Optimization of Large Deformable Elastic Braces in Two-Degrees-of-Freedom Systems

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Review Report  

The manuscript titled "Optimization of Large Deformable Elastic Braces Added to Multi-Degree-of-Freedom Systems" presents a well-structured study on the optimization of stiffness distribution in large deformable elastic braces (LDEBs) to minimize seismic responses in multi-degree-of-freedom (MDOF) building systems.  The topic is timely and relevant to the field of structural dynamics and seismic engineering, and the manuscript's formulation, simulation approach, and findings hold potential for significant practical applications in earthquake-resistant design.

However, the introduction section needs refinement in both clarity and depth to establish a more compelling foundation for the study. Terms like "large deformable elastic braces (LDEBs)" and "multi-degree-of-freedom systems with multi springs" should be better contextualized, especially for readers unfamiliar with these concepts. It would benefit the manuscript to briefly discuss the limitations of conventional bracing systems and clearly articulate how LDEBs provide a novel solution.

It is recommended to enrich the background with recent literature on smart bracing systems, advanced optimization techniques, and dynamic response mitigation strategies.

Major Concerns:

• The introduction lacks a clear statement of the research gap and novelty. Explicitly identifying how this work advances the current state-of-the-art would strengthen the rationale.
• No justification is provided for choosing the three specific earthquake ground motions; this selection process should be clarified.
• The PSO algorithm settings (e.g., swarm size, inertia weight, iteration limits) are not sufficiently detailed for reproducibility.
• The interaction and trade-off between stiffness distribution and maximum story drift are not deeply discussed in terms of physical interpretation.
• Some figures lack clear legends and axis labels, which affects readability.
• Grammatical issues are present throughout the manuscript; a thorough proofreading is necessary.
• Reference formatting should be checked to align with journal guidelines.
• Abbreviations like PSO, MDOF, and LDEBs should be consistently defined upon first use.

The manuscript addresses a significant problem and proposes a promising solution, but it requires major revisions before it can be considered for publication.  

Comments for author File: Comments.pdf

Comments on the Quality of English Language

major revisions required

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript offers a valuable numerical approach for optimizing the stiffness distribution of large deformable elastic braces; however, revisions are necessary to strengthen the theoretical formulation, clarify modeling assumptions, and improve result interpretation. Refining these aspects will significantly enhance the study’s rigor and its relevance to performance-based seismic design.

1. The title conveys the central theme, it is somewhat lengthy and could be more concise. Consider revising it to: "Optimization of Large Deformable Elastic Braces in Multi-DOF Systems". This version remains accurate and improving clarity and readability.
2. The abstract mixes technical content with background context but lacks clarity in articulating the specific innovation. It should better distinguish between problem, methods, results, and implications. For example, explicitly state what the PSO revealed and how the Round Robin results validated it.
3. The manuscript addresses the optimization of LDEBs’ stiffness in MDOF systems, which is relevant. However, the contribution is somewhat incremental. Authors should more clearly emphasize what gap this research fills, e.g., how their PSO-validated Round Robin approach provides advantages over existing methods.
4. The literature review is comprehensive in listing studies but lacks critical evaluation. The authors should add a comparative discussion that clearly articulates what existing optimization techniques (GA, PSO, etc.) miss and how LDEBs uniquely address structural performance under large seismic loads.
5. The use of PSO and Round Robin analysis is justified, but the explanation of their integration lacks rigor. The transition between formulations, assumptions, and computational execution should be more systematically presented. For instance, how the objective function and search space are bounded is not clearly explained.
6. Equations are not consistently numbered or cross-referenced. In Equation (3), key terms like inertia weight and velocity update components are introduced without formal definition. Ensure all variables are defined and equations are presented in a clean, sequential manner.
7. The assumption of damping proportional to stiffness, particularly in the presence of non-linear elastic devices like LDEBs, may oversimplify the physical behavior. Authors should justify this assumption or discuss its implications in the limitations section.
8. The study uses 2-DOF systems as a preliminary step, the simplification may limit generalization to actual multi-story structures. A brief discussion justifying this simplification and a roadmap for extension to more realistic models would add value.
9. The selection of three earthquake inputs (Ohta NS, BCJ-L1, Wakuya NS) is valid, but the justification for scaling to 50 and 90 kine should be grounded in seismic hazard levels or building code prescriptions. Otherwise, the realism of the excitation scenario remains unclear.
10. The discussion in Tables 5–7 and Figure 7 regarding stiffness ratios and ductility is helpful. However, these results are mostly descriptive. The authors should provide quantitative comparative analysis, such as percentage reductions in drift, convergence behavior of PSO, or trade-offs observed.
11. Several figures (e.g., Figures 3, 7, and 9) are unclear or lack proper axis labels, units, or detailed captions. Ensure all figures are high-resolution and self-contained with adequate explanations of what is shown, especially in complex plots like response surfaces.
12. The manuscript lacks a deeper structural interpretation of why stiffness shifts result in specific ductility or drift patterns. For example, how do LDEBs interact with modal behaviors to suppress certain frequencies or amplitudes? A brief dynamic interpretation would strengthen the conclusions.
13. The manuscript contains numerous awkward constructions and grammatical errors (e.g., “it disrupts the continuous usability of buildings,” “harmonizing forces with this natural period”). It is strongly recommended that the authors seek thorough professional language editing.
14. The paper would benefit from a dedicated subsection discussing limitations, e.g., model dimensionality, linearity assumptions, simplification of damping, and outlining future work (e.g., application to 3D structures or comparison with real building data).
15. The study is technically sound, it would benefit from a short discussion on practical applications, e.g., how engineers could use the PSO-based optimization framework in early-stage design or retrofit of steel frames in seismic zones.

 

Comments on the Quality of English Language

Please check the review comments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Review report R2

 

Thank you for submitting the revised version of your manuscript. I have carefully reviewed your response to the previous comments as well as the updated manuscript entitled “Optimization of Large Deformable Elastic Braces added to Multi-Degree-of-Freedom Systems”

 

I am pleased to inform you that all the concerns raised in the previous review have been fully addressed to a satisfactory level. Your thorough revisions, including clarification of the methodology, refinement of figures, and enhancement of the discussion, have significantly improved the quality and clarity of the manuscript. As such, I am happy to recommend acceptance of the manuscript in its current form.

Comments for author File: Comments.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The responses have been made in accordance with the reviewers' comments and the article can be published.