A calculation method for the flexural bearing capacity of CFRP-reinforced timber formwork system

Abstract

The present invention belongs to the field of construction engineering technology and specifically relates to a method for calculating the flexural bearing capacity of a CFRP-reinforced timber formwork system. The method comprises the following steps: obtaining the structural parameters of the CFRP-reinforced timber formwork system, simulating the mechanical properties of the CFRP-reinforced timber formwork system using finite element software, and determining the maximum spacing between adjacent timber beams in the CFRP-reinforced timber formwork system; calculating the stress-strain relationship between timber and carbon fiber cloth based on the structural parameters of the CFRP-reinforced timber formwork system, and establishing a calculation expression for the flexural bearing capacity of timber beams based on the CFRP-reinforced timber formwork system; and calculating the flexural bearing capacity of timber beams at the maximum spacing between adjacent timber beams, combining the maximum spacing between adjacent timber beams in the CFRP-reinforced timber formwork system and the calculation expression for the flexural bearing capacity of timber beams. The method can accurately and conveniently calculate the flexural bearing capacity of the CFRP-reinforced timber formwork system, which can then be applied to the safety assessment of timber components in timber-structured buildings.

Description

Technical Field

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

[0002] The vast majority of ancient Chinese architecture is timber-framed. Due to long-term exposure to the sun and rain, termite infestation, and surface corrosion and aging, these ancient structures are experiencing a gradual decline in safety. Currently, there is no established theoretical basis or analytical design method to guide the engineering application of CERP materials for the reinforcement of timber components, nor are there corresponding standards or regulations to follow. Theories for the reinforcement and repair of timber components are largely derived from theories used for reinforced concrete structures. However, the significant differences in the properties of wood and reinforced concrete make these methods inaccurate and impractical for practical application. Summary of the Invention

[0003] The present invention provides a method for calculating the flexural bearing capacity of a CFRP-reinforced wood formwork system. By analyzing and calculating the flexural bearing capacity of the CFRP-reinforced wood formwork system, the flexural bearing capacity of the CFRP-reinforced wood formwork system can be accurately and conveniently calculated. The method can then be applied to the safety assessment of wood components in wood-structured buildings to ensure the safety and stability of the wood formwork system. Furthermore, the method can determine whether the cross-sectional dimensions of the wood beams and the thickness configuration of the carbon fiber cloth are reasonable according to the design value of the bearing capacity during the design phase, thereby achieving an optimized design effect.

[0004] A method for calculating the flexural bearing capacity of a CFRP-reinforced wood formwork system includes:

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

[0006] Based on the structural parameters of the CFRP-reinforced timber formwork system, the stress-strain relationships of the timber beams and carbon fiber sheets were calculated, and a calculation expression for the bending bearing capacity of the timber beams based on the CFRP-reinforced timber formwork system was established.

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

[0008] By analyzing and calculating 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, which can then be 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, during the design phase, the rationality of the cross-sectional dimensions of the wood beams and the thickness configuration of the carbon fiber cloth can be determined based on the design value of the bearing capacity, thereby achieving the effect of optimized 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, finite element software was used to simulate the mechanical properties of the CFRP-reinforced wood formwork system;

[0012] Based on the effect of carbon fiber cloth on the timber formwork system, the maximum spacing between adjacent timber beams is calculated when carbon fiber cloth is pasted in the reinforced timber formwork system.

[0013] Furthermore, 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 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 in the reinforced timber formwork system.

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

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

[0017] Furthermore, the basic assumptions include:

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

[0019] Assume that the timber beam behaves linearly elastically in tension and perfectly elastic-plastic in compression;

[0020] Assume that the tensile modulus of elasticity and the compressive modulus of elasticity of the timber beam in the direction of grain are the same and constant;

[0021] Assume that the material of the wooden beam is basically uniform on a macro scale;

[0022] Assume 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 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, including:

[0026] Based on the failure state of the CFRP-reinforced timber formwork system, the equilibrium equation and the initial expression of the timber beam's flexural bearing capacity were constructed by combining the performance parameters of the timber beam and the carbon fiber sheet.

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

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

[0029] Furthermore, the calculation of the bending bearing capacity of the wooden beams at 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 includes:

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

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

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

[0033] Spacing calculation module, which 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 timber beam and the carbon fiber sheet based on the structural parameters of the CFRP-reinforced timber formwork system, and to establish a calculation expression for the bending bearing capacity of the timber beam based on the CFRP-reinforced timber 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] By analyzing and calculating the flexural bearing capacity of the CFRP material reinforced wood formwork system, the present invention can accurately and conveniently calculate the flexural bearing capacity of the CFRP material reinforced wood formwork system, which can then be 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 present invention can determine whether the cross-sectional dimensions of the wood beams and the thickness configuration of the carbon fiber cloth are reasonable according to the design value of the bearing capacity during the design phase, thereby achieving the effect of optimized design. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] Figure 2 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 wooden beams during the finite element process;

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

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

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

[0046] Figure 9 Schematic diagram of the stress-strain curve of CFRP material;

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

[0048] Figure 11 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts 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 this 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 an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0053] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood in specific situations.

[0054] Example 1

[0055] Figure 1 The method shown here is a calculation method for the flexural bearing capacity of a CFRP-reinforced wood formwork system. By analyzing and calculating the flexural bearing capacity of a CFRP-reinforced wood formwork system, the flexural bearing capacity of the CFRP-reinforced wood formwork system can be accurately and conveniently calculated. This can then be applied to the safety assessment of wood components in wood-structured buildings, ensuring the safety and stability of the wood formwork system. Furthermore, during the design phase, the cross-sectional dimensions of the wood beams 2 and the thickness of the carbon fiber cloth 3 can be determined based on the design bearing capacity to achieve optimal design. The method specifically includes the following steps:

[0056] S1: Obtain the structural parameters of the CFRP reinforced wood formwork system 1, 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;

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

[0058] In this embodiment, the ultimate compressive strength f 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 diagram shows the structure of CFRP-reinforced timber formwork system 1. Finite element software was used to simulate the structure. Solid elements C3D8R (eight-node linear hexahedron elements) were selected to refine the mesh of timber beam 2 to ensure accurate displacement results. Shell elements S4R (four-node curved thin or thick shells) were used to describe the CFRP, ensuring stable element performance. Tie constraints were also selected to ensure stress transfer between the CFRP and timber beam 2.

[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 of pasting the carbon fiber cloth 3 in the reinforced wood formwork system 1 is calculated.

[0064] Based on the simulation results of finite element software, it can be seen 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 Schematic diagram of carbon fiber stress at the maximum spacing between adjacent wood beams 2 in the finite element process; Figure 6 Schematic diagram of the stress of the wood formwork at the maximum distance between adjacent wood beams 2 in the finite element process; Figure 7 The displacement cloud diagram of the maximum distance between adjacent wooden beams 2 in the finite element process;

[0065] 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;

[0066] 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 timber beam 2 of the reinforced timber formwork system;

[0067] The basic assumptions include:

[0068] (1) Assume that the cross section of the beam 2 conforms to the strain plane section assumption;

[0069] (2) Assume that the beam 2 behaves linearly elastically when in tension and perfectly elastically plastically when in compression;

[0070] (3) Assume that the tensile modulus and compressive modulus of beam 2 in the grain direction are the same and constant;

[0071] (4) Assuming that the material of the wooden beam 2 is basically uniform on a macroscopic scale, there may be natural defects;

[0072] (5) Assume that the mechanical properties of the CFRP material used for reinforcement conform to the linear elastic stress-strain relationship;

[0073] (6) Assume that the thickness of the CFRP material and adhesive used for reinforcement has no effect on the net height of the wooden beam 2;

[0074] (7) Assume that the bonding between the CFRP material and the wooden beam 2 is reliable and the deformation is coordinated.

[0075] 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 respectively when the tension zone of the wood beam 2 reaches the ultimate tensile strain;

[0076] Figure 8 The figure shows a schematic diagram of the stress-strain curve of the beam 2. It can be seen that the stress-strain relationship of the 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 beam 2 is obtained as follows:

[0077] The stress-strain relationship of beam 2 is expressed as:

[0078] σ c =Eεc ,0≤ε c ≤ε ce ;

[0079] σ c =f ce ,ε ce ≤ε c ≤ε cu ;

[0080] σ t =Eε t ,ε t ≤ε te ;

[0081] Where, 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 tension 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;

[0082] Figure 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 elastic, and its 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:

[0083] σ f =E f ε f ,ε f ≤ε fu ;

[0084] Where, 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.

[0085] S23: Based on the failure 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;

[0086] S231: Based on the failure state of the CFRP-reinforced timber formwork system 1, the equilibrium equation and the initial expression for the bending bearing capacity of the timber beam 2 are constructed in combination with the performance parameters of the timber beam 2 and the carbon fiber cloth 3;

[0087] Based on conventional theoretical experience, it is 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.

[0088] like Figure 10 Shown is a stress-strain diagram of the CFRP reinforced wood formwork system 1.

[0089] Among them, the expression of the constructed equilibrium equation is:

[0090] F ce +F c =F te +F f ;

[0091] Where, F ce represents the plastic pressure in the compression zone of beam 2, that is, F c Indicates 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,

[0092] 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 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 wooden beam 2; a represents the compressive elastic distance of the wooden beam 2; c represents the height of the theoretical compression zone of the wooden beam 2; a·c represents the elastic section of the compression zone of the wooden beam 2; (1-a)·c represents the plastic section of the compression zone of the wooden beam 2;

[0093] The initial expression of the bending bearing capacity of beam 2 is:

[0094]

[0095] Where M represents the bending bearing capacity of the wooden beam 2.

[0096] S232: Based on the compatibility relationship between the height of the compression zone of beam 2 and the length of the elastic section of the compression zone of beam 2, construct an expression for the height of the compression zone of beam 2 and the length of the elastic section of the compression zone of beam 2;

[0097] 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:

[0098]

[0099] The expression of the compressive elastic length of beam 2 can be obtained as follows:

[0100]

[0101] 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:

[0102]

[0103] definition: Then the expression for the height of the compression zone of beam 2 can be simplified as:

[0104] c=x1·h+x2·h f ;

[0105] 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.

[0106] S233: Based on the initial expression for the bending bearing capacity of wooden beam 2, combined with the performance parameters of wooden beam 2 and carbon fiber cloth 3, the height of the compression zone of wooden beam 2, and the expression for the length of the elastic section of the compression zone of wooden beam 2, a calculation expression for the bending bearing capacity of wooden beam 2 based on CFRP-reinforced wooden formwork system 1 is established.

[0107] The calculation expression for the bending bearing capacity of the wooden beam 2 based on the CFRP-reinforced wooden formwork system 1 is:

[0108]

[0109] definition: 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:

[0110] M=b·(y1·h 2 +y2·h·h f -y3·h f 2 );

[0111] 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 an order of magnitude, accounting for only 2% of the result, which has a small impact on the calculation results and can be ignored in the actual calculation results. 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:

[0112]

[0113] 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 proportional 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, the proportionality factor y2 depends on the constant value of 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.

[0114] S3: Based on the maximum spacing between adjacent timber beams 2 in the CFRP reinforced timber formwork system 1 and the calculation expression for the bending bearing capacity of timber beam 2, calculate the bending bearing capacity of timber beam 2 under the maximum spacing between adjacent timber beams 2;

[0115] S31: Based on the maximum spacing between adjacent timber beams 2 in the CFRP-reinforced timber formwork system 1 and the unit width load borne by the panel, calculate the bending moment of timber beam 2 under the external load;

[0116] The expression of the unit width linear load borne by the panel is:

[0117] q1=[1.3×(G 1k +(G 2k +g 3k )×h)+1.5×Q 1k ]×b;

[0118] 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 steel bar deadweight; Q 1k Indicates the standard value of the load generated by construction personnel and their equipment;

[0119]

[0120] Where M max represents the bending moment of the wooden beam 2 under the external load, and l represents the maximum spacing;

[0121] 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.

[0122] Among them, the bending moment M of the wooden beam 2 under the external load is max It must be less than the bending bearing capacity M of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1, that is:

[0123]

[0124] Calculations show that when the maximum spacing between adjacent wooden beams 2 is 600 mm, by pasting a layer of carbon fiber cloth 3 with a thickness of 0.111 mm on the bottom of the wooden formwork system, the wooden beam 2 can be reduced from the original interface size of 50×100 mm to 40×50 mm, saving 60% of the wood and significantly reducing wood usage.

[0125] Example 2

[0126] like Figure 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.

[0127] Specifically, a spacing calculation module is used to obtain the structural parameters of the CFRP reinforced wood formwork system 1, 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;

[0128] Specifically, the analysis and calculation module is used to calculate the stress-strain relationship of the wooden beam 2 and the carbon fiber cloth 3 based on the structural parameters of the CFRP reinforced wooden formwork system 1, and establish a calculation expression for the bending bearing capacity of the wooden beam 2 based on the CFRP reinforced wooden formwork system 1;

[0129] 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.

[0130] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0131] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify 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 timber formwork system, simulate the mechanical properties of the CFRP-reinforced timber formwork system using finite element software, and determine the maximum spacing between adjacent timber beams in the CFRP-reinforced timber formwork system; Based on the structural parameters of the CFRP-reinforced timber formwork system, the stress-strain relationships of the timber beams and carbon fiber sheets were calculated, and a calculation expression for the bending bearing capacity of the timber beams based on the CFRP-reinforced timber formwork system was established. Combining the maximum spacing between adjacent beams in the CFRP-reinforced timber formwork system and the calculation expression for the bending capacity of the beams, the bending capacity of the beams at the maximum spacing between adjacent beams was calculated. The calculation of the bending bearing capacity of the wooden beams at 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 includes: Based on the maximum spacing between adjacent timber beams in the CFRP-reinforced timber formwork system and the unit width load borne by the panel, the bending moment of the timber beam under external load is calculated. Based on the bending moment of the timber beam under the action of external loads and the bending capacity of the timber beam, the bending capacity of the timber beam at the maximum spacing between adjacent timber beams is determined; The calculation expression for the bending bearing capacity of the wooden beam 2 based on the CFRP-reinforced wooden formwork system 1 is: ； Where, represents the bending bearing capacity of the timber beam; Indicates the width of the beam; Indicates the ultimate compressive strength of the timber beam; Indicates the ultimate tensile strength of the timber beam; Indicates the height of the wooden beam; represents the elastic modulus of carbon fiber cloth; represents the elastic modulus of the wooden beam; Indicates the thickness of carbon fiber cloth.

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, finite element software was used to simulate the mechanical properties of the CFRP-reinforced wood formwork system; Based on the effect of carbon fiber cloth on the timber formwork system, the maximum spacing between adjacent timber beams is calculated when carbon fiber cloth is pasted in the reinforced timber 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 to 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 in the reinforced timber formwork system. Based on basic assumptions, the stress-strain relationship of the timber beam and the stress-strain relationship of the carbon fiber cloth are established when the tensile zone of the timber beam reaches the ultimate tensile strain. Based on the failure state of the CFRP reinforced timber formwork system, a calculation expression for the bending bearing capacity of timber beams based on the CFRP reinforced timber 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 timber beam complies with the strain plane section assumption; Assume that the timber beam behaves linearly elastically in tension and perfectly elastic-plastic in compression; Assume that the tensile modulus and compressive modulus of the timber beam in the direction of grain are the same and constant; Assume that the material of the wooden beam is basically uniform on a macro scale; Assume 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 for the bending bearing capacity of the wooden beam based on the CFRP reinforced wooden formwork system is established based on the failure state of the CFRP reinforced wooden formwork system, including: Based on the failure state of the CFRP-reinforced timber formwork system, the equilibrium equation and the initial expression of the timber beam's flexural bearing capacity were constructed by combining the performance parameters of the timber beam and the carbon fiber sheet. Based on the compatibility relationship between the height of the compression zone of the timber beam and the length of the elastic section of the compression zone of the timber beam, an expression for the height of the compression zone of the timber beam and the length of the elastic section of the compression zone of the timber beam is constructed; Based on the initial expression of the bending bearing capacity of timber beams, combined with the expressions of the performance parameters of timber beams and carbon fiber cloth, the height of the compression zone of the timber beams, and the length of the elastic section of the compression zone of the timber beams, a calculation expression for the bending bearing capacity of timber beams based on the CFRP-reinforced timber formwork system was established.

6. A system for calculating the bending bearing capacity of the CFRP reinforced wood formwork system according to claim 1, characterized in that: include: Spacing calculation module, which 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 timber beam and the carbon fiber sheet based on the structural parameters of the CFRP-reinforced timber formwork system, and to establish a calculation expression for the bending bearing capacity of the timber beam based on the CFRP-reinforced timber 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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