Method for monitoring bonding slip performance and deterioration evolution of interface in combined member

Abstract

The invention discloses a method for monitoring the bonding slip performance and deterioration evolution of an interface in a combined member, and the method comprises the following steps: carrying out the degreasing cleaning pretreatment of a section with relatively high rigidity in a to-be-detected combined member, and obtaining a pretreated section; distributed optical fiber sensors based on Rayleigh scattering are arranged on the surface of the pretreated profile in the direction of measured cohesive force; bonding the profile on which the distributed optical fiber sensors are arranged with a to-be-detected matrix through an adhesive to prepare a combined component; a uniaxial tensile test is conducted on the combined component, distribution and evolution of steel bar strain in the test process are recorded through a distributed optical fiber sensor, distribution and evolution of the bond-slip relation are obtained, the local bond-slip relation can be researched, and the applicability and precision of a bond-slip model are improved; before uniaxial stretching, working conditions are applied to the composite structure to degrade the structure, and the influence of degradation on the bonding performance of the composite structure can be evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of bond-slip constitutive measurement, in particular to a method for monitoring interface bond-slip performance and degradation evolution thereof in a composite component. Background Art

[0002] Bond is an important mechanical property between two materials. It is the basis for the two materials / two components in a composite component to work together, and it affects the composite properties of the material and the stability of the structure. Taking reinforced concrete structure as an example, the interaction between steel bars and concrete determines the mechanical properties of reinforced concrete structure, including strength, deformation, durability and crack control, and plays a decisive role in the structural performance of reinforced concrete structure under the limit state of normal use and the limit state of bearing capacity. In finite element analysis, the bond-slip relationship directly affects the stress performance and failure mode of the structure, and is crucial to accurately predict and evaluate the structural performance of reinforced concrete. Therefore, the study of the bond-slip relationship between the interfaces of composite components has important research significance and engineering application value.

[0003] The traditional bond-slip relationship between reinforced concrete is extracted by the pull-out test, and the average bond stress obtained by the test is used to characterize the local bond strength of reinforced concrete. However, the bond-slip relationship between reinforced concrete varies in the length direction and is affected by factors such as the local mechanical properties of the component, the local stress conditions, and the historical load. Therefore, the bond-slip relationship measured by the pull-out test cannot be well applied to complex structures. Although researchers have tried to approximate the distribution of bond strength in the length direction by attaching strain gauges externally or internally, the presence of strain gauges affects the bond performance between reinforced concrete and can only provide limited and discrete strain information. The understanding of the bond-slip behavior of reinforced concrete is still very limited despite the large amount of manpower and material resources spent. In addition, strain gauges are not corrosion-resistant and easily damaged, and are not suitable for monitoring the bond-slip relationship between reinforced concrete under complex working conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a method for monitoring the interfacial bond-slip performance and its degradation evolution in a composite component, which can study the local bond-slip relationship and improve the applicability and accuracy of the bond-slip model.

[0005] The technical solution of the present invention is:

[0006] A method for monitoring the interfacial bonding and slip performance in a composite component comprises the following steps:

[0007] S1. Performing degreasing and cleaning pretreatment on the profiles with relatively high stiffness in the composite component to be tested to obtain the pretreated profiles;

[0008] S2, arranging the distributed optical fiber sensor on the surface of the pretreated profile along the direction of the measured bonding force;

[0009] S3, bonding the profile on which the distributed optical fiber sensor is arranged to the substrate to be measured by means of an adhesive to prepare a combined component;

[0010] S4. Performing a uniaxial tensile test on the composite component, recording the distribution and evolution of the steel bar strain during the test by a distributed optical fiber sensor, and obtaining the distribution and evolution of the bond-slip relationship.

[0011] Furthermore, the profiles described in S1 include but are not limited to plain round steel bars, ribbed steel bars, deformed steel bars and FRP bars.

[0012] Furthermore, the composite member described in S3 is not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure, CFRP reinforced concrete structure or CFRP steel structure can be selected according to the test purpose and test requirements.

[0013] Furthermore, the adhesive in S3 is a cyanoacrylate adhesive, which dries quickly and has great rigidity, thereby ensuring coordinated deformation of the distributed optical fiber sensor and the measured profile.

[0014] Furthermore, in S2, the distributed optical fiber sensor and the pre-treated profile are deformed in coordination, and certain protective measures are applied to the distributed optical fiber sensor. The protective measures are arranged in two ways: improving the survival rate of the distributed optical fiber sensor. An optical fiber groove is opened on the profile along the direction of the measured bonding force, and the distributed optical fiber sensor is placed along the optical fiber groove, or a silicone protective layer is covered on the distributed optical fiber sensor to protect the optical fiber sensor.

[0015] Furthermore, the bonding method between the profile and the substrate to be tested is determined according to the test purpose and test requirements, including but not limited to casting bonding between the profile and concrete, and gluing between the FRP cloth and the profile.

[0016] Furthermore, the shapes of the profile and the matrix are determined according to the test purpose and test requirements, and any one of reinforced prismatic components, reinforced cylindrical components, concrete components reinforced with FRP plates, or concrete components reinforced with FRP bars is selected.

[0017] Furthermore, the test loading method of the uniaxial tensile test described in S4 is designed according to the test purpose and test requirements, including but not limited to monotonic loading, cyclic loading considering fatigue factors, and loading-unloading-reloading considering historical load factors. Compared with the bond-slip relationship obtained by the pull-out test, the stress condition of this method is more consistent with the stress condition in actual engineering applications, and the obtained bond-slip relationship is more realistic and accurate.

[0018] Furthermore, a method for monitoring the degradation evolution of the interfacial bond-slip performance in a composite component also includes the following steps: before subjecting the composite component to a uniaxial tensile test, applying working conditions to the composite component to degrade the structure, and obtaining the distribution and evolution of the bond-slip performance of the composite component in a degraded state, which is used to evaluate the impact of the degradation on the bond performance of the composite structure. The working conditions applied to the composite component refer to working conditions that can affect the mechanical properties and performance of the composite structure to be tested, including but not limited to FPR ultraviolet aging, FRP wet-heat aging, and steel bar corrosion damage. The purpose of applying working conditions is to explore and obtain the bond-slip relationship of the component under a certain working condition, and to evaluate the impact of the working condition on the bond-slip relationship.

[0019] Furthermore, a method for monitoring the interfacial bond-slip performance in a composite component can be applied to extract the bond-slip relationship of the cemented components.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention monitors the bond-slip relationship of the composite structure through a uniaxial tensile test. Compared with the bond-slip relationship obtained by the pull-out test, the stress condition of this method is more consistent with the stress condition in actual engineering applications, and the bond-slip relationship obtained is more real and accurate. In addition, it has the ability to analyze the evolution of bond-slip during the load-bearing process, thereby deepening the understanding of the bond-slip relationship of the composite structure and promoting the development and progress of bond-slip monitoring technology. The distributed optical fiber sensor is small in size, light in weight, non-invasive, and does not affect the bonding performance between materials. The measured data results are more real and reliable. The distribution and evolution of the steel bar strain during the test are recorded by distributed optical fiber, and the distribution and evolution of the bonding force and slip value along the force direction are obtained. Compared with the discrete data measured by the strain gauge, it has the ability to study the local bond-slip relationship and can improve the applicability and accuracy of the bond-slip model.

[0022] 2. The bond-slip monitoring technology provided by the present invention can add multiple working conditions to the composite components to obtain the bond-slip relationship between the degraded composite structures under specific working conditions (such as cyclic loading and UV aging of FRP structures), providing support for the study of the bond-slip behavior of composite structures under complex working conditions.

[0023] 3. The bond-slip monitoring technology provided by the present invention can also be used to extract and monitor the bond-slip relationship of bonded components, which can meet the application requirements of various bond-slip relationship models, provide a multivariate and accurate bond-slip model for the bond-slip model of finite element analysis and numerical analysis, and improve the reliability and accuracy of finite element analysis and numerical analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the direct arrangement of the distributed optical fiber sensor of the present invention.

[0025] Figure 2 for Figure 1 Schematic diagram of the structure in cross section.

[0026] Figure 3 This is a schematic diagram of arranging distributed optical fiber sensors in optical fiber grooves processed according to the present invention.

[0027] Figure 4 for Figure 3 Schematic diagram of the structure in cross section.

[0028] Figure 5 This is a schematic diagram of using silicone to protect a distributed optical fiber sensor according to the present invention.

[0029] Figure 6 for Figure 5 Schematic diagram of the structure in cross section.

[0030] Figure 7 It is a schematic diagram of a typical test device for bonding and slippage of reinforced concrete tie rod structure of the present invention.

[0031] Figure 8 Schematic diagram of the distribution and evolution of the bond force of reinforced concrete structure extracted by the present invention.

[0032] Fig. 9 It is a schematic diagram of the bond-slip test of the reinforced concrete tie rod structure of the present invention under cyclic load and corrosion.

[0033] Fig.10 Schematic diagram of strain distribution of reinforced concrete tie rod structures with different corrosion degrees monitored by the present invention.

[0034] Fig.11 for Fig.10 Schematic diagram of the bond force distribution of reinforced concrete tie rod structures with different corrosion degrees extracted from the strain distribution.

[0035] Among them, 1. distributed optical fiber sensor, 2. steel bar, 3. FRP, 4. silicone, 5. concrete. DETAILED DESCRIPTION

[0036] Combine the following Figures 1 to 11, the specific implementation methods of the present invention are described in detail. In the description of the present invention, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation and be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0038] Example

[0039] A method for monitoring the interfacial bond-slip performance in a composite component is used to monitor the bond-slip relationship between a profile and a substrate to be tested, comprising the following steps:

[0040] S1. Degreasing and cleaning the profiles with relatively high stiffness in the composite component to be tested, that is, the main load-bearing materials, to obtain the pretreated profiles, which include but are not limited to plain round steel bars, ribbed steel bars, deformed steel bars, FRP bars and other composite material components with certain stiffness;

[0041] S2. Distributed optical fiber sensors are arranged on the surface of the pretreated profile along the direction of the measured bonding force. The distributed optical fiber sensors and the pretreated profiles are deformed in coordination. The distributed optical fiber sensors used in this embodiment are distributed optical fiber sensors based on Rayleigh scattering, which have higher resolution and accuracy. It is worth noting that different bonding techniques can be used to arrange the optical fibers according to the types of optical fibers used and the test requirements. For example, Figure 1 and Figure 2 As shown in FIG. 1 , the arrangement of the optical fiber sensor is as follows: a sheathed optical fiber with a diameter of 0.9 mm is directly pasted on the ribbed steel bar along the longitudinal rib of the steel bar; Figure 3-Figure 6 The arrangement shown in the figure imposes certain protection measures on the distributed optical fiber sensor to improve the survival rate of the distributed optical fiber sensor. Figure 3 and Figure 4 As shown in FIG. 1 , an optical fiber groove is opened on the profile along the direction of the measured bonding force, and the distributed optical fiber sensor is placed along the optical fiber groove, as shown in FIG. Figure 5 and Figure 6 As shown, a silicone protective layer is covered on the distributed optical fiber sensor to protect the optical fiber sensor.

[0042] S3. The profile on which the distributed optical fiber sensor is arranged is bonded to the substrate to be measured by an adhesive, such as concrete, to prepare a composite component. The profile extends from both ends of the composite component to serve as a tensile clamping section. The specific structure is as shown in the attached Figure 7 As shown, specifically, the bonding between the profile and the substrate to be tested, the bonding method is determined according to the test purpose and test requirements, including but not limited to the pouring bonding between the profile and concrete, and the bonding between the FRP cloth and the profile;

[0043] S4. Perform a uniaxial tensile test on the composite component, and record the distribution and evolution of the steel bar strain during the test by using a distributed optical fiber sensor to obtain the distribution and evolution of the bond-slip relationship. The distribution and evolution of the steel bar strain and its corresponding load during the test are recorded by using a distributed optical fiber sensor and a tensile instrument to obtain the distribution and changes of the bond force and slip value of the composite component, such as Figure 8 As shown, the test loading method of the uniaxial tensile test is designed according to the test purpose and test requirements, including but not limited to monotonic loading, cyclic loading considering fatigue factors, and loading-unloading-reloading loading method considering historical load factors.

[0044] Specifically, the composite component in S3 is not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure, CFRP reinforced concrete structure, and CFRP steel structure can be selected according to the test purpose and test requirements.

[0045] In some embodiments, the adhesive in S3 is a cyanoacrylate adhesive, which is quick-drying and has a large rigidity, to ensure that the distributed optical fiber sensor and the measured profile deform in coordination.

[0046] The shapes of the profile and the matrix are determined according to the test purpose and test requirements, and any one of reinforced prismatic components, reinforced cylindrical components, concrete components reinforced with FRP plates, and concrete components reinforced with FRP bars can be selected.

[0047] Due to the influence of factors such as environment, load and material aging, composite structures will inevitably suffer structural damage and functional degradation during service. These degradations will change the bonding performance of composite structures, seriously reduce the service life of composite structures, and endanger the safety of composite structures. At present, the evaluation of the mechanical properties of composite structures under degraded conditions is mainly based on the monitoring data of local material properties and overall structural performance. There is a lack of direct monitoring methods for the degradation state of bond slip between internal interfaces of composite structures, and the accurate evaluation of the residual performance of composite structures under degraded conditions is limited. The evaluation method of the impact of degradation on the bonding performance of composite structures needs to be improved and developed urgently.

[0048] Before the uniaxial tensile test is performed on the composite component in S4 of this embodiment, working conditions are applied to the composite component to degrade the structure, and the bond slip distribution and evolution of the composite component in the degraded state are obtained to evaluate the effect of degradation on the bonding performance of the composite structure. The working conditions applied to the composite component in S4 refer to working conditions that affect the mechanical properties and performance of the composite structure to be tested, including but not limited to FPR ultraviolet aging, FRP wet heat aging, steel bar corrosion damage, for example Fig. 9 The accelerated corrosion test of reinforced concrete shown in the figure applies the working corrosion environment to the composite components and obtains the following results: Fig.10 , Fig.11 The stress distribution and evolution diagrams and the bond force distribution and evolution diagrams of different corroded components under the same load are shown.

[0049] The above-mentioned method for monitoring the interfacial bond-slip performance in composite components can also be applied to extract the bond-slip relationship of adhesive components.

[0050] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for monitoring the interfacial bond-slip performance in a composite component, used to detect the bond-slip relationship between a profile and a substrate to be tested, characterized in that: The following steps are involved: S1, performing degreasing and cleaning pretreatment on the profiles in the composite component to be tested to obtain the pretreated profiles; S2, arranging the distributed optical fiber sensor on the surface of the pretreated profile along the direction of the measured bonding force; S3, bonding the profile on which the distributed optical fiber sensor is arranged to the substrate to be measured by means of an adhesive to prepare a combined component; S4. Performing a uniaxial tensile test on the composite component, recording the distribution and evolution of the steel bar strain during the test by a distributed optical fiber sensor, and obtaining the distribution and evolution of the bond-slip relationship.

2. A method for monitoring the bond-slip relationship between interfaces of different materials of a composite component according to claim 1, characterized in that: In S2, the distributed optical fiber sensor and the pre-treated profile are deformed in coordination, and the arrangement of the distributed optical fiber sensor includes but is not limited to the following two methods: A fiber optic groove is provided on the profile along the direction of the measured bonding force, and a distributed fiber optic sensor is placed along the fiber optic groove; or, A silicone protective layer is covered on the distributed optical fiber sensor to protect the optical fiber sensor.

3. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The composite member described in S3 is not limited to a specific material, and any one of reinforced concrete structure, steel tube concrete structure, FRP reinforced concrete structure, CFRP reinforced concrete structure or CFRP steel structure can be selected according to the test purpose and test requirements.

4. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The adhesive in S3 is a cyanoacrylate adhesive.

5. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The profiles described in S1 include but are not limited to plain round steel bars, ribbed steel bars, deformed steel bars or FRP bars.

6. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The bonding method between the profile and the substrate to be tested is determined according to the test purpose and test requirements, including but not limited to the pouring bonding between the profile and concrete, and the bonding between the FRP cloth and the profile.

7. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The shapes of the profile and the base are selected from any one of a reinforced prism member, a reinforced cylindrical member, a concrete member reinforced with an FRP plate, or a concrete member reinforced with an FRP bar.

8. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1, characterized in that: The test loading method of the uniaxial tensile test described in S4 is designed according to the test purpose and test requirements, including but not limited to monotonic loading, cyclic loading considering fatigue factors, or loading-unloading-reloading loading method considering historical load factors.

9. The method for monitoring the interfacial bonding and slip performance in a composite component according to claim 1 is characterized in that: The following steps are also included: Before the uniaxial tensile test is performed on the composite component, working conditions are applied to the composite component to degrade the structure, and the bond-slip distribution and evolution of the composite component in the degraded state are obtained to evaluate the influence of the deterioration on the bonding performance of the composite structure. The applied working conditions include but are not limited to FPR ultraviolet aging, FRP wet-heat aging or steel bar corrosion damage.

10. A method for monitoring the interfacial bond-slip performance in a composite component is used to extract the bond-slip relationship of the adhesive assembly.

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