Structural Behaviour of Axially Loaded Concrete-Filled Steel Tube Columns during the Top-Down Construction Method

Round 1

Reviewer 1 Report

The Manuscript entitled: "Structural behaviour of axially loaded concrete-filled steel tube columns during the top-down construction method" is interesting scientific work. The introduction is well written and sufficiently fulfill the information needed for scientific paper. Also the strong part of the article is the description of methodology during conducted research. However the most beneficial would be to improve the presentation of the results and the conclusion to this level. Therefore the Reviewer recommend a revision of the paper as follows:

• The Authors have presented the average value of the concrete compressive strength however it might be beneficial to present the results of the investigation (based on how many samples the test were carried, standard deviation of it etc.
• In 3d model (fig 5) the authors used squares as FEM model but in figure 8 the triangles? why is that? Does it affect the calculations? 
• The figure 9 benefits from presentation of the results obtained for other samples. It might be beneficial to compare the models then. The differences might be visible better than just presenting into the table 5. 
• The reviewer is not convinced about presenting the 0.80L value in figure 9 because its average from measuring the sample. therefore the metric value might be better and presenting the specific for this sample.
• In conclusions the authors stated that the paper presents the full-scale testing however it might be the truth if authors present the results numerical for all of the samples not just one. Therefore the Authors also will be able to compare them and present more scientific conclusions. 
• Moreover the article benefit from some editorial remarks, as: e.g. line [105] 50 mm ? I think in the standard is 150 so it is mistake if not why such samples have been used? line [90] unnecessary space between k and W after 10 should be "10 kW".

Overall merit of the Manuscript is positive therefore i recommend to publish this paper in Applied Science after this major revision. 

Author Response

The authors thank the reviewer for the valuable comments. We have carefully considered these comments and modified the manuscript in order to strengthen our presentation.

In the following responses, we have included the original comments in italic and our response immediately below.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is well grammatically written, and the subject is very interesting.

In terms of the scientific content, I have prepared the following comments for your consideration:  

• The introduction section is incomplete. It should include the organization of the paper at the end. Please modify this section accordingly.
• It is recommended to add a figure that shows the schematic diagram of the whole paper.
• State the research hypothesis
• The authors need to justify their selections of the design values in Table 1
• The authors mentioned “The concrete core of the specimens was left a few centimeters longer than the steel tube during concreting. After 28 days of specimen curing, column end surfaces were finely aligned to even steel tube and concrete core surfaces in the cross-section.” how much was the “few centimeters”? and how did you select them to get an even surface at the end?
• Figure 2 is not clear. Use better version
• How is your measured Pcr compared to the Euler value for critical buckling?
• Have you mounted strain gages in Figure 4 measuring the longitudinal strain or the hoop strain? And why?
• Your FE model was about the composite column (pile) impeded in soil, while your excremental work was without lateral support. How?
• Add an explanation about why your result was closer to some of the codes compared to others.  
• The conclusion part can be improved by creating point-by-point conclusions.  
• Reporting the result is not research, it is a small part of the research. Please add more explanations for all the reported results. Comparing with previous researchers would be helpful
• Finally, nothing was mentioned about the proposed future studies.

Author Response

The authors thank the reviewer for the valuable comments. We have carefully considered these comments and modified the manuscript in order to strengthen our presentation.

In the following responses, we have included the original comments in italic and our response immediately below.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The article benefits from the revision that it can be accepted

Reviewer 2 Report

The authors conducted the required revision