Study on a Novel Variable-Frequency Rolling Pendulum Bearing
Round 1
Reviewer 1 Report
The authors developed a novel variable-frequency rolling pendulum bearing for the protection of acceleration-sensitive equipment which will improve the self-centering capacity. The isolation efficiency of the device under different parameters is validated using shake table tests for the four proposed devices and the results are in good agreement at reducing both acceleration and displacement responses. Different types of ground motions, including the short-period (high-frequency), the intermediate-frequency, and the long-period (low-frequency) ground motions are utilized. The theoretical formula of different variable-frequency rolling pendulum bearings is derived for finding out the dynamic characterization of the device. The complementary numerical model of the novel isolation system is also proposed for further studies. The work is found to be very interesting for the readers as well as the methodology of the work is also appropriate. The work is original and contains new results that advance the research field. The work can be accepted for publication in the journal after doing a proofread for English correction and the equation number should be checked throughout the manuscript.
Author Response
Special thanks to you for your good comments.
Reviewer 2 Report
Dear authors,
I would like to thanks the authors.
First of all please explain the innovativity of the research clearly in the introduction part. For example what are the differences of this research with following researches?
*An innovative isolation bearing for motion-sensitive equipment, DOI: 10.1016/j.jsv.2009.06.022
*Dynamic Behavior of a Simple Rolling Seismic Isolator with a Position Restoring Device
by Sung Chul Hong and Deog-Jae Hur
*Seismic resilient design with base isolation device using friction pendulum bearing and viscous damper
By Xu Chena & Jianfeng Xiong
*Effect of viscous damping devices on the response of seismically isolated structures
By E. D. Wolff ^Cengiz Ipek &Michael C. Constantinou ^Mucip Tapan
*Seismic behavior of variable frequency pendulum isolator
By V. R. Panchal & b R. S. Jangid
1- Please add some up-to-date research (2020 , 2021) to the introduction and references part.
2- Please add some references about combining the viscous damper and base isolation like:
Cost-benefit analysis of seismic-isolated structures with viscous damper based on loss estimation. doi:10.1080/15732479.2016.1236131
3- The abstract may rewrite and provide the numerical results clearly.
4- Please add the quantitative and numerical results to the “ section 6”.
5- Combine some pictures in on picture and name them a, b, … like Fig 27&28 or 39&40 so on. Therefore the number of figures will decrease.
6- Please explain why equation 19 &20 assumed to be zero.
7- Add the specification of viscous damper of experimental program, C? linear or non linear damper?
8- What do you mean by “stable performance” in the following sentence: “ The viscous dampers with stable performance should be incorporated into the isolation bearings. Indeed can we have the viscous damper with stable performance in real seismic events and also considering temperature?
9- Authors should do a thorough review of some paragraphs that seem confusing or difficult to understand.
- There are some blanks in lines like 771 & 814 (re sults), …
11- Specify the maximum error between numerical simulation and experimental program (Fig 58 & 60)
Author Response
Dear Editors and Reviewers:
Thank you for your letter and the reviewers’ comments concerning our manuscript entitled “Study on a novel variable-frequency rolling pendulum bearing” (ID: buildings-1552427). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and made correction which we hope meet with approval. Revised portions are marked in blue in the paper. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:
Reviewer #2:
- Response to comment: (First of all please explain the innovatility of the research clearly in the introduction part. For example, what are the differences of this research with following researches?)
Response: Compared with other isolation devices proposed in the literature, this rolling isolation device is developed as a replacement of sliding isolators in the seismic protection of acceleration sensitive equipment and cultural artifacts in order to minimize residual displacements. Aiming to limit large displacements due to resonance effects, possibly caused by near-fault and long-period ground motions, the variable frequency capability is introduced by using variable curvature rolling surfaces. Meanwhile, viscous damping is added by incorporating fluid dampers within the device to improve energy dissipation performance. It is worth noting that the various tools incorporated in the device are all well known in the literature and in practice, having been used separately in earthquake engineering studies and projects, so that these components can be easily reassembled and mass-produced to protect the acceleration sensitive cultural relics.
In fact, we have stated the scope and the innovation of this research in section 2. To avoid confusing readers, we have combined these two sections into one.
- Response to comment: (Please add some up-to-date research (2020, 2021) to the introduction and reference’s part.)
Response: According to the Reviewer’s suggestion, we have added several latest references published in 2020 and 2021, such as Reyes et al. (2020), Koo et al. (2022), Lal et al. (2022), Hsu et al. (2021), etc.
- Response to comment: (Please add some references about combining the viscous damper and base isolation.)
Response: According to the Reviewer’s suggestion, we have added some references about combining the viscous damper and base isolation, such as Banazadeh et al. (2017), Erkal et al. (2011), Hur et al. (2020), Deringöl et al. (2021), Lal et al. (2022), etc.
- Response to comment: (The abstract may rewrite and provide the numerical results clearly.)
Response: We have written the abstract for the simulated aspects. The simulated results, including relative acceleration responses, relative displacement responses and movement locus of the upper plates, are compared with the shaking table test results.
Due to the limitation of abstract length, we just give a brief description of the goodness of agreement between the simulation and the experiment. More details can be found in section 4 and 5.
- Response to comment: (Please add the quantitative and numerical results to the “section 6”.)
Response: According to the Reviewer’s suggestion, we have written the conclusion part of this paper. The quantitative and inductive descriptions of the numerical results are added to the “section 5” to make the conclusions more convincing.
- Response to comment: (Combine some pictures in on picture and name them a, b, … like Fig 27&28 or 39&40 so on. Therefore, the number of figures will decrease.)
Response: Considering the Reviewer’s suggestion, we have condensed the image numbers, and the number of figures have been reduced from 60 to 37.
- Response to comment: (Please explain why equation 19 &20 assumed to be zero.)
Response: The original form of equation 19 &20 can be expressed as the attachment states.
It is obvious that the mass of the rolling ball is much smaller than the mass of the upper support plate, so that m2/(M+m1) ≈0. Meanwhile, the equation inside the curly brackets has a finite value. Thus, equation 19 &20 can be approximately zero.
- Response to comment: (Add the specification of viscous damper of experimental program, C? linear or nonlinear damper?)
Response: The viscous dampers utilized in the experimental program are linear dampers. To avoid ambiguity, we have highlighted this in the 240th and 421th line.
- Response to comment: (What do you mean by “stable performance” in the following sentence: “The viscous dampers with stable performance should be incorporated into the isolation bearings. Indeed, can we have the viscous damper with stable performance in real seismic events and also considering temperature?)
Response: The reason why we stress out “stable performance” in the 872th line is that the viscous dampers utilized in the program did not work well during the tests. The damper somewhat stuttered during operation, and the damping system did not demonstrate stable performance as expected. Given these, we wish that the viscous dampers with stable performance could be incorporated into the isolation bearings in the future research.
- Response to comment: (Authors should do a thorough review of some paragraphs that seem confusing or difficult to understand.)
Response: Considering the Reviewer’s suggestion, we have done a thorough review of some paragraphs, and changed some paragraphs, especially for the numerical analysis in section 4. The changed paragraphs and sentences are marked blue in this paper.
- Response to comment: (There are some blanks in lines like 771 & 814 (re sults), …)
Response: We have made correction according to the Reviewer’s comments, and some blanks has been removed from the whole paper.
- Response to comment: (Specify the maximum error between numerical simulation and experimental program (Fig 58 & 60))
Response: According to the Reviewer’s suggestion, we have added the maximum error between numerical simulation and experimental program, which are listed in Table 7, 8 and 9. It should be noted that the objects of comparisons are between the recorded peak displacements or peak accelerations in two directions and the simulated results at the same time.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in blue in revised paper. We appreciate for Editors/Reviewers’ warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.
Sincerely,
Authors of this paper
Author Response File: 
Author Response.pdf
