FRP aggregate modification from decommissioned wind turbine blades and its concrete material and structural design methods

Abstract

This invention belongs to the technical field of FRP aggregate concrete modified from decommissioned wind turbine blades, specifically involving the modification of FRP aggregate from decommissioned wind turbine blades and its concrete material and structural design methods. The structural parameters of the concrete containing modified recycled FRP aggregate in this invention include the compressive strength, mix proportion, FRP aggregate replacement rate, and epoxy mortar coating amount. The method provided by this invention can accurately determine the structural parameters of concrete containing modified recycled FRP aggregate from decommissioned wind turbine blades and reinforced concrete beam members containing modified recycled FRP aggregate from decommissioned wind turbine blades, thereby achieving comprehensive design of the compressive strength of the concrete containing modified recycled FRP aggregate from decommissioned wind turbine blades and the bending moment bearing capacity of the reinforced concrete beam members containing modified recycled FRP aggregate from decommissioned wind turbine blades.

Description

Technical Field

[0001] This invention belongs to the technical field of FRP aggregate concrete for the recycling of decommissioned wind turbine blades, specifically involving the modification of FRP aggregate for the recycling of decommissioned wind turbine blades and the design methods for concrete materials and structures. Background Technology

[0002] With the rapid development of the construction industry, the use of traditional building materials has placed enormous pressure on the environment. The excessive consumption of resources such as cement, river sand, and natural coarse aggregates has not only led to resource depletion but also increased carbon emissions. Fiber-reinforced polymer (FRP) composites, due to their high strength, lightweight, corrosion resistance, and fatigue resistance, are used in the manufacture of wind turbine blades. As wind power is an important component of new clean energy, the amount of FRP waste generated from retired wind turbine blades is increasing with equipment upgrades and the expiration of the service life of early units. However, traditional landfilling and incineration methods for treating FRP waste from retired wind turbine blades are not only costly but also cause serious environmental pollution. Recycling and utilizing FRP waste from retired wind turbine blades in concrete preparation can not only reduce the significant environmental harm caused by improper disposal of waste FRP from retired wind turbine blades but also reduce the over-exploitation of resources such as sand and gravel. Therefore, to promote the green recycling and treatment of FRP waste from retired wind turbine blades, it is crucial to continue researching and utilizing FRP aggregate concrete from retired wind turbine blades.

[0003] However, in existing methods for preparing FRP aggregate concrete from decommissioned wind turbine blades, directly adding untreated FRP aggregate from the decommissioned wind turbine blades leads to a decrease in concrete strength and elastic modulus. This results in unstable mechanical properties of the prepared FRP aggregate concrete from decommissioned wind turbine blades, failing to meet the application standards of practical engineering projects. Therefore, surface modification treatment of the FRP waste from decommissioned wind turbine blades is necessary to improve the mechanical properties of FRP aggregate concrete from decommissioned wind turbine blades. Summary of the Invention

[0004] The purpose of this invention is to provide a method for modifying FRP aggregate from decommissioned wind turbine blades and designing concrete materials and structures thereon. The method provided by this invention can accurately determine the structural parameters of concrete containing modified decommissioned wind turbine blade recycled FRP aggregate and reinforced concrete beam members containing modified decommissioned wind turbine blade recycled FRP aggregate, thereby achieving a comprehensive design of the compressive strength of concrete containing modified decommissioned wind turbine blade recycled FRP aggregate and the bending moment bearing capacity of reinforced concrete beam members containing modified decommissioned wind turbine blade recycled FRP aggregate.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for determining the structural parameters of concrete containing modified recycled FRP aggregate. The structural parameters include compressive strength, mix proportion, substitution rate, and encapsulation amount. The substitution rate is the volume percentage of modified recycled FRP aggregate in the coarse aggregate of the concrete containing modified recycled FRP aggregate. The modified recycled FRP aggregate is epoxy mortar modified recycled FRP aggregate. The encapsulation amount is the mass ratio of epoxy mortar to recycled FRP aggregate.

[0007] The determination method includes the following steps: obtaining three structural parameters containing the mix proportion, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion, and determining the remaining structural parameters using formulas (1) to (6);

[0008] Alternatively, the determination method may include the following steps: obtaining compressive strength, substitution rate and wrapping amount, using formulas (1) to (6) to obtain the compressive strength of concrete with natural aggregate, and determining the mix proportion based on the compressive strength of concrete with natural aggregate;

[0009] Alternatively, the determination method may include the following steps: preset compressive strength, obtain any one of mix proportion, substitution rate and wrapping amount, when the obtained structural parameter is mix proportion, obtain the compressive strength of concrete with natural aggregate from mix proportion, obtain the range of the remaining two structural parameters of mix proportion, substitution rate and wrapping amount using formula (1) to (6), the range being the range where the compressive strength of concrete containing modified recycled FRP aggregate is ≥ preset compressive strength under the condition that any one of the parameters of mix proportion, substitution rate and wrapping amount is determined; determine the remaining two structural parameters from the range of the remaining two structural parameters, and determine the compressive strength from mix proportion, substitution rate and wrapping amount using formula (1) to (6);

[0010]

[0011] k s1 =1+0.449s 2 +0.928rs-0.699s (3);

[0012]

[0013] k s2 = -78.696s 2 -1.326rs+47.359s-5.921 (5);

[0014]

[0015] In formulas (1) to (6): f c 'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate.c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. c k represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate.

[0016] Preferably, the method for constructing formulas (1) to (6) includes the following steps:

[0017] Provide concrete specimens, including concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates;

[0018] The concrete specimens were subjected to compressive strength tests to obtain the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates.

[0019] Based on the initial compressive strength information and the alternative compressive strength information, an initial formula is constructed for the compressive strength of concrete with natural aggregate, the compressive strength of concrete containing recycled FRP aggregate, and the recycled FRP aggregate replacement rate, wherein the recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate.

[0020] Based on the initial compressive strength information and the modified compressive strength information, formulas (2) to (6) are constructed;

[0021] The initial formulas are modified using formulas (2) to (6) to obtain formulas (1) to (6).

[0022] Preferably, the method for preparing the modified recycled FRP aggregate includes the following steps:

[0023] The recycled FRP aggregate is mixed with epoxy mortar and then coated and modified to obtain the modified recycled FRP aggregate; the epoxy mortar includes epoxy resin, curing agent and additives.

[0024] Preferably, the mass ratio of the epoxy resin, curing agent and additives is (1-2):(1-5):(12-20).

[0025] Preferably, the recycled FRP aggregate has a particle size range of 5–25 mm and an aspect ratio of <1.6.

[0026] This invention provides a system for determining the structural parameters of concrete containing modified recycled FRP aggregate, including a data acquisition module, an initial formula construction module, a target formula determination module, and an output module;

[0027] The data acquisition module is used to collect compressive strength information obtained from compressive strength tests on concrete specimens. The concrete specimens include concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates. The compressive strength information includes the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates.

[0028] The initial formula construction module obtains the initial compressive strength information and alternative compressive strength information transmitted by the data acquisition module, the compressive strength of the concrete with associated natural aggregate, the compressive strength of the concrete containing recycled FRP aggregate, and the initial formula for the recycled FRP aggregate replacement rate. The recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate.

[0029] The target formula determination module is used to construct formulas (1) to (6);

[0030]

[0031] k s1 =1+0.449s 2 +0.928rs-0.699s (3);

[0032]

[0033] k s2 = -78.696s 2 -1.326rs+47.359s-5.921 (5);

[0034]

[0035] In formulas (1) to (6): f c 'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. ck represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate.

[0036] The output module is used to output the remaining structural parameters.

[0037] This invention provides a method for determining the structural parameters of a reinforced concrete beam member with modified recycled FRP aggregate, wherein the structural parameters include the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate and the structural parameters of the concrete containing modified recycled FRP aggregate.

[0038] The structural parameters of the concrete containing modified recycled FRP aggregate are determined using the method described in the above technical solution;

[0039] The acquisition of the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate includes: converting the actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the compression zone of the reinforced concrete beam member with modified recycled FRP aggregate into an equivalent rectangular stress-strain curve according to the equivalent conditions, wherein the equivalent conditions are that the resultant force of the actual stress-strain curve and the equivalent rectangular stress-strain curve are equal in magnitude and coincide in position; determining the dimensionless parameters k1 and k2 from the actual stress-strain curve and the equivalent rectangular stress-strain curve of the concrete containing modified recycled FRP aggregate according to the equivalent conditions; k1 is determined by formula (7) and k2 is determined by formula (8).

[0040]

[0041] In formulas (7) and (8), k1 is the ratio of the area of ​​the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the area of ​​the equivalent rectangular stress-strain curve; k2 is the ratio of the distance from the resultant point to the compression edge of the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the strain at the compression edge; ε m Let σ be the compressive edge strain of the concrete containing modified recycled FRP aggregate in the beam section of a reinforced concrete beam member; σ is the stress of the concrete containing modified recycled FRP aggregate; ε is the strain of the concrete containing modified recycled FRP aggregate; f is the cross-sectional strain of the reinforced concrete beam member. c 'The compressive strength of concrete containing modified recycled FRP aggregate;'

[0042] The height of the compression zone in the equivalent rectangular stress-strain curve is set to βx, and the equivalent stress uniformly distributed in the equivalent rectangular stress-strain curve is set to αf. cThe coefficients of the equivalent rectangular stress-strain curve are β and α, where β = 2k2 and α = k1 / 2k2; the height of the compression zone of the beam section of the reinforced concrete-modified recycled FRP aggregate member is determined by formula (9):

[0043]

[0044] In formula (9), x is the actual compression zone height of the beam section of the reinforced concrete beam member with modified recycled FRP aggregate, β is the height coefficient of the equivalent rectangular stress-strain curve, α is the strength coefficient of the equivalent rectangular stress-strain curve, and A s f is the area of ​​the tensile reinforcement. y For the tensile strength of the steel reinforcement, f c 'b' represents the compressive strength of concrete containing modified recycled FRP aggregate, and 'b' represents the beam width of the reinforced concrete beam member with modified recycled FRP aggregate.

[0045] The bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate is determined by formula (10):

[0046] M=αf c Formula (10) is given by 'bx(h0-x / 2)'.

[0047] In formula (10), M is the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate, α is the strength coefficient of the equivalent rectangular stress-strain curve, and f c ' is the compressive strength of concrete containing modified recycled FRP aggregate, x is the actual compression zone height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member, b is the beam width of the reinforced-modified recycled FRP aggregate concrete beam member; h0 is the effective height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member;

[0048] The actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the actual compression zone of the steel-reinforced modified recycled FRP aggregate concrete beam member is shown in formula (11):

[0049]

[0050] In formula (11), parameters a and b1 are determined by formulas (12) and (13), respectively:

[0051] a = 1.927 + 0.489r + 1.23r 2 -1.333r 3 Formula (12);

[0052] b1 = 0.129(r + 0.011) -0.571 +57.371(1+rs)-39.124 Formula (13);

[0053] In formulas (11) to (13), f c ε represents the compressive strength of concrete containing modified recycled FRP aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate; σ is the stress of concrete containing modified recycled FRP aggregate; ε is the strain of concrete containing modified recycled FRP aggregate; a is the shape factor of the rising segment of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; b1 is the shape factor of the rising and falling segments of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; r is the substitution rate; s is the amount of encapsulation.

[0054] This invention provides a method for determining the structural parameters of concrete containing modified recycled FRP aggregate. The structural parameters include compressive strength, mix proportion, substitution rate, and coating amount. The substitution rate is the volume percentage of modified recycled FRP aggregate in the coarse aggregate of the concrete containing modified recycled FRP aggregate. The modified recycled FRP aggregate is epoxy mortar modified recycled FRP aggregate. The coating amount is the mass ratio of epoxy mortar to recycled FRP aggregate. This invention uses formulas (1) to (6) to accurately complete the comprehensive design of the mix proportion (corresponding to the compressive strength of natural aggregate concrete), substitution rate (i.e., the substitution rate of modified recycled FRP aggregate), coating amount (i.e., the coating amount of epoxy mortar), and compressive strength of concrete containing modified recycled FRP aggregate.

[0055] This invention provides a system for determining the structural parameters of concrete containing modified recycled FRP aggregate, including a data acquisition module, an initial formula construction module, a target formula determination module, and an output module. The design system provided by this invention enables integrated design from the acquisition of raw data, the construction of equations, and the output of structural parameters (compressive strength, mix proportion, substitution rate, and encapsulation amount) of concrete containing modified recycled FRP aggregate, thus achieving more efficient integrated design of the structural parameters of concrete containing modified recycled FRP aggregate.

[0056] This invention provides a method for determining the structural parameters of reinforced concrete beam members with modified recycled FRP aggregate. The structural parameters include the bending moment bearing capacity of the reinforced concrete beam members with modified recycled FRP aggregate and the structural parameters of the concrete containing modified recycled FRP aggregate. This invention obtains formulas (7) to (13) by performing an equivalent condition transformation on the actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the compression zone of the reinforced concrete beam members. Simultaneously, it introduces related formulas (1) to (6) for the structural parameters of the concrete containing modified recycled FRP aggregate. By combining the parameters obtained from the equivalent condition transformation with the compressive strength of the concrete containing modified recycled FRP aggregate, it is possible to accurately complete the comprehensive design of the bending moment bearing capacity, compressive strength of the concrete containing modified recycled FRP aggregate, mix proportion, substitution rate of modified recycled FRP aggregate, and epoxy mortar coating amount of the reinforced concrete beam members with modified recycled FRP aggregate. Attached Figure Description

[0057] Figure 1 Grading curves for recovering GFRP aggregate and natural coarse aggregate;

[0058] Figure 2 Comparison of experimental and predicted stress-strain curves for concrete containing recycled GFRP aggregate;

[0059] Figure 3 Comparison of experimental and predicted stress-strain curves for concrete containing modified recycled GFRP aggregate;

[0060] Figure 4 This is a schematic diagram showing the relationship between the replacement rate of modified recycled GFRP aggregate, the amount of epoxy mortar coating, and the compressive strength of concrete containing modified recycled GFRP aggregate when the compressive strength of ordinary concrete (i.e., concrete with natural aggregate) is 35 MPa, which is a preferred embodiment of the method for determining the compressive bearing capacity of concrete containing modified recycled GFRP aggregate according to the present invention.

[0061] Figure 5 This diagram illustrates the relationship between the replacement rate of modified recycled FRP aggregate, the amount of epoxy mortar coating, and the bending moment bearing capacity of the reinforced concrete beam member when the compressive strength of ordinary concrete (i.e., concrete with natural aggregate) is 35 MPa, according to a preferred embodiment of the method for determining the design bending moment bearing capacity of reinforced concrete beam members with modified recycled FRP aggregate of the present invention. Detailed Implementation

[0062] This invention provides a method for determining the structural parameters of concrete containing modified recycled FRP aggregate. The structural parameters include compressive strength, mix proportion, substitution rate, and encapsulation amount. The substitution rate is the volume percentage of modified recycled FRP aggregate in the coarse aggregate of the concrete containing modified recycled FRP aggregate. The modified recycled FRP aggregate is epoxy mortar modified recycled FRP aggregate. The encapsulation amount is the mass ratio of epoxy mortar to recycled FRP aggregate.

[0063] The determination method includes the following steps: obtaining three structural parameters containing the mix proportion, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion, and determining the remaining structural parameters using formulas (1) to (6);

[0064] Alternatively, the determination method may include the following steps: obtaining compressive strength, substitution rate and wrapping amount, using formulas (1) to (6) to obtain the compressive strength of concrete with natural aggregate, and determining the mix proportion based on the compressive strength of concrete with natural aggregate;

[0065] Alternatively, the determination method may include the following steps: preset compressive strength, obtain any one of mix proportion, substitution rate and wrapping amount, when the obtained structural parameter is mix proportion, obtain the compressive strength of concrete with natural aggregate from mix proportion, obtain the range of the remaining two structural parameters of mix proportion, substitution rate and wrapping amount using formula (1) to (6), the range being the range where the compressive strength of concrete containing modified recycled FRP aggregate is ≥ preset compressive strength under the condition that any one of the parameters of mix proportion, substitution rate and wrapping amount is determined; determine the remaining two structural parameters from the range of the remaining two structural parameters, and determine the compressive strength from mix proportion, substitution rate and wrapping amount using formula (1) to (6);

[0066]

[0067]

[0068] k s1 =1+0.449s 2 +0.928rs-0.699s (3);

[0069]

[0070] k s2 = -78.696s 2 -1.326rs+47.359s-5.921 (5);

[0071]

[0072] In formulas (1) to (6): f c'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. c k represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate.

[0073] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0074] In this invention, the raw materials for preparing the concrete include coarse aggregate, fine aggregate, cement, and water. In the concrete made with natural aggregate, all coarse aggregate is natural coarse aggregate. In the concrete containing recycled FRP aggregate, the coarse aggregate is either recycled FRP aggregate or a combination of recycled FRP aggregate and natural coarse aggregate. In the concrete containing modified recycled FRP aggregate, the coarse aggregate is either modified recycled FRP aggregate or a combination of modified recycled FRP aggregate and natural coarse aggregate.

[0075] In this invention, the replacement rate is the replacement rate of modified recycled FRP aggregate. The coating amount is the coating amount of epoxy mortar.

[0076] In this invention, the raw materials for preparing the concrete containing modified recycled FRP aggregate include cement, water, coarse aggregate and natural fine aggregate. The coarse aggregate in the concrete containing modified recycled FRP aggregate is modified recycled FRP aggregate, or it is a mixture of modified recycled FRP aggregate and natural coarse aggregate.

[0077] In this invention, the raw materials for preparing the concrete with natural aggregates include cement, water, natural coarse aggregates, and natural fine aggregates.

[0078] In this invention, the mix proportion of the concrete with natural aggregate is the mass ratio of cement, water, natural coarse aggregate, and natural fine aggregate. The one-to-one correspondence between the mix proportion of the concrete with natural aggregate and the compressive strength of the concrete with natural aggregate can be determined from literature data.

[0079] In this invention, the method for preparing the modified recycled FRP aggregate preferably includes the following steps: mixing the recycled FRP aggregate, epoxy resin, curing agent and additives for encapsulation modification to obtain the modified recycled FRP aggregate; the mass ratio of the epoxy resin, curing agent and additives is (1-2):(1-5):(12-20).

[0080] This invention does not have special requirements regarding the source of the recycled FRP material; it can be obtained using methods well-known in the art. In a specific embodiment of this invention, the recycled FRP material is specifically recycled FRP waste from decommissioned wind turbine blades.

[0081] The preferred particle size range of the recycled FRP aggregate is 5–25 mm; the preferred aspect ratio is <1.6. In a specific embodiment of the invention, FRP waste is crushed to obtain recycled FRP aggregate with different particle sizes, typically ranging from 5 mm to 25 mm. This minimizes the impact of different aggregate gradations on the concrete strength after FRP particles replace natural aggregates. The 5 mm–25 mm particle size range is chosen to ensure better continuity of FRP particle gradation and to account for the limited variety of FRP sizes in actual recycling. Furthermore, the aspect ratio of the particles is kept as low as possible (<1.6) to avoid the negative effects of excessively long and narrow FRP aggregate particles. The crushed FRP aggregate is then subjected to particle size distribution testing to ensure that the particle size distribution meets design requirements. Aggregates with uniform particle size distribution can improve the density and strength of concrete. It should be noted that the crushing of FRP differs from that of ordinary natural aggregates; an electric saw is required to cut it into appropriate sizes. In addition, since there is a lot of resin and other filler dust after FRP is crushed, and the surface of the natural coarse aggregate is also covered with dirt, both are rinsed with clean water. Then the natural coarse aggregate is placed in a drying oven to dry, while the recycled FRP aggregate is placed outdoors to dry.

[0082] In this invention, the additives are specifically cement and quartz sand, with a mass ratio of cement to quartz sand of 1:2. The preferred mass ratio of epoxy resin, curing agent, and additives is (1-2):(1-5):(12-20), specifically 1:3:16. The mixing preferably includes the following steps: premixing the recycled FRP aggregate and the additives to obtain a premix; mixing the epoxy resin and curing agent, and then mixing them with the premix. The mixing is carried out under stirring conditions. In this invention, the time for the coating modification after the above-mentioned raw materials are mixed is preferably 3-5 minutes. After the coating modification, initial modified particles are obtained. In this invention, the initial modified particles are preferably cured to obtain the modified recycled FRP aggregate. The curing includes a first stage of curing and a second stage of curing. The first stage of curing is preferably 48 hours. Between the first stage of curing and the second stage of curing, the materials are preferably stirred to separate the aggregates that are bonded together due to a small amount of epoxy mortar between the particles. The second stage of curing is preferably 7 days. This curing is preferably carried out in a curing room.

[0083] In this invention, the natural coarse aggregate in the natural aggregate concrete has the same gradation as the coarse aggregate in the modified recycled FRP aggregate concrete.

[0084] In this invention, the mix proportions of the natural aggregate concrete and the modified recycled FRP aggregate concrete are the same. The raw materials for preparing the concrete include cement, fine aggregate, water, and coarse aggregate. The mix proportion of the concrete includes the mass ratio of cement, fine aggregate, water, and coarse aggregate. In this invention, the coarse aggregate includes natural coarse aggregate and recycled FRP aggregate (or modified recycled FRP aggregate). The proportions of each component can be appropriately adjusted according to specific engineering requirements to meet different mechanical performance requirements.

[0085] In a specific embodiment of the present invention: the determination method specifically includes the following steps: obtaining the mix proportion, substitution rate and wrapping amount, obtaining the compressive strength of concrete with natural aggregate from the mix proportion, and determining the compressive strength of concrete containing modified recycled FRP aggregate using formulas (1) to (6).

[0086] In a specific embodiment of the present invention, the method for determining the parameters specifically includes the following steps: determining the preset compressive strength of the concrete containing modified recycled FRP aggregate, obtaining the mix proportion, obtaining the compressive strength of the concrete containing natural aggregate from the mix proportion, and obtaining the range of substitution rate and encapsulation amount using formulas (1) to (6), wherein the range is the range where the compressive strength of the concrete containing modified recycled FRP aggregate is ≥ the preset compressive strength under the condition of determined mix proportion; determining the remaining substitution rate and encapsulation amount from the range of substitution rate and encapsulation amount, and determining the compressive strength of the concrete containing modified recycled FRP aggregate from the mix proportion, substitution rate and encapsulation amount using formulas (1) to (6).

[0087] In this invention, the method for constructing formulas (1) to (6) includes the following steps:

[0088] Provide concrete specimens, including concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates;

[0089] The concrete specimens were subjected to compressive strength tests to obtain the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates.

[0090] Based on the initial compressive strength information and the alternative compressive strength information, an initial formula is constructed for the compressive strength of concrete with natural aggregate, the compressive strength of concrete containing recycled FRP aggregate, and the recycled FRP aggregate replacement rate, wherein the recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate.

[0091] Based on the initial compressive strength information and the modified compressive strength information, formulas (2) to (6) are constructed;

[0092] The initial formulas are modified using formulas (2) to (6) to obtain formulas (1) to (6).

[0093] This invention provides concrete specimens, including concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates. In this invention, the raw materials for preparing the concrete specimens include coarse aggregates, fine aggregates, cement, and water. The mix proportions of the concrete specimens with natural aggregates, those containing recycled FRP aggregates, and those containing modified recycled FRP aggregates are the same. The coarse aggregate in the concrete specimens with natural aggregates is natural coarse aggregate; the coarse aggregate in the concrete specimens containing recycled FRP aggregates is recycled FRP aggregate, or a mixture of recycled FRP aggregate and natural coarse aggregate; the coarse aggregate in the concrete specimens containing modified recycled FRP aggregates is modified recycled FRP aggregate, or a mixture of modified recycled FRP aggregate and natural coarse aggregate. This invention, based on the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T50081-2019, "Construction Gravel and Crushed Stone" GB / T 14685-2011, and "Construction Sand" GB / T 14684-2011, selects and prepares the natural coarse aggregate, natural fine aggregate, and recycled FRP aggregate required for the above-mentioned concrete specimens, determines the mix proportion of the concrete specimens, and ensures that the gradation of FRP aggregate and gravel (natural coarse aggregate) is consistent during the experimental process. In this invention, the above-mentioned concrete specimens (ordinary concrete specimens with the same mix proportion (i.e., concrete specimens with natural aggregate), ordinary recycled FRP aggregate concrete specimens (i.e., concrete specimens containing recycled FRP aggregate), and modified recycled FRP concrete specimens (i.e., concrete specimens containing modified recycled FRP aggregate)) can be prepared in advance or provided beforehand.

[0094] In preparing the above-mentioned concrete specimens according to the present invention, cement, sand (natural fine aggregate), gravel (natural coarse aggregate), water, and recycled FRP aggregate are prepared separately according to the determined mix proportions. The quality of each material is ensured to meet the standard requirements. Cement, sand, gravel, water, and recycled FRP aggregate are added to a mixer in sequence. The mixer is started and uniformly mixed until all materials are fully mixed to form a homogeneous concrete mixture. The mixing time and speed are adjusted according to the specific requirements of the concrete to ensure the uniformity and fluidity of the mixture. The mixed concrete is poured into a mold and compacted by vibration. Vibration can be performed using mechanical vibration to expel air bubbles from the concrete, improving its density and strength. The concrete specimens are obtained by curing under standard curing conditions for twenty-eight days.

[0095] In this invention, the mix proportions of cementitious material (cement), coarse aggregate, and fine aggregate are the same for the above-mentioned ordinary concrete specimen, ordinary recycled FRP aggregate concrete specimen with a recycled FRP aggregate replacement rate, and epoxy mortar-coated modified recycled FRP aggregate concrete specimen with the specified replacement rate. That is, determining the mix proportion of the ordinary concrete specimen involves selecting fine aggregate (sand), coarse aggregate (gravel), and cementitious material (cement) with a certain aggregate gradation. The proportion of fine aggregate (sand) in the ordinary recycled FRP aggregate concrete specimen and the modified recycled FRP aggregate concrete specimen is consistent with that in the ordinary concrete. In the ordinary recycled FRP aggregate concrete specimen and the modified recycled FRP aggregate concrete specimen, the coarse aggregate replaces part or all of the coarse aggregate according to the corresponding replacement rate.

[0096] After obtaining the concrete specimens, the present invention conducts compressive strength tests on the concrete specimens to obtain the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates.

[0097] This invention conducts compressive strength tests on ordinary concrete specimens (i.e., concrete specimens with natural aggregate) to obtain the initial compressive strength information of the natural aggregate concrete specimens. This invention also conducts compressive strength tests on various ordinary recycled FRP aggregate concrete specimens (i.e., concrete specimens containing recycled FRP aggregate) under different recycled FRP replacement rates to obtain the corresponding replacement compressive strength information for each specimen. Furthermore, it obtains the epoxy mortar coating amount for various recycled FRP aggregate concretes under different recycled FRP aggregate replacement rates; based on the epoxy mortar coating amount, it conducts compressive strength tests on modified recycled FRP aggregate concrete (i.e., concrete specimens containing modified recycled FRP aggregate) under corresponding modified recycled FRP aggregate replacement rates to obtain the corresponding modified compressive strength information for each type of modified recycled FRP aggregate concrete.

[0098] This invention involves conducting uniaxial compression tests on ordinary concrete, various types of ordinary recycled FRP aggregate concrete, and various types of modified recycled FRP aggregate concrete. The initial strength of the ordinary concrete (which can be the average of multiple groups, as shown in Table 2), the recycled FRP aggregate replacement rate and replacement strength of each type of ordinary recycled FRP aggregate concrete (which can be the average of multiple groups at that replacement rate, as shown in Table 2), and the epoxy mortar dosage and modified strength of each type of modified recycled FRP aggregate concrete (which can be the average of multiple groups at that dosage, as shown in Table 3) are obtained respectively.

[0099] In this invention, after obtaining the modified recycled FRP aggregate concrete specimen, a uniaxial compression test is also required to obtain the stress-strain curve, compressive strength, elastic modulus, etc. of the modified recycled FRP-concrete, and to evaluate the mechanical properties of the modified recycled FRP aggregate concrete over time.

[0100] After obtaining the initial compressive strength information, the alternative compressive strength information, and the modified compressive strength information, this invention constructs an initial formula for the compressive strength of concrete with natural aggregate, the compressive strength of concrete containing recycled FRP aggregate, and the recycled FRP aggregate replacement rate based on the initial compressive strength information and the alternative compressive strength information. The recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate. Based on the initial compressive strength information and the modified compressive strength information, formulas (2) to (6) are constructed. Formulas (2) to (6) are used to modify the initial formulas to obtain formulas (1) to (6).

[0101] This invention first obtains the initial compressive strength information of ordinary concrete specimens, the corresponding alternative compressive strength information of ordinary recycled FRP aggregate concrete specimens under the recycled FRP replacement rate, and the modified compressive strength information of modified recycled FRP aggregate concrete specimens under the corresponding recycled FRP aggregate replacement rate; based on the initial compressive strength information and the alternative compressive strength information, an initial formula is constructed between the strength of ordinary concrete and the strength of ordinary recycled FRP aggregate concrete under any corresponding recycled FRP aggregate replacement rate; based on the modified compressive strength information and the initial equation, target formulas are constructed for the initial compressive strength of ordinary concrete, the compressive strength of modified recycled FRP aggregate concrete, the recycled FRP aggregate replacement rate, and the amount of epoxy mortar coating (Formulas (1) to (6)).

[0102] In this invention, based on initial compressive strength information and alternative compressive strength information, an initial formula is constructed between the initial compressive strength of ordinary concrete and the alternative compressive strength of ordinary recycled FRP aggregate concrete under any corresponding recycled FRP aggregate substitution rate, specifically including:

[0103] The initial compressive strength information and various alternative compressive strength information under different recycled FRP aggregate replacement rates are analyzed to obtain the first coefficient of the recycled FRP aggregate replacement rate. Based on the first coefficient, an initial formula is generated between the initial compressive strength of ordinary concrete and the compressive strength of ordinary recycled FRP aggregate concrete under any corresponding recycled FRP aggregate replacement rate.

[0104] The initial compressive strength of ordinary concrete and the corresponding modified compressive strength of recycled FRP aggregate concrete at specific replacement rates under different epoxy mortar coating amounts were obtained. Based on the initial compressive strength of ordinary concrete and the modified compressive strength of recycled FRP aggregate concrete at various specific replacement rates, a quadratic function relationship between the initial compressive strength of ordinary concrete and the modified compressive strength of recycled FRP aggregate concrete at specific replacement rates was obtained.

[0105] Obtain the modified compressive strength information of modified recycled FRP aggregate concrete under the modified recycled FRP aggregate replacement rate, specifically including:

[0106] Obtain the epoxy mortar coating amount of various recycled FRP aggregate concretes under different recycled FRP replacement rates; based on the epoxy mortar coating amount, conduct compressive strength tests on the modified recycled FRP aggregate concretes under the corresponding modified recycled FRP replacement rates to obtain the corresponding modified strength information of various modified recycled FRP aggregate concretes.

[0107] Based on the modified strength information and the initial equation, the target equations for the initial strength of ordinary concrete, the compressive strength of modified recycled FRP aggregate concrete, the recycled FRP replacement rate, and the epoxy mortar coating amount are constructed. Specifically, based on the quadratic function relationship (Formulas 2 to 6), the target formulas for the initial strength of ordinary concrete, the compressive strength of modified recycled FRP aggregate concrete, the modified recycled FRP replacement rate, and the epoxy mortar coating amount are obtained (Formula 1).

[0108] This invention analyzes the relationship between three types of concrete: unmodified ordinary concrete without recycled FRP aggregate replacement, ordinary recycled FRP aggregate concrete with a certain recycled FRP aggregate replacement rate, and modified recycled FRP aggregate concrete with epoxy mortar coating modified under the same recycled FRP aggregate replacement rate. It determines the mathematical relationship between the strength of modified recycled FRP aggregate concrete, the initial strength of ordinary concrete, and the amount of epoxy mortar coating under a certain recycled FRP aggregate replacement rate. Given the initial strength of ordinary concrete and the recycled FRP aggregate replacement rate, the invention can accurately calculate the strength of ordinary recycled FRP aggregate concrete and accurately calculate the required amount of epoxy mortar coating based on the target strength of modified recycled FRP aggregate concrete and the target bearing capacity of the concrete beam prepared from it.

[0109] This invention provides a system for determining the structural parameters of concrete containing modified recycled FRP aggregate, including a data acquisition module, an initial formula construction module, a target formula determination module, and an output module;

[0110] The data acquisition module is used to collect compressive strength information obtained from compressive strength tests on concrete specimens. The concrete specimens include concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates. The compressive strength information includes the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates.

[0111] The initial formula construction module obtains the initial compressive strength information and alternative compressive strength information transmitted by the data acquisition module, the compressive strength of the concrete with associated natural aggregate, the compressive strength of the concrete containing recycled FRP aggregate, and the initial formula for the recycled FRP aggregate replacement rate. The recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate.

[0112] The target formula determination module is used to construct formulas (1) to (6);

[0113]

[0114] k s1 =1+0.449s 2 +0.928rs-0.699s (3);

[0115]

[0116] k s2 = -78.696s 2 -1.326rs+47.359s-5.921 (5);

[0117]

[0118] In formulas (1) to (6): f c 'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. ck represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate.

[0119] The output module is used to output the remaining structural parameters.

[0120] In this invention, the data acquisition module acquires compressive strength information obtained from compressive strength tests on concrete specimens. The concrete specimens include those with natural aggregates, those containing recycled FRP aggregates, and those containing modified recycled FRP aggregates. The raw materials for preparing the concrete specimens include coarse aggregates, fine aggregates, cement, and water. The mix proportions of the concrete specimens with natural aggregates, those containing recycled FRP aggregates, and those containing modified recycled FRP aggregates are the same. The coarse aggregate in the concrete specimens with natural aggregates is natural coarse aggregate, and the coarse aggregate in the concrete specimens containing recycled FRP aggregates is recycled FRP aggregate. The aggregate P is either a mixture of recycled FRP aggregate and natural coarse aggregate, or a mixture of recycled FRP aggregate and natural coarse aggregate. The coarse aggregate in the concrete specimen containing modified recycled FRP aggregate is modified recycled FRP aggregate, or a mixture of modified recycled FRP aggregate and natural coarse aggregate. The modified recycled FRP aggregate is a material modified by coating recycled FRP aggregate with epoxy mortar, wherein the epoxy mortar includes epoxy resin, curing agent, and additives. The compressive strength information includes the initial compressive strength information of the concrete specimen with natural aggregate, the alternative compressive strength information of the concrete specimen containing recycled FRP aggregate, and the modified compressive strength information of the concrete specimen containing modified recycled FRP aggregate.

[0121] This invention transmits the initial compressive strength information and the alternative compressive strength information collected by the data acquisition module to the initial formula construction module. The initial formula construction module then constructs initial formulas relating the compressive strength of concrete with natural aggregate, the compressive strength of concrete containing recycled FRP aggregate, and the replacement rate of recycled FRP aggregate. The replacement rate of recycled FRP aggregate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the recycled FRP aggregate concrete specimen.

[0122] The present invention transmits the initial compressive strength information and the modified compressive strength information collected by the data acquisition module and the initial formula constructed by the initial formula construction module to the target formula determination module, and the target formula determination module obtains formulas (1) to (6).

[0123] In this invention, the output module is used to output the remaining structural parameters.

[0124] In this invention, the mix proportion, substitution rate, and amount of coating, along with formulas (1) to (6), are sent to the output module. The compressive strength of the concrete with natural aggregate is obtained from the mix proportion in the output module, and the compressive strength of the concrete containing modified recycled FRP aggregate is output from the output module.

[0125] In this invention, the preset compressive strength, mix proportion, and formulas (1) to (6) of the concrete containing modified recycled FRP aggregate are sent to the output module. The compressive strength of the concrete with natural aggregate is obtained from the mix proportion in the output module. The range of substitution rate and encapsulation amount is obtained from formulas (1) to (6) in the output module. The range is the range in which the compressive strength of the concrete containing modified recycled FRP aggregate is greater than or equal to the preset compressive strength under the condition that the mix proportion is determined. The remaining substitution rate and encapsulation amount are determined from the range of substitution rate and encapsulation amount. The compressive strength of the concrete containing modified recycled FRP aggregate is determined from the mix proportion, substitution rate, and encapsulation amount using formulas (1) to (6) in the output module.

[0126] This invention provides a design system for modified recycled FRP aggregate concrete, comprising: a data acquisition module for acquiring initial compressive strength information of ordinary concrete, corresponding replacement compressive strength information of ordinary recycled FRP aggregate concrete at the recycled FRP replacement rate, and modified compressive strength information of modified recycled FRP aggregate concrete at the recycled FRP replacement rate; and a formula construction module for constructing an initial formula between the initial compressive strength of ordinary concrete and the replacement compressive strength information of ordinary recycled FRP concrete at any recycled FRP aggregate replacement rate, based on the initial compressive strength information and the replacement compressive strength information. The formula determination module is used to construct a target formula among the initial compressive strength of ordinary concrete, the compressive strength of modified recycled FRP aggregate concrete, the recycled FRP aggregate replacement rate, and the epoxy mortar coating amount, based on the modified compressive strength information and the initial equation. The output module is used to obtain the structural parameters of modified recycled FRP aggregate concrete, input the structural parameters into the target formula, and output the current compressive strength of modified recycled FRP concrete. The structural parameters include the recycled FRP replacement rate, the epoxy mortar coating amount, and the initial compressive strength of concrete with natural aggregate (corresponding mix proportion).

[0127] This invention provides a method for determining the structural parameters of a reinforced concrete beam member with modified recycled FRP aggregate, wherein the structural parameters include the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate and the structural parameters of the concrete containing modified recycled FRP aggregate.

[0128] The structural parameters of the concrete containing modified recycled FRP aggregate are determined using the method described above for determining the structural parameters of concrete containing modified recycled FRP aggregate.

[0129] The acquisition of the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate includes: converting the actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the compression zone of the reinforced concrete beam member with modified recycled FRP aggregate into an equivalent rectangular stress-strain curve according to the equivalent conditions, wherein the equivalent conditions are that the resultant force of the actual stress-strain curve and the equivalent rectangular stress-strain curve are equal in magnitude and coincide in position; determining the dimensionless parameters k1 and k2 from the actual stress-strain curve and the equivalent rectangular stress-strain curve of the concrete containing modified recycled FRP aggregate according to the equivalent conditions; k1 is determined by formula (7) and k2 is determined by formula (8).

[0130]

[0131] In formulas (7) and (8), k1 is the ratio of the area of ​​the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the area of ​​the equivalent rectangular stress-strain curve; k2 is the ratio of the distance from the resultant point to the compression edge of the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the strain at the compression edge; ε m Let σ be the compressive edge strain of the concrete containing modified recycled FRP aggregate in the beam section of a reinforced concrete beam member; σ is the stress of the concrete containing modified recycled FRP aggregate; ε is the strain of the concrete containing modified recycled FRP aggregate; f is the cross-sectional strain of the reinforced concrete beam member. c 'The compressive strength of concrete containing modified recycled FRP aggregate;'

[0132] The height of the compression zone in the equivalent rectangular stress-strain curve is set to βx, and the equivalent stress uniformly distributed in the equivalent rectangular stress-strain curve is set to αf. c The coefficients of the equivalent rectangular stress-strain curve are β and α, where β = 2k2 and α = k1 / 2k2; the height of the compression zone of the beam section of the reinforced concrete-modified recycled FRP aggregate member is determined by formula (9):

[0133]

[0134] In formula (9), x is the actual compression zone height of the beam section of the reinforced concrete beam member with modified recycled FRP aggregate, β is the height coefficient of the equivalent rectangular stress-strain curve, α is the strength coefficient of the equivalent rectangular stress-strain curve, and A s f is the area of ​​the tensile reinforcement. y For the tensile strength of the steel reinforcement, f c 'b' represents the compressive strength of concrete containing modified recycled FRP aggregate, and 'b' represents the beam width of the reinforced concrete beam member with modified recycled FRP aggregate.

[0135] The bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate is determined by formula (10):

[0136] M=αf c Formula (10) is given by 'bx(h0-x / 2)'.

[0137] In formula (10), M is the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate, α is the strength coefficient of the equivalent rectangular stress-strain curve, and f c ' is the compressive strength of concrete containing modified recycled FRP aggregate, x is the actual compression zone height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member, b is the beam width of the reinforced-modified recycled FRP aggregate concrete beam member; h0 is the effective height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member;

[0138] The actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the actual compression zone of the steel-reinforced modified recycled FRP aggregate concrete beam member is shown in formula (11):

[0139]

[0140] In formula (11), parameters a and b1 are determined by formulas (12) and (13), respectively:

[0141] a = 1.927 + 0.489r + 1.23r 2 -1.333r 3 Formula (12);

[0142] b1 = 0.129(r + 0.011) -0.571 +57.371(1+rs) -39.124 Formula (13);

[0143] In formulas (11) to (13), f c ε represents the compressive strength of concrete containing modified recycled FRP aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate; σ is the stress of concrete containing modified recycled FRP aggregate; ε is the strain of concrete containing modified recycled FRP aggregate; a is the shape factor of the rising segment of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; b1 is the shape factor of the rising and falling segments of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; r is the substitution rate; s is the amount of encapsulation.

[0144] In this invention, the method for determining the structural parameters of the steel-modified recycled FRP aggregate concrete beam member includes the following steps: obtaining the mix proportion, substitution rate and wrapping amount of the concrete containing modified recycled FRP aggregate, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion, and determining the compressive strength of the concrete containing modified recycled FRP aggregate using formulas (1) to (6).

[0145] Then, the compressive strength of the concrete containing modified recycled FRP aggregate is used to obtain the bending moment bearing capacity of the reinforced concrete beam member containing modified recycled FRP aggregate according to the following method: the actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the compression zone of the reinforced concrete beam member is converted into an equivalent rectangular stress-strain curve according to the equivalent condition, wherein the resultant force of the actual stress-strain curve and the equivalent rectangular stress-strain curve is equal in magnitude and the point of application coincides; the dimensionless parameters k1 and k2 are determined from the actual stress-strain curve and the equivalent rectangular stress-strain curve of the concrete containing modified recycled FRP aggregate according to the equivalent condition; k1 is determined by formula (7) and k2 is determined by formula (8).

[0146]

[0147] In formulas (7) and (8), k1 is the ratio of the area of ​​the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the area of ​​the equivalent rectangular stress-strain curve; k2 is the ratio of the distance from the resultant point to the compression edge of the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the strain at the compression edge; ε m Let σ be the compressive edge strain of the concrete containing modified recycled FRP aggregate in the beam section of a reinforced concrete beam member; σ is the stress of the concrete containing modified recycled FRP aggregate; ε is the strain of the concrete containing modified recycled FRP aggregate; f is the cross-sectional strain of the reinforced concrete beam member. c 'The compressive strength of concrete containing modified recycled FRP aggregate;'

[0148] The height of the compression zone in the equivalent rectangular stress-strain curve is set to βx, and the equivalent stress uniformly distributed in the equivalent rectangular stress-strain curve is set to αf. c The coefficients of the equivalent rectangular stress-strain curve are β and α, where β = 2k2 and α = k1 / 2k2; the height of the compression zone of the beam section of the reinforced concrete-modified recycled FRP aggregate member is determined by formula (9):

[0149]

[0150] In formula (9), x is the actual compression zone height of the beam section of the reinforced concrete beam member with modified recycled FRP aggregate, β is the height coefficient of the equivalent rectangular stress-strain curve, α is the strength coefficient of the equivalent rectangular stress-strain curve, and A s f is the area of ​​the tensile reinforcement. y For the tensile strength of the steel reinforcement, f c 'b' represents the compressive strength of concrete containing modified recycled FRP aggregate, and 'b' represents the beam width of the reinforced concrete beam member with modified recycled FRP aggregate.

[0151] The bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate is determined by formula (10):

[0152] M=αf c Formula (10) is given by 'bx(h0-x / 2)'.

[0153] In formula (10), M is the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate, α is the strength coefficient of the equivalent rectangular stress-strain curve, and f c ' is the compressive strength of concrete containing modified recycled FRP aggregate, x is the actual compression zone height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member, b is the beam width of the reinforced-modified recycled FRP aggregate concrete beam member; h0 is the effective height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member;

[0154] The actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the actual compression zone of the steel-reinforced modified recycled FRP aggregate concrete beam member is shown in formula (11):

[0155]

[0156] In formula (11), parameters a and b1 are determined by formulas (12) and (13), respectively:

[0157] a = 1.927 + 0.489r + 1.23r 2 -1.333r 3 Formula (12);

[0158] b1 = 0.129(r + 0.011) -0.571 +57.371(1+rs) -39.124 Formula (13);

[0159] In formulas (11) to (13), f c ε represents the compressive strength of concrete containing modified recycled FRP aggregate. c' is the peak strain of concrete containing modified recycled FRP aggregate; σ is the stress of concrete containing modified recycled FRP aggregate; ε is the strain of concrete containing modified recycled FRP aggregate; a is the shape factor of the rising segment of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; b1 is the shape factor of the rising and falling segments of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; r is the substitution rate; s is the amount of encapsulation.

[0160] Alternatively, the determination method may include the following steps: obtaining the bending moment bearing capacity of the steel-modified recycled FRP aggregate concrete beam member, determining the modified compressive strength using formulas (7) to (13), obtaining any two of the result parameters among the mix proportion, substitution rate, and wrapping amount, and when the obtained structural parameters include the mix proportion, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion, and obtaining the remaining structural parameter among the mix proportion, substitution rate, and wrapping amount using formulas (1) to (6).

[0161] Alternatively, the determination method may include the following steps: determining the preset bending moment bearing capacity of the steel-modified recycled FRP aggregate concrete beam member, and obtaining the preset modified compressive strength of the concrete containing modified recycled FRP aggregate using formulas (7) to (13); obtaining any one of the mix proportion, substitution rate, and wrapping amount; when the obtained structural parameter is the mix proportion, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion; obtaining the range of the remaining two structural parameters among the mix proportion, substitution rate, and wrapping amount using formulas (1) to (6); the range being the range where the bending moment bearing capacity of the steel-modified recycled FRP aggregate concrete beam member is greater than or equal to the preset bending moment bearing capacity under the condition that one of the mix proportion, substitution rate, and wrapping amount is determined; determining the data of the remaining two structural parameters from the range of the remaining two structural parameters; determining the modified compressive strength from the determined mix proportion, substitution rate, and wrapping amount using formulas (1) to (6); and determining the bending moment bearing capacity from the determined modified compressive strength using formulas (7) to (13).

[0162] In this invention, the method for determining the structural parameters of the steel-reinforced modified recycled FRP aggregate concrete beam member includes the following steps: determining the preset bending moment bearing capacity of the steel-reinforced modified recycled FRP aggregate concrete beam member, and obtaining the preset compressive strength of the concrete containing modified recycled FRP aggregate using formulas (7) to (13); obtaining the mix proportion, obtaining the compressive strength of the concrete with natural aggregate from the mix proportion, and obtaining the range of the substitution rate and the amount of coating of the concrete containing modified recycled FRP aggregate using formulas (1) to (6), wherein the range is within the range of the mix proportion. Under the condition of a certain ratio, the range of the preset bending moment bearing capacity of the steel-modified recycled FRP aggregate concrete beam member is obtained. The remaining substitution rate and wrapping amount are determined by the range of substitution rate and wrapping amount. The compressive strength of the concrete containing modified recycled FRP aggregate is determined by the mix proportion, substitution rate and wrapping amount using formulas (1) to (6). The preset bending moment bearing capacity of the steel-modified recycled FRP aggregate concrete beam member is determined by the compressive strength of the concrete containing modified recycled FRP aggregate using formulas (7) to (13).

[0163] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0164] Example 1

[0165] This embodiment designed 15 standard cylindrical compressive strength specimens (ф150mm×300mm). This embodiment mainly considers the volume replacement rate (r) of natural coarse aggregate with recycled GFRP aggregate from decommissioned wind turbine blades (used in this embodiment): 0%, 30%, 50%, 70%, and 100%. The volume replacement rate r = recycled GFRP aggregate from decommissioned wind turbine blades / (recycled GFRP aggregate from decommissioned wind turbine blades + natural coarse aggregate); each volume replacement rate r has 3 replicate specimens to minimize experimental error. The specific designations of each group of specimens are shown in Table 1. For example, FRP30 indicates that the volume replacement rate r of recycled GFRP aggregate from decommissioned wind turbine blades to natural coarse aggregate is 30%, and so on. The concrete mix proportions of this embodiment (kg / m³) are... 3 As shown in Table 1, this mix design has a water-cement ratio of 0.45, which allows the target cube (150mm×150mm×150mm cube) to achieve a compressive strength of approximately 40MPa. All specimens were stored at approximately 25℃ after casting and demolded after 24 hours. The specimens were then placed in a standard curing room for 28 days at a temperature of 20±2℃ and a relative humidity of 95%.

[0166] Table 1. Concrete mix proportions (kg / m³) 3 )

[0167]

[0168] The compressive strength test was conducted using a 3000KN MTS servo hydraulic press with a displacement control rate of 0.3mm / min. Force sensors were used to measure the force, and four longitudinal LVDTs were used to monitor the longitudinal displacement. Data was acquired on a computer using a Dewesoft dynamic acquisition box. The test results are summarized in Table 2. The results show that as the volume replacement rate (r) of recycled GFRP aggregate from decommissioned wind turbine blades to natural coarse aggregate increases, the compressive strength gradually decreases, and the decrease is significant: when the volume replacement rate (r) is 50%, the compressive strength decreases by 63.76%, and when the recycled GFRP aggregate from decommissioned wind turbine blades completely replaces the natural coarse aggregate, the compressive strength is approximately one-seventh of the control group (FRP0). The elastic modulus of RFAC (recycled GFRP aggregate concrete) from decommissioned wind turbine blades gradually decreases with increasing volume replacement rate (r) of the recycled GFRP aggregate. For peak strain, within the volume replacement rate (r) range of 0% to 50%, the peak strain first decreases and then increases with increasing r; the same trend is observed when the volume replacement rate (r) exceeds 50%. Furthermore, Figure 2 The test results and predicted results of the stress-strain curves of axial compression tests on decommissioned wind turbine blades using recycled GFRP aggregate concrete under a replacement rate r = 100% are also presented. Figure 2 The replacement rate r = 100%, and the horizontal axis represents strain. The results show that although the experimental and predicted results of the volume replacement rate r of recycled GFRP aggregate for different decommissioned wind turbine blades are slightly different, they generally provide a good estimate of the stress and strain changes of the concrete made from recycled GFRP aggregate for decommissioned wind turbine blades under compression.

[0169] Table 2. Axial compression test results of GFRP aggregate concrete specimens from decommissioned wind turbine blades.

[0170]

[0171] Example 2

[0172] Epoxy mortar wrapping treatment:

[0173] ① Prepare recycled GFRP aggregate and epoxy mortar for retired wind turbine blades. The epoxy mortar includes epoxy resin (A material, Lica-131 carbon fiber adhesive (Nanjing Haituo Composite Materials Co., Ltd.)), curing agent (B material), cement and quartz sand (C material, the mass ratio of cement and quartz sand is 1:2), several pallets, and an electronic scale.

[0174] ② Weigh out m mass of recycled GFRP aggregate from decommissioned wind turbine blades, and simultaneously weigh out materials A, B and C in a mass ratio of 1:3:16; Epoxy mortar coating amount s = mass of epoxy mortar / mass of recycled GFRP aggregate from decommissioned wind turbine blades;

[0175] ③ Pour the recycled GFRP aggregate from the decommissioned wind turbine blades into a small mixer, and pour in the weighed C material together. Then mix for 1 to 2 minutes to ensure that the C material fully covers the surface of the recycled GFRP aggregate from the decommissioned wind turbine blades.

[0176] ④ Mix the weighed A and B materials evenly in a container, then start the mixer and slowly and evenly pour the mixture into the mixing drum;

[0177] ⑤ After the mixture is poured in, let the mixer continue to mix for 3-5 minutes. Then, take out the wrapped retired wind turbine blades, recycle the GFRP aggregate, place it on a tray, and put it in the curing room for curing.

[0178] ⑥ After curing for 48 hours, take out the wrapped GFRP aggregate from the decommissioned wind turbine blades and pour it back into the mixer for 1 minute. The purpose is to separate the aggregates that are stuck together due to a small amount of epoxy mortar between the particles. Finally, pour out the GFRP aggregate from the decommissioned wind turbine blades and put it into the curing room for 7 days.

[0179] In this embodiment, three modified recycled FRP aggregates from decommissioned wind turbine blades were prepared with epoxy mortar and recycled GFRP aggregates from decommissioned wind turbine blades at mass ratios (coating amount s) of 0.25, 0.3, and 0.35, for use in subsequent concrete pouring.

[0180] This embodiment designed 6 groups of modified GFRP aggregate concrete (MRFAC) for decommissioned wind turbine blades, with 3 replicate specimens in each group, for a total of 18 standard cylindrical compressive strength specimens (ф150mm×300mm). The entire experiment involved two independent variables: epoxy mortar coating amount s and the volume replacement rate r of the decommissioned wind turbine blade recycled GFRP aggregate to natural coarse aggregate. On the one hand, modified decommissioned wind turbine blade recycled GFRP aggregate was prepared with an epoxy mortar coating amount s of 0.25, and 4 groups of MRFAC specimens with different volume replacement rates r (30%, 50%, 70%, 100%) were designed to study the improvement of mechanical properties after modification. On the other hand, with a volume replacement rate r of 100%, the epoxy mortar coating amount s was changed to 0.3 and 0.35 respectively as another 2 groups to analyze the effect of different epoxy mortar coating amounts on compressive strength. The specific labels of each specimen are shown in Table 3. For example, FRP30-S0.25 indicates that the ratio of the epoxy mortar coating amount of the modified decommissioned wind turbine blade recycled GFRP aggregate to the mass of the decommissioned wind turbine blade recycled GFRP aggregate (epoxy mortar coating amount s) is 0.25, and the volume replacement rate r of the decommissioned wind turbine blade recycled GFRP aggregate to natural coarse aggregate is 30%, and so on.

[0181] Table 3 Design of GFRP aggregate concrete specimens for modified decommissioned wind turbine blades

[0182] Specimen GFRP aggregate replacement rate r Epoxy mortar coating amount s FRP30 30％ 0 FRP50 50％ 0 FRP70 70％ 0 FRP100 100％ 0 FRP30-S0.25 30％ 0.25 FRP50-S0.25 50％ 0.25 FRP70-S0.25 70％ 0.25 FRP100-S0.25 100％ 0.25 FRP100-S0.3 100％ 0.30 FRP100-S0.35 100％ 0.35

[0183] Table 4 shows the peak stress, corresponding peak strain, and elastic modulus of modified concrete specimens made from recycled GFRP aggregate from decommissioned wind turbine blades with different GFRP replacement rates (r). After being coated with epoxy mortar, the overall compressive strength of the recycled GFRP aggregate from decommissioned wind turbine blades showed a significant increase compared to the unmodified specimens, ranging from approximately 18% to 86%. When the coating amount (s = 0.25) was constant, the increase in compressive strength first decreased and then increased with increasing replacement rate. When the replacement rate (r) was 30%, the modified axial compressive strength increased by 21.4% compared to the unmodified specimens. At a replacement rate (r) of 50%, the increase slightly decreased to 18.6%. Further increases in replacement rate (r) to 70% and 100% resulted in increases of 29.4% and 72.2%, respectively. This indicates that the epoxy mortar coating modification method can better improve the compressive strength of concrete with more modified recycled GFRP aggregate from decommissioned wind turbine blades, especially in cases with initial defects (initial defects refer to poor bonding between the recycled GFRP aggregate and the concrete matrix in decommissioned wind turbine blades that are not coated with epoxy mortar, resulting in voids and lower strength and modulus of elasticity). In specimens with the same replacement rate r (100%), different coating amounts s showed similar increases in compressive strength, approximately 70%–86%, but the group with the best effect was the FRP100-S0.30 group.

[0184] Figure 3 A comparison of experimental and predicted results for the axial compressive stress-strain curves of GFRP aggregate concrete in modified decommissioned wind turbine blades is presented. Overall, the model proposed in this invention performs well at various substitution rates, especially when the amount of epoxy mortar coating increases, the model curves show a higher degree of agreement with the experimental curves. Figure 3 When the substitution is r = 100%, the amount of wrapping is s = 0.25, the horizontal axis represents strain, and the vertical axis represents stress.

[0185] Table 4. Axial compression test results of GFRP aggregate concrete specimens for modified decommissioned wind turbine blades.

[0186]

[0187]

[0188] The above allows us to obtain the initial strength of ordinary concrete, the replacement strength of ordinary recycled FRP aggregate concrete under a certain FRP replacement rate for decommissioned wind turbine blades, and the modified strength and epoxy mortar dosage of modified decommissioned wind turbine blade recycled FRP aggregate concrete under the same FRP replacement rate. It is worth noting that the FRP replacement rate for decommissioned wind turbine blades mentioned in this embodiment includes 30%, 50%, 70%, and 100%, but is not limited to these. It may include only a few of these rates, or it may include multiple other replacement rates. Furthermore, the FRP replacement rate may be a non-integer value, such as 9% or 17%.

[0189] Then, by comparing the stress-strain curves (strain on the horizontal axis and stress on the vertical axis), peak stress (concrete strength), initial slope (i.e. elastic modulus), and elastic modulus change characteristics before and after modification under different FRP replacement rates for decommissioned wind turbine blades, constitutive equations were established for the peak stress of modified decommissioned wind turbine blade recycled FRP aggregate concrete, the FRP aggregate replacement rate of decommissioned wind turbine blades, and the change in epoxy mortar coating amount.

[0190] Based on initial strength information and replacement strength information, this invention constructs an initial equation relating the initial strength of ordinary concrete to the strength of ordinary recycled FRP aggregate concrete under any corresponding recycled FRP aggregate replacement rate, as shown in equation (1).

[0191] Based on the modified strength information and initial equations, this invention constructs target equations relating the initial strength of ordinary concrete, the compressive strength of modified decommissioned wind turbine blade recycled FRP aggregate concrete, the replacement rate of decommissioned wind turbine blade recycled FRP aggregate, and the amount of epoxy mortar coating. As shown in equations (2)-(6).

[0192] Finally, this invention obtains the target parameters of the modified decommissioned wind turbine blade recycled FRP aggregate concrete, and inputs the target parameter data into the target equation, which outputs the current compressive strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete. The target parameters include the FRP replacement rate of the decommissioned wind turbine blade, the amount of epoxy mortar coating, and the initial strength of ordinary concrete.

[0193] This invention utilizes constitutive equations to determine the compressive strength of modified concrete using recycled FRP aggregate from decommissioned wind turbine blades, under specific conditions of FRP aggregate replacement rate and epoxy mortar coating amount. Figure 3 ).

[0194] Understandably, given that at least one of the target parameters—including the FRP aggregate replacement rate of decommissioned wind turbine blades, the amount of epoxy mortar coating, and the initial strength of ordinary concrete—is already determined by existing technology, it is impossible to determine the compressive strength of modified decommissioned wind turbine blade FRP aggregate concrete using additional data. In other words, after setting the target strength of modified decommissioned wind turbine blade FRP aggregate concrete, existing technology cannot select other data (such as the FRP aggregate replacement rate and epoxy mortar coating amount) based on the preset target strength and determined data (such as mix proportion) to ensure that the compressive strength of the obtained modified decommissioned wind turbine blade FRP aggregate concrete is greater than or equal to the preset target strength.

[0195] In some implementations, the determined data of the target parameters (target parameters) and the preset target strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete are obtained. The preset target strength is used as the compressive strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete in the target formula, and the determined data (target parameters) are input into the target equation. The target equation outputs the data range of the parameter to be confirmed, and the target data of the parameter to be confirmed is determined according to the data range. The determined data and target data are input into the target equation, and the target equation outputs the current compressive strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete, so that the current compressive strength is above the preset target strength.

[0196] In the first implementation of the present invention Figure 4This diagram illustrates the relationship between the FRP aggregate replacement rate (r), epoxy mortar coating amount (s), and compressive strength of the modified decommissioned wind turbine blade FRP aggregate concrete when the ordinary concrete strength is 35 MPa. The target strength and concrete mix proportion of the modified decommissioned wind turbine blade FRP aggregate concrete are determined; that is, the target parameter is the initial strength of the ordinary concrete (natural aggregate concrete). Obtain the current initial strength of ordinary concrete and the preset target compressive strength of modified FRP aggregate concrete for decommissioned wind turbine blades. Input the preset target strength as the compressive strength and the current initial strength into the target equation. The target equation outputs the data ranges corresponding to the current replacement rate r and the current epoxy mortar coating amount s of the modified FRP aggregate concrete for decommissioned wind turbine blades. Based on the data ranges corresponding to the current replacement rate and the current epoxy mortar coating amount of the modified FRP aggregate concrete for decommissioned wind turbine blades, determine the target replacement rate and the target epoxy mortar coating amount (i.e., the area above the design target plane). Input the initial strength, target replacement rate, and target epoxy mortar coating amount into the target equation. The target equation outputs the current compressive strength of the modified FRP aggregate concrete for decommissioned wind turbine blades, so that the current compressive strength is above the preset target strength.

[0197] Specifically, by setting the same mix proportion for concrete, a certain amount of recycled FRP aggregate from decommissioned wind turbine blades is added to it. The replacement rate of recycled FRP aggregate from decommissioned wind turbine blades varies within a certain range. Different amounts of epoxy mortar are used to modify it so that it can reach the target strength.

[0198] It should be noted that the target parameters can be one, two, or three of the following: the replacement rate of FRP paste recycled from decommissioned wind turbine blades, the amount of epoxy mortar coating, and the initial strength. When all three are clear, the compressive strength can be obtained directly and accurately. However, when only one or two data points are clear, it is necessary to determine the range of the undefined data points so that the compressive strength obtained from the target equation within this range is greater than or equal to the preset target strength. The undefined data points within the corresponding range are then identified as target values, and the compressive strength obtained by substituting them into the target equation is above the preset target strength.

[0199] Furthermore, based on the above-mentioned method for determining the compressive bearing capacity of modified decommissioned wind turbine blades using recycled FRP aggregate concrete, the present invention also provides a system for determining the compressive bearing capacity of modified decommissioned wind turbine blades using recycled FRP aggregate concrete, wherein the system includes:

[0200] The data acquisition module is used to acquire the initial strength information of ordinary concrete, the corresponding replacement strength information of ordinary decommissioned wind turbine blade recycled FRP aggregate concrete under the replacement rate of recycled FRP aggregate, and the modified strength information of epoxy mortar-coated recycled FRP aggregate concrete for decommissioned wind turbine blades under the replacement rate of recycled FRP aggregate.

[0201] The equation construction module is used to construct an initial equation between the initial strength of ordinary concrete and the strength of ordinary decommissioned wind turbine blade recycled FRP aggregate concrete under any corresponding FRP aggregate replacement rate for any decommissioned wind turbine blade, based on the initial strength information and the replacement strength information.

[0202] The equation determination module is used to construct target equations relating the initial strength, the compressive strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete, the replacement rate of the decommissioned wind turbine blade recycled FRP aggregate, and the amount of epoxy mortar wrapping, based on the modified strength information and the initial equation.

[0203] The strength generation module is used to obtain the target parameters of the modified recycled aggregate concrete and input the target parameters into the target equation. The target equation outputs the current compressive strength of the modified decommissioned wind turbine blade recycled FRP aggregate concrete. The target parameters include one of the following: the recycled FRP aggregate replacement rate of the decommissioned wind turbine blade, the amount of epoxy mortar coating, and the initial strength of ordinary concrete.

[0204] In a second implementation of the present invention, modified decommissioned wind turbine blade recycled FRP aggregate concrete is used to prepare reinforced-modified decommissioned wind turbine blade recycled FRP aggregate concrete beams, and a bending moment bearing capacity design method for reinforced-modified decommissioned wind turbine blade recycled FRP aggregate concrete beams based on the FRP aggregate replacement rate and epoxy mortar replacement rate of decommissioned wind turbine blades is proposed.

[0205] Figure 5 The beam is 250mm high and 150mm wide, with two 14mm diameter deformed steel bars as tension reinforcement and a strength of 400MPa. The target design bearing capacity is 26kN·m. A schematic diagram showing the relationship between the recycled FRP replacement rate of the modified recycled FRP aggregate, the amount of epoxy mortar coating, and the bearing capacity of the modified recycled FRP aggregate concrete beam from decommissioned wind turbine blades is presented when the ordinary concrete strength is 35MPa. The target bending moment bearing capacity and concrete mix proportion are determined; that is, the target parameter is the initial strength of the ordinary concrete. The current initial strength of the ordinary concrete and the preset target strength of the modified recycled FRP aggregate concrete are obtained. Then, the relationship between the target strength and the bearing capacity of the modified recycled FRP aggregate concrete beam is established.

[0206] In calculating the bending moment of the concrete beam section containing recycled FRP aggregate from modified decommissioned wind turbine blades, in order to simplify the calculation, the actual stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades in the compression zone of the reinforced concrete beam member is converted into an equivalent rectangular stress-strain curve according to the equivalent condition. The equivalent condition is that the resultant force of the actual stress-strain curve and the equivalent rectangular stress-strain curve are equal in magnitude and coincide in position. The dimensionless parameters k1 and k2 are determined from the actual stress-strain curve and the equivalent rectangular stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades according to the equivalent condition. k1 is determined by formula (7) and k2 is determined by formula (8).

[0207]

[0208] In formulas (7) and (8), k1 is the ratio of the area of ​​the actual stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades to the area of ​​the equivalent rectangular stress-strain curve; k2 is the ratio of the distance from the resultant point to the compression edge of the actual stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades to the strain at the compression edge; ε m Let σ be the compressive edge strain of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades in the beam section of a reinforced concrete beam member; σ is the stress in the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; ε is the strain in the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; and f is the strain in the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades. c 'The compressive strength of concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades;'

[0209] The height of the compression zone in the equivalent rectangular stress-strain curve is set to βx, and the equivalent stress uniformly distributed in the equivalent rectangular stress-strain curve is set to αf. c The coefficients of the equivalent rectangular stress-strain curve are β and α, where β = 2k2 and α = k1 / 2k2; the height of the compression zone of the beam section of the reinforced concrete beam member with recycled FRP aggregate from the decompressed wind turbine blades is determined by formula (9):

[0210]

[0211] In formula (9), x is the actual compression zone height of the beam section of the reinforced concrete beam member with recycled FRP aggregate from decommissioned wind turbine blades, β is the height coefficient of the equivalent rectangular stress-strain curve, α is the strength coefficient of the equivalent rectangular stress-strain curve, and A s f is the area of ​​the tensile reinforcement. y For the tensile strength of the steel reinforcement, f c'b' represents the compressive strength of concrete containing modified recycled FRP aggregate, and 'b' represents the beam width of the reinforced concrete beam member with modified recycled FRP aggregate from decommissioned wind turbine blades.

[0212] The bending moment bearing capacity of the reinforced concrete beam member made of recycled FRP aggregate from the modified decommissioned wind turbine blades is determined by formula (10):

[0213] M=αf c Formula (10) is given by 'bx(h0-x / 2)'.

[0214] In formula (10), M is the bending moment bearing capacity of the reinforced concrete beam member made of recycled FRP aggregate from decommissioned wind turbine blades, α is the strength coefficient of the equivalent rectangular stress-strain curve, and f c 'x' represents the compressive strength of concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; 'b' represents the beam width of the reinforced concrete beam containing recycled FRP aggregate from modified decommissioned wind turbine blades; 'h0' represents the effective height of the beam section of the reinforced concrete beam containing recycled FRP aggregate from modified decommissioned wind turbine blades.

[0215] The actual stress-strain curve of the concrete containing the modified decompressed wind turbine blade recycled FRP aggregate in the actual compression zone of the steel-reinforced-modified decompressed wind turbine blade recycled FRP aggregate concrete beam member is shown in formula (11):

[0216]

[0217] In formula (11), parameters a and b1 are determined by formulas (12) and (13), respectively:

[0218] a = 1.927 + 0.489r + 1.23r 2 -1.333r 3 Formula (12);

[0219] b1 = 0.129(r + 0.011) -0.571 +57.371(1+rs) -39.124 Formula (13);

[0220] In formulas (11) to (13), f c ε represents the compressive strength of concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades. c' is the peak strain of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; σ is the stress of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; ε is the strain of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; a is the shape factor of the rising segment of the actual stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; b1 is the shape factor of the rising and falling segments of the actual stress-strain curve of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades; r is the replacement rate; s is the amount of encapsulation.

[0221] This invention uses the compressive strength of concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades, corresponding to the preset target design bending moment bearing capacity, as the compressive strength and the current initial strength, as input into formulas (1) to (6). Formulas (1) to (6) output the data ranges corresponding to the current replacement rate and the current epoxy mortar coating amount of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades. Based on the data ranges corresponding to the current replacement rate and the current epoxy mortar coating amount of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades, the target replacement rate and the target epoxy mortar coating amount (i.e., the area above the design target plane) are determined. The current replacement strength, the target replacement rate, and the target epoxy mortar coating amount are input into the target equation, and the target equation outputs the current compressive strength of the concrete containing recycled FRP aggregate from modified decommissioned wind turbine blades, so that the design bearing capacity of the current concrete beam containing recycled FRP aggregate from modified decommissioned wind turbine blades is above the preset target bearing capacity.

[0222] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for determining the structural parameters of concrete containing modified recycled FRP aggregate, characterized in that, The structural parameters of concrete containing modified recycled FRP aggregate include compressive strength, mix proportion, replacement rate, and coating amount. The replacement rate is the volume percentage of modified recycled FRP aggregate in the coarse aggregate of the concrete. The modified recycled FRP aggregate is epoxy mortar modified recycled FRP aggregate. The coating amount is the mass ratio of epoxy mortar to recycled FRP aggregate. The determination method includes the following steps: obtaining three structural parameters containing the mix proportion, the three structural parameters containing the mix proportion include the mix proportion, and also include any two of the compressive strength, substitution rate and encapsulation amount of concrete containing modified recycled FRP aggregate; obtaining the compressive strength of concrete with natural coarse aggregate from the mix proportion; and determining the remaining structural parameters using formulas (1) to (6), the remaining structural parameters being the compressive strength, substitution rate or encapsulation amount of concrete containing modified recycled FRP aggregate; Alternatively, the determination method may include the following steps: obtaining the compressive strength, replacement rate and wrapping amount of concrete containing modified recycled FRP aggregate, obtaining the compressive strength of concrete with natural aggregate using formulas (1) to (6), and determining the mix proportion based on the compressive strength of concrete with natural aggregate. Alternatively, the determination method may include the following steps: preset compressive strength, obtain any one of the mix proportion, substitution rate and wrapping amount, when the obtained structural parameter is the mix proportion, obtain the compressive strength of the concrete with natural aggregate from the mix proportion, and use formulas (1) to (6) to obtain the range of the remaining two structural parameters among the mix proportion, substitution rate and wrapping amount, wherein the range is the range where the compressive strength of the concrete containing modified recycled FRP aggregate is ≥ the preset compressive strength under the condition that any one of the mix proportion, substitution rate and wrapping amount is determined; determine the remaining two structural parameters from the range of the remaining two structural parameters, and use formulas (1) to (6) to determine the compressive strength from the mix proportion, substitution rate and wrapping amount; k s1 =1+0.449s 2 +0.928rs-0.699s (3); k s2 =-78.696s 2 -1.326rs+47.359s-5.921 (5); In formulas (1) to (6): f c 'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. c k represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate.

2. The determination method according to claim 1, characterized in that, The construction method of formulas (1) to (6) includes the following steps: Provide concrete specimens, including concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates; The concrete specimens were subjected to compressive strength tests to obtain the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates. Based on the initial compressive strength information and the alternative compressive strength information, an initial formula is constructed for the compressive strength of concrete with natural aggregate, the compressive strength of concrete containing recycled FRP aggregate, and the recycled FRP aggregate replacement rate, wherein the recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate. Based on the initial compressive strength information and the modified compressive strength information, formulas (2) to (6) are constructed; The initial formulas are modified using formulas (2) to (6) to obtain formulas (1) to (6).

3. The determination method according to claim 2, characterized in that, The method for preparing the modified recycled FRP aggregate includes the following steps: The recycled FRP aggregate is mixed with epoxy mortar and then coated and modified to obtain the modified recycled FRP aggregate; the epoxy mortar includes epoxy resin, curing agent and additives.

4. The determination method according to claim 3, characterized in that, The mass ratio of the epoxy resin, curing agent and additives is (1-2):(1-5):(12-20).

5. The determination method according to claim 3, characterized in that, The recycled FRP aggregate has a particle size range of 5–25 mm and an aspect ratio of <1.

6.

6. A system for determining structural parameters of concrete containing modified recycled FRP aggregate, characterized in that, It includes a data acquisition module, an initial formula construction module, a target formula determination module, and an output module; The data acquisition module is used to collect compressive strength information obtained from compressive strength tests on concrete specimens. The concrete specimens include concrete specimens with natural aggregates, concrete specimens containing recycled FRP aggregates, and concrete specimens containing modified recycled FRP aggregates. The compressive strength information includes the initial compressive strength information of the concrete specimens with natural aggregates, the alternative compressive strength information of the concrete specimens containing recycled FRP aggregates, and the modified compressive strength information of the concrete specimens containing modified recycled FRP aggregates. The initial formula construction module obtains the initial compressive strength information and alternative compressive strength information transmitted by the data acquisition module, the compressive strength of the concrete with associated natural aggregate, the compressive strength of the concrete containing recycled FRP aggregate, and the initial formula for the recycled FRP aggregate replacement rate. The recycled FRP aggregate replacement rate is the volume percentage of recycled FRP aggregate in the coarse aggregate of the concrete specimen containing recycled FRP aggregate. The target formula determination module is used to construct formulas (1) to (6); k s1 =1+0.449s 2 +0.928rs-0.699s (3); k s2 =-78.696s 2 -1.326rs+47.359s-5.921 (5); In formulas (1) to (6): f c 'F represents the compressive strength of concrete containing modified recycled FRP aggregate.' co ε is the compressive strength of concrete with natural aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate, r is the replacement rate, and k is the peak strain. s1 k is the elastic modulus coefficient of concrete related to the amount of wrapping. s2 The peak strain coefficient of concrete related to the amount of encapsulation, where s is the amount of encapsulation and E is the peak strain coefficient. c k represents the elastic modulus of concrete containing modified recycled FRP aggregate. e The elastic modulus of concrete is related to the replacement rate. The output module is used to output one remaining structural parameter based on any three structural parameters of the concrete containing modified recycled FRP aggregate. The structural parameters of the concrete containing modified recycled FRP aggregate include compressive strength, mix proportion, substitution rate, and encapsulation amount. The substitution rate is the volume percentage of modified recycled FRP aggregate in the coarse aggregate of the concrete. The modified recycled FRP aggregate is epoxy mortar modified recycled FRP aggregate. The encapsulation amount is the mass ratio of epoxy mortar to recycled FRP aggregate.

7. A method for determining the structural parameters of a reinforced concrete beam member made of modified recycled FRP aggregate, characterized in that, The structural parameters include the bending moment bearing capacity of reinforced concrete beam members with modified recycled FRP aggregate and the structural parameters of concrete containing modified recycled FRP aggregate. The structural parameters of the concrete containing modified recycled FRP aggregate are determined by the method described in any one of claims 1 to 6; The acquisition of the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate includes: converting the actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the compression zone of the reinforced concrete beam member with modified recycled FRP aggregate into an equivalent rectangular stress-strain curve according to the equivalent conditions, wherein the equivalent conditions are that the resultant force of the actual stress-strain curve and the equivalent rectangular stress-strain curve are equal in magnitude and coincide in position; determining the dimensionless parameters k1 and k2 from the actual stress-strain curve and the equivalent rectangular stress-strain curve of the concrete containing modified recycled FRP aggregate according to the equivalent conditions; k1 is determined by formula (7) and k2 is determined by formula (8). In formulas (7) and (8), k1 is the ratio of the area of ​​the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the area of ​​the equivalent rectangular stress-strain curve; k2 is the ratio of the distance from the resultant point to the compression edge of the actual stress-strain curve of concrete containing modified recycled FRP aggregate to the strain at the compression edge; ε m Let σ be the compressive edge strain of the concrete containing modified recycled FRP aggregate in the beam section of a reinforced concrete beam member; σ is the stress of the concrete containing modified recycled FRP aggregate; ε is the strain of the concrete containing modified recycled FRP aggregate; f is the cross-sectional strain of the reinforced concrete beam member. c 'The compressive strength of concrete containing modified recycled FRP aggregate;' The height of the compression zone in the equivalent rectangular stress-strain curve is set to βx, and the equivalent stress uniformly distributed in the equivalent rectangular stress-strain curve is set to αf. c The coefficients of the equivalent rectangular stress-strain curve are β and α, where β = 2k2 and α = k1 / 2k2; the height of the compression zone of the beam section of the reinforced concrete-modified recycled FRP aggregate member is determined by formula (9): In formula (9), x is the actual compression zone height of the beam section of the reinforced concrete beam member with modified recycled FRP aggregate, β is the height coefficient of the equivalent rectangular stress-strain curve, α is the strength coefficient of the equivalent rectangular stress-strain curve, and A s f is the area of ​​the tensile reinforcement. y For the tensile strength of the steel reinforcement, f c 'b' represents the compressive strength of concrete containing modified recycled FRP aggregate, and 'b' represents the beam width of the reinforced concrete beam member with modified recycled FRP aggregate. The bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate is determined by formula (10): M=αf c Formula (10) is given by 'bx(h0-x / 2)'. In formula (10), M is the bending moment bearing capacity of the reinforced concrete beam member with modified recycled FRP aggregate, α is the strength coefficient of the equivalent rectangular stress-strain curve, and f c ' is the compressive strength of concrete containing modified recycled FRP aggregate, x is the actual compression zone height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member, b is the beam width of the reinforced-modified recycled FRP aggregate concrete beam member; h0 is the effective height of the beam section of the reinforced-modified recycled FRP aggregate concrete beam member; The actual stress-strain curve of the concrete containing modified recycled FRP aggregate in the actual compression zone of the steel-reinforced modified recycled FRP aggregate concrete beam member is shown in formula (11): In formula (11), parameters a and b1 are determined by formulas (12) and (13), respectively: a = 1.927 + 0.489r + 1.23r 2 -1.333r 3 Formula (12); b1 = 0.129(r + 0.011) -0.571 +57.371(1+rs) -39.124 Formula (13); In formulas (11) to (13), f c ε represents the compressive strength of concrete containing modified recycled FRP aggregate. c ' is the peak strain of concrete containing modified recycled FRP aggregate; σ is the stress of concrete containing modified recycled FRP aggregate; ε is the strain of concrete containing modified recycled FRP aggregate; a is the shape factor of the rising segment of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; b1 is the shape factor of the rising and falling segments of the actual stress-strain curve of concrete containing modified recycled FRP aggregate; r is the substitution rate; s is the amount of encapsulation.

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