Experimental and Numerical Investigation of the Anti-Overturning Theory of Single-Column Pier Bridges
Round 1
Reviewer 1 Report
The paper concerns about the overturning on-site and numerical investigation of a single-column bridge. The results of the experimental test are used to cross-validate the numerical model. Once it has been showed the elastic model better simulate the experimental results, sensitive analyses are performed to analyse the influence of various parameters on the overturning capacity of the bridge.
The paper is well organized and provide some usefull results. However, this reviewer thinks that considering the following comments have to be consdiered to improve the overall quality of the work carried out.
1 1. English has to be revised, with particular focus on the technical words. For instance, it is quite unusual to use the word “car” for what in reality is a “truck”.
2. In the introduction section, the authors should spend a few words on the importance of assessing the structural response of bridges up to collapse, thus justifying their specific objective.
On the other hand, considering the work is mainly focused on numerical modelling, they should also provide an extended description of available modelling approaches employed to model the structural response of bridge components/systems. Thus, referring to the application of simplified FEM approaches as, for instance, the fiber FB-based models in [1], 3D solid model similarly to the one adopted in the present study, e.g. in [2], and those more advanced based on discrete element modelling prone to explicitly assess the bridge failure mechanism also in case of decks subjected to a combined torsional-flexural action as shown in [3].
3. Please, make clearer the difference between the rigid and elastic models adopted for the subsequent analyses. I did not clearly understand why you refer to an “elastomer” rather than “elastic model”. I suggest adjusting the figures’ legends too.
4. In Section 2.3 additional technical details should be provided for justifying the position of loads, e.g., considering the theory of influence lines and/or torsion demand.
5. Please at line 263, give some references about.
6. For what concern the numerical modelling additional details should be given for a better characterization. Indeed, the specification of the mesh discretization adopted for the various structural components is not enough, thus details of material properties (e.g., Young and Shear moduli assumed), constitutive relationship for contacts, etc.
7. For the box-girder section of the main deck should be provided additional details. In particular, the torsional and flexural inertias, the cross-section area…
8. It is preferable that Figure 11 includes additional details, for instance, adding a view of the cross-section and a zoom view at bearings location.
9. It would be appreciated if technical justifications are given for the assumed variations of the explored parameters from Section 4.1 to Section 4.5. Indeed, I would like to note that the design characteristics also account for additional constraints (e.g., related to other loads and economic aspects).
10. I do not clearly see the necessity of investigating the modification of the concrete self-weight (Section 4.3). On the other hand, to me is more meaningful a modification of the superimposed non-structural loads (G2) that it is very common to happen in existing bridges for instance due to the re-asphalting operations (see for instance [3]). Please introduce a clarification of the assumptions, or state this is a simplified way of considering a variation of G2 loads.
Please consider the main comments given above for introducing changes. This reviewer believes the article needs major revisions; thus a re-review is required.
REFERENCES
[1] Scattarreggia, N., T. Qiao, and D. Malomo. 2021. “Earthquake Response Modeling of Corroded Reinforced Concrete Hollow-Section Piers via Simplified Fiber-Based FE Analysis.” Sustainability 2021, Vol. 13, Page 9342, 13 (16): 9342. Multidisciplinary Digital Publishing Institute. https://doi.org/10.3390/SU13169342
[2] Xu, Z., X. Lu, H. Guan, X. Lu, and A. Ren. 2013a. “Progressive-Collapse Simulation and Critical Region Identification of a Stone Arch Bridge.” Journal of Performance of Constructed Facilities, 27 (1): 43–52. American Society of Civil Engineers. https://doi.org/10.1061/(ASCE)CF.1943-5509.0000329.
[3] Scattarreggia, N., W. Galik, P. M. Calvi, M. Moratti, A. Orgnoni, and R. Pinho. 2022a. “Analytical and Numerical Analysis of the Torsional Response of the Multi-Cell Deck of a Collapsed Cable-Stayed Bridge.” Eng Struct, 265 (114412). https://doi.org/10.1016/j.engstruct.2022.114412.
Author Response
Dear Reviewer,
Thank you for your comments, which were valuable for improving our paper. The manuscript was carefully revised according to your suggestions. Our response to your comments is attached.
In addition, we found that the language needed to be improved to give the reader a clear understanding of the main points of our paper. Therefore, we used American Journal Experts (AJE) to polish the language of our modified manuscript. With their help, some grammatical errors and awkward sentences were corrected in the modified paper.
Best regards,
Qingfei Gao
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper studies the anti-overturning problem of single-column pier. Based on the field anti-overturning stability test of concrete continuous box girder bridge with single-column pier at K503-647.4 of expressway, and using the finite element analysis software ANSYS to simulate the field test, the effects of side-span ratio, bridge span, support spacing and eccentricity on the anti-overturning stability of single-column pier are discussed, and the relevant suggestions for anti-overturning stability design and reinforcement of single-column pier are given. This paper has a certain engineering application value. On the whole, the research content of this paper is only to verify the existing theoretical research on anti-overturning of single-column piers, and the innovation is not prominent enough, so it is suggested to revise it again.
Questions and suggestions:
1. The field test is a highlight of this paper. In this paper, the author gives a more complete introduction to the early test design, including the selection of loading vehicles, the arrangement of measuring points, data collection and so on, but there is a lack of explanation of the loading phenomenon in the test process. for example, the overall deformation state of the main beam under the vehicle partial load. The reviewer suggested that the relevant instructions during the test should be supplemented.
2. For the specific layout of loaded vehicles, only the lateral partial load arrangement is introduced, and the specific layout form of vehicle longitudinal bridge is not clearly introduced, only figure 6 shows the introduction of three kinds of vehicle working conditions. and the corresponding load conditions are not explained in the parameter analysis of section 4. Most of the previous studies are aimed at the anti-overturning of the specific single-column piers with overturning accidents, and the most unfavorable vehicle load arrangement is considered to be when the accident occurs, the reviewers think that this paper only discusses the vehicle load. It is suggested to supplement the most unfavorable discussion on the longitudinal bridge layout of vehicle load.
3. Sections 2.4 and 2.5 of the paper introduce the test of the displacement in the middle of the span and the strain of the bottom plate and web of the box girder, but the test data of this part are not reflected in the subsequent analysis, and the whole beam is deformed in the process of overturning loading. however, this phenomenon is not explained in this paper. The reviewers suggest that the function and analysis of the arrangement of the measuring points in this part should be further supplemented, and the explanation of the deformation of the beam under the action of partial load should be added.
4. The main work of this paper is to compare the supporting force at each pier support under the action of vehicle eccentric load, and through the law that the supporting force of the two supports at the abutment position is different caused by the vehicle eccentric load under different working conditions.To a certain extent, it shows that the reaction force of bridge piers changes with the partial load of vehicles. The change of the reaction force at the bearing of the single-column pier bridge until the void is only the first initial stage of the overturning failure of the bridge, But the subsequent bearing deformation and the overall slip of the structure are also the focus of the study, although a refined finite element bearing simulation is established in this paper, the supporting force of the bearing is only extracted. As a result, the innovation point of the research work is not prominent enough, so it is suggested to supplement the relevant data analysis.
5. It is suggested that the chart number and text errors of the paper should be verified again, for example, the number of figure 7 is missing, and the description of size unit is missing in figure 3.
Author Response
Dear Reviewer,
Thank you for your comments, which were valuable for improving our paper. The manuscript was carefully revised according to your suggestions. Our response to your comments is attached.
In addition, we found that the language needed to be improved to give the reader a clear understanding of the main points of our paper. Therefore, we used American Journal Experts (AJE) to polish the language of our modified manuscript. With their help, some grammatical errors and awkward sentences were corrected in the modified paper.
Best regards,
Qingfei Gao
Author Response File: Author Response.pdf
Reviewer 3 Report
The highlight of this study can be the field test of a sample bridge. However, only the design of the test is given and the corresponding description is even too brief and rough. The phenomena during the loading are not mentioned. Besides, the discussion on the test results is somewhat “superficial” since only the bearing reaction forces are investigated, neglecting the other measured values mentioned in Section 2.4 and 2.5, such as the deformations or strains of the main girder. The other parts such as the theory, the modeling method, influencing factors and the conclusions of this study seem to be less novel compared with the literature review in Introduction.
(1) Some sentences are too difficult to read. For example, the last sentence in Abstract, the second sentence in the second paragraph of Introduction.
(2) In Section 2.3, only the spacing of the multiple vehicles is shown in Figure 6, but the vehicle loading location in the most unfavorable case is not given in detail. It is recommended to draw the distribution of the vehicles in the elevation.
(3) In Section 2.4 and 2.5, the locations of the measuring points in the bridge layout are still confusing and more importantly, the measured strains and the displacements of the girder seem useless in the following content of the manuscript.
(4) The description of the theoretical calculation method in Section 3.1 can be very confusing, redundant and little relevant to the following content of the manuscript. For example, the American code is mentioned to control the bearing stress at first, but all the following content seems to be little relevant. Besides, is there any difference between Formula (1) and Formula (2)? If not, then why are the two Chinese codes separately and detailedly introduced?
(5) More details of the numerical model should be provided in Section 3.2. Firstly, the dimensions and material properties (especially the compression modulus) of the bearings should be given. The reaction forces of the bearings without eccentric loads should also be provide. Besides, since not all readers are familiar with ANSYS, please briefly describe the basic mechanical behavior of the selected element. For example, please explain whether solid65 is an elastic element or a nonlinear element which can simulate the full tensile and compressive behaviors of concrete.
(6) In the reviewer’s opinion, Figure 12 - Figure 17 should be presented in tabular form or plotted as histograms but not line charts. The reason is that the abscissas of these figures are bearing number without any physical meaning. What do the slopes among the points mean? For the same reason, Figure 19 – Figure 22 can also be presented in the form of line graph since the abscissas are with physical meaning and the line graph is more proper to show the relationship between the x-data and y-data (It doesn’t mean that the histograms cannot be used in this case).
(7) In Line 285, what does “the abutment of the side pier of the single-column pier bridge” mean?
(8) The word “ASNYS” in Line 327 in Page 11 should be revised as “ANSYS”.
(9) The descriptions should be more concise. For example, in Line 350 in Page 12, the description “between the finite element model of the rigid body and the finite element of the elastic body” is too redundant.
(10) In Line 400 – 402 in Page 15, the expression “Because the single span of each finite element model bridge is small, the span of each bridge span should be kept consistent in the same model” is confusing. What does it mean?
(11) In Conclusion in Page 18, it is recommended to merge the first two points.
Author Response
Dear Reviewer,
Thank you for your comments, which were valuable for improving our paper. The manuscript was carefully revised according to your suggestions. Our response to your comments is attached.
In addition, we found that the language needed to be improved to give the reader a clear understanding of the main points of our paper. Therefore, we used American Journal Experts (AJE) to polish the language of our modified manuscript. With their help, some grammatical errors and awkward sentences were corrected in the modified paper.
Best regards,
Qingfei Gao
Author Response File: Author Response.pdf
Reviewer 4 Report
In this research, the authors have introduced a study tackling the anti-overturning theory of single-column pier bridges, where a case study is developed by considering the separation overpass of the He-Da Expressway. The overturning stability test is developed by using ANSYS platform alongside the onsite test. The relationship between the design parameters of single-column pier bridges and the ability of a bridge to resist collapse are studied, and a theoretical basis for the anti-overturning design research and effective reinforcement of single-column pier bridges is provided. Subsequently, a comparison is employed between the onsite investigation and analytical results by considering the error percentage on different number of supports. This research topic is considered interesting, but I think that this study needs more work to be considered for publication. Where the literature review should include more details. Moreover, the methodology and main problem of the research should be described significantly. Finally, the datasets are not utilized and compared extensively/efficiently. Due to these facts, the paper should go through major revisions. Some detailed comments are added in the following to enhance the paper.
1. The abstract serves more as a statement of objectives than a comprehensive summary of the entire article. The methodology and is not sufficiently explained, the results are not stated, and the conclusions are not apparent. Not all parts are covered.
2. In the introduction the authors should discuss more the structural modeling-related uncertainties on the overturning stability demands by considering the past case studies regarding the developed numerical models and experimental onsite investigation that are performed for different approaches that consider the anti-overturning design. Additionally, an overview of the different countermeasures and mitigations for reducing the overturning stability should be added. Moreover, the authors should describe more about the existing highway bridge specifications in China that do not make clear provisions on the lateral overturning stability of bridges, which leads to many bridge overturning accidents under the action of certain overloaded vehicles, although they meet the requirements of the design specifications, because this will reflect the main issue of the present research. Moreover, the authors should discuss different cases that have been developed around the world for instance studying the lateral overturning stability of curved single-column pier bridges. See the following and other related references and add them to the literature for more information:
· Ge, L., Dan, D., Yan, X. and Zhang, K., 2020. Real time monitoring and evaluation of overturning risk of single-column-pier box-girder bridges based on identification of spatial distribution of moving loads. Engineering Structures, 210, p.110383.
· Dong, F. and Zhang, H., 2022. Probabilistic Safety Factor Calculation of the Lateral Overturning Stability of a Single-Column Pier Curved Bridge under Asymmetric Eccentric Load. Symmetry, 14(8), p.1534.
3. In The methodology there should be some more clarification regarding the structural system investigation where the authors should focus more on the variations in support reactions, weight distribution (identification system of moving loads), stiffness, and strength of the structural system used and try to build a comparative study by varying these parameters. These are important parameters that should be clarified extensively.
4. The authors should check the title and change it to be more consistent because using fielding word is not applicable it should be experimental, site investigation or field investigation.
5. The paper lacks proper description with regard to the problem addressed. For instance, how the modeling of adjacent investigated bridge is developed. Additionally, how are the results and developed models verified? What are the main limitations and the investigated parameters that the authors consider it in their models? The displacement measurement and variation should be defined clearly in the methodology and how it was considered in this study. Most importantly these variations should be illustrated with some figures of the developed model in ANSYS.
6. The results should be analyzed and discussed extensively because the authors are not shedding the light on the most important outcome of the research. The results are only being stated without comparison between them or with other studies done before. The comparative section should be more extensive when comparing the main results described in models taking into consideration the different introduced parameters. The authors should shed the light on the significance of this paper which is the variation between the experimental onsite investigations and the analytical model and how they can be compared, and what are the main reasons behind the variation between them. This can be covered by adding a table or small paragraph that compares the varied values. This comparative part will show the readers the important outcomes that have been reached by this research.
7. A paragraph should be added in the conclusion to discuss how this research can help in future work. Additionally, the main gaps that can be investigated further in the future should be discussed for instance: how the different types, irregularity of structural systems, and typologies of bridges, will be covered by the developed approach. Moreover, how this comparative study can be built to develop new and innovative approaches. Subsequently, the solutions should be given such as using different types of foundations or rehabilitating the bridge with different bracing structural systems that should be further investigated in the future for different bridge types and typologies.
General comment: The English and writing style should be reviewed and improved in the paper there are mistakes especially in using transitional words. Some of the references are having the year in bolt but other the year is written normally check the references number (16 to 30) the references should be modified based on MDPI template.
Author Response
Dear Reviewer,
Thank you for your comments, which were valuable for improving our paper. The manuscript was carefully revised according to your suggestions. Our response to your comments is attached.
In addition, we found that the language needed to be improved to give the reader a clear understanding of the main points of our paper. Therefore, we used American Journal Experts (AJE) to polish the language of our modified manuscript. With their help, some grammatical errors and awkward sentences were corrected in the modified paper.
Best regards,
Qingfei Gao
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have accounted for the comments of this reviewer.
Author Response
Dear Reviewer,
Thanks for your help and good comments.
Regards,
Qingfei
Reviewer 2 Report
All the review comments have been properly answered, and it is suggested to publish this paper.
Author Response
Dear Reviewer,
Thanks for your help and good comments.
Regards,
Qingfei
Reviewer 4 Report
Figure 14 and Figure 15 need to be improved.
Author Response
Dear Reviewer,
Thank you for your comments, which were valuable for improving our paper. The manuscript was carefully revised according to your suggestions. Our response to your comments is attached.
Best regards,
Qingfei Gao
Author Response File: Author Response.pdf
Round 3
Reviewer 4 Report
Authors revised comment accordingly
