Seismic Responses of Aqueducts Using a New Type of Self-Centering Seismic Isolation Bearing

Round 1

Reviewer 1 Report

This study carried out a series of shaking table tests of aqueducts isolated by IPGB, and the simulated method of IPGB is also proposed in this paper. In general, this study is real and interesting, some minor issues need to be revised to improve this paper.

1. On page 2, Line 45-47: the author mentioned that the displacement of FPB and LRB is always much larger when the intensity of ground motions is large. Who did this comparison between FPB, LRB and new isolation bearings? What’re the advantages of the new isolation bearings? No reference is citied in this sentence while this is the key problem that the reader may be interested in.

2. In Introduction, corresponding description of the IPGB is too limited. This is one of the main problems in this study. The author is suggested to supplement the description of IPGB in the section of Introduction.

3. On page 10, Line 228: the author displayed the seismic isolation rate of IPGB here, one major problem here is that the author seemed to neglect the effect of vertical ground motions at all. Existing research demonstrated that the vertical ground motion has a significant impact on the seismic isolation rate especially in near-fault regions. Please explain why did the author neglect the effect of the vertical ground motions?

Chen Z, Jia P. Seismic response of underground stations with friction pendulum bearings under horizontal and vertical ground motions [J]. Soil Dynamics and Earthquake Engineering, 2021, 151: 106984.

4. In section 5, what kind of element is selected by the author to simulate the pier? The detailed information of the simulation should be provided by the author, especially the piers as these strongly influences the relative motion of the IPGB. Some of the latest related reference about the pier modelling should be considered in the manuscript.”

Zhong, Jian; Shi, Longfei, Yang, Tao; Liu, Xiaoxian; Wang, Yixian. Probabilistic seismic demand model of UBPRC columns conditioned on Pulse-Structure parameters. Engineering Structures. 2022, 270:114829.”

Zhong Jian; Zheng, XiangLin; Wu, Qiaofei; Jiang, LinWei, He, Min; Dang, XinZhi. Seismic fragility and resilience assessment of bridge columns with dual-replaceable composite link beam under near-fault GMs. Structures 2023; 47: 412-24.

5. In section 5, when the author simulated the IPGB, the friction coefficient seemed to be assumed as a constant. However, the friction coefficient highly depends on the variation of the velocity. Please explain the reason.

Wen J, Han Q, Du X. Shaking table tests of bridge model with friction sliding bearings under bi-directional earthquake excitations [J]. Structure and Infrastructure Engineering, 2019, 15(9): 1264-1278.

 

6. Some grammar mistakes should be revised.

Author Response

Dear reviewer：

We appreciate the time and effort you have dedicated to providing insightful feedback on ways to strengthen our paper. Thus, it is with great pleasure that we resubmit our paper for further consideration. We have incorporated changes that reflect the detailed suggestions you have graciously provided. We also hope that our edits and the responses we provide below satisfactorily address all the issues and concerns you have noted.

 

Comments and Suggestions for Authors

This study carried out a series of shaking table tests of aqueducts isolated by IPGB, and the simulated method of IPGB is also proposed in this paper. In general, this study is real and interesting, some minor issues need to be revised to improve this paper.

1. On page 2, Line 45-47: the author mentioned that the displacement of FPB and LRB is always much larger when the intensity of ground motions is large. Who did this comparison between FPB, LRB and new isolation bearings? What’re the advantages of the new isolation bearings? No reference is citied in this sentence while this is the key problem that the reader may be interested in.

Response 1: Research of bridge shows that the bearing and residual displacements of FPB and LRB are large under strong earthquakes, and the relevant references have been supplemented in the introduction. The author of this paper has compared the seismic performances of aqueducts using FPBs and IPGBs under the same earthquakes, and the advantage of IPGB is the maximum displacement and residual displacement are smaller.

Takahashi Y. Damage of rubber bearings and dampers of bridges in 2011 Great East Japan Earthquake. Proceedings of the International Symposium on Engineering Lessons Learned from the 2011 Great East Japan Earthquake,2012.

Liu Yanhui, et al. Seismic simulation shaking table test of high pier isolation continuous beam China Journal of Highway and Transport 2015,Volume 28, pp. 60-68+94.

Chen, Y, J., et al. Study on seismic isolation of long span double deck steel truss continuous girder bridge. Applied Sci-ences-Basel 2022.

2. In Introduction, corresponding description of the IPGB is too limited. This is one of the main problems in this study. The author is suggested to supplement the description of IPGB in the section of Introduction.

Response 2: IPGB has the feature of self-centering, which is pointed out in the introduction, and the detailed description of the bearing is shown in the section 2.2.

3. On page 10, Line 228: the author displayed the seismic isolation rate of IPGB here, one major problem here is that the author seemed to neglect the effect of vertical ground motions at all. Existing research demonstrated that the vertical ground motion has a significant impact on the seismic isolation rate especially in near-fault regions. Please explain why did the author neglect the effect of the vertical ground motions?

Chen Z, Jia P. Seismic response of underground stations with friction pendulum bearings under horizontal and vertical ground motions [J]. Soil Dynamics and Earthquake Engineering, 2021, 151: 106984.

Response 3: Due to the limitation of experimental equipment, the influence of vertical ground motion cannot be considered temporarily in this paper. The author will study this problem in the future.

4. In section 5, what kind of element is selected by the author to simulate the pier? The detailed information of the simulation should be provided by the author, especially the piers as these strongly influences the relative motion of the IPGB. Some of the latest related reference about the pier modelling should be considered in the manuscript.”

Zhong, Jian; Shi, Longfei, Yang, Tao; Liu, Xiaoxian; Wang, Yixian. Probabilistic seismic demand model of UBPRC columns conditioned on Pulse-Structure parameters. Engineering Structures. 2022, 270:114829.”

Zhong Jian; Zheng, XiangLin; Wu, Qiaofei; Jiang, LinWei, He, Min; Dang, XinZhi. Seismic fragility and resilience assessment of bridge columns with dual-replaceable composite link beam under near-fault GMs. Structures 2023; 47: 412-24.

Response 4: In this paper, the aqueduct adopts the seismic isolation system, and the pier is basically in the elastic state in the test, so the elastic beam element with a reduced stiffness is used to simulate the pier. The advantage of this simulation is to facilitate the future application of designers and reduce the calculation cost.

5. In section 5, when the author simulated the IPGB, the friction coefficient seemed to be assumed as a constant. However, the friction coefficient highly depends on the variation of the velocity. Please explain the reason.

Wen J, Han Q, Du X. Shaking table tests of bridge model with friction sliding bearings under bi-directional earthquake excitations [J]. Structure and Infrastructure Engineering, 2019, 15(9): 1264-1278.

Response 5: Relevant research shows that using constant friction coefficient to simulate sliding friction can well estimate the displacement of bearing and structure, and fixed friction coefficient is also convenient for further parameter analysis of aqueducts using IPGBs . Therefore, the friction coefficient used in the paper is constant, and the value is 0.03.

Dao, N, D., et al. Predicting the displacement of triple pendulum bearings in a full-scale shaking experiment using a three-dimensional element. Earthquake Engineering & Structural Dynamics 2013, Volume 42, pp. 1677-1695.

 

6. Some grammar mistakes should be revised.

Response6: It has revised in the article.

Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries. We have worked hard to incorporate your feedback and hope that these revisions persuade you to accept our submission.

　　Thank you and kind regards.

Your sincerely,

Dong Yang

Reviewer 2 Report

This paper proposes a new kind of self-centering seismic isolation bearing, Inclined Plane Guide Bearing (IPGB for short), and is studied experimentally/numerically for the aqueduct seismic design.  A typical aqueduct project and the setting of IPGBs are introduced. The shaking table test design, test cases, and test results of two different pier-height aqueducts are presented. Also, a numerical simulation method applicable to trenches with IPGBs is proposed, and the accuracy of the method is verified by comparing the results of the numerical simulation method and the shaking table test. However, there are several issues that the authors must address before the paper is to be accepted. These comments are listed as follows:

 

1. In the numerical modeling section (Sec. 5), the numerical model is absent. It is recommended to add a discretized scheme to this section.
2. There is no mention of how the boundary conditions are applied around the model. It is necessary to explain this issue in detail in a separate section of the paper.
3. The conclusion part of the manuscript is very poorly interpreted. This section needs to be reviewed and the results better displayed.

      4.      To enrich the technical literature, some works about the used approaches can be added to the references.

 

5. The paper requires extensive editorial work.

Author Response

Dear reviewer：

We appreciate the time and effort you have dedicated to providing insightful feedback on ways to strengthen our paper. Thus, it is with great pleasure that we resubmit our paper for further consideration. We have incorporated changes that reflect the detailed suggestions you have graciously provided. We also hope that our edits and the responses we provide below satisfactorily address all the issues and concerns you have noted.

 

Comments and Suggestions for Authors

This paper proposes a new kind of self-centering seismic isolation bearing, Inclined Plane Guide Bearing (IPGB for short), and is studied experimentally/numerically for the aqueduct seismic design.  A typical aqueduct project and the setting of IPGBs are introduced. The shaking table test design, test cases, and test results of two different pier-height aqueducts are presented. Also, a numerical simulation method applicable to trenches with IPGBs is proposed, and the accuracy of the method is verified by comparing the results of the numerical simulation method and the shaking table test. However, there are several issues that the authors must address before the paper is to be accepted. These comments are listed as follows:

 

1. In the numerical modeling section (Sec. 5), the numerical model is absent. It is recommended to add a discretized scheme to this section.

Response 1: The discretization modeling method has been supplemented in section 5, and corresponding references have also been supplemented.

2. There is no mention of how the boundary conditions are applied around the model. It is necessary to explain this issue in detail in a separate section of the paper.

Response 2:The boundary conditions of the model have been supplemented in section 5.

3. The conclusion part of the manuscript is very poorly interpreted. This section needs to be reviewed and the results better displayed.

Response 3:The conclusion of the paper has been revised.

4. To enrich the technical literature, some works about the used approaches can be added to the references.

Response 4: The methods used in the paper are supplemented with corresponding references.

5. The paper requires extensive editorial work.

Response 5:The article has been modified.

 

Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries. We have worked hard to incorporate your feedback and hope that these revisions persuade you to accept our submission.

　　Thank you and kind regards.

Your sincerely,

Dong Yang

 

Reviewer 3 Report

The article presents the verification of the aqueduct structure in the event of an earthquake by means of model testing. However, it is not clear what materials were used for the model tests. Doubts are also raised by the selection of the scale coefficients of the test model. There are inconsistencies and inconsistencies in designations (e.g. "PGA") in the manuscript. Some wording needs rewording.

In its current form, the article is not suitable for publication in Sustainability.

General remarks

1. The authors presented research on models. Were the test results validated against the actual design?

2. The article should explain why such and not other "the similarity ratio of the test model" was adopted (Table 1). Why are some "scale factors" less than 1 and others equal to 1. How can the model chosen in this way correspond to the real structure? It should be described.

3. Describe what type of concrete and type of reinforcing steel was used in the construction of the aqueduct. What concrete were the test models made of?

4. Please explain what kind of reinforcement was used (what parameters) in the tested models.

5. The description should be extended to the comparison of numerical and test methods presented in Figures 17 and 18.

The article is not well written and needs improvement.

Specific remarks

6. 45 line: Explain the abbreviations FPB and LRB.

7. 76 line: The aqueduct consists of girders. Please correct your sentence.

8. 98 line: Explain the abbreviation PTFE.

9. 132 line, Fig. 4 : Explain what D and k mean on the axis of abscissa.

10. 166 line: To be specified in kN .

11. 185 line: The abbreviation PGA should be explained.

12. 187 line: It should be explained in the article what the white noise phenomenon is.

13. 189 line, line 1 : "PAG" or "PGA" should be clarified.

14. 189 line, Table 3: What does the abbreviation "SJ" mean in the table should be described.

15. 228 line: Please add "R".

16. 228 line, Table 5, line 1 : "PAG" or "PGA" should be clarified.

17. 265 line: Incomprehensible. The sentence should be worded differently.

18. 283 line: Please explain the quantities in this sentence.

I recommend reviewing the manuscript with comments to make it suitable for publication in Sustainability.

Author Response

Dear reviewer：

We appreciate the time and effort you have dedicated to providing insightful feedback on ways to strengthen our paper. Thus, it is with great pleasure that we resubmit our paper for further consideration. We have incorporated changes that reflect the detailed suggestions you have graciously provided. We also hope that our edits and the responses we provide below satisfactorily address all the issues and concerns you have noted.

Comments and Suggestions for Authors

The article presents the verification of the aqueduct structure in the event of an earthquake by means of model testing. However, it is not clear what materials were used for the model tests. Doubts are also raised by the selection of the scale coefficients of the test model. There are inconsistencies and inconsistencies in designations (e.g. "PGA") in the manuscript. Some wording needs rewording.

In its current form, the article is not suitable for publication in Sustainability.

General remarks

1. The authors presented research on models. Were the test results validated against the actual design?

Response 1: The test model is designed through the similarity law, and the results of the test model can be scaled to get the results of the actual structure through the similarity ratios.

2. The article should explain why such and not other "the similarity ratio of the test model" was adopted (Table 1). Why are some "scale factors" less than 1 and others equal to 1. How can the model chosen in this way correspond to the real structure? It should be described.

Response 2: The design method of the similarity ratios of the test model is described in section 3.1, and the references of the design method is also supplemented.

3. Describe what type of concrete and type of reinforcing steel was used in the construction of the aqueduct. What concrete were the test models made of?

Response 3: The aqueduct pier is made of C40 concrete and HRB400 reinforcement, and the material used for the aqueduct pier of the test model is consistent with the actual aqueduct. The relevant information is supplemented in section 3.1.

4. Please explain what kind of reinforcement was used (what parameters) in the tested models.

Response 4: The test model uses HRB400 reinforcement. The elastic modulus of reinforcement is 2.08×10⁵MPa, and yield strength is 401MPa. The material parameters of the test model is supplemented in section 4.1.

5. The description should be extended to the comparison of numerical and test methods presented in Figures 17 and 18.

Response 5: It has been revised and the maximum value error between the test and the numerical results has been added in section 5. 

Specific remarks

6. 45 line: Explain the abbreviations FPB and LRB.

Response 6: FPB is short for friction pendulum bearing and LRB is short for lead rubber bearing.

7. 76 line: The aqueduct consists of girders. Please correct your sentence.

Response 7: It is modified in the paper.

8. 98 line: Explain the abbreviation PTFE.

Response 8: PTFE is short for polytetrafluoroethylene.

9. 132 line, Fig. 4 : Explain what D and k mean on the axis of abscissa.

Response 9: D represents the displacement, k is the equivalent stiffness when the restoring force switches between positive and negative values, and Figure 4 has been modified to make it clearer.

10. 166 line: To be specified in kN .

Response 10: It has been modified to the international standard weight unit kg.

11. 185 line: The abbreviation PGA should be explained.

Response 11: PGA is short for Peak Ground Acceleration.

12. 187 line: It should be explained in the article what the white noise phenomenon is.

Response 12: In the shaking table test, white noise is used to get the natural vibration period of the structure and the test results of white noise cases have been given in the paper.

13. 189 line, line 1 : "PAG" or "PGA" should be paper.

Response 13: It has been clarified in the paper.

14. 189 line, Table 3: What does the abbreviation "SJ" mean in the table should be described.

Response 14: SJ is the abbreviation of the name of artificial ground motions.

15. 228 line: Please add "R".

Response 15: It has been added.

16. 228 line, Table 5, line 1 : "PAG" or "PGA" should be clarified.

Response 16: It has been clarified in the paper.

17. 265 line: Incomprehensible. The sentence should be worded differently.

Response 17: The sentence has been rewritten.

18. 283 line: Please explain the quantities in this sentence.

Response 18: The equation has been rewritten to make it clearer.

Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries. We have worked hard to incorporate your feedback and hope that these revisions persuade you to accept our submission.

　　Thank you and kind regards.

Your sincerely,

Dong Yang

Round 2

Reviewer 1 Report

All the comments are well addressed.