Force Performance Analysis and Numerical Simulation of Assembled Ribbed-Slab Abutments

Round 1

Reviewer 1 Report

The study presented in the document examines the structural performance of assembled rib-plate bridge abutments using two connection methods: bull leg bolt and flange connections. It assesses bending and shear performance and uses numerical analysis to compare these to cast-in-place structures. The methodology appears robust, employing experimental testing and numerical simulation to analyze the force performance and structural integrity. Some pontual questions:

1) How exactly were the parameters for the numerical models, especially the Concrete Damage Plasticity parameters, validated with experimental outcomes? Please, add a table with parameters.

2) Can the study detail the adaptability of the tested connection methods for various bridge scales and designs to understand their broader applicability?

3) The authors are invited to improve the Figure 1.

4) The authors are invited to present in the an image in the introduction, explaining the connector typologies at the beginning influence reader comprehension and the study's narrative.

5) Why the authors did not applied the computation of the ductility index, in order to decide against measuring the ductility index in Figure 4, and could you explore the impact of including such measurements? See an detailed discussion in https://www.fracturae.com/index.php/fis/article/view/4621

6) Why was the shear test plot not included?

7) In Figure 8, how would the clarity and usefulness of the data be improved by separating the representations of normal concrete, flange, and bolt units?

8) Regarding the 0.4 bond coefficient value derived from previous work, could you provide more context or justification for this choice?

9) To improve reproducibility, what specific information could be added to clarify the stress-strain relationships for both concrete and steel used in your models?

10) The paper is very interesting, but the authors should improve the explanation to improve the reproducibility. I recommend adding the Abaqus CAE and/or inp file to help in future studies and improve the citation of the paper.

11) Authors are requested to explain the model of CDP.

Author Response

How exactly were the parameters for the numerical models, especially the Concrete Damage Plasticity parameters, validated with experimental outcomes? Please, add a table with parameters.

Reply：The relevant parameters of concrete damage are calculated according to the code, and the specific parameters are consistent with the code.

Table 3. Parameters related to plastic damage of concrete

Can the study detail the adaptability of the tested connection methods for various bridge scales and designs to understand their broader applicability?

Reply：In the early stage of this paper, the use of the type of abutment in this province was investigated. Ribbed abutments are widely used in this province, so this connection method is aimed at Bridges with ribbed abutments. In addition, this paper takes the two-lane background as the background and mainly considers the mechanical performance of ribbed abutments.

The authors are invited to improve the Figure 1.

Reply：The undeleted Chinese characters have been modified.

The authors are invited to present in the an image in the introduction, explaining the connector typologies at the beginning influence reader comprehension and the study's narrative.

Reply：At present, the connection methods of prefabricated structures can be divided into three kinds: "dry connection", "wet connection" and "glue joint". "Wet connection" is generally used to splice components by means of slurry anchor connection and grouting sleeve. This connection method has better structural durability and integrity, but it involves more wet construction and generally has a longer construction period. "Dry connection" is generally used to splice components with less wet work such as bolt connection and welding connection. This connection method has the advantages of short construction period and high degree of component assembly. However, the gap between prefabricated components is easy to cause corrosion of connectors and poor structural durability. "Glue joints" are generally connected by coating epoxy resin on the contact surface of prefabricated components. Epoxy resin has strong bonding ability with concrete, can effectively transfer load, and has good toughness, fatigue resistance and impact resistance. However, the construction technology is high, the bonding quality is unstable, and there are aging problems. Therefore, this paper chooses "dry connection" and "glue joint" two connection methods for assembly design.

Why the authors did not applied the computation of the ductility index, in order to decide against measuring the ductility index in Figure 4, and could you explore the impact of including such measurements?

Reply：The abutment cap plays a role in supporting the upper bridge panel. This paper explores the mechanical performance of the structure under vertical load, focusing on the stress at the position of the abutment cap. If the vertical deformation of the structure is too large and the bridge panel collapses, the structure cannot continue to be used even if the structure has not reached the ultimate bearing capacity, so the ductility coefficient of the structure is not measured in this paper. Only the mechanical properties of the structure under small deformation are investigated.

Why was the shear test plot not included?

Reply：There are some defects in the shear test, and strain gauges are not arranged at the joints to measure the strain of the structure. However, this shear test focuses on the shear capacity of the flange joint, and takes the slip of the interface (such as bolt breakage) and the failure of the structure to continue bearing as the structural failure indicators.

 In Figure 8, how would the clarity and usefulness of the data be improved by separating the representations of normal concrete, flange, and bolt units?

Reply：In this paper, ABAQUS software is used to conduct finite element numerical analysis. FIG. 8 shows the structure after assembly, in which the ordinary concrete, flanges and bolts are all built by solid elements. In addition, the ordinary concrete, flanges and bolts are built by 8-node hexahedral linear reduction integral element (C3D8R), and the rebar is built by 2-node truss element (T3D2). The concrete damage plastic model is adopted (assuming that the tensile damage is elastic, and can simulate the compressive plasticity of concrete, and assuming that the concrete will have two different damage modes due to stretching or compression, which can simulate the characteristics of the concrete in the force and deformation more realistically, and at the same time, the relevant distribution of cracks can be simulated by inputting the damage factors in the model). The constitutive relation of C50 concrete is established, and the constitutive relation of reinforcement is adopted as a two-fold model, and the reinforcement skeleton is connected with the concrete entity by embedding constraint. The FLP3 model is adopted at the joint. The contact between the concrete Surface, flange surface, bolt surface and flange surface is set as surface-to-surface contact, in this setting, the normal contact is "hard contact", and the tangential contact is friction. In order to simulate the bonding and sliding action between different components, the friction coefficient was determined to be 0.4 through multiple verification because the bonding quality of the structural joints could not be determined. The structure boundary is set with fixed constraints at the bottom of the floor according to the test conditions.

Regarding the 0.4 bond coefficient value derived from previous work, could you provide more context or justification for this choice?

Reply：In this paper, the friction coefficient of 0.4 is calculated by referring to the relevant literature, and then the model is tried out. After comparing the test results, it is determined by combining various factors.

To improve reproducibility, what specific information could be added to clarify the stress-strain relationships for both concrete and steel used in your models?

Reply：The relevant constitutive parameters of concrete and steel have been added in the paper.

Table 3. Parameters related to plastic damage of concrete

Table 4. Steel material parameter

The paper is very interesting, but the authors should improve the explanation to improve the reproducibility. I recommend adding the Abaqus CAE and/or inp file to help in future studies and improve the citation of the paper.

Reply：We are sorry that we cannot add CAE file for the time being due to the ongoing research.

Authors are requested to explain the model of CDP.

Reply：The concrete damage plastic model assumes that the tensile damage is elastic, and can simulate the compressive plasticity of concrete. It also assumes that the concrete will have two different damage modes due to tensile or compression, which can simulate the characteristics of the concrete in the stress and deformation more truly. Meanwhile, the damage factors in the model can simulate the relevant distribution of cracks.

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors investigate the structural performance of assembled rib-plate bridge abutments (ARBA) with two different connection methods: bull leg bolt and flange connections. In addition, they explored the bending and shear performance of the connection parts and related areas to

assess the damage characteristics and modes of these ARBA. Manuscript subject is interesting and falls within the journal topic. In general, the manuscript is well written and presented regarding both experimental and theoretical (FEM model) approach.

Authors should address to the following minor issues:

1.      Introduction: state of art in domain of the paper should be improved. References are cited without individualisation.

2.      In these circumstances, the novelty of the paper is not so well described in respect to the state of art. What are the new findings resulting from manuscript?

3.      In general, the references are old. ‘Fresh air’ is needed.

4.      Figure 1, (a). English should be used.

Author Response

1.Introduction: state of art in domain of the paper should be improved. References are cited without individualisation.

Reply：Since there are few papers on the direction of abutment and few studies on assembling ribbed abutment, most of the references are early engineering application reports and assembling articles on other parts of bridge.

2. In these circumstances, the novelty of the paper is not so well described in respect to the state of art. What are the new findings resulting from manuscript?

Reply：Prefabrication technology is through the factory prefabrication of each component of the bridge, and then the use of appropriate transport tools to transport all kinds of components to the site for assembly, without the need for mold pouring, only a short closure of traffic can achieve the purpose of saving time, small traffic impact, and reduce dust pollution. In view of the lack of research on the assembly of abutments at present, this paper designs two assembly methods and compares the loading methods of the two connection methods. The research shows that the mechanical performance of flanged rib-plate abutments under vertical load can reach "equivalent to cast-in-place".

3. In general, the references are old. ‘Fresh air’ is needed.

Reply：Because there are few papers on the direction of abutment and few studies on assembling ribbed abutment, the references are mostly early content. At present, most of the existing assembled abutments are engineering examples, and few articles have conducted in-depth research on assembled abutments.

4. Figure 1, (a). English should be used.

Reply：This omission has been corrected, thank you for your correction.

Author Response File: Author Response.docx

Reviewer 3 Report

The introduction provides a comprehensive review of the current state of research in a particular field. While the introduction does a good job of outlining the historical context and current practices, it could be improved in several areas to make it more scholarly.

Firstly, instead of simply citing in a group previous study, a deeper analysis of key studies should be done separately to highlight better how your work diverges from previous findings. Specifically, you should discuss the specific contributions and limitations of past research and explicitly articulate the innovative aspects of your approach or findings. This will help readers understand how your methodology or analysis improves upon or challenges existing practices and what novel aspects your work brings to the table.

Secondly, while the introduction briefly mentions experimental investigations and finite element analysis, the methodological framework needs to be explained in more detail. This includes detailing the novel aspects of your work and specifying the instruments used on the test. It's also important to mention whether they are calibrated or not.

The study introduces the choice of cow leg bolt connection and flange plate connection, but the rationale behind selecting these variations for ARBA requires further explanation. You should discuss the criteria or preliminary findings that led to focusing on these variations. Furthermore, context about international standards regarding construction structures and specific tests for these kinds of structures and joints must be included.

Please describe the fracture characteristics of the bolts shown in Figure 7. This includes identifying the type of fracture (e.g. brittle, ductile, fatigue), describing the surface features of the fracture, and noting any patterns or inconsistencies observed across different samples or loading conditions. Additionally, please propose any mitigation strategies or design improvements that could enhance the reliability and safety of these bolts.

Limitations related to the experimental setup, FE simulations, or the generalizability of the results need to be discussed. Additionally, while economic considerations are mentioned, providing a more detailed analysis or comparison of the cost implications of using ARBA with the recommended parameters versus traditional cast-in-place methods must be analyzed.

Your research's conclusions are informative but could benefit from greater specificity regarding the quantitative differences observed. Stating the percentage by which the bearing capacities and deformation capacities differ would provide a clearer understanding of the significance of the findings.

Provide further elaboration on the conditions or factors that enable ARBA to achieve "equivalent" performance to cast-in-place abutments under certain conditions. For example, must specific environmental, material, or design considerations be met to achieve this equivalence?

Figures and tables need to be resized and the typescript format should be consistent. Figures and tables need to be resized and the typescript format should be consistent.

There is a minor spelling mistake in the English text

Author Response

The introduction provides a comprehensive review of the current state of research in a particular field. While the introduction does a good job of outlining the historical context and current practices, it could be improved in several areas to make it more scholarly.

Firstly, instead of simply citing in a group previous study, a deeper analysis of key studies should be done separately to highlight better how your work diverges from previous findings. Specifically, you should discuss the specific contributions and limitations of past research and explicitly articulate the innovative aspects of your approach or findings. This will help readers understand how your methodology or analysis improves upon or challenges existing practices and what novel aspects your work brings to the table.

Secondly, while the introduction briefly mentions experimental investigations and finite element analysis, the methodological framework needs to be explained in more detail. This includes detailing the novel aspects of your work and specifying the instruments used on the test. It's also important to mention whether they are calibrated or not.

The study introduces the choice of cow leg bolt connection and flange plate connection, but the rationale behind selecting these variations for ARBA requires further explanation. You should discuss the criteria or preliminary findings that led to focusing on these variations. Furthermore, context about international standards regarding construction structures and specific tests for these kinds of structures and joints must be included.

Please describe the fracture characteristics of the bolts shown in Figure 7. This includes identifying the type of fracture (e.g. brittle, ductile, fatigue), describing the surface features of the fracture, and noting any patterns or inconsistencies observed across different samples or loading conditions. Additionally, please propose any mitigation strategies or design improvements that could enhance the reliability and safety of these bolts.

Limitations related to the experimental setup, FE simulations, or the generalizability of the results need to be discussed. Additionally, while economic considerations are mentioned, providing a more detailed analysis or comparison of the cost implications of using ARBA with the recommended parameters versus traditional cast-in-place methods must be analyzed.

Your research's conclusions are informative but could benefit from greater specificity regarding the quantitative differences observed. Stating the percentage by which the bearing capacities and deformation capacities differ would provide a clearer understanding of the significance of the findings.

Provide further elaboration on the conditions or factors that enable ARBA to achieve "equivalent" performance to cast-in-place abutments under certain conditions. For example, must specific environmental, material, or design considerations be met to achieve this equivalence?

 Figures and tables need to be resized and the typescript format should be consistent. Figures and tables need to be resized and the typescript format should be consistent.

Reply：

1. Based on existing engineering examples, some scholars have carried out a preliminary discussion on the connection mode of prefabricated abutment with the help of experimental and numerical analysis methods. The results show that H-shaped steel piles can effectively reduce shear damage and greatly improve the compressive performance of Bridges. However, the positioning requirements of H-shaped steel piles are high, and the quality of welding places cannot be guaranteed. And the weld position is prone to corrosion [15]-[17]; Prestressed bar connection has a good bearing capacity and can meet the seismic design requirements [15], but prestressed bar connection requires high precision and complicated processes. The results show that this connection method is suitable for longitudinal load distribution of prefabricated abutments, but it does not consider the weak position of the structure and has too many joints. In view of the lack of research on the assembly of abutments at present, this paper designs two assembly methods and compares the loading methods of the two connection methods. The research shows that the mechanical performance of flanged rib-plate abutments under vertical load can reach "equivalent to cast-in-place"
2. In this paper, two new assembly methods for ribbed abutment are designed to carry out static test. The instruments used in the test are calibrated according to the specifications.
3. In this paper, the static test is carried out on two kinds of assembly schemes and cast-in-place abutments to compare the mechanical properties of the structures. The results show that the rib-plate abutments connected by flanges are superior to the rib-plate abutments with rubber joints and can achieve "equivalent cast-in-place" in terms of mechanical properties. Therefore, the rib-plate abutments connected by flanges are selected as the foundation structure for subsequent parameter analysis. The shear test in section 1.3 is a test for the overall shear resistance of the joint.
4. This paper proposes an assembly scheme for ribbed abutment structure, focusing on the overall mechanical performance. In the shear test, the failure of ordinary bolts is brittle failure, and the shear strength of the flange joint surface is focused on in the shear test. The slip of the interface (such as bolt fracture) and the failure of the structure to continue bearing are taken as structural failure indicators.
5. Due to the wide range of economic aspects, including component costs, labor costs, site closure costs, etc., and the test model in this paper is a scaled structure, so the economic aspects cannot provide detailed reference for the time being. However, in the test preparation stage, comprehensive comparison shows that the cost of assembly rib-plate abutments connected by flanges is higher than that of cast-in-place abutments, specifically, the flange structure is steel structure. At scale, it is about 3,000 RMB; Second, the assembly time of the rib bridge connected by the flange is fast and the process is simple, and the cast-in-place structure needs the vertical plate support mold, and can enter the next process after pouring and maintenance.
6. Table 2 shows the percentage difference between the two different connection modes and the cast-in-place abutment, and Table 3 compares the errors in the test and model verification of the flange connected ribbed abutment.
7. The materials of the test and finite element simulation model in this paper are consistent with the actual engineering conditions, including the reinforcement ratio and stirrup ratio of the scaled abutment are consistent with the actual engineering structure of the abutment, so the design method of the abutment in the actual project can be used.
8. The gaps you pointed out have been corrected, thank you for your correction.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors answered all the questions

Reviewer 3 Report

The authors have successfully addressed all the comments.