Experimental Study on the Rotational Stiffness of Pocket Type Scaffolding Connection According to the Rotation Direction
Hiroki Ishibashi
Round 1
Reviewer 1 Report
In this paper, the bilinear rotational stiffness models of the pocket-type connections are developed based on the experimental test results. The reviewer recommends the authors address the following comments and revise the manuscript for a resubmission.
1. As shown in Figure 6(b), the pin appears to be sliding out of the pocket after the test of upward rotation. How does this sliding behavior between a pin and pocket affect the moment–rotation curves?
2. In Figure 11(c), the relationship between stress and rotation of UP-1-SG-H and UP-2-SG-H is significant different. Can you describe this reason why the stress of UP-2-SG-H decreased after rotation of 0.15?
3. The effects of sliding behavior observed during the test of upward rotation is ignored in Equation (2) when developing bilinear rotational stiffness model. This can cause the overestimation of initial rotational stiffness.
4. Is it required to consider the plasticization of connections in the design of scaffoldings? Please clarify whether the plastic deformation capacity of the connection needs to be considered in the design.
5. As shown in Figure 13, it is difficult to determine the connection types for lateral rotation (i.e., semi-rigid and nominally pin) due to the large uncertainty associated with the initial stiffness. Can you give some opinions on how the various uncertainties associated with the parameters of moment–rotation curves, such as initial stiffness and maximum moment, should be taken into account in the design of scaffoldings?
Author Response
We appreciate your careful review and valuable comments. Your comments have been helpful in improving the quality of our research. Revisions were made according to comments from the reviewer.
Please see the attached file.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This article presents experimental work to study the rotational stiffness of pocket type scaffolding connection according to the rotation direction. A total of 30 specimens with cantilever specimens for each rotation direction were tested. The following points need to be added to the manuscript:
1. In the text, it is unclear what is the main focus of the study whether to develop a bilinear rotational stiffness model or examine the capacity of a pocket-type connection to bending moments in the downward, upward, and lateral rotation directions.
2. The authors need to show the material stress-strain curve of steel pipes, pockets, and pins obtained from the tensile test in addition to Table 2.
3. The load-displacement (Figures 8 to 10) and moment–rotation curves (Figure 13) do not explain the events that occur during loading (e.g., yielding, bending in the pin, deformation of the pocket, etc.)
4. The author must give the application of k1 and k2 values shown in Table 5 in terms of moment calculations for each condition (downward, upward, and lateral rotation).
Author Response
We appreciate your careful review and valuable comments. Your comments have been helpful in improving the quality of our research. Revisions were made according to comments from the reviewer.
Please see the attached file.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The revised manuscript satisfactorily addressed the reviewer's comments and is recommended to be accepted.
Author Response
Thank you for your careful review and valuable comments.
Reviewer 2 Report
The author does not do some of the suggestions from the reviewers as follows:
2. The authors need to show the material stress-strain curve of steel pipes, pockets, and pins obtained from the tensile test in addition to Table 2.
3. The load-displacement (Figures 8 to 10) and moment–rotation curves (Figure 13) do not explain the events that occur during loading (e.g., yielding, bending in the pin, deformation of the pocket, etc.)
4. The author must provide the application of k1 and k2 values shown in Table 5 in terms of moment calculations for each condition (downward, upward, and lateral rotation).
Author Response
Thank you for your careful review and valuable comments.
Re-revisions were made according to your comments.
Please see the attached file for the authors' response.
Author Response File: Author Response.docx
