient vibration tests have been conducted on n.5 spans of the bridge….” to “Ambient vibration tests have been conducted on 5 spans of the bridge”.
- The position of the accelerometers should be added in Fig. 5.
- Line 278: The accelerometers that have not been considered in the processing must be marked with a different color in Fig. 7.
- Numerical analysis indicates that modal shapes are either translational in z-direction or combined y-translational-rotational. However, the installation of all sensors in the bicycle lane at the edge of the bridge and none at mid-section of the bridge does not allow the clear separation of the different modes. This possibly explains why identical frequencies have been identified in Z- and Y-direction. The authors should provide comments in the text.
- It would be useful if identified damping ratios would be added.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thank you for your improving. In some questions the Reviewer cannot see response of this question. Thus please one more time try to response of these points:
- “Please show the boundary conditions in numerical models. This aspect is very important due to the correct updating numerical models with experiment.“
In opinion of the Reviewer, the Authors response is not suitable to the question.
- “Please show the mode shape for first five frequencies and in addition, please try to explain tendency and compare their behaviour.”
In opinion of the Reviewer, the Authors response is not suitable to the question.
- (RC): What is value of damping ratio for your numerical research in modal analysis?
In opinion of the Reviewer, the Authors response is not suitable to the question. Please check the paper with this type of analysis and cited in the text. In addition, the state of the art in this paper should be enriched the paper with modal analysis.
- “(RC): Line 388 – 389 – why are you analysing the elastic and linear behaviour if your load had a dynamic character.
(AR): An elastic-linear dynamic analysis is always possible. The aim of the activity is to optimize the elastic- linear dynamic behaviour based on the information coming by output-only dynamic experimental tests. Therefore, is not important to highlight the presence and the nature of the loads. The approach is very classical and traditional in the field of the dynamic experimental tests on real civil structures.”
So why was analysed this aspect if as wrote the Authors “An elastic-linear dynamic analysis is always possible” and “The approach is very classical and traditional in the field of the dynamic experimental tests on real civil structures”. What is novelty in this research?
- “(RC): In the experimental research you shown the time history record (Figure 8 and 9). In numerical analysis you don’t used any dynamic excitations, thus please explain the time history records of figures 13. This is true?
(AR): Yes, as explained previously the aim is to improve the modelling by the information coming by the experimental activity. The time histories have been illustrated to show that the acquired measurements have been typical of structural responses under ambiental vibrations. For this reason, has been possible the application of some classical identification procedures to such recorded accelerations.”
So what is the damping in Time History?
- “(RC): Table 5 – please explain in detail the differences of these results.
(AR): As explained in the manuscript, these are the differences between experimental (identified) and numerical frequencies using nominal parameters. Subsequently, such differences have been improved varying the value of the Elastic Modulus (E).”
In opinion of the Reviewer, the Authors response is not suitable to the question.
- “(RC): In the discussion, please compare your results with similar research, which were cited in the text. In addition, please explain the tendency and what have impact of your research.
(AR): Some other comments have been added in the discussion section of the revised manuscript.”
In opinion of the Reviewer, the Authors response is not suitable to the question.
- “(RC): What is the density of FE in numerical program?
(AR): If the reviewer means the mass density, the following values have been added in the manuscript: for cls 25 KN/m3 while for steel 76,98 KN/m3.”
In opinion of the Reviewer, the Authors response is not suitable to the question. The Reviewer would like to know how is density of mesh of finite element (FE)?
- “(RC): References are really poor. Please add a few papers about similar research (look on the point 2). This is good journal of your research? The Reviewer cannot see paper from Buildings Journal.
(AR): Yes, the authors think that the selected Journal can be considered reasonable for this type of research. Moreover, the manuscript has been submitted for a Special Issue titled “Advanced Methodologies and Technologies in Structural Monitoring”. In any way, the references have been enriched.”
In opinion of Reviewer, the references are really poor. The number of 23 references is not acceptable in scientific paper. Below you can find some papers from numerical analysis with modal analysis:
- https://doi.org/10.1016/j.ymssp.2018.07.026
- https://doi.org/10.1016/j.tust.2020.103808
- https://doi.org/10.1016/j.istruc.2022.02.040
- https://doi.org/10.1016/j.measurement.2021.109048
- https://doi.org/10.1016/j.ymssp.2021.107855
- https://doi.org/10.1016/j.istruc.2022.03.063
- http://dx.doi.org/10.1016/j.engstruct.2017.08.066
Please read these papers and if the Authors agree with the Reviewer please add to the references. In addition, please find other papers.
And the end I hope that my comments will be helpful for the authors.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
Thank you for your improving. I have last comment i.e. please improve the title of your paper. The current title "Recursive/Multiple tests for dynamic identification on a reinforced concrete multi-span arch bridge" is good but use this combination "Recursive/Multiple..." is not acceptable. In my opinion the title of "Multiple tests for dynamic identification on a reinforced concrete multi-span arch bridge" will be sufficient.
Author Response
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Author Response File: Author Response.pdf
