Comparative Study of Damping on Pultruded GFRP and Steel Beams
Round 1
Reviewer 1 Report
The authors conducted modal analysis and studied the dynamic behaviour of GFRP (glass fibre reinforced polymer) and steel plates. Major revisions are considered necessary by the reviewer. The motivations of research are not effectively communicated to the readers. The authors must clearly explain how the research results be used in real applications. The support conditions of specimens are not reported. What were the restrain conditions, support stiffnesses, and magnitudes of support settlements? Do the support conditions resemble any real-life scenario? If yes, examples of real-life scenarios should be given. If no, what was the rationale of the research design? Besides, the authors should explain the details of the "support perturbation" phenomenon. Under what physical conditions do the "support perturbation" exist (or otherwise)? The presentation of some tables has rooms for improvement, for example, table 14. A list of mathematical symbols and their respective units should be given. The references citation format is improper.
Author Response
The authors thank the reviewer for his positive assessment of our work.
Attached, please find a detailed response to the specific remarks and the actions prompted by each remark.
Our best regards.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper deals with modal characteristics and damping on steel and pulruded CFRP beams Theoretical background such as Euler-Bernoullli's beam theory, & experiment set-up were presented. Experimental results were then compared with the theroretical values.
In general, the paper is systematic and well organised. However, some revision should be considered to enchance the quality of the paper. The proposed revision are following.
1) (pg 2, 1 Introduction) The motivation of this work can be further highlighted, especially why Pultruded GCRP beams are pontential replacement of Steel. Readers of Polymers are from various backgrounds.
2) (pg 3, 2 Theoretical background)
Section 2.1 Vibrations of a free-free beams/Euler-Bernouli's beam theory is an established theory. This section should be cited, or removed from this manuscripts.
3) (pg 3) Define C1, C2, C3, C4. or to add "C1, C2, C3, C4 are constants of integration, determined by b.c."
4) (pg 8; section 3.2.1) Suggest to explain why 1040 x 100 x 10 mm and not 1000 x 100 x 10 mm; similary why 250 x 98 x 10 mm and not 250 x 100 x 10 mm.
5) (pg 9) suggest to explain how density was measured.
6) (pg 10) Details of accelerometer are not provided.
7) (pgs 13, 14) sub titles 4.1 & 4.2. Please leave a space between 4.1 and 1000 in 4.1.1000. mm-span.
8) Throughout the paper - Please confirm this -> 'Power density spectrum' or 'power spectrum density' (PSD)?
9) Throughout the paper - please check the usage of 'span' and 'length'.
10) Table 9, resonance freq for Modes 2-6, S-1000 are all having +/- 0.118. This is an interesting/unusual trend. Suggest to check the data again.
11) Table 12, unit is missing?
12) Tables can be further discussed.
For example Table 15. C-250 and C-500 had higher natural frequencies than S-250 & S-500 in all modes. However, at 1000 mm span, an opposite trend was observed, where C-1000 had lower natural frequencies than S-1000. -> it will be great if further discussion can be provided.
13) Check the format of refs 10 & 22.
Author Response
The authors thank the reviewer for his positive assessment of our work.
Attached, please find a detailed response to the specific remarks and the actions prompted by each remark.
Our best regards.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The reviewer's comments have been addressed. The authors should proof-read the manuscript to eliminate grammatical and formatting errors.
