Effect of Layer Arrangement on Bending Strength of Cross-Laminated Timber (CLT) Manufactured from Poplar (Populus deltoides L.)

Round 1

Reviewer 1 Report

The manuscript deals with the analysis of layer arrangement of CLT on its stiffness and strength, based on static mechanical testing supported by analytic calculations and finite element modelling. The structure of the paper is traditional, having wide and deep introduction, followed by material and methods, results and discussion and conclusions. The methodology is proper. The results are well presented, with a lot of comparisons and discussion on data find on MOE and MOR in relation to the major and minor axis of CLT, and fracture characteristics, found. The conclusion are well supported by the findings.

Comments / Remarks:

P8, P9 It is suggested to join Figure 3 and Figure 4 into one. Please add as well information on the meaning of the bar in columns present.

Please reconsider the section 3.1.2 from the point of view of optimal CLT construction. Namely, after the joining of figures 3 and 4, it should be obvious, which CLT construction is generally, when we consider both axes (major and minor), optimal. Please consider to give this information (MOE) as an average one (MOE_average = (MOE_major + MOE_minor)/2, or even calculate it according to the Hankinsson (Eq. 10). It is especially suggested that you are using Hankinsson solution in all the tested case. It can even give you the idea of optimal angle between lamellaes in 3-layered CLT.

Section 3.1.3 (P10, P11)

Please join Figure 5 and Figure 6 in a new one. Consider as well, according to the above remark, to calculate average MOR and to find the define the optimal CLT construction.

Please consider to add a graph with the relationship of MOE and MOR for the tested CLT plates! Please give the information, if MOR is reliably predicted by MOE in any of tested CLT plates!

Section 3.2.2.

Please consider to join Figure 11 and Figure 12 in a new one. Since the values are of different scale, you might use primary and secondary axis. That kind of figure will support additionally the joined data in figures at sections 3.1.2 and 3.1.3.

4. conclusions

Please rewrite this section according to the suggestions to re-analyze the data in sections 3.1.2, 3.1.3 and 3.2.2 Please explain clearly what is the optimal arrangement of CLT layers (by adding info on optimal angle between lamellaes), to get the highest average (combined) MOE and MOR.

 

 

Author Response

Manuscript ID: buildings-1687483

Paper title: Effect of layer arrangement on bending strength of cross-laminated timber (CLT)

Authors: Akbar Rostampour Haftkhani, Hojat Hematabadi

 

The authors thank the editor and the reviewers for giving us the opportunity to submit a revised draft of our manuscript. We really appreciate the editor and the reviewers for their precious time in reviewing the paper and adding invaluable comments. All the comments were carefully addressed. Here is a point-by-point response to the reviewers’ comments.

 

 

Author's Reply to the Review Report (Reviewer 1):

Comments and Suggestions for Authors

 The manuscript deals with the analysis of layer arrangement of CLT on its stiffness and strength, based on static mechanical testing supported by analytic calculations and finite element modeling. The structure of the paper is traditional, having a wide and deep introduction, followed by material and methods, results and discussion and conclusions. The methodology is proper. The results are well presented, with a lot of comparisons and discussion on data find on MOE and MOR in relation to the major and minor axis of CLT, and fracture characteristics, found. The conclusion are well supported by the findings.

 

(Reviewer 1):

 

 Comments / Remarks:

P8, P9 It is suggested to join Figure 3 and Figure 4 into one. Please add as well information on the meaning of the bar in columns present.

Figures 3 and 4 were combined into a new one and the information was added on.

Please reconsider the section 3.1.2 from the point of view of optimal CLT construction. Namely, after the joining of figures 3 and 4, it should be obvious, which CLT construction is generally, when we consider both axes (major and minor), optimal. Please consider to give this information (MOE) as an average one (MOE average = (MOE major + MOE minor)/2, or even calculate it according to the Hankinson (Eq. 10). It is especially suggested that you are using Hankinson solution in all the tested case. It can even give you the idea of optimal angle between lamellaes in 3-layered CLT.

 

Part 3.1.5. for finding the optimal CLT construction based on mechanical properties was added to the text. In this part, the value of Average MOE and MOR in both major and minor directions were calculated and the optimal CLT constructions based on the MOE and MOR in various orientations were specified.

Section 3.1.3 (P10, P11)

Please join Figure 5 and Figure 6 in a new one. Consider as well, according to the above remark, to calculate average MOR and to find the define the optimal CLT construction.

Figures 5 and 6 were combined into a new one and the optimal CLT construction based on MOR in various orientations were presented in table 4.

 

Please consider to add a graph with the relationship of MOE and MOR for the tested CLT plates! Please give the information, if MOR is reliably predicted by MOE in any of tested CLT plates!

Part 3.1.4 was added to the text and the relationship between MOE and MOR in various orientations was indicated in Figure 5.

 

Section 3.2.2.

Please consider to join Figure 11 and Figure 12 in a new one. Since the values are of different scale, you might use primary and secondary axis. That kind of figure will support additionally the joined data in figures at sections 3.1.2 and 3.1.3.

Combing the figures 11 and 12 leads to providing a messy new one since each arrangement has 3 bars, so joining 2 graphs together leads to having a new one with 27 bars, which may be confusing for readers.

4. conclusions

Please rewrite this section according to the suggestions to reanalyze the data in sections 3.1.2, 3.1.3 and 3.2.2 Please explain clearly what is the optimal arrangement of CLT layers (by adding info on optimal angle between lamellaes), to get the highest average (combined) MOE and MOR.

The optimal arrangement of CLT based on both MOE and MOR values was discussed in the text and a conclusion of them was added to the conclusion part of the paper.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

Thank you very much for the interesting research. The topic of the manuscript is in accordance with the Journal requirements.

The manuscript deals with the bending performance of CLT elements. Different layer arrangement and their influence on bending strength were investigated.

The focus of the manuscript was set on poplar wood. The topic of the paper is interesting for experts in the field of timber engineering.

I have several remarks:

1. Language: Appropriate
2. The title: Maybe add the word poplar (Populus deltoides L.)
3. Abstract: ok. Please specify in which dimensions are the arrangements.
4. Keywords: poplar is missing

Specific comments:

1. Ranging in thickness from 20 mm. I don’t know about the CLT with a thickness of just 20mm.
2. STAR documentation is more or less ok but some relevant papers are missing. Please add European research because the pioneers in CLT are from Austria (TU Graz), Germany, Sweden, etc. For example, you are stating on the 2^nd page: Therefore, many researchers… Please write some of them
3. CLT in lower density and higher-density wood. Please specify do you speak about softwood or hardwood.
4. Something is wrong with the references. Buck et al. [17] is not number 17, Navaratman is not [23], Li is not [24], [27] does not exist in the list of publications
5. Page 3: 2 different fonts were used
6. Page 4: word were is missing in the 1^st sentence
7. Table 1: Mean values are presented in the table?
8. Figure 2: samples of each group are presented. Can you also add all of the results? Again, what values are shown in the graph?
9. Figure 3-6. The graph is showing the results with maximum values and mean values? Minimal values are not shown.
10. Figure 7: please add captions a), b), c), d) with explanations in the text of the Figure
11. Mention new wood species used for CLT. As your paper is about poplar, at least mention it in the conclusion part.

In the end, the work is promising and very interesting. I hope that the above-mentioned suggestions can improve the quality of the manuscript.

 

Author Response

Manuscript ID: buildings-1687483

Paper title: Effect of layer arrangement on bending strength of cross-laminated timber (CLT)

Authors: Akbar Rostampour Haftkhani, Hojat Hematabadi

 

The authors thank the editor and the reviewers for giving us the opportunity to submit a revised draft of our manuscript. We really appreciate the editor and the reviewers for their precious time in reviewing the paper and adding invaluable comments. All the comments were carefully addressed. Here is a point-by-point response to the reviewers’ comments.

 

 

Author's Reply to the Review Report (Reviewer 2):

(Reviewer 2):

Comments and Suggestions for Authors

 Dear authors,

Thank you very much for the interesting research. The topic of the manuscript is in accordance with the Journal requirements.

The manuscript deals with the bending performance of CLT elements. Different layer arrangement and their influence on bending strength were investigated.

The focus of the manuscript was set on poplar wood. The topic of the paper is interesting for experts in the field of timber engineering.

I have several remarks:

1. Language: Appropriate
2. The title: Maybe add the word poplar (Populus deltoides L.)

The word of poplar (Populus deltoides L.) was added to the title.

3. Abstract: ok. Please specify in which dimensions are the arrangements.

The dimensions of CLTs were added to the text in the Abstract.

4. Keywords: poplar is missing

The poplar was added as a keyword

Specific comments:

1.Ranging in thickness from 20 mm. I don’t know about the CLT with a thickness of just 20mm.

In fact, due to the lack of enough equipment in the lab such as a big press and bending test machine, the author had to make the pilot specimens. On the other hand, for the specimens to meet the D198 standard based on a span to depth of about 30, the researcher had to manufacture the CLTs with low thickness

2. STAR documentation is more or less ok but some relevant papers are missing. Please add European research because the pioneers in CLT are from Austria (TU Graz), Germany, Sweden, etc. For example, you are stating on the 2 page: Therefore, many researchers… Please write some of them.

We tried to prepare a comprehensive and related literature review for paper from all over the world. If the reverent reviewer suggests a relevant reference to help the improvement of the article, we will be delighted to add it to the article.

 

3. CLT in lower density and higher-density wood. Please specify do you speak about softwood or hardwood.

The species of hardwoods and softwoods were added to the text to make a clear speech for readers.

4. Something is wrong with the references. Buck et al. [17] is not number 17, Navaratman is not [23], Li is not [24], [27] does not exist in the list of publications.

All the references were checked and corrected again by Endnote.

5. Page 3: 2 different fonts were used

The whole of the manuscript was set based on the same font.

6. Page 4: word were is missing in the 1 sentence.

It was corrected.

7. Table 1: Mean values are presented in the table? Yes
8. Figure 2: samples of each group are presented. Can you also add all of the results? Again, what values are shown in the graph?

The graph was presented only to show the relationship between force and displacement under out-of-plane bending loading. MOR and MOE values were accordingly calculated and all of them were presented in the results section of the article.

 

9. Figure 3-6. The graph is showing the results with maximum values and means values? Minimal values are not shown.

Figures 3-6 indicate the average of MOE or MOR for each group in the major or the minor directions of CLT. However, in the new revised version of the manuscript, we joined together some graphs based on another reviewer’s comments.

10. Figure 7: please add captions a), b), c), d) with explanations in the text of the Figure

There are captions a, b, c and d under each picture inside the figure.

11. Mention new wood species used for CLT. As your paper is about poplar, at least mention it in the conclusion part.

We added the scientific name of our species, poplar (Populus deltoides L.) in the first sentence of the conclusion.

 

In the end, the work is promising and very interesting. I hope that the above mentioned suggestions can improve the quality of the manuscript.

 

Thanks again, dear Reviewer

Corresponding author: Hojat Hematabadi

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has been correctly revised according to the comments and remarks in the revision report of the 1st version.