Sustainable Design for CFS Structures: Experimental Data and Numerical Models of Hinged Connections
, Vasile-Mircea Venghiac 1, Ioana Olteanu-Dontov 1, Ancuta Rotaru 2 and Ionut-Ovidiu Toma 1
Round 1
Reviewer 1 Report
The paper presented a new design method for predicting the strength of cold-formed steel sections, where experimental and numerical approaches are used for this purpose. The paper is interesting and well discussed the methodology and results. However, there are some comments that are needs to be addressed by the authors to further improve the paper which listed as follows:
· The main gap and/or difference between this study with the existing studies needs to be highlighted clearly in the Abstract.
· The abstract could be improved by providing the key results; some results established from the experimental and numerical investigations of this paper
· In general, the Abstract is quite general and could be more informative by providing some background on the case of study and why this research is required?, what is the main problem of the study?, what is the main method of experiment had been used? The number of specimens?...etc. In another word, the objectives of this work are evidently given in the abstract but the sentence could be modified to give more clarity to the research.
· The recent related papers that are discussed/cited in the literature are good, but I would like to suggest being improved the literature by adding another 3-5 references that are published in the latest three years (2020-2022).
· The limitations of this study need to be clearly discussed and highlighted in the introduction and/or conclusions.
· In the introduction, please avoid the large bulk citations, such as those mentioned on page 2 section 1.2 which are [21-27] and [28-35]. It will be better if you highlight the main concern/activity of each of these references, Or at least small bulk citations (2-3 references) that have the same main common point.
· Unitize the font size of the Y and X axes of all figures with charts, specifically for Figures 2, 5, 6, 7, 13, 14, 16-18, and 22.
· The current argument of conclusions is good and could be further interested by mentioning your current study limits and suggesting some future research topics related to the field of this paper.
Author Response
We are grateful for your time and efforts in considering and reviewing this manuscript. We have substantially revised our manuscript after reading the comments. In the attached file are our point-by-point responses to each of your comments. Please kindly review the updated version.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This is a well-written paper that presents a new design approach for CFS profile joints to accurately predict their realistic behavior, achieving the optimum design of the structural system in terms of strength and overall rigidity. Experimental tests calibrate the numerical model that accounts for the axial stiffness of the hinged joints between the CFS profiles. The main parameters of the research are the thickness of the steel sheet and the connector type. This paper is well-organized and useful. It can be published after addressing the following changes. I have a few comments for you to consider:
1. The technical writing of this paper needs to be improved for all the sections. (e.g. section 1.2 CFS can provide various complex shapes- This statement is Wrong-Check grammatical errors).Also very similar errors in page 2 line 79: The CFS can take any shape, from structural systems in frames, lattice systems, rigid structural panels or combinations of the above. 2. In the introduction part a separate paragraph can be added that highlights the benefits of the channel section. Literatures pertaining to the above could add more flavour for the readers which would ensure the advantages/benefits of using channel sections. 3. Sections 1.1 Sustainability of cold-formed steel structures & 1.2 Prefabrication and versatility of CFS structures can be combined into a single section stating these two subheadings in the introduction. 4. The main parameter in this study is the thickness of the steel sheet and the connector type. It would be better to highlight the literature pertaining to these two parameters in the introduction section. 5. Page 3 line 111, the make details of “ZWICK / ROELL 1000 SP” should be mentioned. 6. In Figure 2, the 5 graphs mentioned- Whether they are before forming or after the C profile forming needs to be mentioned. The material properties whether the corner coupons were also tested or not should be included in the section 2: Materials and methods. 7. Figure 3. Geometry and dimensions for the tested joints, C profile characteristics respectively are not clearly explained. The 1-1, 3-3, and 2-2 mentioned don’t have continuity, and the steps in making up the joints need explanation. 8. Page 4: line 133 the statement is unclear. 9. The connector type mentioned in Table 2 is not highlighted in Figure 3. 10. Figure 4 and its testing methods should be moved to section 3: Experimental testing methods. 11. Figures 5 and 6 which mention the result of SSPR and STS. The reason why there is a huge difference between these two types of connectors should be highlighted. 12. In FEM, the self-drilling screws are not modeledand how the fixity of the screws was achieved? 13. Section 4: it is unclear (1) what uniaxial stress-strain curve was used and (2) what kind of "classical metal plasticity model" was used. 14. Was the effect of residual stresses consideredin this study? 15. In section 4 what was the element used? 16. Since the cross-sections considered are made through cold-working, it is expected to undergo strength enhancement in the corner regions of the Cross-Sections-Was this considered in this study? 17. Section 4 must be given separate sub-divisions and mentions clearly all the details pertaining to the modelling methodology followed: a) Material properties b) Type of element and mesh sizes c) Load applications and boundary condition d) Material and geometrical imperfection 18. Justification of the experimental study conducted etc. Few figures showing the failure pattern matching with that of the experimental studies need to be added in the numeral validation. 19. Figure 7: Check the line markings of I-IV. 20. Figure 14: the notations ki-I,ke-II and kp-III- Need proper explanation. 21. Section 5 which says as case study: Clearly explain the details about the truss taken for the application of the joint details. 22. The failure mechanism of the top chord, bottom chords, and diagonal chord for the peak loading condition (250N-3500N) can be shown separately as the truss member is a symmetrical geometry. 23. Page 18-Section showing Discussion as section 4 and conclusion as 5. Clearly numbering the subheadings in a sequential order. 24. Please conduct an extensive literature review. Some of the most relevant references which are not in the literature review section are: i. Flexural capacity of gapped built-up cold-formed steel channel sections including web stiffeners Journal of Constructional Steel Research 172, 106154 ii. Moment capacity of back-to-back cold-formed steel channels with edge-stiffened holes, un-stiffened holes, and plain webs Engineering Structures 235, 112042. iii. Effect of angle stiffeners on the flexural strength and stiffness of cold-formed steel beams. Steel and Composite Structures, An International Journal 33 (2), 225-243.Author Response
We are grateful for your time and efforts in considering and reviewing this manuscript. We have substantially revised our manuscript after reading the comments. In the attached file are our point-by-point responses to each of your comments. Please kindly review the updated version.
Author Response File: Author Response.docx
Reviewer 3 Report
Some quantitative details in brief in abstract are requested
Please avoid such large block citation “[2–16].” ; maximum 3 it will be enough and discuss each of them separately . The same apply everywhere in this manuscript
Please avoid bullet point 1-5 in introduction as this is a research paper and not a report
Which are the novelty and sustainability aspect of this work ? IT is not clear at all
“C profiles have S355 steel grade.” Why this material and not other, any justification ?
Instead of Force – displacement results it will be much better putting stress strain curve
Some details in section 4.1. are well know and should be removed. Please be more concise. Rather I expect to see details of boundary condition and mesh
The conventional model curve presented in 22 is not feasible at wall as there is just the elastic part
The conclusions are very long and not much quantitative details linked to results- therefore please revise them accordingly
Please highlight better the sustainability aspect of this work
Author Response
We are grateful for your time and efforts in considering and reviewing this manuscript. We have substantially revised our manuscript after reading the comments. In the attached file are our point-by-point responses to each of your comments. Please kindly review the updated version.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The revised manuscript was checked and accepted
Reviewer 2 Report
References 2 and 8 are the same. Reference 2 has the wrong first author, please check. Otherwise, the paper is ready for publication. Congratulations to the authors and thanks to them for addressing my comments.
Reviewer 3 Report
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