Optimization method of CFRP elastic modulus under weakened bending resistance of wooden beam structure

Abstract

The present invention discloses a method for optimizing the elastic modulus of CFRP under the weakened bending resistance of a wooden beam structure. The method comprises the following steps: S1, building a wooden beam structure model; S2, analyzing the elastic modulus of the wooden beam; S3, simulating the wooden beam reinforcement structure; S4, calculating and analyzing the elastic modulus of the wooden beam again; S5, analyzing the bending resistance of the wooden beam by an optimization algorithm; the present invention establishes a structural model of the wooden beam through a finite element analysis model, simulates the optimization of the wooden beam, and combines the bending resistance optimization scheme of the wooden beam through a genetic algorithm to achieve maximum bending resistance optimization, so that the wooden beam has a higher service life and safety in subsequent use; during the simulation calculation, not only the center of the wooden beam is calculated, but also the riveted joint of the wooden beam is calculated, which can effectively eliminate the influence of the support at the connection of the riveted joint on the bending resistance, and according to the difference in influence between the center and the riveted joint, the weight ratio is distributed to improve the accuracy of the calculation.

Description

Technical Field

[0001] The invention belongs to the technical field of wood beam auxiliary technology, and more specifically, particularly relates to a method for optimizing the elastic modulus of CFRP when the bending resistance of a wood beam structure is weakened. Background Art

[0002] A wooden beam is supported by a support, and the external forces it bears are mainly lateral force and shear force, and the components that are mainly deformed by bending are called beams. Wooden beams are a type of beam classified by material. Wooden beams are widely used in ancient architecture. In modern architecture, natural materials such as wooden floors and wooden beams are used to decorate homes. There is no luxurious decoration, but simple and plain.

[0003] Although there are many advantages to using wooden structures in buildings, there are still many disadvantages. For example, the construction schedule is tight, it is difficult to control the moisture content in wooden materials, and wooden components often rot and crack during use. If a large amount of high-quality wood is used and appropriate measures are taken to dry the water in the wood, the construction cost will increase. In addition, wood does not have good fire resistance. Therefore, pure wooden structures are rarely used in antique buildings.

[0004] The load-bearing capacity and structural stability of a timber beam depend primarily on several factors:

[0005] Material strength: The type, density and moisture of the wood will affect its strength. Commonly used woods include pine, oak, etc., and each type of wood has different load-bearing capacity.

[0006] Cross-sectional dimensions: The width and height of a beam affect its bending strength. Larger cross-sectional dimensions can support greater loads.

[0007] Support conditions: The support method of the wooden beam (such as simple support, fixed support) will affect its stability and bearing capacity.

[0008] Type of loads: Timber beams need to consider different types of loads such as static loads, dynamic loads and impact loads.

[0009] Span: The larger the span of the wooden beam, the more stringent the cross-sectional dimensions and support conditions required.

[0010] After long-term use, the bending resistance of wooden beams is prone to weakening. In order to enhance the bending resistance of wooden beams, it is necessary to optimize the wooden beams and improve their bending resistance so that they have higher bending resistance and improve their service life and safety.

[0011] However, there are some problems with the existing technology: when optimizing the bending performance of wooden beams, the existing technology directly reinforces the riveted joints of the wooden beams, or reinforces the center of the wooden beams, which can easily damage the overall structure of the wooden beams, and does not simulate the optimization scheme of the wooden beams, resulting in certain errors in the optimization of the wooden beams. Therefore, we propose a method for optimizing the CFRP elastic modulus under the weakened bending resistance of the wooden beam structure. Summary of the invention

[0012] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for optimizing the CFRP elastic modulus when the bending resistance of a wooden beam structure is weakened. A structural model of the wooden beam is constructed through a finite element analysis model, carbon fiber reinforced polymer is pasted on the wooden beam, and the best solution for optimizing the bending resistance of the wooden beam is obtained through calculation and analysis, thereby improving the bending resistance of the wooden beam and improving the service life and safety of the wooden beam.

[0013] To achieve the above object, the present invention provides the following technical solution: A method for optimizing the elastic modulus of CFRP under the weakened bending resistance of a wooden beam structure, comprising the following steps:

[0014] S1. Build a wooden beam structure model: Establish a wooden beam structure model through a finite element analysis model, and determine the material properties of the wooden beam and carbon fiber reinforced polymer;

[0015] S2. Analyze the elastic modulus of the beam: simulate and analyze the behavior of the beam under weakening conditions under the finite element analysis model, and calculate the bending stress σ, bending deformation δ, the height c of the tensile zone of the beam section and the bending bearing capacity m of the beam;

[0016] S3. Simulate the reinforcement structure of wooden beams: reinforce the wooden beams under the finite element analysis model, that is, paste carbon fiber reinforced polymers at the riveted joints of the wooden beams, paste carbon fiber reinforced polymers at the center of gravity and physical damage of the wooden beams, and strengthen the support of the riveted points of the wooden beams, and use wooden triangular reinforcement plates to install and connect between the wooden beams and the columns;

[0017] S4. Calculate and analyze the elastic modulus of the wood beam again: that is, simulate and analyze the behavior of the wood beam under different load and weakening conditions under the finite element analysis model, and calculate the bending stress σ', bending deformation δ', height c' of the tensile zone of the wood beam section and bending bearing capacity m' of the wood beam;

[0018] S5. Optimization algorithm to analyze the bending resistance of wooden beams: The bending resistance of wooden beams after carbon fiber reinforced polymer is pasted is calculated and analyzed by genetic algorithm to obtain the best carbon fiber reinforced polymer pasting position on the wooden beams.

[0019] Optionally, the acquisition of the material properties of the wooden beam in S1 is performed by detecting internal defects of the wooden beam through ultrasonic testing or acoustic emission testing, and the ultrasonic testing or acoustic emission testing is mainly used to detect physical damage and humidity changes of the wooden beam, and the finite element analysis model is used to simulate the overload and aging of the wooden beam;

[0020] The physical damage includes cracks, decay and insect damage;

[0021] The humidity change includes humidity change causing the wooden beam to expand or contract;

[0022] The overload is that the wooden beam bears overload for a long time, which causes the mechanical properties of the wooden beam to decrease;

[0023] The said ageing is the degradation of the wood beams over time, reducing their mechanical properties.

[0024] Optionally, the calculation of the bending stress σ in S2 takes the center point of the wooden beam as the calculation position, and the calculation formula is as follows:

[0025]

[0026] in, is the bending stress at the center of the beam, is the bending stress of the riveted joints at both ends of the beam, M1 and M2 are the bending moments at the center point and the riveted joint respectively, H is the cross-sectional height of the beam, and the value is taken as I is the moment of inertia of the cross section, w1 and w2 represent the weights of the center point and the riveted joint, and w1+w2=1, and w1 is four times w2;

[0027] Similarly, the calculation of the bending deformation δ takes the center point of the wooden beam as the calculation position, and the calculation formula is as follows:

[0028]

[0029] in, is the bending amount at the center of the beam, It is expressed as the bending amount of the riveted joint of the wooden beam, P1 and P2 are the concentrated loads acting on the center and the riveted joint respectively, and P1=2P2, E is the elastic modulus of the wooden beam, L is the length of the wooden beam, w1 and w2 are the weights of the center point and the riveted joint, and w1+w2=1, and w1 is four times of w2.

[0030] Optionally, the bending stress σ' and bending deformation δ' of the wooden beam after the carbon fiber reinforced polymer is attached in S4 are calculated in the same manner as the bending stress σ and bending deformation δ of the wooden beam before the carbon fiber reinforced polymer is attached;

[0031] The concentrated load of the wood beam after the carbon fiber reinforced polymer is attached includes the weight of the wood beam itself and the measurement force applied to the wood beam, while the concentrated load of the wood beam before the carbon fiber reinforced polymer is attached is only the weight of the wood beam itself, and other parameters remain unchanged;

[0032] And the bending moment M is calculated using the central load, then the calculation of the bending moment M is as follows:

[0033] Among them, P represents the concentrated load acting on the center, that is, the weight of the wooden beam itself, and P=P1, and L represents the length of the wooden beam.

[0034] Optionally, the calculation formula for the height c of the tensile zone of the wood beam cross section in S2 is as follows:

[0035] Where c is the height of the tensile zone of the beam section; B is the width of the beam section; H is the height of the beam section; f b is the bending strength of wood after considering the size effect, r b The bending strength of the beams is weakened by physical damage and humidity changes;

[0036] The calculation formula of the bending bearing capacity m of the wooden beam is as follows:

[0037]

[0038] Among them, f b is the bending strength of wood after considering the size effect; c is the height of the tensile zone of the wood beam section; B is the width of the wood beam section; m is the bending bearing capacity of the wood beam.

[0039] Optionally, the calculation method of the height c' of the tensile zone of the cross section of the wooden beam after the carbon fiber reinforced polymer is attached and the bending bearing capacity m' of the wooden beam in S4 is the same as the calculation method of the height c of the tensile zone of the cross section of the wooden beam and the bending bearing capacity m of the wooden beam before the carbon fiber reinforced polymer is attached;

[0040] The calculation formula for the height c' of the tensile zone of the timber beam section is as follows

[0041] Where c is the height of the tensile zone of the beam section; B is the width of the beam section; H is the height of the beam section; f b is the bending strength of wood after considering the size effect, r b The bending strength of the beam weakened by physical damage and humidity changes; E b E is the bending elastic modulus of wood; f is the elastic modulus of carbon fiber cloth; A f is the cross-sectional area of ​​the carbon fiber cloth;

[0042] The calculation formula of the bending bearing capacity m' of the wooden beam is as follows:

[0043] Among them, f b is the bending strength of wood after considering the size effect; c is the height of the tensile zone of the wood beam section; B is the width of the wood beam section; m is the bending bearing capacity of the wood beam; E f is the elastic modulus of carbon fiber cloth; A f is the cross-sectional area of ​​the carbon fiber cloth; E b is the bending elastic modulus of wood; α is the empirical coefficient considering the degree of fiber influence, that is, the fiber influence of physical damage and humidity change of the wooden beam, S is the surface area of ​​the wooden triangular reinforcement board, and Z is the thickness of the wooden triangular reinforcement board.

[0044] Optionally, the reinforcement steps of the wooden beam reinforcement structure in S3 are as follows:

[0045] S301, horizontally pasting carbon fiber reinforced polymer at the mortise and tenon joints between the two ends of the wooden beam and the column, with the carbon fiber reinforced polymer and the wooden beam kept horizontal, and fixing the carbon fiber reinforced polymer to the wooden beam and the column respectively by rivets;

[0046] S302, vertically pasting two layers of carbon fiber reinforced polymer at the connection between the wooden beam and the carbon fiber reinforced polymer again, and fixing the connection by rivets;

[0047] S303, installing a wooden triangular reinforcement plate between the lower angles of the wooden beam and the column by means of rivets, and bonding carbon fiber reinforced polymer to the wooden triangular reinforcement plate, the wooden beam and the column, and fixing them by means of rivets;

[0048] S304, pasting carbon fiber reinforced polymer at the center of the wooden beam, and the carbon fiber reinforced polymer is tied to the wooden beam for a circle and fixedly connected by rivets;

[0049] S305, pasting carbon fiber reinforced polymer at the location where the wooden beam has physical damage, and the carbon fiber reinforced polymer is tied to the wooden beam for a week and fixedly connected by rivets.

[0050] Optionally, when the carbon fiber reinforced polymer is pasted horizontally, the width of the carbon fiber reinforced polymer is one-third of the height of the wooden beam, and when the carbon fiber reinforced polymer is pasted vertically, the width of the carbon fiber reinforced polymer is one-third of the length of the carbon fiber reinforced polymer connected to the wooden beam, and the width of the carbon fiber reinforced polymer pasted horizontally is at least 5 cm, the width of the carbon fiber reinforced polymer pasted vertically is at least 10 cm, the width of the carbon fiber reinforced polymer pasted at the center of the wooden beam is at least one-quarter of the length of the wooden beam, and the width of the carbon fiber reinforced polymer pasted on the physically damaged wooden beam is at least twice the length of the physical damage.

[0051] Optionally, the calculation process of the genetic algorithm is as follows:

[0052] S501, determining that the bending deformation δ and the bending deformation δ' of the wood beam maintain the same bending degree before and after the carbon fiber reinforced polymer is pasted, and the bending degree of the wood beam is simulated by adjusting the concentrated load through a finite element analysis model;

[0053] S502, after determining that the bending deformation of the wood beam is the same, respectively calculate the bending stress σ', the height c' of the tensile zone of the wood beam cross section and the bending bearing capacity m' of the wood beam;

[0054] S503, performing calculation and setting for pasting carbon fiber reinforced polymer respectively, namely horizontal pasting; vertical pasting; center pasting; wooden triangular reinforcement plate; pasting at the physical damage position; and then performing combined calculation by genetic algorithm;

[0055] S504, respectively calculating the result of each optimization method in S503 according to the calculated bending stress σ', the height c' of the tensile zone of the wood beam section and the bending bearing capacity m' of the wood beam;

[0056] S505. Combining the optimization schemes through a genetic algorithm and performing calculation analysis to determine the optimal method for selecting the elastic modulus of CFRP under the weakened bending resistance of the wooden beam structure.

[0057] Optionally, the calculation process of the genetic algorithm is as follows:

[0058] The probability of selection is the ratio of its fitness to the total fitness of the population:

[0059]

[0060] Among them, f i is the fitness of the ith individual, n is the population size, is the sum of all individual fitnesses;

[0061] Among them, when calculating and selecting, the combination options of carbon fiber reinforced polymer pasting without center pasting and physical damage will be eliminated, and the optimal method will be selected for the combination of carbon fiber reinforced polymer pasting with center pasting and physical damage, that is, the option with the maximum value of the bending bearing capacity m' of the wooden beam.

[0062] Technical effects and advantages of the present invention:

[0063] The present invention establishes a structural model of a wooden beam through a finite element analysis model, realizes simulation processing of optimization of the wooden beam, reduces damage to the wooden beam during the optimization processing of the physical wooden beam, and realizes calculation of the bending stress σ, bending deformation δ, height c of the tensile zone of the wooden beam cross section and bending bearing capacity m of the wooden beam when simulating the wooden beam, and calculates the bending stress σ', bending deformation δ', height c' of the tensile zone of the wooden beam cross section and bending bearing capacity m' of the wooden beam after simulating the anti-bending optimization processing of the wooden beam, so as to facilitate comparison and judgment of data before optimization, and realizes combination of anti-bending optimization schemes of the wooden beam through a genetic algorithm, realizes maximum anti-bending optimization, and makes the wooden beam have a higher service life and safety in use during subsequent use;

[0064] The present invention calculates not only the center of the wooden beam but also the riveted joint of the wooden beam during simulation calculation, which can effectively eliminate the influence of the support at the riveted joint connection on the anti-bending, and distributes the weight ratio according to the influence difference between the center and the riveted joint to improve the calculation accuracy, and realizes the combined calculation of the carbon fiber reinforced polymer pasting position of the wooden beam through the genetic algorithm to select the optimal solution;

[0065] In order to effectively enhance the bending resistance, carbon fiber reinforced polymers must be pasted to the center of the wooden beam to effectively improve the bending resistance of the center of the wooden beam, and carbon fiber reinforced polymers must be pasted to the physical damaged parts of the wooden beam to improve the strength of the physical damaged parts of the wooden beam, increase the toughness, and improve the bending resistance. Pasting carbon fiber reinforced polymers on the rivet joints at both ends can prevent the rivet joints from falling off when the bending resistance of the wooden beam is weakened, thereby improving the stability of the wooden beam connection. The present invention improves the bending resistance by pasting carbon fiber reinforced polymers to the center and physical damaged parts of the wooden beam, and prevents the rivet joints from loosening and falling off. The wooden beam can be supported by setting a wooden triangular reinforcement plate, thereby improving the bending resistance and overall strength of the wooden beam structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0067] Figure 1 It is a schematic diagram of the steps provided by the present invention;

[0068] Figure 2 It is a schematic diagram of the reinforcement steps of the wooden beam reinforcement structure provided by the present invention;

[0069] Figure 3 It is a schematic diagram of the calculation flow of the genetic algorithm provided by the present invention. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] like Figures 1 to 3 As shown, the CFRP elastic modulus optimization method provided by the embodiment of the present invention under the condition of weakened bending resistance of the wooden beam structure includes the following steps:

[0072] S1. Build a wooden beam structure model: Establish a wooden beam structure model through a finite element analysis model, and determine the material properties of the wooden beam and carbon fiber reinforced polymer;

[0073] S2. Analyze the elastic modulus of the beam: simulate and analyze the behavior of the beam under weakening conditions under the finite element analysis model, and calculate the bending stress σ, bending deformation δ, the height c of the tensile zone of the beam section and the bending bearing capacity m of the beam;

[0074] S3. Simulate the reinforcement structure of wooden beams: reinforce the wooden beams under the finite element analysis model, that is, paste carbon fiber reinforced polymers at the riveted joints of the wooden beams, paste carbon fiber reinforced polymers at the center of gravity and physical damage of the wooden beams, and strengthen the support of the riveted points of the wooden beams, and use wooden triangular reinforcement plates to install and connect between the wooden beams and the columns;

[0075] S4. Calculate and analyze the elastic modulus of the wood beam again: that is, simulate and analyze the behavior of the wood beam under different load and weakening conditions under the finite element analysis model, and calculate the bending stress σ', bending deformation δ', height c' of the tensile zone of the wood beam section and bending bearing capacity m' of the wood beam;

[0076] S5. Optimization algorithm to analyze the bending resistance of wooden beams: The bending resistance of wooden beams after carbon fiber reinforced polymer is pasted is calculated and analyzed by genetic algorithm to obtain the best carbon fiber reinforced polymer pasting position on the wooden beams.

[0077] It is further explained that the acquisition of the material properties of the wooden beam in S1 detects the internal defects of the wooden beam through ultrasonic testing or acoustic emission testing, and the ultrasonic testing or acoustic emission testing is mainly used to detect physical damage and humidity changes of the wooden beam, and the finite element analysis model is used to simulate the overload and aging of the wooden beam;

[0078] The physical damage includes cracks, decay and insect damage;

[0079] The humidity change includes humidity change causing the wooden beam to expand or contract;

[0080] The overload is that the wooden beam bears overload for a long time, which causes the mechanical properties of the wooden beam to decrease;

[0081] The said aging is the deterioration of the wood beams over time, which reduces their mechanical properties;

[0082] By testing wooden beams through ultrasonic testing or acoustic emission testing, it is possible to accurately detect wooden beams without damaging their structure, especially the internal structure of wooden beams. Through detection, internal physical damage can be obtained to protect the existing structural safety of the wooden beams.

[0083] In this embodiment, preferably, the calculation of the bending stress σ in S2 takes the center point of the wooden beam as the calculation position, and the calculation formula is as follows:

[0084]

[0085] in, is the bending stress at the center of the beam, is the bending stress of the riveted joints at both ends of the beam, M1 and M2 are the bending moments at the center point and the riveted joint respectively, H is the cross-sectional height of the beam, and the value is taken as I is the moment of inertia of the cross section, w1 and w2 represent the weights of the center point and the riveted joint, and w1+w2=1, and w1 is four times w2;

[0086] Similarly, the calculation of the bending deformation δ takes the center point of the wooden beam as the calculation position, and the calculation formula is as follows:

[0087]

[0088] in, is the bending amount at the center of the beam, It is represented by the bending amount of the riveted joint of the wood beam, P1 and P2 represent the concentrated loads acting on the center and the riveted joint respectively, and P1=2P2, E is the elastic modulus of the wood beam, L represents the length of the wood beam, w1 and w2 represent the weights of the center point and the riveted joint, and w1+w2=1, and w1 is four times of w2;

[0089] By calculating the bending stress of the wood beam, we can get the stress distribution of the wood beam in the bending state, that is, the wood beam is mainly subjected to the gravity at the center of gravity and the support force at both ends of the riveted joints. For the bending resistance of the wood beam, the gravity at the center of gravity is mainly considered, and the support force of the riveted joints at both ends has a relatively small influence. By distributing the weights, the calculation of the overall bending force of the wood beam is maintained, and the influence of the support force of the riveted joints at both ends is weakened.

[0090] Bending deformation is the deformation of a wooden beam when it is bent under force. When simulating the structure of a wooden beam, the size of the bending deformation is used as the standard for applying concentrated loads, which facilitates accurate comparison and comparison of the additional concentrated loads after the wooden beam is optimized for bending resistance.

[0091] Optionally, the bending stress σ' and bending deformation δ' of the wooden beam after the carbon fiber reinforced polymer is attached in S4 are calculated in the same manner as the bending stress σ and bending deformation δ of the wooden beam before the carbon fiber reinforced polymer is attached;

[0092] The concentrated load of the wood beam after the carbon fiber reinforced polymer is attached includes the weight of the wood beam itself and the measurement force applied to the wood beam, while the concentrated load of the wood beam before the carbon fiber reinforced polymer is attached is only the weight of the wood beam itself, and other parameters remain unchanged;

[0093] And the bending moment M is calculated using the central load, then the calculation of the bending moment M is as follows:

[0094] Where P represents the concentrated load acting at the center, that is, the weight of the beam itself, and P = P1, L represents the length of the beam;

[0095] After the beam is optimized by gluing carbon fiber reinforced polymer, a concentrated load needs to be applied to the beam to make the bending degree of the beam adapt to the bending deformation δ. In addition, the concentrated load of the beam needs to be redistributed during calculation. The applied measurement force and the beam itself need to be added. The concentrated load is the weight of the beam, and the center of gravity is at the center of the beam. The calculation formula is as follows:

[0096]

[0097] Where F is the applied force.

[0098] Further explanation: the calculation formula of the height c of the tensile zone of the wood beam cross section in S2 is as follows:

[0099] Where c is the height of the tensile zone of the beam section; B is the width of the beam section; H is the height of the beam section; f bis the bending strength of wood after considering the size effect, r b The bending strength of the beams is weakened by physical damage and humidity changes;

[0100] The calculation formula of the bending bearing capacity m of the wooden beam is as follows:

[0101]

[0102] Among them, f b is the bending strength of wood after considering the size effect; c is the height of the tensile zone of the wood beam section; B is the width of the wood beam section; m is the bending bearing capacity of the wood beam;

[0103] Through the above calculation, the height of the tensile zone of the wooden beam when it is bent can be obtained. Because the wooden beam is damaged, it will affect the bending resistance of the wooden beam. When calculating, it is necessary to consider the physical damage factors of the wooden beam. After removing the influence of the physical damage factors of the wooden beam, the actual height of the tensile zone of the wooden beam is obtained, which is convenient for realizing accurate calculation of the parameters of the wooden beam and eliminating the existing influence.

[0104] Furthermore, the calculation method of the height c' of the tensile zone of the cross section of the wooden beam after the carbon fiber reinforced polymer is attached and the bending bearing capacity m' of the wooden beam is the same as the calculation method of the height c of the tensile zone of the cross section of the wooden beam and the bending bearing capacity m of the wooden beam before the carbon fiber reinforced polymer is attached;

[0105] The calculation formula for the height c' of the tensile zone of the timber beam section is as follows

[0106] Where c is the height of the tensile zone of the beam section; B is the width of the beam section; H is the height of the beam section; f b is the bending strength of wood after considering the size effect, r b The bending strength of the beam weakened by physical damage and humidity changes; E b E is the bending elastic modulus of wood; f is the elastic modulus of carbon fiber cloth; A f is the cross-sectional area of ​​the carbon fiber cloth;

[0107] The calculation formula of the bending bearing capacity m' of the wooden beam is as follows:

[0108] Among them, f b is the bending strength of wood after considering the size effect; c is the height of the tensile zone of the wood beam section; B is the width of the wood beam section; m is the bending bearing capacity of the wood beam; E f is the elastic modulus of carbon fiber cloth; A f is the cross-sectional area of ​​the carbon fiber cloth; E bis the bending elastic modulus of wood; α is the empirical coefficient considering the fiber influence, that is, the fiber influence of physical damage and humidity change of the wood beam, S is the surface area of ​​the wooden triangular reinforcement board, and Z is the thickness of the wooden triangular reinforcement board;

[0109] After the reinforcement and optimization treatment, the bending resistance of the wooden beam is improved. During the calculation process, the performance of the optimized material is added to the calculation, which makes it easier to compare the height c' of the tensile zone of the wooden beam section and the bending bearing capacity m' of the wooden beam with those before optimization, so that the effect of the wooden beam optimization can be clearly obtained.

[0110] Furthermore, the reinforcement steps of the wooden beam reinforcement structure in S3 are as follows:

[0111] S301, horizontally pasting carbon fiber reinforced polymer at the mortise and tenon joints between the two ends of the wooden beam and the column, with the carbon fiber reinforced polymer and the wooden beam kept horizontal, and fixing the carbon fiber reinforced polymer to the wooden beam and the column respectively by rivets;

[0112] S302, vertically pasting two layers of carbon fiber reinforced polymer at the connection between the wooden beam and the carbon fiber reinforced polymer again, and fixing the connection by rivets;

[0113] S303, installing a wooden triangular reinforcement plate between the lower angles of the wooden beam and the column by means of rivets, and bonding carbon fiber reinforced polymer to the wooden triangular reinforcement plate, the wooden beam and the column, and fixing them by means of rivets;

[0114] S304, pasting carbon fiber reinforced polymer at the center of the wooden beam, and the carbon fiber reinforced polymer is tied to the wooden beam for a circle and fixedly connected by rivets;

[0115] S305, pasting carbon fiber reinforced polymer at the position where the wooden beam has physical damage, and the carbon fiber reinforced polymer is tied to the wooden beam for one week and fixedly connected by rivets;

[0116] When simulating the anti-bending optimization of wooden beams, the wooden beams are treated with anti-bending treatment to the maximum extent possible to improve their anti-bending performance. In addition, there is a certain order in the pasting of carbon fiber reinforced polymers to facilitate maintaining the stable connection of the carbon fiber reinforced polymers. The carbon fiber reinforced polymers are fixed again by rivets to maintain the stable connection of the carbon fiber reinforced polymers and prevent the carbon fiber reinforced polymers from falling off.

[0117] Optionally, when the carbon fiber reinforced polymer is pasted horizontally, the width of the carbon fiber reinforced polymer is one-third of the height of the wooden beam, and when the carbon fiber reinforced polymer is pasted vertically, the width of the carbon fiber reinforced polymer is one-third of the length of the carbon fiber reinforced polymer connected to the wooden beam, and the width of the carbon fiber reinforced polymer pasted horizontally is at least 5 cm, the width of the carbon fiber reinforced polymer pasted vertically is at least 10 cm, the width of the carbon fiber reinforced polymer pasted at the center of the wooden beam is at least one-quarter of the length of the wooden beam, and the width of the carbon fiber reinforced polymer pasted on the wooden beam with physical damage is at least twice the length of the physical damage;

[0118] By setting the size of the carbon fiber reinforced polymer, the contact area of ​​the carbon fiber reinforced polymer can be increased, and the optimized treatment of the carbon fiber reinforced polymer on the wooden beam can be improved, with higher strength, especially for the setting of the damaged and center parts of the wooden beam. The bonding is carried out according to the bending curvature of the wooden beam to improve the bending resistance of the center of the wooden beam. The length setting of the damaged part is convenient for completely wrapping the damaged part and facilitating the bonding and connection of the intact part to improve the overall strength.

[0119] In this embodiment, preferably, the calculation process of the genetic algorithm is as follows:

[0120] S501, determining that the bending deformation δ and the bending deformation δ' of the wood beam maintain the same bending degree before and after the carbon fiber reinforced polymer is pasted, and the bending degree of the wood beam is simulated by adjusting the concentrated load through a finite element analysis model;

[0121] S502, after determining that the bending deformation of the wood beam is the same, respectively calculate the bending stress σ', the height c' of the tensile zone of the wood beam cross section and the bending bearing capacity m' of the wood beam;

[0122] S503, performing calculation and setting for pasting carbon fiber reinforced polymer respectively, namely horizontal pasting; vertical pasting; center pasting; wooden triangular reinforcement plate; pasting at the physical damage position; and then performing combined calculation by genetic algorithm;

[0123] S504, respectively calculating the result of each optimization method in S503 according to the calculated bending stress σ', the height c' of the tensile zone of the wood beam section and the bending bearing capacity m' of the wood beam;

[0124] S505, combining the optimization schemes through a genetic algorithm, and performing calculation and analysis to determine the optimal method for selecting the elastic modulus of CFRP under the weakened bending resistance of the wooden beam structure;

[0125] By calculating each step in the optimization of wooden beams and performing combined verification and testing on all steps, different combinations can be obtained, which facilitates more optimization choices and enables the acquisition of the optimal solution.

[0126] Furthermore, the calculation process of the genetic algorithm is as follows:

[0127] The probability of selection is the ratio of its fitness to the total fitness of the population:

[0128]

[0129] Among them, f i is the fitness of the ith individual, n is the population size, is the sum of all individual fitnesses;

[0130] Among them, when calculating and selecting, the combination options of carbon fiber reinforced polymers that do not have center bonding and physical damage are eliminated, and the combination of carbon fiber reinforced polymers that have center bonding and physical damage is selected. The optimal method is the option of the maximum value of the bending bearing capacity m' of the wooden beam;

[0131] In order to enhance the bending resistance of wooden beams, and the bending part of the wooden beams is mainly located in the center, all combination options that do not include oil center gluing are eliminated. For wooden beams, physical damage seriously affects the bending resistance of wooden beams. Pasting carbon fiber reinforced polymers on the damaged parts of wooden beams can maintain the integrity of the wooden beams and improve their bending resistance. Therefore, it is necessary to paste carbon fiber reinforced polymers on the damaged parts of wooden beams to improve their strength.

[0132] Example:

[0133] Combine optimization schemes through genetic algorithms and perform computational analysis;

[0134] The bending part of the wood beam is mainly located at the center, so all the combination options that do not include oil center pasting are eliminated. For the wood beam, physical damage seriously affects the bending resistance of the wood beam. Pasting carbon fiber reinforced polymer on the damaged part of the wood beam can maintain the integrity of the wood beam and improve the bending resistance. When the genetic algorithm combines the schemes, the selected combinations include the combination options of pasting carbon fiber reinforced polymer at the center and pasting carbon fiber reinforced polymer at the physical damage.

[0135] The first combination, pasting carbon fiber reinforced polymer at the center and pasting carbon fiber reinforced polymer at the physical damage: after pasting carbon fiber reinforced polymer at the center and the physical damage of the wood beam, a concentrated load is applied to the wood beam under the finite element analysis model, so that the bending deformation δ' of the wood beam reaches the bending deformation δ when the carbon fiber reinforced polymer is not pasted, that is, under the same bending deformation condition, the bending stress σ' of the wood beam after optimization is compared with the bending stress σ before optimization;

[0136] w1 is 0.8, w2 is 0.2, where H is the height of the beam section, the height is constant, the bending moments of M1 and M2 are also constant parameters, which are 2 meters and 0.5 meters respectively, the length of the beam L is 5 meters, and the height of the beam section H is 0.3 meters; then:

[0137]

[0138] For the calculation of applied F, After the beam is optimized, I changes. Let I1 before optimization. Where B is the width of the beam, which is 0.3 meters; suppose it is I2 before optimization, but

[0139] Bring in It is calculated that σ'=216.01778;

[0140] but

[0141] The performance is relatively improved by 80.015%;

[0142] And the corresponding bending bearing capacity of the optimized beam m' is compared with the bending bearing capacity of the beam before optimization m, f b is 888.889, r b is 300, c = 0.076, E f 300GPa, A f 0.0125m 2 ,E b 10GPa;

[0143]

[0144] but

[0145] The performance is improved by 18.33% relative to the previous level.

[0146] The second combination, pasting carbon fiber reinforced polymer at the center and at the physical damage, and pasting horizontal carbon fiber reinforced polymer at the riveted joint of the wood beam, the wood beam applies a concentrated load to the wood beam under the finite element analysis model, so that the bending deformation δ' of the wood beam reaches the bending deformation δ when the carbon fiber reinforced polymer is not pasted, that is, under the same bending deformation condition, the bending stress σ' of the wood beam after optimization is compared with the bending stress σ before optimization;

[0147] Adding a level of carbon fiber reinforced polymer is mainly used to increase the anti-shedding performance, and the tensile strength of the carbon fiber reinforced polymer is 1500MPa;

[0148] but,

[0149]

[0150] The performance is relatively improved by 92.515%;

[0151] And the corresponding bending bearing capacity of the optimized beam m' is compared with the bending bearing capacity of the beam before optimization m,

[0152]

[0153] The performance is improved by 29.18% relative;

[0154] The third combination, pasting carbon fiber reinforced polymer at the center and pasting carbon fiber reinforced polymer at the physical damage, pasting horizontal carbon fiber reinforced polymer at the riveted joint of the wooden beam, and pasting vertical carbon fiber reinforced polymer at the end of the horizontal carbon fiber reinforced polymer, the wooden beam applies a concentrated load to the wooden beam under the finite element analysis model, so that the bending deformation δ' of the wooden beam reaches the bending deformation δ when the carbon fiber reinforced polymer is not pasted, that is, under the same bending deformation conditions, the performance of the optimized bending stress σ' of the wooden beam is improved by 92.515% compared with the bending stress σ before optimization, and the corresponding bending bearing capacity m' of the wooden beam after optimization is improved by 29.18% compared with the bending bearing capacity m of the wooden beam before optimization; that is, pasting the vertical carbon fiber reinforced polymer is used to prevent the horizontal carbon fiber reinforced polymer from falling off, and the actual performance improvement is zero;

[0155] The fourth combination, pasting carbon fiber reinforced polymer at the center and pasting carbon fiber reinforced polymer at the physical damage, pasting horizontal carbon fiber reinforced polymer at the riveted joint of the wooden beam, pasting vertical carbon fiber reinforced polymer at the end of the horizontal carbon fiber reinforced polymer, fixing a wooden triangular reinforcement plate at the riveted joint of the wooden beam, and pasting carbon fiber reinforced polymer on the wooden triangular reinforcement plate, applying a concentrated load to the wooden beam under the finite element analysis model, so that the bending deformation δ' of the wooden beam reaches the bending deformation δ when the carbon fiber reinforced polymer is not pasted, that is, under the same bending deformation condition, the bending stress σ' of the wooden beam after optimization is compared with the bending stress σ before optimization, and the material of the wooden triangular reinforcement plate is the same as that of the wooden beam;

[0156]

[0157] The performance has been improved by 107.33%

[0158] And the corresponding bending bearing capacity of the optimized beam m' is compared with the bending bearing capacity of the beam before optimization m,

[0159]

[0160] The performance is improved by 42.045%;

[0161] The fifth combination, pasting carbon fiber reinforced polymer at the center and pasting carbon fiber reinforced polymer at the physical damage, pasting horizontal carbon fiber reinforced polymer at the riveted joint of the wooden beam, pasting vertical carbon fiber reinforced polymer at the end of the horizontal carbon fiber reinforced polymer, fixing the wooden triangular reinforcement plate at the riveted joint of the wooden beam, pasting carbon fiber reinforced polymer on the wooden triangular reinforcement plate, and adopting a multi-layer pasting method for all carbon fiber reinforced polymers, and at least a double-layer carbon fiber reinforced polymer, applying a concentrated load to the wooden beam under the finite element analysis model, so that the bending deformation δ' of the wooden beam reaches the bending deformation δ when the carbon fiber reinforced polymer is not pasted, that is, under the same bending deformation conditions, the bending stress σ' of the wooden beam after optimization is compared with the bending stress σ before optimization,

[0162]

[0163] The performance has been improved by 108.129%

[0164] And the corresponding bending bearing capacity of the optimized beam m' is compared with the bending bearing capacity of the beam before optimization m,

[0165]

[0166] The performance is relatively improved by 60.0204%.

[0167] The combined data table for data implementation calculation is as follows:

[0168]

[0169]

[0170] Through the above simulation experiment analysis, pasting carbon fiber reinforced polymers on the center and physical damage of the wooden beam can effectively enhance the bending resistance of the wooden beam, and for the riveted joints at both ends of the wooden beam, the horizontal carbon fiber reinforced polymer can reduce the risk of the riveted joints falling off, and the improvement in the bending resistance is relatively weak. Further improvement in the vertical carbon fiber reinforced polymer pasted on the horizontal carbon fiber reinforced polymer is also relatively weak. Adding a wooden triangular reinforcement plate can further improve the stability of the connection of the wooden beam, and the improvement in the bending resistance is generally limited. When multiple layers of carbon fiber reinforced polymer are pasted, there is a significant increase in the bending resistance. In summary, choosing the fifth combination as the optimization of the bending resistance of the wooden beam can not only effectively improve the bending resistance of the wooden beam, but also provide support for the stability connection of the wooden beam, maintain the connectivity of the wooden beam, and prevent the riveted joints at both ends of the wooden beam from falling off when bending deformation occurs.

[0171] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of a wooden beam structure, characterized in that: The steps include: S1. Build a wooden beam structure model: Establish a wooden beam structure model through a finite element analysis model, and determine the material properties of the wooden beam and carbon fiber reinforced polymer; S2. Analysis of the elastic modulus of the beam: The behavior of the beam under weakening conditions is simulated and analyzed in the finite element analysis model, and the bending stress is calculated , bending deformation , Height of the tensile zone of the beam section and bending capacity of wooden beams ; The bending stress in S2 The calculation is to take the center point of the wooden beam as the calculation position, and the calculation formula is as follows: ， in, is the bending stress at the center of the beam, is the bending stress of the riveted joints at both ends of the beam, are the bending moments at the center point and the riveted joint, is the cross-sectional height of the beam, and is taken as , is the moment of inertia of the cross section, represents the weights of the center point and the riveted joint, and ,as well as yes four times; Similarly, the bending deformation The calculation is to take the center point of the wooden beam as the calculation position, and the calculation formula is as follows: ， in, is the bending amount at the center of the beam, It is expressed as the bending amount of the riveted joint of the wood beam, denote the concentrated loads acting on the center and the riveted joint, respectively, and , is the elastic modulus of the beam, is the length of the beam, represents the weights of the center point and the riveted joint, and ,as well as yes four times; The height of the tensile zone of the timber beam section in S2 The calculation formula is as follows: ,in, is the height of the tensile zone of the timber beam section; is the cross-sectional width of the beam; is the cross-sectional height of the beam; The bending strength of wood after considering the size effect is: The bending strength of the beams is weakened by physical damage and humidity changes; The bending bearing capacity of the wooden beam The calculation formula is as follows: ， in, is the bending strength of wood after considering the size effect; is the height of the tensile zone of the timber beam section; is the cross-sectional width of the beam; is the bending bearing capacity of the timber beam; S3. Simulate the reinforcement structure of wooden beams: reinforce the wooden beams under the finite element analysis model, that is, paste carbon fiber reinforced polymers at the riveted joints of the wooden beams, paste carbon fiber reinforced polymers at the center of gravity and physical damage of the wooden beams, and strengthen the support of the riveted points of the wooden beams, and use wooden triangular reinforcement plates to install and connect between the wooden beams and the columns; S4. Calculate and analyze the elastic modulus of the beam again: that is, simulate and analyze the behavior of the beam under different load and weakening conditions under the finite element analysis model, and calculate the bending stress , bending deformation , Height of the tensile zone of the beam section and bending capacity of wooden beams ; Bending stress of the wood beam in S4 after bonding with carbon fiber reinforced polymer and bending deformation Bending stress of the wood beam before bonding carbon fiber reinforced polymer and bending deformation is calculated in the same way; The concentrated load of the wood beam after the carbon fiber reinforced polymer is attached includes the weight of the wood beam itself and the measurement force applied to the wood beam, while the concentrated load of the wood beam before the carbon fiber reinforced polymer is attached is only the weight of the wood beam itself, and other parameters remain unchanged; and bending moment Using the central load calculation, the bending moment The calculation of is as follows: ,in, They represent the concentrated load acting at the center, which is the weight of the beam itself, and , It is expressed as the length of the beam; The height of the tensile zone of the wooden beam cross section after the carbon fiber reinforced polymer is pasted on the wooden beam in S4 and bending capacity of wooden beams The height of the tensile zone of the wood beam section before bonding carbon fiber reinforced polymer and bending capacity of wooden beams is calculated in the same way; Height of the tensile zone of the beam section The calculation formula is as follows ,in, is the height of the tensile zone of the timber beam section; is the cross-sectional width of the beam; is the cross-sectional height of the beam; The bending strength of wood after considering the size effect is: The bending strength of the beams is weakened by physical damage and humidity changes; is the bending elastic modulus of wood; is the elastic modulus of carbon fiber cloth; is the cross-sectional area of ​​the carbon fiber cloth; The bending bearing capacity of the wooden beam The calculation formula is as follows: ,in, is the bending strength of wood after considering the size effect; is the height of the tensile zone of the timber beam section; is the cross-sectional width of the beam; is the bending bearing capacity of the timber beam; is the elastic modulus of carbon fiber cloth; is the cross-sectional area of ​​the carbon fiber cloth; is the bending elastic modulus of wood; An empirical coefficient is used to consider the fiber influence degree, that is, the fiber influence of physical damage and humidity change of the wood beam. is the surface area of ​​the wooden triangular reinforcement plate, is the thickness of the wooden triangular reinforcement board; S5. Optimization algorithm to analyze the bending resistance of wooden beams: The bending resistance of wooden beams after carbon fiber reinforced polymer is pasted is calculated and analyzed by genetic algorithm to obtain the best carbon fiber reinforced polymer pasting position on the wooden beams.

2. The method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of wooden beam structure according to claim 1, characterized in that: The acquisition of the material properties of the wooden beam in S1 is performed by detecting internal defects of the wooden beam through ultrasonic testing or acoustic emission testing, and the ultrasonic testing or acoustic emission testing is used to detect physical damage and humidity changes of the wooden beam, and the finite element analysis model is used to simulate the overload and aging of the wooden beam; The physical damage includes cracks, decay and insect damage; The humidity change includes humidity change causing the wooden beam to expand or contract; The overload is that the wooden beam bears overload for a long time, which causes the mechanical properties of the wooden beam to decrease; The said ageing is the degradation of the wood beams over time, reducing their mechanical properties.

3. The method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of wooden beam structure according to claim 1, characterized in that: The reinforcement steps of the wooden beam reinforcement structure in S3 are as follows: S301, horizontally pasting carbon fiber reinforced polymer at the mortise and tenon joints between the two ends of the wooden beam and the column, with the carbon fiber reinforced polymer and the wooden beam kept horizontal, and fixing the carbon fiber reinforced polymer to the wooden beam and the column respectively by rivets; S302, vertically pasting two layers of carbon fiber reinforced polymer at the connection between the wooden beam and the carbon fiber reinforced polymer again, and fixing the connection by rivets; S303, installing a wooden triangular reinforcement plate between the lower angles of the wooden beam and the column by means of rivets, and bonding carbon fiber reinforced polymer to the wooden triangular reinforcement plate, the wooden beam and the column, and fixing them by means of rivets; S304, pasting carbon fiber reinforced polymer at the center of the wooden beam, and the carbon fiber reinforced polymer is tied to the wooden beam for a circle and fixedly connected by rivets; S305, pasting carbon fiber reinforced polymer at the location where the wooden beam has physical damage, and the carbon fiber reinforced polymer is tied to the wooden beam for a week and fixedly connected by rivets.

4. The method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of wooden beam structure according to claim 3, characterized in that: When the carbon fiber reinforced polymer is pasted horizontally, the width of the carbon fiber reinforced polymer is one-third of the height of the wooden beam, and when the carbon fiber reinforced polymer is pasted vertically, the width of the carbon fiber reinforced polymer is one-third of the length of the carbon fiber reinforced polymer connected to the wooden beam, and the width of the carbon fiber reinforced polymer pasted horizontally is at least 5 cm, and the width of the carbon fiber reinforced polymer pasted vertically is at least 10 cm. The width of the carbon fiber reinforced polymer pasted at the center of the wooden beam is at least one-quarter of the length of the wooden beam, and the width of the carbon fiber reinforced polymer pasted on the physically damaged wooden beam is at least twice the length of the physical damage.

5. The method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of wooden beam structure according to claim 4, characterized in that: The calculation process of the genetic algorithm is as follows: S501. Determine the bending deformation of the wood beam before and after the carbon fiber reinforced polymer is attached and bending deformation The same bending degree was maintained and the bending degree of the timber beam was simulated by adjusting the concentrated load through the finite element analysis model; S502. After determining that the bending deformation of the wooden beam is the same, calculate the bending stress , Height of the tensile zone of the beam section and bending capacity of wooden beams ; S503, performing calculation and setting for pasting carbon fiber reinforced polymer respectively, namely horizontal pasting; vertical pasting; center pasting; wooden triangular reinforcement plate; pasting at the physical damage position; and then performing combined calculation by genetic algorithm; S504, according to the calculation of bending stress , Height of the tensile zone of the beam section and bending capacity of wooden beams Calculate the result of each optimization method in S503 respectively; S505. Combining the optimization schemes through a genetic algorithm and performing calculation analysis to determine the optimal method for selecting the elastic modulus of CFRP under the weakened bending resistance of the wooden beam structure.

6. The method for optimizing the elastic modulus of CFRP under the condition of weakened bending resistance of wooden beam structure according to claim 1, characterized in that: The calculation process of the genetic algorithm is as follows: The probability of selection is the ratio of its fitness to the total fitness of the population: ， in, is the fitness of the ith individual, is the population size, is the sum of all individual fitnesses; Among them, when calculating and selecting, the combination options of carbon fiber reinforced polymer pasting without center pasting and physical damage are eliminated, and the combination of carbon fiber reinforced polymer pasting with center pasting and physical damage is selected as the best method, that is, the bending bearing capacity of the wooden beam Maximum value option.

Images