Method for calculating flexural capacity of CFRP reinforced wood formwork system

Abstract

The invention belongs to the technical field of constructional engineering, and particularly relates to a method for calculating flexural capacity of a CFRP (carbon fiber reinforced plastic) reinforced wood formwork system, which comprises the following steps: acquiring structural parameters of the CFRP reinforced wood formwork system, simulating mechanical properties of the CFRP reinforced wood formwork system by adopting finite element software, and determining the maximum distance between adjacent wood beams in the CFRP reinforced wood formwork system; based on the structural parameters of the CFRP reinforced wood formwork system, the stress-strain relation between wood and the carbon fiber cloth is calculated, and a calculation expression of the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established; and calculating the flexural capacity of the wood beams under the maximum spacing of the adjacent wood beams by combining the calculation expressions of the maximum spacing of the adjacent wood beams and the flexural capacity of the wood beams in the CFRP reinforced wood template system. The flexural capacity of the CFRP material reinforced wood formwork system can be accurately and conveniently calculated, and then the method is applied to safety evaluation of wood components in wood structure buildings.

Description

Technical Field

[0001] The invention belongs to the technical field of construction engineering, and in particular relates to a method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system. Background Art

[0002] Most of the ancient Chinese buildings are wooden structures. Due to long-term exposure to the sun and rain, termite infestation, corrosion and aging of the components, the safety of these ancient buildings has been declining year by year. At present, there is no theoretical basis and analysis and design method to guide the engineering application of CERP materials to strengthen wooden components, and there are no corresponding specifications and regulations to follow. The reinforcement and repair theory of wooden components is more derived from the reinforcement theory of reinforced concrete structures, but there is a big difference between the performance of wood and reinforced concrete, and its accuracy and practicality in practical applications are not high. Summary of the invention

[0003] The present invention provides a method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system. By analyzing and calculating the bending bearing capacity of the CFRP material reinforced wood formwork system, the bending bearing capacity of the CFRP material reinforced wood formwork system can be accurately and conveniently calculated, and then applied to the safety assessment of wood components in wood structure buildings to ensure the safety and stability of the wood formwork system. In addition, the method can judge whether the cross-sectional size of the wood beam and the thickness configuration of the carbon fiber cloth are reasonable according to the design value of the bearing capacity in the design stage, so as to achieve the effect of optimizing the design.

[0004] A method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system, comprising:

[0005] Obtain the structural parameters of the CFRP reinforced wood formwork system, simulate the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determine the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system;

[0006] Based on the structural parameters of the CFRP reinforced wood formwork system, the stress-strain relationship of the wood beam and the carbon fiber cloth is calculated respectively, and the calculation expression of the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established;

[0007] Combined with the maximum spacing between adjacent wooden beams in the CFRP reinforced wooden formwork system and the calculation expression of the bending bearing capacity of wooden beams, the bending bearing capacity of wooden beams under the maximum spacing between adjacent wooden beams is calculated.

[0008] Through the analysis and calculation of the flexural bearing capacity of the CFRP material reinforced wood formwork system, the flexural bearing capacity of the CFRP material reinforced wood formwork system can be accurately and conveniently calculated, and then applied to the safety assessment of wood components in wood structure buildings to ensure the safety and stability of the wood formwork system. In the design stage, the cross-sectional size of the wood beam and the thickness configuration of the carbon fiber cloth can be judged to be reasonable according to the design value of the bearing capacity, so as to achieve the effect of optimizing the design.

[0009] Furthermore, the obtaining of structural parameters of the CFRP reinforced wood formwork system, simulating the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determining the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system include:

[0010] Obtain the structural parameters of the CFRP reinforced wood formwork system;

[0011] Based on the preset boundary conditions, the finite element software was used to simulate the mechanical properties of the CFRP reinforced wood formwork system;

[0012] Based on the influence of carbon fiber cloth on the wood formwork system, the maximum spacing between adjacent wood beams is calculated under the condition of sticking carbon fiber cloth in the reinforced wood formwork system.

[0013] Furthermore, based on the structural parameters of the CFRP reinforced wood formwork system, the stress-strain relationship between the wood beam and the carbon fiber cloth is calculated respectively, and a calculation expression for the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established, including:

[0014] Based on the failure state of the reinforced timber formwork system under bending test, a basic assumption is made about the failure state of the timber beams of the reinforced timber formwork system.

[0015] Based on basic assumptions, the stress-strain relationship of the wood beam and the stress-strain relationship of the carbon fiber cloth are established when the tensile zone of the wood beam reaches the ultimate tensile strain.

[0016] Based on the failure state of the CFRP reinforced wood formwork system, a calculation expression for the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established.

[0017] Furthermore, the basic assumptions include:

[0018] Assume that the cross section of the wood beam complies with the strain plane section assumption;

[0019] Assume that the timber beam exhibits linear elastic behavior when in tension and ideal elastic-plastic behavior when in compression;

[0020] Assume that the tensile elastic modulus and compressive elastic modulus of the wood beam in the direction along the grain are the same and are constant;

[0021] Assume that the material of the wood beam is basically uniform macroscopically;

[0022] It is assumed that the mechanical properties of the CFRP material used for reinforcement conform to the linear elastic stress-strain relationship;

[0023] It is assumed that the thickness of the CFRP material and adhesive used for reinforcement has no effect on the clear height of the wooden beam;

[0024] It is assumed that the bonding between CFRP material and wooden beam is reliable and the deformation is coordinated.

[0025] Furthermore, based on the damage state of the CFRP reinforced wood formwork system, a calculation expression for the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established, including:

[0026] Based on the failure state of the CFRP reinforced wood formwork system, the equilibrium equation and the initial expression of the bending bearing capacity of the wood beam are constructed by combining the performance parameters of the wood beam and the carbon fiber cloth.

[0027] Based on the compatibility relationship between the height of the compression zone of the wooden beam and the length of the elastic section of the compression zone of the wooden beam, an expression for the height of the compression zone of the wooden beam and the length of the elastic section of the compression zone of the wooden beam is constructed;

[0028] Based on the initial expression of the bending bearing capacity of wooden beams, combined with the expressions of the performance parameters of wooden beams and carbon fiber cloth, the height of the compression zone of the wooden beams, and the length of the elastic section of the compression zone of the wooden beams, a calculation expression for the bending bearing capacity of wooden beams based on the CFRP reinforced wooden formwork system is established.

[0029] Furthermore, the calculation expression of the maximum spacing between adjacent wooden beams and the bending bearing capacity of wooden beams in the CFRP reinforced wooden formwork system is combined to calculate the bending bearing capacity of wooden beams at the maximum spacing between adjacent wooden beams, including:

[0030] Based on the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system and the unit width load borne by the panel, the bending moment of the wood beam under the external load is calculated;

[0031] Based on the bending moment of the wooden beam under the action of external load and combined with the bending capacity of the wooden beam, the bending capacity of the wooden beam under the maximum spacing between adjacent wooden beams is determined.

[0032] A system for calculating the bending bearing capacity of a CFRP reinforced wood formwork system, comprising:

[0033] A spacing calculation module is used to obtain the structural parameters of the CFRP reinforced wood formwork system, simulate the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determine the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system;

[0034] An analysis and calculation module is used to calculate the stress-strain relationship of the wood beam and the carbon fiber cloth based on the structural parameters of the CFRP-reinforced wood formwork system, and to establish a calculation expression for the bending bearing capacity of the wood beam based on the CFRP-reinforced wood formwork system;

[0035] The discrimination calculation module is used to combine the maximum spacing between adjacent wooden beams in the CFRP reinforced wooden formwork system and the calculation expression of the bending bearing capacity of the wooden beams to calculate the bending bearing capacity of the wooden beams under the maximum spacing between adjacent wooden beams.

[0036] The beneficial effects of the present invention are:

[0037] The present invention can accurately and conveniently calculate the flexural bearing capacity of the CFRP material reinforced wood formwork system by analyzing and calculating the flexural bearing capacity of the CFRP material reinforced wood formwork system, and then apply it to the safety assessment of wood components in wood structure buildings to ensure the safety and stability of the wood formwork system. In addition, the present invention can judge whether the cross-sectional size of the wood beam and the thickness configuration of the carbon fiber cloth are reasonable according to the design value of the bearing capacity in the design stage, so as to achieve the effect of optimizing the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of the present invention;

[0039] Figure 2 It is a schematic diagram of the structure of the CFRP reinforced wood formwork system in the present invention;

[0040] Figure 3 Schematic diagram of mesh unit division in the finite element process;

[0041] Figure 4 Add boundary condition diagrams to the finite element process;

[0042] Figure 5 Schematic diagram of carbon fiber stress at the maximum spacing between adjacent wood beams during the finite element process;

[0043] Figure 6 Schematic diagram of the stress of the wood formwork at the maximum distance between adjacent wood beams in the finite element process;

[0044] Figure 7 It is the displacement cloud diagram of the maximum distance between adjacent wood beams in the finite element process;

[0045] Figure 8 Schematic diagram of stress-strain curve of wooden beam;

[0046] Fig. 9 Schematic diagram of stress-strain curve of CFRP material;

[0047] Fig.10 The stress-strain diagram of the CFRP reinforced wood formwork system;

[0048] Fig.11 It is a schematic diagram of the system structure of the present invention.

[0049] Reference numerals:

[0050] 1. CFRP reinforced wooden formwork system; 2. Wooden beams; 3. Carbon fiber cloth. DETAILED DESCRIPTION

[0051] 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.

[0052] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0053] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples, and a person of ordinary skill in the art can understand the specific meanings of the above terms in this application under specific circumstances.

[0054] Example 1

[0055] Figure 1 The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system is shown. By analyzing and calculating the bending bearing capacity of a CFRP reinforced wood formwork system, the bending bearing capacity of the CFRP reinforced wood formwork system can be accurately and conveniently calculated, and then applied to the safety assessment of wood components in wood structure buildings to ensure the safety and stability of the wood formwork system. In addition, the cross-sectional dimensions of the wood beam 2 and the thickness configuration of the carbon fiber cloth 3 can be judged to be reasonable according to the design value of the bearing capacity in the design stage to achieve the effect of optimizing the design. Specifically, the following steps are included:

[0056] S1: obtaining structural parameters of the CFRP reinforced wood formwork system 1, simulating the mechanical properties of the CFRP reinforced wood formwork system 1 using finite element software, and determining the maximum spacing between adjacent wood beams 2 in the CFRP reinforced wood formwork system 1;

[0057] S11: Obtaining structural parameters of the CFRP reinforced wood formwork system 1;

[0058] In this embodiment, the ultimate compressive strength of the wooden beam 2 is ce =34MPa, ultimate tensile strength of beam 2 f te =

[0059] 71MPa, elastic modulus of wood beam 2 E = 9000MPa, elastic modulus of carbon fiber cloth 3 E f =210000MPa.

[0060] S12: Based on the preset boundary conditions, the mechanical properties of the CFRP reinforced wood formwork system 1 were simulated using finite element software;

[0061] In this embodiment, Figure 2 The structure diagram of the CFRP reinforced wood formwork system 1 is shown. The finite element software is used to simulate the structure, and the solid unit C3D8R (eight-node linear hexahedron unit) is selected to mesh the wood beam 2 structure to make the displacement result accurate, and the shell unit S4R (four-node curved thin shell or thick shell) is used to describe the CFRP to make the unit performance stable; at the same time, the tie constraint is selected to realize the stress transfer between the CFRP and the wood beam 2 material.

[0062] Figure 3 Shown is a schematic diagram of grid unit division; Figure 4 Shown is a schematic diagram of boundary condition constraints.

[0063] S13: Based on the influence of the carbon fiber cloth 3 on the wood formwork system, the maximum spacing between adjacent wood beams 2 under the condition that the carbon fiber cloth 3 is pasted in the reinforced wood formwork system 1 is calculated.

[0064] Based on the simulation results of the finite element software, it can be known that when the thickness of the newly poured concrete floor on the upper part of the reinforced wooden formwork system is 200mm, when the carbon fiber cloth 3 is not pasted on the wooden formwork system, the spacing between adjacent wooden beams 2 is 250mm. When a layer of carbon fiber cloth 3 with a thickness of 0.111mm is pasted on the bottom of the wooden formwork system, the spacing between adjacent wooden beams 2 is 600mm, and at this time, the stress and deflection of the wooden beams 2 and the carbon fiber cloth 3 are within the safety range of the specification. The maximum stress of the carbon fiber cloth 3 is 115MPa, which is less than the tensile strength of 3000MPa; the stress of the wooden formwork is 3.191MPa, which is less than the tensile strength of 71MPa; the spacing displacement between adjacent wooden beams 2 is 2.088mm, which is less than the deflection limit of 2.4mm. Among them, Figure 5 It is a schematic diagram of carbon fiber stress at the maximum spacing between adjacent wood beams 2 in the finite element process; Figure 6 It is a schematic diagram of the stress of the wood formwork at the maximum spacing between adjacent wood beams 2 in the finite element process; Figure 7 It is the displacement cloud diagram of the maximum spacing between adjacent wood beams 2 in the finite element process;

[0066] S2: Based on the structural parameters of the CFRP reinforced wood formwork system 1, the stress-strain relationship of the wood beam 2 and the carbon fiber cloth 3 is calculated respectively, and a calculation expression for the bending bearing capacity of the wood beam 2 based on the CFRP reinforced wood formwork system 1 is established;

[0067] S21: Based on the failure state of the reinforced timber formwork system under bending test, a basic assumption is made about the failure state of the timber beam 2 of the reinforced timber formwork system;

[0068] The basic assumptions include:

[0069] (1) Assume that the cross section of the beam 2 conforms to the strain plane assumption;

[0070] (2) Assume that the beam 2 exhibits linear elastic behavior when subjected to tension and ideal elastic-plastic behavior when subjected to compression;

[0071] (3) Assume that the tensile elastic modulus and compressive elastic modulus of beam 2 in the direction parallel to the grain are the same and are constant;

[0072] (4) Assuming that the material of the wooden beam 2 is basically uniform on a macroscopic scale, it may contain natural defects;

[0073] (5) Assume that the mechanical properties of the CFRP material used for reinforcement conform to the linear elastic stress-strain relationship;

[0074] (6) Assume that the thickness of the CFRP material and adhesive used for reinforcement has no effect on the clear height of the wooden beam 2;

[0075] (7) It is assumed that the bonding between the CFRP material and the wooden beam 2 is reliable and the deformation is coordinated.

[0076] S22: Based on the basic assumptions, the stress-strain relationship of the wood beam 2 and the stress-strain relationship of the carbon fiber cloth 3 are established when the tension zone of the wood beam 2 reaches the ultimate tensile strain;

[0077] Figure 8 The figure shows a schematic diagram of the stress-strain curve of the wooden beam 2. It can be seen that the stress-strain relationship of the wooden beam 2 is linear when it is tensile, and the stress-strain relationship is elastic-plastic when it is compressed. The stress-strain relationship expression of the wooden beam 2 is obtained as follows:

[0078] The expression of stress-strain relationship of beam 2 is:

[0079] σ c =Eεc ,0≤ε c ≤ε ce ;

[0080] σ c =f ce ,ε ce ≤ε c ≤ε cu ;

[0081] σ t =Eε t ,ε t ≤ε te ;

[0082] In the formula, σ c represents the compressive stress in the compression zone of beam 2; ε c represents the strain in the compression zone of beam 2; E represents the elastic modulus of beam 2; ε ce represents the maximum elastic compressive strain of beam 2; f ce represents the ultimate compressive strength of beam 2; ε cu represents the ultimate compressive strain of beam 2; σ t represents the tensile stress in the tensile zone of beam 2; ε t represents the strain in the tensile zone of beam 2; ε te represents the ultimate tensile strain of beam 2;

[0083] Fig. 9 The figure shows a schematic diagram of the stress-strain curve of the CFRP material. It can be seen that the stress-strain of the carbon fiber cloth 3 can be regarded as linear elasticity, and the tensile stress is equal to the product of the elastic modulus of the carbon fiber cloth 3 and the tensile strain, that is, the stress-strain relationship expression of the carbon fiber cloth 3 is:

[0084] σ f =E f ε f ,ε f ≤ε fu ;

[0085] In the formula, σ f represents the stress of carbon fiber cloth 3; E f Represents the elastic modulus of carbon fiber cloth 3; ε f represents the strain of carbon fiber cloth 3; ε fu represents the ultimate strain of carbon fiber cloth 3.

[0086] S23: Based on the damage state of the CFRP reinforced wood formwork system 1, a calculation expression for the bending bearing capacity of the wood beam 2 based on the CFRP reinforced wood formwork system 1 is established;

[0087] S231: Based on the failure state of the CFRP reinforced wood formwork system 1, the equilibrium equation and the initial expression of the bending bearing capacity of the wood beam 2 are constructed in combination with the performance parameters of the wood beam 2 and the carbon fiber cloth 3;

[0088] Based on conventional theoretical experience, it can be known that the failure mode of the wooden beam 2 in the CFRP reinforced wooden formwork system 1 is: the tensile zone of the wooden beam 2 reaches the ultimate tensile strain, the wooden beam 2 breaks, and the CFRP is not damaged.

[0089] like Fig.10 Shown is a stress-strain schematic diagram of the CFRP reinforced wood formwork system 1.

[0090] Among them, the expression of the constructed equilibrium equation is:

[0091] F ce +F c =F te +F f ;

[0092] In the formula, F ce represents the plastic pressure in the compression zone of beam 2, that is, F c represents the elastic pressure in the compression zone of beam 2, that is, F c =f ce ·(1-a)·c·b;F te represents the tensile force in the tension zone of beam 2, that is,

[0093] F f represents the tensile force of CFRP material, that is f ce represents the ultimate compressive strength of beam 2; b represents the width of beam 2; h represents the width of beam 2; f Indicates the thickness of carbon fiber cloth 3; f te represents the ultimate tensile strength of beam 2; E represents the elastic modulus of beam 2; E f represents the elastic modulus of the carbon fiber cloth 3; h represents the height of the wood beam 2; a represents the compressive elastic distance of the wood beam 2; c represents the height of the theoretical compressive zone of the wood beam 2; a·c represents the elastic section of the compressive zone of the wood beam 2; (1-a)·c represents the plastic section of the compressive zone of the wood beam 2;

[0094] The initial expression of the bending bearing capacity of beam 2 is:

[0095]

[0096] Where M represents the bending bearing capacity of the wooden beam 2.

[0097] S232: constructing an expression for the height of the compression zone of the wooden beam 2 and the length of the elastic section of the compression zone of the wooden beam 2 based on the compatibility relationship between the height of the compression zone of the wooden beam 2 and the length of the elastic section of the compression zone of the wooden beam 2;

[0098] Among them, the compatibility relationship expression between the height of the compression zone of beam 2 and the length of the elastic section of the compression zone of beam 2 is:

[0099]

[0100] The expression of the compressive elastic length of beam 2 can be obtained as follows:

[0101]

[0102] Combined with the initial expression of the bending bearing capacity of beam 2, the expression of the height of the compression zone of beam 2 is obtained as follows:

[0103]

[0104] definition: Then the expression of the height of the compression zone of beam 2 can be simplified as:

[0105] c=x1·h+x2·h f ;

[0106] It can be seen that the height c of the compression zone of the wood beam 2 includes a first part which is proportional to the height h of the wood beam 2 and a second part which is proportional to the thickness h of the carbon fiber cloth 3. f The second part is proportional to the first part. The proportionality coefficient x1 in the first part depends on the constant value of the ultimate compressive strength f of the beam 2 ce 、Ultimate tensile strength of beam 2 f te , the proportionality factor x2 in the second part depends on the constant value of the ultimate compressive strength f of the beam 2 ce 、Ultimate tensile strength of beam 2 f te , elastic modulus E of wooden beam 2, elastic modulus E of carbon fiber cloth 3 f That is, the height c of the compression zone of the beam 2 is linearly dependent on the height h of the beam 2 and the thickness h of the carbon fiber cloth 3. f , which is affected by material properties and geometric dimensions.

[0107] S233: Based on the initial expression of the bending bearing capacity of the wooden beam 2, combined with the performance parameters of the wooden beam 2 and the carbon fiber cloth 3, the height of the compression zone of the wooden beam 2, and the length of the elastic section of the compression zone of the wooden beam 2, a calculation expression for the bending bearing capacity of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1 is established.

[0108] Among them, the calculation expression of the bending bearing capacity of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1 is:

[0109]

[0110] definition: Then the calculation expression of the bending bearing capacity of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1 can be converted to:

[0111] M=b·(y1·h 2 +y2·h·h f -y3·h f 2 );

[0112] When the thickness of carbon fiber cloth 3h f When it is less than 0.2mm, y3·h f 2 The difference between the term and other results is only 2% of the result, which has a small impact on the calculation result and can be ignored in the actual calculation result. The calculation expression of the bending bearing capacity of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1 can be further simplified to:

[0113]

[0114] It can be seen that the bending bearing capacity M of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1 is related to the height h of the wooden beam 2 and the thickness h of the carbon fiber cloth 3. f , is proportional to the width b of beam 2. Among them, the proportionality coefficient y1 depends on the constant value of the ultimate compressive strength f of beam 2 ce 、Ultimate tensile strength of beam 2 f te , beam 2 width b, proportionality factor y2 depends on the constant value beam 2 ultimate compressive strength f ce 、Ultimate tensile strength of beam 2 f te , elastic modulus E of wooden beam 2, elastic modulus E of carbon fiber cloth 3 f , wooden beam 2 width b.

[0115] S3: Combined with the maximum spacing between adjacent wood beams 2 in the CFRP reinforced wood formwork system 1 and the calculation expression of the bending bearing capacity of the wood beam 2, the bending bearing capacity of the wood beam 2 under the maximum spacing between adjacent wood beams 2 is calculated;

[0116] S31: Based on the maximum spacing between adjacent wood beams 2 in the CFRP reinforced wood formwork system 1 and the unit width load borne by the panel, the bending moment of the wood beam 2 under the external load is calculated;

[0117] The expression of the unit width linear load borne by the panel is:

[0118] q1=[1.3×(G 1k +(G 2k +g 3k )×h)+1.5×Q 1k ]×b;

[0119] Where q1 represents the unit width linear load borne by the panel; G 1k Indicates the standard value of the self-weight of the formwork and its support; G 2kIndicates the standard value of concrete deadweight; G 3k Indicates the standard value of the steel bar’s deadweight; Q 1k Indicates the standard value of the load generated by construction personnel and their equipment;

[0120]

[0121] Where M max represents the bending moment of the beam 2 under the external load, and l represents the maximum spacing;

[0122] S32: Based on the bending moment of the wooden beam 2 under the external load and in combination with the bending bearing capacity of the wooden beam 2, the bending bearing capacity of the wooden beam 2 at the maximum spacing between adjacent wooden beams 2 is determined.

[0123] Among them, the bending moment M of the wooden beam 2 under the external load is max It must be smaller than the bending bearing capacity M of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1, that is:

[0124]

[0125] After calculation, it can be known that: when the maximum spacing between adjacent wooden beams 2 is 600mm, by pasting a layer of carbon fiber cloth 3 with a thickness of 0.111mm on the bottom of the wooden formwork system, the wooden beam 2 can be reduced from the original interface size of 50×100mm to 40×50mm, saving 60% of wood and greatly reducing the amount of wood used.

[0126] Example 2

[0127] like Fig.11 As shown, this embodiment provides a system for calculating the bending bearing capacity of a CFRP reinforced wood formwork system 1, including a spacing calculation module, an analysis calculation module and a discrimination calculation module.

[0128] Specifically, a spacing calculation module is used to obtain structural parameters of the CFRP reinforced wood formwork system 1, and simulate the mechanical properties of the CFRP reinforced wood formwork system 1 using finite element software, and determine the maximum spacing between adjacent wood beams 2 in the CFRP reinforced wood formwork system 1;

[0129] Specifically, the analysis and calculation module is used to calculate the stress-strain relationship of the wood beam 2 and the carbon fiber cloth 3 based on the structural parameters of the CFRP reinforced wood formwork system 1, and establish a calculation expression for the bending bearing capacity of the wood beam 2 based on the CFRP reinforced wood formwork system 1;

[0130] Specifically, the discrimination calculation module is used to calculate the bending bearing capacity of the wooden beam 2 under the maximum spacing between adjacent wooden beams 2 in the CFRP reinforced wooden formwork system 1 by combining the maximum spacing between adjacent wooden beams 2 and the calculation expression of the bending bearing capacity of the wooden beam 2.

[0131] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0132] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system, characterized in that: include: Obtain the structural parameters of the CFRP reinforced wood formwork system, simulate the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determine the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system; Based on the structural parameters of the CFRP reinforced wood formwork system, the stress-strain relationship of the wood beam and the carbon fiber cloth is calculated respectively, and the calculation expression of the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established; Combined with the maximum spacing between adjacent wooden beams in the CFRP reinforced wooden formwork system and the calculation expression of the bending bearing capacity of wooden beams, the bending bearing capacity of wooden beams under the maximum spacing between adjacent wooden beams is calculated.

2. The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system according to claim 1, characterized in that: The obtaining of structural parameters of the CFRP reinforced wood formwork system, simulating the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determining the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system include: Obtain the structural parameters of the CFRP reinforced wood formwork system; Based on the preset boundary conditions, the finite element software was used to simulate the mechanical properties of the CFRP reinforced wood formwork system; Based on the influence of carbon fiber cloth on the wood formwork system, the maximum spacing between adjacent wood beams is calculated under the condition of sticking carbon fiber cloth in the reinforced wood formwork system.

3. The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system according to claim 1, characterized in that: The structural parameters of the CFRP reinforced wood formwork system are used to calculate the stress-strain relationship between the wood beam and the carbon fiber cloth, and establish a calculation expression for the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system, including: Based on the failure state of the reinforced timber formwork system under bending test, a basic assumption is made about the failure state of the timber beams of the reinforced timber formwork system. Based on basic assumptions, the stress-strain relationship of the wood beam and the stress-strain relationship of the carbon fiber cloth are established when the tensile zone of the wood beam reaches the ultimate tensile strain. Based on the failure state of the CFRP reinforced wood formwork system, a calculation expression for the bending bearing capacity of the wood beam based on the CFRP reinforced wood formwork system is established.

4. The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system according to claim 3, characterized in that: The basic assumptions include: Assume that the cross section of the wood beam complies with the strain plane section assumption; Assume that the timber beam exhibits linear elastic behavior when in tension and ideal elastic-plastic behavior when in compression; Assume that the tensile elastic modulus and compressive elastic modulus of the wood beam in the direction along the grain are the same and are constant; Assume that the material of the wood beam is basically uniform macroscopically; It is assumed that the mechanical properties of the CFRP material used for reinforcement conform to the linear elastic stress-strain relationship; It is assumed that the thickness of the CFRP material and adhesive used for reinforcement has no effect on the clear height of the wooden beam; It is assumed that the bonding between CFRP material and wooden beam is reliable and the deformation is coordinated.

5. The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system according to claim 3, characterized in that: The calculation expression of the bending bearing capacity of the wooden beam based on the CFRP reinforced wooden formwork system is established based on the damage state of the CFRP reinforced wooden formwork system, including: Based on the failure state of the CFRP reinforced wood formwork system, the equilibrium equation and the initial expression of the bending bearing capacity of the wood beam are constructed by combining the performance parameters of the wood beam and the carbon fiber cloth. Based on the compatibility relationship between the height of the compression zone of the wooden beam and the length of the elastic section of the compression zone of the wooden beam, an expression for the height of the compression zone of the wooden beam and the length of the elastic section of the compression zone of the wooden beam is constructed; Based on the initial expression of the bending bearing capacity of wooden beams, combined with the expressions of the performance parameters of wooden beams and carbon fiber cloth, the height of the compression zone of the wooden beams, and the length of the elastic section of the compression zone of the wooden beams, a calculation expression for the bending bearing capacity of wooden beams based on the CFRP reinforced wooden formwork system is established.

6. The method for calculating the bending bearing capacity of a CFRP reinforced wood formwork system according to claim 1, characterized in that: The method combines the maximum spacing between adjacent wooden beams in the CFRP reinforced wooden formwork system and the calculation expression of the bending bearing capacity of the wooden beams to calculate the bending bearing capacity of the wooden beams at the maximum spacing between adjacent wooden beams, including: Based on the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system and the unit width load borne by the panel, the bending moment of the wood beam under the external load is calculated; Based on the bending moment of the wooden beam under the action of external load and combined with the bending capacity of the wooden beam, the bending capacity of the wooden beam under the maximum spacing between adjacent wooden beams is determined.

7. A system for calculating the bending bearing capacity of the CFRP reinforced wood formwork system according to claim 1, characterized in that: include: A spacing calculation module is used to obtain the structural parameters of the CFRP reinforced wood formwork system, simulate the mechanical properties of the CFRP reinforced wood formwork system using finite element software, and determine the maximum spacing between adjacent wood beams in the CFRP reinforced wood formwork system; An analysis and calculation module is used to calculate the stress-strain relationship of the wood beam and the carbon fiber cloth based on the structural parameters of the CFRP-reinforced wood formwork system, and to establish a calculation expression for the bending bearing capacity of the wood beam based on the CFRP-reinforced wood formwork system; The discrimination calculation module is used to combine the maximum spacing between adjacent wooden beams in the CFRP reinforced wooden formwork system and the calculation expression of the bending bearing capacity of the wooden beams to calculate the bending bearing capacity of the wooden beams under the maximum spacing between adjacent wooden beams.

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