Design Procedure of a Mono-Anchor Head for 2360 MPa High-Strength Steel Strand

Round 1

Reviewer 1 Report

This paper presents the design procedure of a mono-anchor head based on test and FEM investigations, which is quite practical for actual engineering works. According to the reviewer, however, the following questions/problems should be noted before acceptance:

 1.      There is a lack of explanation for some nomenclatures, e.g. PTI in the abstract. 

2.      Fig. 1: several sub-captions were used, i.e. four Fig. 1(b) in this figure.

3.      Equation (2) seems incorrect, please recheck it. The same expression appears in Equation (7), which is also incorrect.

4.      Table 1: the unit of D, H, and A should be given.

5.      Why the test is designed using the same contact area A? Given the different D and H, does it mean the angle theta is calibrated to keep the contact area the same? As in the following analysis, A is clearly a factor in the design, and thus it is better to consider it as a variable in the test.

6.      Fig. 14: the equations and the deductions should be given in the text, instead of being included in the figure.

7.      Line 394: “Fig. 19” is incorrect.

8.      The design procedure in Section 6 seems very specific, since the load, the allowable hoop strain, etc. are all provided in detail. Is it a universal way to follow when designing such a anchor head? Also, with respect to the theme of this paper, how is the originality can be shown by proposing this procedure?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The overall topic seems relevant, and the design of the experimental program seems appropriate. Some suggestions for improving the paper include:

-          You developed a design procedure for monostrand anchors, but a couple of things are unclear to me.  First, what are the limitations on this design method?  It is only for the high strength strands?  What diameter strands?  It is limited by the type if steel used in the anchor head?  By the type of wedge (2 piece vs 3 piece)?  Based on these limitations it seems to me that these heads are not redesigned often so I am unsure of the value of a method to design them, when likely a manufacturer is going to develop one or maybe 2 anchors that works and produce those.

 

-          In line 66-67 you state that “when anchoring a high-strength strand wire, an anchor head that satisfies the PTI performance standard for the anchoring device must be improved.”  It is unclear to me based on your previous statements why this is true.  If an anchor device meets the strain limits in the standard why must it still be improved?

 

-          I am a bit concerned about Equation 1 that relates the change in diameter to wedge depth.  The change in diameter is not the only thing that can affect the depth of the wedges in the anchor.  As the wedge teeth penetrate the strand, the depth increases.  As the force is transferred to the strand the strand elongates and gets thinner, allowing the wedges to penetrate further.  The wedges can also crack at the contact points with the strand which can increase penetration.  Relating it to only the diameter change seems an oversimplification.

 

-          Equation 2 should be stress = P/A (you seem to be missing the A)

 

-          Line 138, what are the units for 0.3 and 0.7? 

 

-          For the load-displacement curves in Figure 5, how is displacement determined?  Does it include the anchor seating or is it just strand elongation?

 

-          I am not sure what the sentence that states “The behavior characteristics according to the configuration…” in lines 185-187 means.  This could be clarified.

 

-          What do the different colored lines in Figure 6 represent?  Are they different gages on the same sample? Figure 4 seems to indicate there are only 2 gages on the anchor, but each graph seems to have 8 lines. 

 

-          I am a bit confused about the discussion of different carburized depths.  You mention 1-mm and 3-mm deep carburized specimens, but from all of the data it seems like these are not different.  Could the discussion about different depths be removed to improve the clarity of this section (4.2)?

 

-          Why were the coefficients of friction of 0.3 and 0.5 chosen for the interaction of individual wires and the anchor-wedge interface? It seems like these (particularly the anchor-wedge interface) would have a significant impact on the results, but no justification was given for using these particular values. 

 

-          Line 394,  I think it should be Figure 18 not 19.

 

-          Line 472, I think it should be “plastic hoop strain is less than or equal to” not “more than or equal to”.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The author have answered all questions in a proper way. Yet, I would suggest to modify Section 6 to give a more generalized design procedure, and highlight the novelty of this study as provided in Q&A 8. Meanwhile, it should be noted about the consistency of the symbols used in the paper. Some are still easy to cause misunderstandings, e.g. Figure 2 still uses theta as the angle of the anchor head. In addition, A is also used to indicate the area in Eq. 7, 10, 11.

Author Response

Please see the attachment.

Author Response File: Author Response.docx