Reinforcing beam reinforced by adopting retired wind power blade and method for determining bending rigidity of reinforcing beam

Abstract

The invention provides a reinforcing beam reinforced by adopting an out-of-service wind power blade and a method for determining the bending rigidity. According to the reinforcing beam, a plurality of grooves are formed in at least one surface of a reinforced concrete beam; the reinforcing layer comprises reinforcing ribs and a cement-based composite matrix, a plurality of protrusions are arranged on the surface of the cement-based composite matrix, the protrusions are arranged at intervals in the length direction of the cement-based composite matrix, and the protrusions are correspondingly embedded into the grooves, so that the reinforcing layer is connected with the reinforced concrete beam to obtain a reinforced concrete reinforced beam; wherein the reinforcing ribs are obtained by disassembling and cutting a main beam of the retired wind power blade. According to the reinforcing beam, the combining capacity of the reinforced concrete beam and the reinforcing layer is high, mutual slippage is avoided, the retired wind power blade composite material resources are utilized, the environment is protected, and the cost is saved while high-performance reinforcing treatment can be conducted on the damaged reinforced concrete beam structure or the reinforced concrete beam structure with insufficient bearing capacity.

Description

Technical Field

[0001] This invention generally relates to the field of architectural design technology, and specifically to a reinforced beam reinforced with decommissioned wind turbine blades and a method for determining its bending stiffness. Background Technology

[0002] In related technologies, a widely used reinforcement method for addressing the insufficient load-bearing capacity of in-service or aging reinforced concrete beam structures is the external application of fiber-reinforced polymer (FRP) sheets or strips for flexural or shear reinforcement. This type of organic FRP external reinforcement technology has advantages such as light weight, high strength, and convenient construction, and has been widely used in engineering. However, FRP itself is an organic polymer material with poor high-temperature resistance, and its performance is easily degraded or even failed under high-temperature environments such as fires. Furthermore, existing reinforcement layers composed of FRP bars and cement-based materials still suffer from the problem of cracking of the cement-based material in the tension zone, affecting the stability of the reinforcement effect. Additionally, the interfacial bonding between the FRP bars and the cement matrix is ​​weak, and peeling or slippage may occur under long-term loads or environmental effects, further weakening the overall cohesive load-bearing capacity. Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a reinforced beam reinforced with decommissioned wind turbine blades and a method for determining its bending stiffness. The reinforced beam has a strong bond between the reinforced concrete beam and the reinforcement layer, avoiding mutual slippage. Moreover, by utilizing the composite material resources of decommissioned wind turbine blades, it is possible to achieve high-performance reinforcement of damaged or insufficiently load-bearing reinforced concrete beam structures while being environmentally friendly and cost-effective.

[0004] In a first aspect, the present invention provides a reinforced beam reinforced with decommissioned wind turbine blades, comprising: A reinforced concrete beam 1 has a plurality of grooves 14 on at least one surface, and the plurality of grooves 14 are spaced apart along the length direction of the reinforced concrete beam 1. The reinforcing layer 2 includes reinforcing bars and a cement-based composite matrix 23. The reinforcing bars are embedded inside the cement-based composite matrix 23 to form a reinforcing skeleton. Multiple protrusions 24 are provided on the surface of the cement-based composite matrix 23. The multiple protrusions 24 are spaced apart along the length direction of the cement-based composite matrix 23, and the multiple protrusions 24 are correspondingly embedded in multiple grooves 14 so that the reinforcing layer 2 is connected to the reinforced concrete beam 1 to obtain a reinforced concrete beam. The reinforcing bars are obtained by disassembling and cutting the main beam of the retired wind turbine blade.

[0005] As an optional solution, the number of protrusions 24 is the same as the number of grooves 14, and the distance between two adjacent protrusions 24 is equal to the distance between two adjacent grooves 14, with the positions of the protrusions 24 and the grooves 14 corresponding one-to-one.

[0006] As an optional solution, the height of the protrusion 24 is equal to the depth of the groove 14, the width of the protrusion 24 is equal to the width of the groove 14, the height of the protrusion 24 is 4-6mm, the width of the protrusion 24 is 5-8mm, and the distance between two adjacent protrusions 24 is 8-10mm.

[0007] As an optional solution, the reinforcing bars include longitudinal square bars 21 and transverse square bars 22. The tensile strength of each longitudinal square bar 21 and transverse square bar 22 is 800-1400 MPa, the elastic modulus of each longitudinal square bar 21 and transverse square bar 22 is 30-70 GPa, the cross-sectional height of each longitudinal square bar 21 and transverse square bar 22 is 4-6 mm, and the cross-sectional width of each longitudinal square bar 21 and transverse square bar 22 is 6-10 mm.

[0008] As an optional solution, the fiber extension direction of the longitudinal square bar 21 is consistent with the axis of the longitudinal square bar 21, and the fiber extension direction of the transverse square bar 22 is consistent with the axis of the transverse square bar 22.

[0009] As an optional option, the thickness of the cement-based composite matrix 23 is 25-80 mm, and the tensile fracture strain of the cement-based composite matrix 23 is 1.5-3.0%.

[0010] As an alternative, the reinforced concrete 1 consists of a frame formed by longitudinal steel bars 11 and stirrups 12, and concrete 13 poured inside and outside the frame.

[0011] In a second aspect, the present invention provides a method for determining the bending stiffness of a reinforced beam reinforced with decommissioned wind turbine blades, as described in the first aspect, specifically including: Determine the geometric parameters and elastic modulus of reinforced concrete beam 1 and reinforcement layer 2; Based on the geometric parameters and elastic modulus of reinforced concrete beam 1 and strengthening layer 2, determine the flexural stiffness of the reinforced concrete strengthening beam in the uncracking state. K in The details are as follows:

[0012] In the formula: E con The elastic modulus of reinforced concrete beam 1 is given. E s To determine the elastic modulus of reinforcement layer 2, b To reinforce the cross-sectional width of the system, h con To reinforce the beam's cross-sectional height,h s The cross-sectional thickness of the reinforcement layer; Bending stiffness based on the uncracking state K in Calculate the flexural stiffness after cracking without considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. K post The details are as follows: K post =0.35 K in Based on the longitudinal reinforcement ratio ρ of reinforced concrete beam 1 b FRP reinforcement ratio of reinforcement layer 2 r s The reduction factor, which takes into account the interface slip between reinforced concrete beam 1 and reinforcement layer 2, is determined by a predetermined reduction factor. β ; According to the reduction factor β Calculate the bending stiffness of the reinforced concrete reinforced beam considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. K f Specifically as follows:

[0013] in, K f Used to evaluate the actual flexural stiffness of reinforced concrete beams under normal serviceability limit conditions.

[0014] As an optional solution, based on the longitudinal reinforcement ratio of reinforced concrete beam 1 r b FRP reinforcement ratio of reinforcement layer 2 r s A finite element numerical model of a reinforced concrete beam was established, and different longitudinal reinforcement ratios for reinforced concrete beam 1 were set. r b FRP reinforcement ratio of reinforcement layer 2 r s Parametric analysis was conducted to determine the reduction factor considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. β The details are as follows:

[0015] in, k 1, k 2 represents the coefficients obtained through parametric analysis and linear regression fitting. c It is a constant.

[0016] As an optional solution, k 1,k 2 and constants c It is obtained through the following steps: Determine the actual stiffness of the reinforced concrete beam after cracking. K real , In the formula, Δ represents the mid-span deflection. l For a simply supported beam, the span is long. q The magnitude of the uniformly distributed load; according to K real and K post The actual reduction factor is calculated by reverse calculation. β r The details are as follows:

[0017] Will β r Substitute reduction factor β The formula combines the set r b and r s Perform linear regression fitting to obtain k 1, k 2 and constants c .

[0018] This invention utilizes a reinforced beam made from decommissioned wind turbine blades. The reinforcing ribs of the reinforced layer are formed by disassembling and cutting the decommissioned wind turbine blades, replacing traditional high-cost FRP (fiberglass reinforced plastic) ribs. This solves the problems of difficult wind turbine blade recycling and disposal, facilitating the high-value reuse of decommissioned wind turbine blades and realizing the resource-based and functional reuse of waste composite materials, resulting in significant environmental benefits and sustainable development value. Furthermore, it reduces the cost of the reinforced layer. By setting a groove structure on the reinforced concrete beam and a corresponding protrusion structure on the reinforced layer, the interlocking of the groove and protrusion enhances the mechanical interlocking and interface anchoring capacity between the reinforced concrete beam and the reinforced layer, significantly improving the interface shear and anti-slip performance. This overcomes the problem of easy peeling or failure of the interface in traditional reinforced layers, ensuring stable and reliable long-term service performance. Attached Figure Description

[0019] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a reinforced beam structure using decommissioned wind turbine blades, as an embodiment of this application. Figure 2 This is a schematic diagram of the reinforced concrete beam in the reinforced beam reinforced with decommissioned wind turbine blades, as described in an embodiment of this application. Figure 3 This is a schematic diagram of the reinforcement layer in a reinforced beam reinforced with decommissioned wind turbine blades, as described in an embodiment of this application. Figure 4 The method for determining the bending stiffness of a reinforced beam reinforced with decommissioned wind turbine blades, as described in an embodiment of this application, yields a comparison chart of the stiffness and the actual stiffness.

[0020] In the picture, 1. Reinforced concrete beam; 11. Longitudinal reinforcement; 12. Stirrups; 13. Concrete; 14. Groove. 2. Reinforcing layer; 21. Longitudinal square reinforcement; 22. Transverse square reinforcement; 23. Cement-based composite matrix; 24. Protrusion. Detailed Implementation

[0021] The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present application will now be described in detail with reference to embodiments.

[0022] In recent years, inorganic reinforcement technology has gradually developed. Its basic idea is to add a composite reinforcement layer consisting of FRP bars and high-performance cement-based materials to the surface of reinforced concrete beams, combining the high strength of FRP with the high-temperature resistance of cement-based materials. This type of composite inorganic reinforcement system, to a certain extent, balances load-bearing capacity and fire resistance, becoming a promising new solution to replace traditional FRP external reinforcement.

[0023] However, the inorganic reinforcement layer composed of FRP bars and cement-based materials in related technologies still has certain shortcomings: First, FRP bars, as a high-performance material, are expensive and not conducive to large-scale engineering applications; second, cement-based materials are prone to cracking in the tension area, affecting the stability of the reinforcement effect; in addition, the interfacial bonding performance between FRP bars and cement matrix is ​​weak, and peeling or slippage may occur under long-term load or environmental action, further weakening the overall cooperative load-bearing capacity.

[0024] To address the aforementioned problems, embodiments of this application provide a reinforced beam strengthened with decommissioned wind turbine blades, such as... Figure 1-3 As shown, it includes: A reinforced concrete beam 1 has a plurality of grooves 14 on at least one surface, and the plurality of grooves 14 are spaced apart along the length direction of the reinforced concrete beam 1. The reinforcing layer 2 includes reinforcing bars and a cement-based composite matrix 23. The reinforcing bars are embedded inside the cement-based composite matrix 23 to form a reinforcing skeleton. Multiple protrusions 24 are provided on the surface of the cement-based composite matrix 23. The multiple protrusions 24 are spaced apart along the length direction of the cement-based composite matrix 23, and the multiple protrusions 24 are correspondingly embedded in multiple grooves 14 so that the reinforcing layer 2 is connected to the reinforced concrete beam 1 to obtain a reinforced concrete beam. The reinforcing bars are obtained by disassembling and cutting the main beam of the retired wind turbine blade.

[0025] Understandably, multiple grooves 14 are opened on the surface of the reinforced concrete beam 1 to form a stepped toothed rough surface, and multiple protrusions 24 are set on the surface of the cement-based composite matrix 23 of the reinforcement layer 2 to form a stepped toothed rough surface. Through the interlocking of the concave and convex surfaces, the reinforcement layer 2 and the reinforced concrete beam 1 can be anchored, improving the anchoring performance and reducing the relative slippage between the interfaces.

[0026] The embodiments of this application employ a reinforced beam reinforced with decommissioned wind turbine blades, which solves the problems of high cost and weak interfacial bonding performance of existing reinforced beams, making them prone to slippage. By disassembling and cutting decommissioned wind turbine blades to form the reinforcing ribs of the reinforced layer, the traditional high-cost FRP rib material is replaced. On the one hand, this solves the problems of difficult recycling and disposal of wind turbine blades, which is conducive to the high-value reuse of decommissioned wind turbine blades and the resource-based and functional reuse of waste composite materials, which has significant environmental benefits and sustainable development value. On the other hand, it reduces the cost of the reinforced layer. By setting a groove structure on the reinforced concrete beam 1 and a corresponding protrusion structure on the reinforced layer, the concave-convex fit enhances the mechanical interlocking and interfacial anchoring ability between the reinforced concrete beam 1 and the reinforced layer, significantly improving the interfacial shear resistance and anti-slip performance, overcoming the problem of easy peeling or failure of the interface of traditional reinforced layers, and ensuring the stable and reliable performance of long-term service.

[0027] In some embodiments, the number of protrusions 24 is the same as the number of grooves 14, and the distance between two adjacent protrusions 24 is equal to the distance between two adjacent grooves 14, and the positions of the protrusions 24 and the grooves 14 correspond one-to-one.

[0028] In this embodiment, the number of protrusions 24 and grooves 14 are the same and the spacing is equal, which can ensure that the protrusions 24 and grooves 14 can reliably fit together, thereby enabling the reinforced concrete beam 1 and the reinforcement layer 2 to reliably mechanically interlock, and improving the anchorage capacity between the reinforced concrete beam 1 and the reinforcement layer 2.

[0029] In a preferred embodiment, the height of the protrusion 24 is equal to the depth of the groove 14, the width of the protrusion 24 is equal to the width of the groove 14, the height of the protrusion 24 is 4-6 mm, the width of the protrusion 24 is 5-8 mm, and the distance between two adjacent protrusions 24 is 8-10 mm.

[0030] Specifically, the height of the protrusion 24 or the groove 14 may be, but is not limited to, 4mm, 5mm or 6mm, the width of the protrusion 24 or the groove 14 may be, but is not limited to, 5mm, 6mm, 7mm or 8mm, and the distance between two adjacent protrusions 24 or two adjacent grooves 14 is 8mm, 9mm or 10mm. The dimensions of the protrusions and grooves in this embodiment are beneficial to improving the mechanical bonding and anchoring performance between the subsequent reinforcement layer 2 and the original reinforced concrete beam 1.

[0031] In some embodiments, the reinforcing bars include longitudinal square bars 21 and transverse square bars 22. The tensile strength of each of the longitudinal square bars 21 and the transverse square bars 22 is 800-1400 MPa, the elastic modulus of each of the longitudinal square bars 21 and the transverse square bars 22 is 30-70 GPa, the cross-sectional height of each of the longitudinal square bars 21 and the transverse square bars 22 is 4-6 mm, and the cross-sectional width of each of the longitudinal square bars 21 and the transverse square bars 22 is 6-10 mm.

[0032] In this embodiment, the reinforcing bars include longitudinal square bars 21 and transverse square bars 22, both of which have excellent mechanical properties.

[0033] In some embodiments, the fiber extension direction of the longitudinal square bar 21 is consistent with the axis of the longitudinal square bar 21, and the fiber extension direction of the transverse square bar 22 is consistent with the axis of the transverse square bar 22.

[0034] In this embodiment, the fiber extension direction of the longitudinal square bar 21 is aligned with the axis, and the extension direction of the transverse square bar 2 is aligned with the axis. This is beneficial to make full use of the anisotropic properties of fiber-reinforced composite materials, so that their extremely high tensile strength and elastic modulus can be fully utilized in the axial direction, thereby most effectively bearing the tensile stress caused by bending deformation and significantly improving the overall axial stiffness and crack resistance of the reinforcement layer.

[0035] Furthermore, the thickness of the cement-based composite matrix 23 is 25–80 mm, and the tensile fracture strain of the cement-based composite matrix 23 is 1.5–3.0%, which is beneficial to significantly improve crack resistance and energy dissipation capacity.

[0036] The engineering cement-based composite matrix used has a high tensile fracture strain (1.5% to 3.0%), which works in conjunction with the high-strength retired blade square reinforcement to effectively suppress cracking of the reinforcement layer, improve ductility and energy dissipation capacity. The integral cast-in-place reinforcement layer can significantly enhance the bending stiffness and load-bearing capacity of the reinforced component, and is suitable for the high-performance reinforcement requirements of bending components.

[0037] In some embodiments, the reinforced concrete 1 is composed of a frame formed by longitudinal steel bars 11 and stirrups 12, and concrete 13 poured inside and outside the frame.

[0038] In summary, the reinforced beam structure of the embodiments of this application not only realizes the resource reuse of retired wind turbine blades and improves the green and low-carbon performance of structural reinforcement, but also significantly improves the load-bearing capacity, durability and crack resistance of the structure through the synergistic effect of inorganic materials and high-performance reinforcing bars, and has good engineering applicability and promotion prospects.

[0039] In practical construction, the processing method of the reinforced beam using decommissioned wind turbine blades in the embodiments of this application is as follows: The reinforced concrete beam 1 requiring reinforcement undergoes surface treatment. Adherence and loose layers on the bottom surface of the original concrete are removed. A groove 14 is formed at the reinforcement area using an electric chisel or mechanical cutting equipment, resulting in a stepped toothed rough surface to improve the bonding and anchoring performance between the subsequent reinforcement layer 2 and the original structure. The height of the groove 14 is 4–6 mm, the width is 5–8 mm, and the spacing between two adjacent grooves 14 is 8–10 mm. According to the design requirements, reinforcing bars are set in the reinforcement area. The reinforcing bars are made of glass fiber reinforced resin composite square bars, including longitudinal square bars 21 and transverse square bars 22. These square bars are obtained by disassembling and cutting the main beam of the retired wind turbine blade. The longitudinal square bars 21 and transverse square bars 22 each have a cross-sectional height of 4-6 mm and a width of 6-10 mm, and have a tensile strength of 800-1400 MPa and an elastic modulus of 30-70 GPa. A pre-mixed, uniformly applied high-toughness engineering cement-based composite matrix 23 is applied to the surface of the reinforcing bar using either a spraying or layered application method. The cement-based composite matrix 23 has a thickness of 25–80 mm, exhibits good formability and workability, and possesses a tensile fracture strain of 1.5–3.0%, effectively enhancing the deformation capacity and crack control performance of the reinforcement layer. Finally, after spraying or plastering, the reinforcement layer should be wet-cured for no less than 7 days according to the specifications to ensure that the material reaches the design strength. After curing, it can be put into normal use to form a reinforced composite structural beam.

[0040] Secondly, embodiments of this application provide a method for determining the bending stiffness of a reinforced beam reinforced with decommissioned wind turbine blades, specifically including: S10. Determine the geometric parameters and elastic modulus of reinforced concrete beam 1 and reinforcement layer 2; S20. Assuming that both reinforced concrete 1 and the strengthening layer 2 are homogeneous materials and well bonded, based on the derivation of material mechanics formulas, determine the bending stiffness of the reinforced concrete strengthening beam in the uncracking state according to the geometric parameters and elastic modulus of the reinforced concrete beam 1 and the strengthening layer 2. K in The details are as follows:

[0041] In the formula: E con The elastic modulus of reinforced concrete beam 1 is given. E s To determine the elastic modulus of reinforcement layer 2, b To reinforce the cross-sectional width of the system, h con To reinforce the beam's cross-sectional height, h s The cross-sectional thickness of the reinforcement layer; S30, Bending stiffness based on the uncracking state K in Calculate the flexural stiffness after cracking without considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. K post The details are as follows: K post =0.35 K in , Right now,

[0042] S40, Based on the longitudinal reinforcement ratio ρ of reinforced concrete beam 1 b FRP reinforcement ratio of reinforcement layer 2 r s Determine the reduction factor considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. β ; It is understood that the reinforced concrete reinforced beam in the embodiments of this application is a composite component, so its overall stiffness composition can still be understood as the stiffness generated by the independent operation of the upper reinforced concrete beam 1 and the reinforcement layer 2, as well as the stiffness generated by the shear force transferred due to the bond between the two. However, it should be noted that since the bond between the two cannot completely transfer the shear force in the initial stage, this part of the stiffness needs to be reduced, hence the introduction of a reduction factor. β , S50, based on the reduction factor β Calculate the bending stiffness of the reinforced concrete reinforced beam considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. K f Specifically as follows:

[0043] in, K f Used to evaluate the actual flexural stiffness of reinforced concrete beams under normal serviceability limit conditions.

[0044] In some embodiments, S40, a reduction factor is determined that takes into account the interface slip between the reinforced concrete beam 1 and the strengthening layer 2. β ,include: Based on the longitudinal reinforcement ratio of reinforced concrete beam 1 r b FRP reinforcement ratio of reinforcement layer 2 r s A finite element numerical model of a reinforced concrete beam was established, and different longitudinal reinforcement ratios for reinforced concrete beam 1 were set. r b FRP reinforcement ratio of reinforcement layer 2 r s Parametric analysis was conducted to determine the reduction factor considering the interface slip between reinforced concrete beam 1 and reinforcement layer 2. β The details are as follows:

[0045] in, k 1, k 2 represents the coefficients obtained through parametric analysis and linear regression fitting. c It is a constant.

[0046] Specifically, k 1, k 2 and constants c It is obtained through the following steps: Determine the actual stiffness of the reinforced concrete beam after cracking. K real , In the formula, Δ represents the mid-span deflection. l For a simply supported beam, the span is long. q The magnitude of the uniformly distributed load; according to K real and K post The actual reduction factor is calculated by reverse calculation. β r The details are as follows:

[0047] Will β r Substitute reduction factor β The formula combines the set r b and r s Perform linear regression fitting to obtain k 1, k 2 and constants c .

[0048] In summary, the method for determining the bending stiffness of the reinforced beam reinforced with decommissioned wind turbine blades in the embodiments of this application can reliably calculate the bending stiffness of the reinforced concrete reinforced beam with interface slippage between the reinforced concrete beam 1 and the reinforcement layer 2. K f This facilitates the design of reinforcement methods for reinforced concrete beam 1 according to actual working conditions during actual processing, thereby further improving the stability and reliability of reinforced concrete reinforced beams.

[0049] The following specific embodiment illustrates the method for determining the bending stiffness of a reinforced beam reinforced with decommissioned wind turbine blades according to the present invention.

[0050] (1) Formula for calculating bending stiffness before cracking without considering slippage between the two Assuming that both reinforced concrete 1 and the strengthening layer 2 are homogeneous materials with good bonding, the bending stiffness of the reinforced concrete beam in the uncracking state is determined based on the geometric parameters and elastic modulus of the reinforced concrete beam 1 and the strengthening layer 2, derived from the formulas of mechanics of materials. K in The details are as follows:

[0051] In the formula: E con The elastic modulus of reinforced concrete beam 1 is given. E s To determine the elastic modulus of reinforcement layer 2, b To reinforce the cross-sectional width of the system, h con To reinforce the beam's cross-sectional height, h s The cross-sectional thickness of the reinforcement layer; (2) Formula for calculating bending stiffness after cracking without considering slippage between the two According to the "Code for Design of Concrete Structures" (GB50010-2010) and related research, the stiffness expression of reinforced concrete after cracking is approximately 30%~40% of that before cracking. Based on existing experimental data, this embodiment takes a value of 0.35. Therefore, the bending stiffness after cracking is not considered under the condition of slippage between the two. K post )for:

[0052] (3) Formula for calculating bending stiffness after cracking, considering slippage between the reinforced beam and the reinforced layer According to the above formula, the reinforced beam in this example is a composite component. Therefore, in the derivation of the stiffness of the service section in this embodiment, its overall stiffness composition can still be understood as the stiffness generated by the independent operation of the upper and lower reinforced beams and the reinforced layer, as well as the stiffness generated by the shear force transferred due to the bond between the two. However, it should be noted that since the bond between the two cannot completely transfer the shear force in the initial stage, this part of the stiffness needs to be reduced, hence the introduction of a reduction factor. β Then, considering the flexural stiffness of both reinforced concrete beam 1 and reinforcement layer 2 under the condition of slippage. K f for:

[0053] (4) To obtain the reduction factor β A two-dimensional numerical model was established based on the general-purpose finite element software ABAQUS, and parameter analysis was performed. The parameters considered mainly included the longitudinal reinforcement ratio of reinforced concrete beam 1. r b FRP reinforcement ratio of reinforcement layer 2 r s ; The actual post-cracking stiffness is calculated using the following formula. K real : ; After calculating the actual stiffness, the actual reduction factor βr can be calculated using the following formula. The results of the parameter analysis are shown in Table 1:

[0054] Table 1. Parameter Analysis and Results

[0055] (4) Obtain the reduction coefficient formula by fitting regression. Establish β and r b as well as r s The relationship was determined, and a linear fit was performed to obtain... β and r b as well as r s The relationship is as follows, and the bending stiffness of the reinforced concrete beam that can slip at the interface between the reinforced concrete beam 1 and the reinforcement layer 2 is... K f Combined as follows:

[0056] K f Compared with actual stiffness Kreal For example Figure 4 As shown (where, Figure 4 The solid line represents the calculated result. K f The circle represents the actual stiffness. K real The variance of the residual of the fitting formula is 0.00319, indicating that the calculation formula has high accuracy and can predict the actual bending stiffness of reinforced concrete beams under normal service limit state.

[0057] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A reinforced beam augmented with decommissioned wind turbine blades, characterized in that, The application relates to a reinforced concrete beam (1) provided with a plurality of grooves (14) on at least one surface of the reinforced concrete beam (1), the grooves (14) being arranged at intervals along the length direction of the reinforced concrete beam (1); a reinforcing layer (2) comprising reinforcing bars and a cement-based composite matrix (23), the reinforcing bars being embedded in the cement-based composite matrix (23) to form a reinforcing framework, the surface of the cement-based composite matrix (23) being provided with a plurality of protrusions (24) arranged at intervals along the length direction of the cement-based composite matrix (23), the protrusions (24) being embedded in the grooves (14) correspondingly, so that the reinforcing layer (2) is connected with the reinforced concrete beam (1) to form a reinforced concrete beam; wherein the reinforcing bars are obtained by disassembling and cutting a retired wind power blade main beam. The number of the protrusions (24) is consistent with the number of the grooves (14), the interval between two adjacent protrusions (24) is equal to the interval between two adjacent grooves (14), and the positions of the protrusions (24) and the grooves (14) correspond to each other. The height of the protrusions (24) is equal to the groove depth of the grooves (14), the width of the protrusions (24) is equal to the width of the grooves (14), the height of the protrusions (24) is 4-6 mm, the width of the protrusions (24) is 5-8 mm, and the interval between two adjacent protrusions (24) is 8-10 mm.

2. A reinforced beam for enhancing a retired wind turbine blade according to claim 1, wherein, The reinforcing bars comprise longitudinal square bars (21) and transverse square bars (22), the tensile strength of the longitudinal square bars (21) and the transverse square bars (22) is 800-1400 MPa, the elastic modulus of the longitudinal square bars (21) and the transverse square bars (22) is 30-70 GPa, the cross-section height of the longitudinal square bars (21) and the transverse square bars (22) is 4-6 mm, and the cross-section width of the longitudinal square bars (21) and the transverse square bars (22) is 6-10 mm.

3. A reinforced beam for enhancing a retired wind turbine blade according to claim 2, wherein, The fiber extension direction of the longitudinal square bars (21) is consistent with the axis of the longitudinal square bars (21), and the fiber extension direction of the transverse square bars (22) is consistent with the axis of the transverse square bars (22).

4. The reinforced beam with enhanced reinforcement using decommissioned wind turbine blades of claim 1, wherein, The thickness of the cement-based composite matrix (23) is 25-80 mm, and the tensile fracture strain of the cement-based composite matrix (23) is 1.5-3.0%.

5. A reinforced beam for enhanced reinforcement using decommissioned wind turbine blades according to claim 4, wherein, The reinforced concrete (1) is formed by a frame formed by longitudinal steel bars (11) and stirrups (12) and concrete (13) poured in and outside the frame.

6. The reinforced beam with enhanced reinforcement using decommissioned wind turbine blades of claim 1, wherein, The application further discloses a method for manufacturing the reinforced concrete beam (1) and the reinforcing layer (2).

7. A reinforced beam enhanced with decommissioned wind turbine blades according to any one of claims 1-6, characterized in that, The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined.

8. A method of determining the flexural rigidity of a reinforced beam using decommissioned wind turbine blades according to any one of claims 1-7, characterized in that, The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined. The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined. determining the bending stiffness of the reinforced concrete beam in the uncracked state as a function of the geometric parameters and the elastic modulus of the reinforced concrete beam (1) and of the reinforcement layer (2) K in in particular as follows: wherein: E con E is the elastic modulus of the reinforced concrete beam (1), E s E2 is the elastic modulus of the reinforcement layer (2), b b is the cross-sectional width of the reinforcement system, h con h is the cross-sectional height of the reinforced beam, h s t is the cross-sectional thickness of the reinforcement layer. based on the bending stiffness in the uncracked state K in calculate the bending stiffness after cracking without taking into account the interfacial slip between the reinforced concrete beam (1) and the reinforcement layer (2) K post as follows: K post= 0.35 K in based on the reinforcement ratio of the longitudinal reinforcement of the reinforced concrete beam (1) The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined. b based on the reinforcement ratio of the FRP of the reinforcement layer (2) The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined. s a reduction factor that takes into account the interface slip between the reinforced concrete beam (1) and the reinforcement layer (2) is determined by a predetermined reduction factor β ; According to the reduction coefficient β , the bending stiffness of the reinforced concrete beam is calculated considering the interface slip of the reinforced concrete beam (1) and the reinforcement layer (2) K f Specifically as follows: wherein, K f to assess the actual flexural stiffness of the reinforced concrete strengthened beam under the serviceability limit state.

9. The method of determining the flexural rigidity of a reinforced beam employing decommissioned wind turbine blades according to claim 8, wherein, said determining is based on a reduction factor taking into account the interfacial slip of the reinforced concrete beam (1) and the reinforcement layer (2) β comprising: a longitudinal reinforcement ratio of the reinforced concrete beam (1) The geometric parameters and the elastic modulus of the reinforced concrete beam (1) and the reinforcing layer (2) are determined. b a FRP reinforcement ratio of the reinforcement layer (2) ​ s a finite element numerical model of the reinforced concrete beam is established, different longitudinal reinforcement ratios of the reinforced concrete beam (1) ​ b a FRP reinforcement ratio of the reinforcement layer (2) ​ s a reduction coefficient considering the interface slip of the reinforced concrete beam (1) and the reinforcement layer (2) is determined by parameter analysis β , specifically as follows: wherein k 1, k 2 is a coefficient obtained by parametric analysis and linear regression fitting, c is a constant.

10. The method of determining the bending stiffness of a reinforced beam augmented with decommissioned wind turbine blades according to claim 9, wherein, The k 1, k 2 and constant c By the following steps: Determining actual stiffness of the reinforced concrete reinforced beam after cracking K real , , where Δ is the midspan deflection, l is the simply supported beam span length, q is the uniform load magnitude; According to K real and K post The actual reduction factor is calculated inversely β r Specifically as follows: The formula of the reduction factor β r is brought into the formula of the reduction factor β combined with the set ​ b and ​ s linear regression fitting, get k 1, k 2 and constant c .

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