Characteristic Value of the Modulus of Elasticity (MOE) for Natural and Planted Larch in Northeast China

Round 1

Reviewer 1 Report

The work deal with the characterization of dimension lumber aimed to be used in the building sector. The properties of the lumber coming from natural resource and from plantation are then compared.

The topic is of interest, the investigation was carried out correctly and the results were presented in a clear and exhaustive way. Therefore the manuscript should be published after minor changes.

Generally speaking:

• Density should be reported always in kg/m3 (international scientific unit)
• The captions of tables and figures should be more informative: everything should be clearly explained so that the reader may have a look to them without the need to go along the text.

Lines 61-62. An example of real application of NDT to stress grade the larch lumber can be found in: Brunetti et al. Visual and machine grading of larch (Larix decidua Mill.) structural timber from the Italian Alps. Materials and Structures (2016) 49:2681–2688

Line 84. Natural and planted logs were of similar size. Further information could be interesting for the discussions about the comparison between their properties. I.e. ring with, age …

Figure 3. From the figure it is clear that the displacement during the bending test is measured at mid-span. This is what the European standardization calls “global” modulus of elasticity and it includes also a shear component. The pure bending modulus (local modulus) is determined inside the middle third. To get the pure bending modulus, the global one should be corrected. Please, specify which static modulus do you measured.

Figure 4. Explain in the caption what FFV stands for.

Lines 150-151: from the figure 4 it is clear that 15.81 GPa is the mean value of dynamic modulus and 15.25 GPa the static modulus. In the text the opposite is written. Moreover, the text inside brackets is not necessary.

Figure 5. The boxplots should be explained in the captions.

Lines 204-205: The comparison between natural and planted lumber properties should be discussed further. What is the proof that trees in plantations grow faster? The ring width? The younger age of logs with similar dimension? Please, improve.

Lines 208-212. Also the discussion about the SPF (explain the acronym) should be improved.

Lines 279-283. Even though technical standards are cited, a brief explanation of what is a characteristic value (5th-percentile?) and a brief description of the parametric and non-parametric methods to calculate it should be added.

Table 6. Parameter: it should be parametric

Line 311. What is the “horizontal factor”?

Lines 314-316. About the mention to the C strength classes described in the EN 338, the comparison should be taken very carefully for several reasons: (1) the assignment to a strength class is done considering three characteristics values, that is the 5th percentile of bending strength and density and the MEAN value of MOE; (2) the static modulus is the pure bending modulus and not the global one (see comment above); (3) the bending test is done edgewise and not flatwise; (4) very often the limiting factor is not MOE but strength.

Lines 317-318. Also the reference to the GB 5005 required further explanations.

Author Response

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Reviewer 2 Report

See the comments in the attachment. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,
I see your paper valuable for potential readers due to highly practical tests and useful and applicable results. However, I have some questions and critical comments:

- when talking about visual grading (line 318) did you take into account natural imperfections of wood in your test samples (knots, cracks, …) or did you use samples free of any imperfections? Natural imperfections might effect results of testing.

In case of samples free of imperfections are the results anf obtained values applicable to real sturctural lumber with imperfections?

- line 64 and 65: please correct dynamic elastic modulus to „Edynamic“ and static elastic modulus to „Estatic“

- line 83: the correct name is Larix gmelinii (not Larix gemlini)

With regards!

Author Response

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Round 2

Reviewer 2 Report

Revisions attached.

Comments for author File: Comments.pdf

Author Response

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• Line 29, the positive effects were explained.
• Line 32, the artificial forest wood was replaced by plantation wood. To avoid the misunderstanding, the artificial wood in the paper were modified to plantation wood.
• Line 71, the sentence was expanded.
• Line 73, the acritical was deleted and changed to planation.
• Line 193, the Discussions was replaced by discussion.
• Line 203-205, the sentence was expanded.

Author Response File: Author Response.pdf