Parametric Study of Three Types of Timber Connections with Metal Fasteners Using Eurocode 5

Round 1

Reviewer 1 Report

I consider the article under review to be interesting and beneficial. In their analysis, the authors use proven methodological procedures used in the design of wooden buildings. The authors explained the calculation methodology used precisely. The calculation methodology is, in my opinion, correct as well as the calculated values. The authors use the given methodology for comparative analysis of different designs of joints of wooden buildings. The authors chose a joint design that has the potential for application in real practice. The description of connections - calculated variables is sufficient. The calculated results are suitably interpreted in the table. The conclusions drawn are correct. The article fits into the topic of the special issue "Structural Design and Computational Methods". In my opinion, the article is suitable for publication in both professional and presentation terms. 

Author Response

The authors thank the reviewer for the careful reading of the manuscript, for the time spend, and for the constructive and positive comments.

Reviewer 2 Report

In this manuscript, the authors present the results of three types of timber connections, in double-shear, with 9 metal dowel-type fasteners, using the simplified equations from the Eurocode 5. This manuscript is still in a draft form in terms of the depth of the analysis and presentation. so it should be regrettably rejected. some issues are provided as follows:

1. There are so many English Spelling and Grammar errors in this manuscript, so the English language should be checked, edited and corrected carefully. For example, “...is ready for use and deliver” at line 32 of page 1, and so on.
2. The introduction of this manuscriptlacks research trends and existing problems, and there are too many popular science about Timber connections. The references in Introduction should be more specific and should not be directly listed as [1-6] at line 26, 30, 36 of page 1.
3. Contributions of the authors is to study the performance of three types of timber cThe Section 2 and Section 3 are the existing research results, while Section 4 is a new research, which is just a simple analytical calculation (Tables 2~4). So, the whole article lacks innovation.

Author Response

The authors thank the reviewer for his time and detailed review, constructive comments, and suggestions to improve our manuscript. All comments will be addressed. News introductions in the manuscript have been introduced highlighted in green.

1-All modifications or additions, for the English language, were introduced in the manuscript.

2-The Introduction has been rewritten and new references have been included.

3-Section 4.1 and 4.2 were verified with all the parametric studies developed and more conclusions were introduced. In addition, a new section 4.3 was introduced. We think that this new section (Numerical simulation on the S-W-S connection) increases the quality of our work. The main objective was to discuss the associated problem that can arise when the dowel diameter increases, also increasing the hole in the wood connection. This situation can lead to lower cross-section strength, the bearing failure mode and stress concentration around the hole.

Reviewer 3 Report

Dear authors,

thank you very much for your article, which topic is quite actual. A lot of work has been done, but unfortunately I do not see the scientific potential in the article, which is required for articles in this journal.

The content of your article is a parametric calculation according to EC5. As a good addition to support your results, I would consider performing destructive laboratory tests on the samples you calculated and subsequent comparison.

For use in practice, the support of numerical modeling of tested samples is suitable with the possibility of finding places, for example, with high stress concentration and the possibility of predicting the behavior of joints of similar parameters (type and method of failure, etc.) which will be useful for the practise.

My questions and comments:

1) Why was chosen glulam and not grown wood, which is commonly used for large cross-sections?

2) What are the dimensions of the tested samples?

- please add pictures, it is very difficult to find it in the text.

 3) Why were dowels used as fasteners and not bolts, which are used more often for joints in glulam or large corss-sections?

4) Why was chosen, the value of kmod = 0.8 which corresponds to medium-term load (max. 6 months) and not permanent action?

5) Why did you choose dowel with diameter of 6 mm? According to EC5 chapter 8.6.(2) The dowel diameter should be greater than 6 mm.

6) Moisture plays a huge role in wooden structures and their joints. Is it possible to apply your results to other humidity that is commonly found in wooden structures or only for a standard moisture content of 12%?

Line 247 – “the number of the bolts”  Bolts or dowels?

Line 254 – please erase “cos” in the equation (11)

Best regards.

 

 

Author Response

The authors thank the reviewer for his time and detailed review, constructive comments, and suggestions to improve our manuscript. All comments will be addressed. News introductions in the manuscript have been introduced highlighted in green.

 

1-Authors chose glulam because has high-quality and is characterized by a high structural capacity, aesthetic aspects, allowing possibilities of free form in construction, between others. It was an option of course.

2- All parameters used in the study are defined in tables 2, 3 and 4. The authors added a new the figure 4, which characterizes all the necessary dimensions. Authors are grateful for this observation.

3-The motivation for choosing the dowels was the following: dowels are one of the most used types of timber connections, and the authors will reproduce in ongoing works the studied configurations in 3D computational models and circular dowels are the most useful to use.

A new section 4.3 (Numerical simulation on the S-W-S connection) was introduced, which increases the quality of our work. The main objective was to discuss the associated problem that can arise when the dowel diameter increases, also increasing the hole in the wood connection. This situation can lead to lower cross-section strength, the bearing failure mode and stress concentration around the hole.

4-The authors are grateful for this observation. Kmod was changed and the value 0.6 was introduced and the parametric study presented reflects the new results, as shown in tables 2, 3 and 4.

5-Also the dowel diameter was changed, and the calculations were reformulated for values of 8, 10 and 12 mm. All the obtained results were presented in tables 2, 3, 4 and 5.

6-The wood density is not a fixed value and depends on the moisture content. This value varies greatly from species to species. Equation 7, which determines the characteristic embedment strength in the timber member, includes the value of the characteristic wood density.

7-The correction of equation 11 and the term bolts were introduced.

Round 2

Reviewer 2 Report

In this manuscript, the authors present the results of three types of timber connections, in double-shear, with 9 metal dowel-type fasteners. Three connections with all parameters are given and the design parameters are study in section 4. Although the authors added some new research contents in the revised manuscript and the workload is relatively large, I still think the innovation needs to be improved.

A numerical simulation is added to verify the effect of the dowel diameter in S-W-S connection, but the material properties are not introduced, which has a great impact on the results.

So, it should be regrettably rejected.

Author Response

The authors thank the reviewer for the careful reading of the manuscript and for the time spend.

The numerical simulation presented in section 4.3 includes the material properties defined in section 1 (lines 143 to 151) as mentioned in (lines 380 to 383).

Reviewer 3 Report

Dear authors,

thank you for editing your article.

Best regards.

Author Response

The authors thank the reviewer for the careful reading of the manuscript and for the time spend.

Round 3

Reviewer 2 Report

Thank the authors for their modifications. This manuscript can be accepted.