Experimental Testing and Residual Performance Evaluation of Existing Hangers with Steel Pipe Protection Taken from an In-Service Tied-Arch Bridge

Round 1

Reviewer 1 Report

Interesting paper that rather concerns practitioners than scientists.

Concerning the technical content I have one remark: In table 4 the test results of the PE sheath tensile properties are shown. It is stated that the PE material was re-molten (re-melted), specimen made from this and then tested. It should be known, that re- molten PE does not provide the same mechanical properties than virgin PE. So assessing remolten PE with requirements of virgin PE ist not appropriate.

Please mention this.

Author Response

Response to Reviewers' Comments (Manuscript ID: applsci-2607540)

Title: Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge

Author's Response

Dear Editors and Reviewers,

Thank you for allowing us to submit a revised version of the manuscript "Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge" for publication in the Applied Sciences. We sincerely appreciate the time and effort you and the reviewers dedicated to providing feedback on our manuscript and are grateful for our paper's insightful and constructive comments. The thorough review helped immensely in shaping and improvement of the manuscript. We have incorporated most of the suggestions made by the reviewers. Please see below; Fonts in blue have been provided for a point-by-point response to the reviewers' comments and concerns. Also, it should be noted that all of the editors' and reviewers' suggestions have been applied to the paper in addition to the reviewer's comments.

Reviewers' comments:

Reviewer #1:

Author’s Response: Thank you for your constructive comment. During the initial design of the test, the authors reviewed a large number of specifications, among which, the national standard GB/T 9352 (Plastic-Compression molding of test specimens of thermoplastic materials) specifies the general principles and steps for the preparation of molded specimens and test pieces of thermoplastics. The specimens can be obtained from the test pieces by machining or stamping. In addition, the industry standard CJ/T 297 (High-density polyethylene sheathing compounds for bridge cable) specifies the sampling and testing methods for high-density polyethylene sheathing compounds for bridge cables. The national standard GB/T 18365 (Hot-extruded PE protection paralleled high-strength wire cable for cable-stayed bridge) specifies the main performance indexes of high-density polyethylene sheathing compounds.

The authors in the above specification based on the mechanical properties of PE sheath test design, first of all, the old PE material is remelted and processed into a sheet material, the thickness needs to be no greater than 1mm, and then through the stamping way to prepare the specimen in line with the requirements of the size of Fig. 1, and then the mechanical properties of the test.

Figure 1. PE sheath sample size

As the finished PE sheath is cylindrical, there is a certain curvature, and the thickness is about 6mm, as shown in Figure 2. It is difficult to get a specimen whose thickness, size, and smoothness meet the requirements by cutting directly. Therefore, it is necessary to prepare the specimen by heating and remelting. It can be said that even if it is an old sheath, it should still meet the specification requirements. Therefore it is better to use the specification as an evaluation criterion. The authors would like to have the support of the reviewers. Thank you.

 

Figure 2. PE sheath thickness measurement

It should be noted that the English language of the paper was revised with the assistance of professionals. We appreciate your time in reviewing this paper.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper describes an assessment procedure for in-service hangers' remaining functioning performance based on field inspection and indoor tests. The assessment methods were described in detail and are interesting for engineers. Following are several comments for improving the manuscript.

1. Section 4 describes the inspection or test methods and results. However, how to use those results to evaluate the remaining functioning performance needs to be clarified.

2. Conclusions No. (1) states, "The service expansion's operational performance can be evaluated with greater precision." How do we know the "precision" of the evaluation method?

3. Please check if the following sentences need revisions.

Page 3, Line 65. "Cable-stayed bridges also belong to cable-stayed bridges..."

 

Page 6, Line 199. "...to varying degrees by varying degrees of varying degrees..."

Moderate editing of English language is required.

Author Response

Response to Reviewers' Comments (Manuscript ID: applsci-2607540)

Title: Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge

Author's Response

Dear Editors and Reviewers,

Thank you for allowing us to submit a revised version of the manuscript "Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge" for publication in the Applied Sciences. We sincerely appreciate the time and effort you and the reviewers dedicated to providing feedback on our manuscript and are grateful for our paper's insightful and constructive comments. The thorough review helped immensely in shaping and improvement of the manuscript. We have incorporated most of the suggestions made by the reviewers. Please see below; Fonts in blue have been provided for a point-by-point response to the reviewers' comments and concerns. Also, it should be noted that all of the editors' and reviewers' suggestions have been applied to the paper in addition to the reviewer's comments.

Reviewers' comments:

Reviewer #2:

This paper describes an assessment procedure for in-service hangers' remaining functioning performance based on field inspection and indoor tests. The assessment methods were described in detail and are interesting for engineers. Following are several comments for improving the manuscript.

1. Section 4 describes the inspection or test methods and results. However, how to use those results to evaluate the remaining functioning performance needs to be clarified.

Author’s Response: Thank you for your constructive comment. A new section 4.6 has been added to the article, which provides a comprehensive assessment of hanger distress and mechanical test results, and a statistical analysis of 86 hanger replacement cases on bridges of the same type, concluding with maintenance recommendations. Detailed elaboration has been added to the text.

 

2. Conclusions No. (1) states, "The service expansion's operational performance can be evaluated with greater precision." How do we know the "precision" of the evaluation method?

Author’s Response: Thank you for pointing these out. A comprehensive literature study found that the existing studies mainly focused on the corrosion and fatigue damage of the steel wire inside the hanger or the damage of the anchor structure at the end of the hanger, but failed to effectively combine the two, thus proposing a more comprehensive and reasonable method of evaluating the work performance of in-service hangers. In addition, most of the existing research focuses on the deterioration of conventional structure hangers, while the special structure of hangers protected by external steel pipes receives less attention. The existing literature is mainly based on theoretical analysis or corrosion tests on single steel wires and lacks comprehensive experimental analysis and research. Meanwhile, the authors have realized that the expression of conclusion (1) is not proper and have deleted conclusion (1).

3. Please check if the following sentences need revisions.

Page 3, Line 65. "Cable-stayed bridges also belong to cable-stayed bridges..."

Page 6, Line 199. "...to varying degrees by varying degrees of varying degrees..."

Author’s Response: Thank you for pointing these out.

Page 3, line 65, has been revised to read: Cable-stayed bridge is also a cable bearing system, which has the advantages of strong spanning ability, simple structure, and good aerodynamic stability. It plays an important role in the development of bridges.

Page 6, line 199, was amended to read: 35 % of the anchor heads are seriously corroded, and nearly half of the anchor heads are soaked in water. The anti-corrosion grease filled in the anchor box is aged to varying degrees due to long-term soaking in water, and the anti-corrosion ability is reduced.

4 Moderate editing of English language is required.

Author’s Response: It should be noted that the English language of the paper was revised with the assistance of professionals. We appreciate your time in reviewing this paper.

Author Response File: Author Response.pdf

Reviewer 3 Report

1.The introduction is excessively verbose. From a scientific perspective, it's essential to succinctly demonstrate the significance of the research and identify the gaps in existing studies, thereby posing relevant scientific questions.

2.There's a lack of innovation in the experimental and analytical methods. The author needs to provide a more detailed elaboration.

3.Figure 8 should be revised to present the workflow of the test and analysis clearly.

4.Detailed analyses should be supplemented in Section 4 to support the conclusion.

5.More charts and figures should be made in Section 4 to explain the detailed results of tests.

6.Different types of bridges with hangers should be discussed. Otherwise, research limitations should mention it.

7.In addition to waterproofing measures, other measures should be discussed in Section 5.

Minor editing of English language required.

Author Response

Response to Reviewers' Comments (Manuscript ID: applsci-2607540)

Title: Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge

Author's Response

Dear Editors and Reviewers,

Thank you for allowing us to submit a revised version of the manuscript "Experimental testing and residual performance evaluation of existing hangers with steel pipe protection taken from an in-service tied-arch bridge" for publication in the Applied Sciences. We sincerely appreciate the time and effort you and the reviewers dedicated to providing feedback on our manuscript and are grateful for our paper's insightful and constructive comments. The thorough review helped immensely in shaping and improvement of the manuscript. We have incorporated most of the suggestions made by the reviewers. Please see below; Fonts in blue have been provided for a point-by-point response to the reviewers' comments and concerns. Also, it should be noted that all of the editors' and reviewers' suggestions have been applied to the paper in addition to the reviewer's comments.

Reviewers' comments:

Reviewer #3:

1.The introduction is excessively verbose. From a scientific perspective, it's essential to succinctly demonstrate the significance of the research and identify the gaps in existing studies, thereby posing relevant scientific questions.

Authors' Response: We thank the reviewer for this important comment. The introduction section has been revised and streamlined, and the revised introduction points out the shortcomings of the existing research as well as the significance of the research in this paper.

 

2.There's a lack of innovation in the experimental and analytical methods. The author needs to provide a more detailed elaboration.

Authors' Response: Thank you for mentioning that. Due of limited testing, in-service hangers' operating condition is hard to assess. This is why it is vital to do extensive experimental testing and research on replacing defective hangers, assessing their operating state, and offering maintenance advice.

The more severe 2~13# hangers of Dongkuan Bridge were chosen for replacement after careful consideration of force and disease. The old hangers were dismantled and tested indoors to evaluate their overall performance.

First, a detailed appearance inspection identified the disease conditions of various parts of the old hangers, including the corrosion of anchor cups, anchor rings, sealing cylinders, and PE sheaths, and the causes of the diseases. The demolished old hanger must also be static load tested to appropriately assess the hanger's bearing capacity and anchoring performance. After disassembling the old hanger to evaluate steel wire corrosion, steel wires, anchor cups, anchor rings, and PE sheaths are tested inside for mechanical qualities. Finally, the old hanger's performance is assessed by examining its hanger-specific testing and mechanical characteristics.

Text details have been added.

3.Figure 8 should be revised to present the workflow of the test and analysis clearly.

Authors' Response: We thank the reviewer for bringing this to our attention. FIG. 8 has been modified to present a clearer picture of the workflow of testing and analysis. The current figure number for this flowchart is 11.

 

4.Detailed analyses should be supplemented in Section 4 to support the conclusion.

Authors’ Response: Thank you for pointing this out. A detailed analysis of the results of each test has been added in Section 4.

 

5.More charts and figures should be made in Section 4 to explain the detailed results of tests.

Authors’ Response: Thank you for pointing this out. Pictures related to the tests have been added in Section 4 and a detailed description of the test results has been provided.

 

6.Different types of bridges with hangers should be discussed. Otherwise, research limitations should mention it.

Authors' Response: We thank the reviewer for this important comment. The authors have added research limitations in the penultimate paragraph of the preface. below:

It should be noted that there are various constructions of hangers and their anchoring methods, which are generally categorized into flexible and rigid hangers. The subject of this paper is the flexible hanger with the addition of a protective steel pipe. Other types of hangers are not within the scope of this paper.

 

7.In addition to waterproofing measures, other measures should be discussed in Section 5.

Authors' Response: We thank the reviewer for bringing this to our attention. Tied arch bridges distribute weight from the main girder to the arch ribs through the hanger. Because the hanger structure is thin, it is the most disease-prone cable-stayed part. Most illnesses have been detected in hangers of cable-stayed bridges. Water buildup corrodes steel wires, anchor heads, and other components, causing various illnesses. This article concludes that anti-drainage measures at the anchor end of the hanger should be prioritized.

The authors also mention additional metrics in the conclusion:

With the evolution of hanger construction technology, the widespread use of new materials, and the updating of testing techniques, high-tech methods should be used to improve non-destructive hanger testing during daily and periodic inspection. If hangers need to be replaced, use modern materials and technologies to improve their longevity.

 

8 Minor editing of English language required.

Authors' Response: It should be noted that the English language of the paper was revised with the assistance of professionals. We appreciate your time in reviewing this paper.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The revised manuscript addressed this reviewer's comments well.

Reviewer 3 Report

The authors have already addressed all the proposed issues well. I have no more questions.