Compressive Strength of Aged Timber Members in Traditional Building: Considering Differences in Heartwood and Sapwood
Round 1
Reviewer 1 Report
· The segments for taking the samples for testing to clarify in other parameters , not just in function of λ
· In the beginning just to present the definition : What is clear specimens and what is another
· KQ excellent analyse and function from different deffects
Author Response
The following comments should be addressed:
Point 1: The segments for taking the samples for testing to clarify in other parameters, not just in function of λ.
Response 1: The presence of defects has significant difference between the SW and the HW, resulting in their different strengths. Therefore, it is necessary to study the strength differences of the heartwood and sapwood.
Therefore, the sampling position is considered, and the function is defined as λ.
Point 2: In the beginning just to present the definition: What is clear specimens and what is another?
Response 2: Clear specimen is recomended by Standard (CRIWI 1992). Another is standard specimen, they were prepared according to the CRIWI 1992, the dimension is the same as CRIWI 1992, but they include the defects. Because the components in the actual building are defective, the purpose of this is to make the test specimens consistent with the actual building.
Clear specimens do not include defects, while standard specimen include defects, this is the difference between clear specimen and standard specimen.
Point 3: KQ is excellent analyse and function from different deffects.
Response 3: Thank you very much for your appreciation.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Attached review suggestions
Comments for author File: 
Comments.pdf
Author Response
The following comments should be addressed:
Point 1: Literature survey [lines 26-28]
“Due to the environment suitable for fungi growth temperature and humidity, aged timber member in traditional buildings lead to decay of wood” [26-28].
This is statement could be improving. There are specific publications which confirm that some wood insects such as “Hylotrupes bajulus” focuses its attacks on new wood, reducing its activity on old wood.
Response 1: These statements are ambiguous, and we have modified as “Due to the environment suitable for fungi growth temperature and humidity, the decay of timber member in traditional buildings would occur.” And we have modified it in the text in Line 27 to 29 of Page 1.
Point 2: Literature survey [lines 60]
“This fact suggests that the parallel-to-grain compressive strength of clear specimens cannot represent the strength of on-site structural members with damage and decay, which can be accumulating with the service life” [60-63]
This is statement could be improving. Look for references about timber creep behaviour too.
Response 2: Thank you for your comment. Yes, you are right, the creep will increase with the time, but the slowing creep rate as the amount of accumulated creep increases (Hanhijarvi, 2000). We have added it in Line 63 of Page 2.
Point 3: Materials and methods [line 97-99]
“The authors hope that work in this study may form the first step in the development of this relationship for future practices with maintenance of heritage timber structures.” [97-99]
This is statement is not relevant for the research.
Response 3: Yes, you are right. It is not relevant for the research. And they have been deleted.
Point 4: Materials and methods [line 108-111]
“However, we have assumed that the rate of decay in wood is uniformly the same over hundreds of years of its existence with old timber, and the extent of decay caused by these factors will increase linearly with time.” [108-111]
This is statement is not correct. The rate of decay is not join with time. It is the ambient conditions (humidity and temperature), pest density, or wood specie characteristics (natural durability) the main conditions of the decay’s rate.
Question: Could you cite any publication that supports this statement?
Response 4: Thank you for your comment. Yes, you are right, the ambient conditions have the directive effect on the rate of decay.
Because climate change over hundreds of years is unknown, the effect of temperature and humidity on building components is cumulative, and the process is assumed to be linear. This statement has been added in Line 110 to 112 of Page 3.
Point 5: Materials and methods [line 141-142]
“Therefore, the differences in their statistical strengths may be mainly due to the age effect.” [141-142]
Question: Is this statement an affirmation or a hypothesis? Because wood is a natural, anisotropic and heterogeneous, whose variability in mechanical properties is wide, even between pieces extracted from the same tree.
Response 5: Thank you for your comment. This statement is a hypothesis. It is precisely because the variability is so wide that we have to assume, otherwise there are too many factors result in not analyzing.
We make a hypothesis, and then verify our hypothesis through experiments, which is the thinking and process of this study.
Point 6: Results and discussion [line 150]
“standard deviation (s)” [141-142]
It is often used the acronym convention “SD” to refer to “standard deviation”. Please, correct it.
Response 6: We apologize for this confusion. We have modified it in Line 154 of Page 5 and Table 3 and Table 4 of Page 6.
Point 7: Results and discussion [line 150-151]
“parallel-to-grain compressive strength of standard specimens (fc) [141-142]
In several international timber standards as, for example, Eurocode 5 (Standard EN 1995-1-1:2004), it is often used the acronym convention “fc,0” to refer to the compressive strength along the grain.
Response 7: We apologize for this confusion. We have modified it in Line 155 of Page 5 and the whole text.
Point 8: Results and discussion [line 153]
“and fm is the average value of fl” [153]
In several international timber standards as, for example, Eurocode 5 (Standard EN 1995-1-1:2004), it is often used the acronym convention “fm” to refer to the bending strength. Please, correct it and use a new symbol, such as for example “fc,0,mean” and “fc,0,log”.
Response 8: We apologize for this confusion. We have modified it in Line 157 of Page 5 and the whole text.
Point 9: Results and discussion [Table 3]
Please, correct standard desviation acronym (SD), and improve format errors.
Response 9: We apologize for this confusion. We have modified Table 3 of Page 6.
Point 10: Results and discussion [Table 4]
Please, correct standard desviation acronym (SD).
Response 10: We apologize for this confusion. We have modified Table 4 of Page 6.
Point 11: Results and discussion [180-181]
Please, correct format errors.
Response 11: We apologize for this confusion. We have modified it in the whole text.
Point 12: Results and discussion [Figure 5]
Question: Why is it drawing a line with the text “30.30M” and “35.2M”?
Response 12: “30.30M” and “35.2M” are the mean parallel-to-grain compressive strength of aged and new logs. The reason for drawing the line is to highlight the dispersion of the aged logs compared to new logs.
Point 13: Results and discussion [line 198-201]
“Results show that the distributions of γσ of HW and SW of the aged CL are similar. The maxima and range of data of the HW of new CL are significantly higher than those of the other three groups. The distribution of γσ of the SW of the new CL is relatively centralized.” [198-201]
Question: How do you know if results distributions are similar, different or significantly higher? Have you done any statistical analyses? Which one?
The assumptions of independence, normality, and homoscedasticity for the dates and results must be done based on a statistical analyse. In any other case these statements cannot be taken as valid.
Response 13: We apologize for the puzzle to you. The maxima and range of data of the HW of new CL are significantly higher than those of the other three groups, which could be conclded from Fig. 6(b). We have added the label with “HW of aged timber”, “SW of aged timber”, “HW of new timber”and “SW of new timber” in Fig. 6(b) of Page.
Point 14: Results and discussion [Figure 6.a and Figure 7]
Both figures are similar. Could be possible select and use just one of them?
Response 14: Thank you for your comment. We merged the two diagrams, as shown in Fig. 6(a). The numbers of the following figures were changed in turn.
Point 15: Results and discussion [Table 5]
Please, correct mean compressive strength acronym (fm), and improve format errors in the left column.
Response 15: Thank you for your comment. We have modified the“fm” into “fc,0,mean” in Table 5 of Page 9.
Point 16: Results and discussion [227]
“where KP is the ratio of experimental parallel-to-grain compressive strength to that recommended in design code. KP=1.0 as recommended in the design code.” [227]
Question: Ok, KP=1.0 it is taken because it is recommended in the design code. But, what is it mean? Could you choose other value for your test set-up?
Response 16: Thank you for your comment. KP is equation accuracy affects coefficient, we are sorry for this serious error, and we have restated it in Line 230 of Page 9 of the original text. We could choose other value of KA and KQ for our test set-up. Because KA is the ratio of the actual geometric quantity to the standard value of the same quantity; KQ is the reduction factor of material strength defined as the product of influence coefficients. KA and KQ are related to test, so they could be choosed other value. While KP is not related to test, so it could not be choosed other value.
Point 17: Results and discussion [Table 7]
Please, correct mean compressive strength acronym (fm).
Response 17: Thank you for your comment. We have modified the“fm” into “fc,0,mean” in Table 10 of Page 9.
Point 18: Degradation of compressive strength with time [259-263]
“The model on the cumulative damage of timber considering temperature and humidity effects can also be derived based on a large number... where parameters A = 13.9526, B = 25.0498 with the stress level usually not exceeding 0.35 in a traditional timber structure” [259-263]
Question: Test are running on small samples, however parameters are taking according to structure system (tradictional building). And also, there are not any referent about wood specie or creep behaviour. Could you explain deeply this choise?
Response 18: The parameters in the literature (Wang, 2008; Yang et al., 2012) are also based on small specimens, not structural systems. Test of this study are running on small samples, therefore, the model and parameters can be directly applied to our sample.
Point 19: Degradation of compressive strength with time [in general]
“4. Degradation of compressive strength with time” [247-299]
All this chapter and its equations are cited mainly from (Wang, 2008). Is there another reference?
Response 19: Thank you for your comment.Wang's model (Wang, 2008) is optimized on the basis of predecessors. We use Wang's latest model, so we mainly refer to Wang's model. In addition, other literatures(Yang et al., 2012; Qin and Yang, 2018; Li 2004) are also cited.
According to your suggestion, we have also added some relevant literature(Sørensen et al., 2005). The text and references have been supplemented accordingly.
Point 20: Conclusions [321-333]
This is statement is not relevant for the research.
Response 20: Yes, you are right. They are research prospect, rather than conclusion. And they have been deleted.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
In general the requested clarifications are done by author
