An anti-buckling system and design method integrating stress-driven self-regulation and cathodic protection functions

Abstract

This application discloses an anti-buckling system and design method that integrates stress-driven self-regulation and cathodic protection functions. The anti-buckling system includes composite reinforcement, a power supply, and a sensor assembly, which are mounted on a steel column. The composite reinforcement serves as multiple diagonal-stayed components, which are symmetrically distributed on both sides of the steel column. Each diagonal-stayed component includes an insulated shape-memory alloy core and fiber-reinforced composite material filaments, which are disposed in grooves within the shape-memory alloy core. The ends of the shape-memory alloy core corresponding to each diagonal-stayed component are connected to the positive and negative poles of a power supply, respectively. The fiber-reinforced composite material filaments corresponding to each diagonal-stayed component are connected to the positive pole of the power supply, while the steel column is connected to the negative pole of the power supply. This application can improve the corrosion resistance of steel columns under coastal environments and seismic loads, as well as their anti-buckling performance under external loads.

Description

Technical Field

[0001] The present application relates to the technical field of steel structure protection, and in particular to an anti-buckling system and a design method that integrates stress-driven self-regulation and cathodic protection functions. Background Art

[0002] The buckling resistance of steel structures plays a vital role in the safety and durability of buildings, especially when subjected to lateral loads and earthquakes. Existing buckling-resistant devices, such as traditional stiffening components, external support frames, and damping devices, while improving the stability of components to a certain extent, still have some shortcomings. For example, traditional stiffening devices have poor corrosion resistance and are particularly susceptible to damage in humid or corrosive environments, resulting in high maintenance costs. Damping devices often cannot be restored to their original state after an earthquake, have limited energy dissipation characteristics, and are difficult to adapt to high-intensity external impacts. Furthermore, many devices have poor ductility and are prone to brittle failure under large deformation conditions.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] The main purpose of this application is to provide an anti-buckling system and design method that integrates stress-driven self-adjustment and cathodic protection functions, aiming to solve the problem in the existing technology that when steel structures are anti-buckling under coastal environments and seismic loads through anti-buckling devices, the corrosion resistance, impact resistance or ductility of the devices are poor, resulting in poor corrosion resistance of the steel structures.

[0005] According to a first aspect of an embodiment of the present application, there is provided an anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions, comprising a composite bar, a power supply, and a sensor assembly, wherein the composite bar and the sensor assembly are mounted on a steel structure column; the composite bar comprises a plurality of diagonal-stayed assemblies, which are symmetrically distributed on both sides of the steel structure column; each of the diagonal-stayed assemblies comprises an insulated shape memory alloy structure and a fiber-reinforced composite structure, wherein the fiber-reinforced composite structure is disposed in a groove of the shape memory alloy structure; the two ends of the shape memory alloy structure corresponding to each diagonal-stayed assembly are respectively connected to the positive and negative poles of the power supply, and the fiber-reinforced composite structure corresponding to each diagonal-stayed assembly is connected to the positive pole of the power supply, while the steel structure column is connected to the negative pole of the power supply; when the sensor assembly detects that the strain of the steel structure column reaches a preset condition, the power supply applies an excitation current to the shape memory alloy structure corresponding to the stretched diagonal-stayed assembly, so that the stretched diagonal-stayed assembly is restored to a target length.

[0006] Optionally, in one embodiment of the present application, a first transverse support and a second transverse support are respectively provided on both sides of the steel structure column, and the multiple inclined-braced assemblies include a first inclined-braced, a second inclined-braced, a third inclined-braced and a fourth inclined-braced, the two ends of the first inclined-braced are respectively connected to the top end of the steel structure column and the upper side end of the first transverse support, the two ends of the second inclined-braced are respectively connected to the top end of the steel structure column and the upper side end of the second transverse support, the two ends of the third inclined-braced are respectively connected to the bottom end of the steel structure column and the lower side end of the first transverse support, and the two ends of the fourth inclined-braced are respectively connected to the bottom end of the steel structure column and the lower side end of the second transverse support.

[0007] Optionally, in one embodiment of the present application, the sensing assembly includes a first strain sensor and a second strain sensor, the first strain sensor is arranged on the first inclined-pull, and the second strain sensor is arranged on the second inclined-pull; when the first strain sensor detects that the strain of the first inclined-pull is greater than a preset value, the power supply applies an excitation current to the first inclined-pull and the third inclined-pull to restore the first inclined-pull and the third inclined-pull to their initial lengths; when the first strain sensor detects that the strain of the second inclined-pull is greater than a preset value, the power supply applies an excitation current to the second inclined-pull and the fourth inclined-pull to restore the second inclined-pull and the fourth inclined-pull to their initial lengths.

[0008] Optionally, in one embodiment of the present application, the groove is filled with an insulating layer, and the fiber-reinforced composite structure is insulated from the shape memory alloy structure by the insulating layer.

[0009] Optionally, in one embodiment of the present application, each of the inclined-stayed components includes a reinforcement segment, two variable-section segments and two installation segments, the two installation segments are located at both ends, the reinforcement segment is located in the middle, each of the variable-section segments is respectively connected to one end of the reinforcement segment and one of the installation segments, and the diameter of the reinforcement segment is smaller than the diameter of the installation segment.

[0010] Optionally, in one embodiment of the present application, the groove is an annular groove, the cross-section of the annular groove is circular or rectangular, the annular groove is used to anchor the fiber reinforced composite structure, and the ultimate strain range of the fiber reinforced composite structure is 1.5%-2%.

[0011] The second aspect of the embodiment of the present application also provides an anti-buckling design method for an anti-buckling system with integrated stress-driven self-regulation and cathodic protection functions based on any one of the above-mentioned schemes, wherein the anti-buckling design method includes: determining the size and material properties of the shape memory alloy structure, and constructing a relationship between the shape memory alloy structure and the corresponding fiber-reinforced composite structure; determining the angle of the shape memory alloy structure and the amount of the fiber-reinforced composite structure according to the size, the material properties and the relationship; according to the angle and the amount, after the shape memory alloy structure and the corresponding fiber-reinforced composite structure are formed into a diagonal assembly, multiple diagonal assemblies are installed on a steel structure column. If the stiffness of the steel structure column reaches the critical stiffness, the anti-buckling design of one diagonal assembly is completed.

[0012] Optionally, in one embodiment of the present application, the material properties include the axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure and the strengthening section modulus; determining the size and material properties of the shape memory alloy structure specifically includes: determining the size of the shape memory alloy structure based on the parameters of the steel structure column; determining the axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure and the strengthening section modulus based on the stress-strain curve of the shape memory alloy structure.

[0013] Optionally, in one embodiment of the present application, the relationship is as follows:

[0014] ;

[0015] in, is the area of the fiber reinforced composite structure, is the elastic modulus of the fiber-reinforced composite structure, is the winding angle of the fiber reinforced composite structure, is the strain of the necked section of the shape memory alloy structure, is the axial strain conversion coefficient corresponding to the necking strain of the shape memory alloy structure, is the radius of the shape memory alloy structure, is the distance from the center of the shape memory alloy structure section to the center of the fiber reinforced composite structure section, is the elastic modulus conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure, is the area conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure; is the cross-sectional area of the shape memory alloy structure, is the stress corresponding to the strain at the necking section of the shape memory alloy structure, is the strengthening section modulus of the shape memory alloy structure.

[0016] Optionally, in one embodiment of the present application, the critical stiffness is expressed as:

[0017] ;

[0018] in, is the critical stiffness, is the allowable stress of the cable-stayed component, is the design stress at both ends of the cable-stayed assembly, is the height of the rectangular column, is the design axial pressure for the rectangular column.

[0019] Beneficial effects: The present application provides an anti-buckling system and design method integrating stress-driven self-adjustment and cathodic protection functions. In the anti-buckling system, a diagonal-stayed assembly is formed by a memory alloy structure and a corresponding fiber-reinforced composite structure. Multiple diagonal-stayed assemblies are installed on a steel structure column. The strain is detected by a sensing assembly on the surface of the steel structure column, so that an excitation current is applied to the fiber-reinforced composite structure in the tensioned diagonal-stayed assembly through a power supply to restore it to the original target length. In this way, the steel structure column is protected by each diagonal-stayed assembly under coastal environment and seismic load, thereby improving the corrosion resistance of the structure. The diagonal-stayed assembly can also perform self-adjustment to improve the recovery ability of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A perspective view of a preferred embodiment of the anti-buckling system of the present invention that integrates stress-driven self-adjustment and cathodic protection functions;

[0022] Figure 2 A schematic plan view of an SMA-CFRP reinforcement in a preferred embodiment of the anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions of the present application;

[0023] Figure 3 This is a schematic structural diagram of the SMA-CFRP reinforcement in a preferred embodiment of the anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions of the present application;

[0024] Figure 4 This is a flow chart of a preferred embodiment of the anti-buckling design method of the present application;

[0025] Figure 5This is a graph showing the SMA-CFRP stress-strain relationship of a preferred embodiment of the anti-buckling design method of the present application;

[0026] Figure 6 This is a schematic diagram of the compressive buckling mechanism of SMA-CFRP reinforcement in a preferred embodiment of the anti-buckling design method of the present application.

[0027] Description of reference numerals:

[0028] 11. First inclined pull; 12. Second inclined pull; 13. Third inclined pull; 14. Fourth inclined pull;

[0029] 20. Steel structure column; 21. First transverse support; 22. Second transverse support.

[0030] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and effects of this application clearer and more specific, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. The described embodiments are only possible technical implementations of this application and are not all possible implementations. Based on the embodiments in this application, those skilled in the art can fully combine the embodiments of this application to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of this application.

[0032] First, the terms involved in the embodiments of the present application are introduced: shape memory alloy (Shape Memory Alloy, abbreviated as SMA), that is, the shape memory alloy structure of the present application is SMA tendon; carbon fiber reinforced composite material (Carbon Fiber Reinforced Polymer, abbreviated as CFRP), that is, the carbon fiber reinforced composite structure of the present application is CFRP fiber; the diagonal component of the present application is SMA-CFRP tendon, and multiple diagonal components constitute the composite tendon.

[0033] The following describes an anti-buckling system and design method with integrated stress-driven self-adjustment and cathodic protection functions in accordance with an embodiment of the present application with reference to the accompanying drawings. In response to the problem in the related art mentioned above that when a steel structure is subjected to anti-buckling under a coastal environment and seismic loads through an anti-buckling device, the device has poor corrosion resistance, impact resistance or ductility, resulting in poor corrosion resistance of the steel structure, the present application provides an anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions. In the anti-buckling system, a diagonal assembly is formed by a memory alloy structure and a corresponding fiber-reinforced composite structure. Multiple diagonal assemblies are installed on a steel structure column. The strain is detected by a sensing assembly on the surface of the steel structure column, and an excitation current is applied to the fiber-reinforced composite structure in the stretched diagonal assembly through a power supply to restore it to its original target length. In this way, the steel structure column is protected by each diagonal assembly under a coastal environment and seismic loads, thereby improving the corrosion resistance of the structure. The diagonal assembly can also be self-reset to improve the recovery ability of the structure. This solves the technical problem in related technologies that when steel structures are subjected to anti-buckling devices in coastal environments and seismic loads, the devices have poor corrosion resistance, impact resistance or ductility, resulting in poor corrosion resistance of the steel structures.

[0034] The anti-buckling system of the present application combines fiber-reinforced composite materials with shape memory alloys (SMAs), and has the advantages of high strength, high energy dissipation, and high ductility. Fiber-reinforced composite materials have the advantages of high strength and corrosion resistance, while the self-resetting properties of SMAs can help the device return to its original shape after deformation under stress, thereby improving the self-recovery ability of the structure. In addition, wrapping fiber-reinforced composite materials such as CFRP on the surface of shape memory alloys can effectively inhibit the necking of SMAs and significantly improve the strength and large plastic deformation capacity of SMAs after yielding, which exhibits an excellent buffering effect when resisting large-scale buckling failure of components. In other words, the present application can improve the corrosion resistance of steel structural columns under coastal environments and seismic loads and their anti-buckling performance under external loads.

[0035] The following specific embodiments are used to describe the technical solution of the present application in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0036] like Figure 1As shown, an embodiment of the present application provides an anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions, which includes a composite bar, a power supply (not shown in the figure), and a sensor assembly (not shown in the figure). The composite bar and the sensor assembly are installed on a steel structure column 20; the composite bar includes multiple diagonal components, which are symmetrically distributed on both sides of the steel structure column 20; each of the diagonal components includes an insulated shape memory alloy structure (i.e., a shape memory alloy core) and a fiber-reinforced composite structure (i.e., a fiber-reinforced composite material filament), the fiber-reinforced composite structure being disposed in a groove of the shape memory alloy structure, and the two ends of the shape memory alloy structure corresponding to each diagonal component are respectively connected to the positive and negative poles of the power supply, and the fiber-reinforced composite structure corresponding to each diagonal component is connected to the positive pole of the power supply, and the steel structure column 20 is connected to the negative pole of the power supply; when the sensor assembly detects that the strain of the steel structure column 20 reaches a preset condition, the power supply applies an excitation current to the shape memory alloy structure corresponding to the stretched diagonal component to restore the stretched diagonal component to a target length.

[0037] The multiple inclined-stayed components (SMA-CFRP reinforcement) in the embodiment of the present application are divided into a portion of inclined-stayed components subjected to tension and another portion of inclined-stayed components subjected to compression. A stimulation current is applied to the SMA reinforcement corresponding to the inclined-stayed components subjected to tension to restore their length to a target length (i.e., the original length, which may also be another set length).

[0038] It should be noted that, by applying current to the fiber reinforced composite structure (CFRP fiber) through a power supply to perform cathodic protection on the steel structure column 20, this is a set of anti-corrosion cathodic protection system, which can improve the corrosion resistance of the steel structure column 20; in addition, by applying an excitation current to the shape memory alloy structure (SMA tendon) through a power supply, the length of the SMA tendon is self-reset, which is another set of self-recovery system with self-reset function, which can improve the recovery of the steel structure column 20 after buckling due to external loads (earthquake or impact), thereby improving the service life and safety of the steel structure column 20 through the cooperation of these two systems.

[0039] It is understood that self-adjustment of the shape memory alloy structure (SMA tendon) can be achieved by heating or applying current to the SMA tendon. In this embodiment, the power supply applies a stimulation current to the SMA tendon to achieve self-adjustment of length, which can also be understood as temperature adjustment by applying current to the SMA tendon.

[0040] This application addresses the issues of existing steel structures being susceptible to corrosion and lacking self-reset functionality when buckled in coastal environments and under seismic loads. In an embodiment of the application, spiral grooves (i.e., grooves) are applied to the surface of the SMA reinforcement (i.e., shape memory alloy structure) and carbon fiber reinforced plastic (CFRP) is embedded to form a fiber-reinforced composite structure. This allows for an SMA-CFRP reinforcement (i.e., a cable-stayed assembly) that combines stress-driven self-reset with cathodic protection. The overall technical effects of the anti-buckling system of the embodiment of the application are: significantly improving the anti-buckling capacity of the steel structure, enhancing its corrosion resistance in coastal environments, and improving the structure's recovery after buckling due to external loads (earthquakes or impacts). This significantly improves the service life and safety of the steel structure, making it particularly suitable for coastal and earthquake-prone environments while reducing the maintenance cost of the structure.

[0041] In one embodiment of the present application, Figure 1 As shown, a first transverse support 21 and a second transverse support 22 are respectively provided on both sides of the steel structure column 20, and the multiple inclined-stayed components include a first inclined-stayed 11, a second inclined-stayed 12, a third inclined-stayed 13 and a fourth inclined-stayed 14. The two ends of the first inclined-stayed 11 are respectively connected to the top end of the steel structure column 20 and the upper side end of the first transverse support 21, the two ends of the second inclined-stayed 12 are respectively connected to the top end of the steel structure column 20 and the upper side end of the second transverse support 22, the two ends of the third inclined-stayed 13 are respectively connected to the bottom end of the steel structure column 20 and the lower side end of the first transverse support 21, and the two ends of the fourth inclined-stayed 14 are respectively connected to the bottom end of the steel structure column 20 and the lower side end of the second transverse support 22.

[0042] It can be understood that the plurality of oblique-stayed assemblies in this embodiment include four oblique-stayed assemblies, namely, a first oblique-stayed assemblies 11 , a second oblique-stayed assemblies 12 , a third oblique-stayed assemblies 13 and a fourth oblique-stayed assemblies 14 .

[0043] Specifically, in the embodiment of the present application, the SMA-CFRP reinforcement (cambered assembly) is installed in the steel structure column 20 as an anti-buckling inclined-stayed system, and an activation current is applied to generate a pre-tightening force.

[0044] like Figure 1As shown, the SMA-CFRP bar anti-buckling diagonal system is installed in a steel structure column 20 (a rectangular column in the embodiment of the present application). The SMA-CFRP bar anti-buckling diagonal is symmetrically installed on both sides of the long side of the rectangular column with smaller inertia, that is, the diagonal assembly is divided into two parts and installed on both sides of the steel structure column 20, which are the two sides of the long side with smaller inertia. In the middle of the rectangular column, there is a transverse support made of stainless steel, namely the first transverse support 21 and the second transverse support 22. The first diagonal 11 (SMA-CFRP bar anti-buckling diagonal) and the second diagonal 12 are installed on the upper side of the first transverse support 21 and the second transverse support 22 respectively. The third diagonal groove and the fourth diagonal 14 are installed on the lower side of the first transverse support 21 and the second transverse support 22. The angle between the first oblique brace 11, the second oblique brace 12, the third oblique brace 13, and the fourth oblique brace 14 and the steel structure column 20 (rectangular column) is q (the preset angle in this embodiment is 45 degrees). The total length of the first oblique brace 11, the second oblique brace 12, the third oblique brace 13, and the fourth oblique brace 14 is L. Therefore, the length of the first transverse support 21 and the second transverse support 22 is sinqL.

[0045] In one embodiment of the present application, the sensing assembly includes a first strain sensor and a second strain sensor. The first strain sensor is disposed on the first inclined member 11, and the second strain sensor is disposed on the second inclined member 12. When the first strain sensor detects that the strain of the first inclined member 11 is greater than a preset value, the power supply applies an excitation current to the first inclined member 11 and the third inclined member 13 to restore the first and third inclined members 11 and 13 to their initial lengths. When the first strain sensor detects that the strain of the second inclined member 12 is greater than a preset value, the power supply applies an excitation current to the second and fourth inclined members 12 and 14 to restore the first and third inclined members 11 and 13 to their initial lengths. The strain sensors detect strain by sensing changes in the resistance of the inclined members.

[0046] Specifically, in the present application, a self-recovery system with a self-reset function is provided, wherein the strain of the first inclined rope 11 and the second strain sensor of the second inclined rope 12 are used to monitor the strain of the inclined rope so as to determine the buckling condition thereof. When the strain of the second strain sensor of the second inclined rope 12 is less than 0 and the strain of the first strain sensor of the first inclined rope 11 is greater than a preset value (in this embodiment, M y N d l / (12 EIE s A b sinq), M y is the buckling moment of the rectangular column, N dDesign axial pressure for rectangular columns, l is the height of the rectangular column, EI is the stiffness of the rectangular column, E s is the elastic modulus of the SMA-CFRP reinforcement, A b is the area of the SMA-CFRP reinforcement section, q is the angle between the diagonal brace and the rectangular column), the rectangular column buckles toward the second transverse support 22, the second diagonal brace 12 and the fourth diagonal brace 14 are compressed, and the first diagonal brace 11 and the third diagonal brace 13 are stretched. At this time, an activation current can be applied to the stretched first diagonal brace 11 and the third diagonal brace 13 to restore them to their original length, realizing the self-adjustment function of the SMA-CFRP tendon anti-buckling diagonal brace system. When the strain of the first diagonal brace 11 is less than 0 and the strain sensor strain of the second diagonal brace 12 is greater than the preset value (i.e. M y N d l / (12 EIE s A b sinq), the rectangular column buckles toward the first transverse support 21, the first and third inclined cables 11 and 13 are compressed, and the second and fourth inclined cables 12 and 14 are tensile. At this time, an activation current can be applied to the second and fourth inclined cables 12 and 14 to restore them to their original lengths, realizing the self-adjustment function of the SMA-CFRP tendon anti-buckling inclined cable-stayed system.

[0047] In the present application, in an anti-corrosion cathodic protection system, the fiber-reinforced composite structure (i.e., CFRP fiber) of the first inclined brace 11, the second inclined brace 12, the third inclined brace 13, and the fourth inclined brace 14 is connected to the positive power supply of the cathodic protection system, and the rectangular column is connected to the negative power supply of the cathodic protection system, thereby realizing the cathodic protection function of the SMA-CFRP tendon anti-buckling system and effectively suppressing the corrosion of the rectangular column.

[0048] In an embodiment of the present application, the groove is filled with an insulating layer, and the fiber-reinforced composite structure is insulated from the shape memory alloy structure by the insulating layer.

[0049] Specifically, a 0.2 mm thick layer of insulating material, i.e., the insulating layer, is coated between the CFRP fibers and the SMA surface.

[0050] In one embodiment of the present application, each of the inclined-stayed components includes a reinforcement segment, two variable-section segments and two mounting segments, the two mounting segments are located at both ends, and the reinforcement segment is located in the middle, each of the variable-section segments is respectively connected to one end of the reinforcement segment and one of the mounting segments, and the diameter of the reinforcement segment is smaller than the diameter of the mounting segment.

[0051] Specifically, such as Figure 2 and Figure 3 As shown, the SMA rib is divided into three regions along its length: the installation section, the variable section, and the reinforcement section. The two ends are 300 mm long and 30 mm in diameter installation sections, the inner section is 50 mm long and the variable section is 50 mm long, and the center section is a 12 mm diameter reinforcement section. The length can be determined according to actual design requirements. In this embodiment, it is 1500 mm. The diameter ratio of the installation section to the reinforcement section is 2.5-3. The installation section is provided with an annular groove 2 mm wide and 4 mm deep 20 mm from the variable section. The uniformly shaped groove begins at this point and covers the variable section and reinforcement section. The groove at the annular groove section needs to be chamfered to prevent severing of the CFRP fibers.

[0052] In one embodiment of the present application, the groove is an annular groove, the cross-section of the annular groove is circular or rectangular, the annular groove is used to anchor the fiber reinforced composite structure, and the ultimate strain range of the fiber reinforced composite structure is 1.5%-2%.

[0053] Specifically, the grooves in the embodiment of the present application are at an angle of 45 degrees to the horizontal direction, but are not limited thereto. The fiber composite material is CFRP with an ultimate strain of 1.5% to 2% and an elastic modulus of 200 GPa (Gigapascal).

[0054] In the embodiments of this application, CFRP fibers are wrapped around the surface of the SMA-CFRP bars, suppressing their necking under large deformations and significantly improving their strength and ductility. These fibers are suitable for use as energy-dissipating braces to resist structural buckling under seismic loads. The CFRP fibers wrapped around the surface of the SMA-CFRP bars can also serve as auxiliary anodes for cathodic protection, inhibiting structural corrosion and increasing the service life of coastal concrete structures. SMAs possess stress-driven properties, generating self-driven stresses after structural buckling, enabling the structure to self-regulate.

[0055] See also Figure 2 The preparation method of the SMA-CFRP reinforcement (slant-stayed component) of this application is as follows:

[0056] Step K1: To ensure the self-resetting ability of the SMA-CFRP reinforcement, the SMA reinforcement needs to be pre-tensioned (5%-6%) before preparation. The SMA reinforcement used in this application is a plain round reinforcement.

[0057] In step K2, the metal SMA surface is provided with a plurality of grooves at a predetermined angle to the horizontal. These grooves are filled with a fiber composite material. Furthermore, in the embodiment of the present application, the grooves are at a 45-degree angle to the horizontal, but this is not limiting. The fiber composite material is CFRP with an ultimate strain of 1.5% to 2% and an elastic modulus of 200 GPa (gigapascals).

[0058] In step K3, all grooves are of the same shape, either circular or rectangular. In this embodiment, the grooves are circular. The grooves should be evenly spaced across the SMA's cross section and length. In this embodiment, four grooves are evenly spaced across the cross section, with a spacing of 100 mm along the length. The groove width is approximately 2.5-3 mm, and the groove volume accounts for approximately 35% to 50% of the SMA's volume.

[0059] In step K4, the SMA is divided into three sections along its length: the mounting section, the variable-section section, and the reinforcement section. The two ends have mounting sections 300 mm long and 30 mm in diameter, the inner section is a 50 mm variable-section section, and the center section is a 12 mm diameter reinforcement section. The length can be determined based on actual design requirements; in this embodiment, 1500 mm is used. The diameter ratio of the mounting section to the reinforcement section is 2.5-3. An annular groove 2 mm wide and 4 mm deep is defined in the mounting section 20 mm from the variable-section section. A uniform groove is created starting from this point, encompassing both the variable-section and reinforcement sections. The annular groove section should be chamfered to prevent severing of the CFRP fibers.

[0060] Step K5: The function of the annular groove is to anchor the CFRP. The CFRP is filled starting from the annular groove, and in order to ensure the anchoring effect, the fibers in the annular grooves at both ends need to be wrapped at least 2 times.

[0061] In step K6, a 0.2 mm thick insulating material layer needs to be evenly applied on the SMA surface before filling the CFRP fibers.

[0062] Step K7, each beam area is about 2 mm 2 A 2200 mm long CFRP fiber is soaked in epoxy resin and wound around the annular groove at one end of the SMA. After wrapping around the annular groove twice, it is wrapped along the spiral grooves opened in the variable-section section and reinforcement section of the SMA to the annular groove of the mounting section at the other end. After wrapping around twice, the excess CFRP fiber is cut off.

[0063] In step K8, the SMA-CFRP reinforcement wrapped with CFRP fibers is placed in a curing chamber at 45 degrees Celsius for 24 hours. The preset angle, CFRP content, and stiffness of the resulting SMA-CFRP reinforcement (cable-stayed component) must satisfy the aforementioned relationship to prevent necking.

[0064] Based on the above embodiments, the present application also provides an anti-buckling design method for an anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to any one of the above solutions, such as Figure 4 As shown, the anti-buckling design method includes:

[0065] In step S101 , the size and material properties of the shape memory alloy structure are determined, and a relationship between the shape memory alloy structure and the corresponding fiber reinforced composite structure is constructed.

[0066] In one possible implementation, the material properties include the axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure, and the modulus of the strengthening section. The dimensions of the shape memory alloy structure are determined based on the parameters of the steel column; and the axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure, and the modulus of the strengthening section are determined based on the stress-strain curve of the shape memory alloy structure.

[0067] In a possible implementation, the relationship between the fiber-reinforced composite structure and the shape memory alloy structure is as follows:

[0068] ;

[0069] in, is the area of the fiber reinforced composite structure, is the elastic modulus of the fiber-reinforced composite structure, is the winding angle of the fiber reinforced composite structure, is the strain of the necked section of the shape memory alloy structure, is the axial strain conversion coefficient corresponding to the necking strain of the shape memory alloy structure, is the radius of the shape memory alloy structure, is the distance from the center of the shape memory alloy structure section to the center of the fiber reinforced composite structure section, is the elastic modulus conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure, is the area conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure; is the cross-sectional area of the shape memory alloy structure, is the stress corresponding to the strain at the necking section of the shape memory alloy structure, is the strengthening section modulus of the shape memory alloy structure.

[0070] In other words, in order to prevent necking, the preset angle, CFRP amount, and stiffness of the SMA-CFRP reinforcement (cable-stayed component) should satisfy the above relationship.

[0071] Specifically, in the above relationship, 、 and The expression is as follows:

[0072]

[0073] It should be noted that, see Figure 1 and Figure 5 When the SMA-CFRP reinforcement (cambered component) is in equilibrium or the axial force is less than the preload of the SMA-CFRP reinforcement, no deformation occurs. When the load is greater than the preload of the SMA-CFRP reinforcement, compression or tensile deformation occurs. When under tension, the SMA-CFRP reinforcement bears the entire load. It can dissipate a large amount of energy through its anti-necking, high strength and large deformation characteristics to maintain structural stability. To prevent tensile failure of SMA-CFRP, the maximum internal stress of the SMA-CFRP reinforcement must be less than the allowable stress of the SMA-CFRP reinforcement. .

[0074] exist Figure 5 In the stress-strain curve of the shape memory alloy structure, the arrow position of the SMA rib corresponds to the necking point. The axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure, and the strengthening section modulus of the SMA rib are obtained from the curve.

[0075] That is, when constructing SMA-CFRP reinforcement, the present application first selects the SMA reinforcement to be reinforced, and determines the axial strain at the necking, the cross-sectional stress corresponding to the strain at the necking, and the strengthening section modulus of the stress-strain curve of the necking section based on the local engineering stress-strain curve of the necking section corresponding to the SMA reinforcement.

[0076] In step S102, the angle of the shape memory alloy structure and the amount of the fiber reinforced composite structure are determined according to the size, the material properties and the relationship.

[0077] Specifically, determine the geometric dimensions of the SMA and basic material properties 、 、 The elastic modulus of the CFRP fiber, the fiber winding angle (i.e., the preset angle of the SMA rib groove), and the fiber area can then be determined based on the above relationship. After determining the CFRP fiber angle, spiral grooves along the SMA axis are created in the SMA variable-section and reinforcement sections.

[0078] In step S103, after the shape memory alloy structure and the corresponding fiber reinforced composite structure are formed into a diagonal assembly according to the angle and the amount, multiple diagonal assemblies are installed on the steel structure column. If the stiffness of the diagonal assembly (i.e., the rectangular column) reaches the critical stiffness, the anti-buckling design of one diagonal assembly is completed.

[0079] In a possible implementation, the critical stiffness is expressed as: ;in, is the critical stiffness, is the allowable stress of SMA-CFRP reinforcement, is the design axial pressure of the rectangular column, is the design stress at both ends of the cable-stayed assembly, is the height of the rectangular column.

[0080] The compressive buckling mechanism of SMA-CFRP reinforcement is Figure 6 The model shown in the figure is simple supported. The self-restoring anti-buckling force is simplified to a concentrated force. The resultant force of the SMA-CFRP reinforcement on the tension side acts on the rectangular column through the lateral support, which is a concentrated anti-buckling force.

[0081] When the rectangular column buckles, the stress of the tensile SMA-CFRP reinforcement is (Design stress). At the critical buckling state, the axial force in the SMA rod is It can be calculated by the following formula:

[0082] ; (1)

[0083] Where, is the area of the SMA-CFRP reinforcement section, is the axial force in the SMA rod, is the stress at both ends.

[0084] Anti-buckling concentrated force , calculated as follows:

[0085] ; (2)

[0086] Where, is the stress of the tensile SMA-CFRP reinforcement, is the area of the SMA-CFRP reinforcement section, is the angle between the cable-stayed member and the rectangular column.

[0087] To prevent buckling, the internal stress of the SMA-CFRP reinforcement calculated by the above formulas (1) and (2) is Need to be less than the allowable stress of SMA-CFRP reinforcement , as follows:

[0088] ; (3)

[0089] when The maximum mid-span deflection of the anti-buckling system within the elastic range is It can be calculated according to the following formula:

[0090] ; (5)

[0091] Where, is the stiffness of the rectangular column, is the height of the rectangular column.

[0092] Substituting formula (2) into formula (5) yields formula (6):

[0093] ; (6)

[0094] Where, is the stiffness of the rectangular column, is the height of the rectangular column, is the area of the SMA-CFRP reinforcement section, is the angle between the cable-stayed member and the rectangular column.

[0095] When the SMA-CFRP reinforcement is in a critical state, its axial stress reaches the design stress When a plastic hinge appears in the SMA-CFRP reinforcement, the mid-span displacement is considered to reach its maximum value. To prevent buckling, the self-adjusting moment at the end point should be greater than the bending moment, as shown in the following formula:

[0096] ; (7)

[0097] Substituting formula (6) into formula (7) yields formula (8):

[0098] ; (8)

[0099] The right side of formula (8) is the critical stiffness, and the critical stiffness of the anti-buckling system can be expressed as: .

[0100] Therefore, when designing the SMA-CFRP reinforcement anti-buckling system, it is only necessary to meet the critical stiffness required to prevent the SMA-CFRP reinforcement from stretching to its limit. K 0 is enough.

[0101] That is, in this application, a module is first constructed based on the SMA-CFRP reinforcement design equation, that is, the design equation of the SMA-CFRP reinforcement is constructed using a relational formula. Then, the preset angle of the SMA-CFRP reinforcement and the amount of CFRP are determined based on the SMA-CFRP reinforcement design equation. The prepared SMA-CFRP reinforcement is used as an anti-buckling diagonal tension structure to construct an anti-buckling system. Then, the anti-buckling equation of the SMA-CFRP reinforcement in the tension state is determined, that is, equations (1) to (8). Finally, the anti-buckling strength of the SMA-CFRP reinforcement and the stiffness of the rectangular column are determined.

[0102] This application improves material utilization by preparing and designing SMA-CFRP bars and calculating the preset angle, CFRP dosage, and stiffness of the SMA-CFRP bars based on actual engineering conditions. The SMA-CFRP bars in this application can serve as the diagonal bracing for the structural buckling-resistant system. A corresponding design method is established, and a formula is proposed to calculate the critical stiffness of the rectangular columns in this system during buckling, ensuring the effectiveness of the buckling-resistant design.

[0103] In the description of this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0104] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0105] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0106] It should be noted that, in this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0107] The terms "first," "second," "third," "fourth," etc. (if any) in the specification and claims of the present application and in the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that the numbers used in this way are interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or apparatus.

[0108] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative 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 disclosure. In this specification, the illustrative expressions 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.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions, characterized in that: The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions comprises a composite bar, a power supply and a sensor component, wherein the composite bar and the sensor component are installed on a steel structure column; The composite reinforcement includes a plurality of diagonal components, and the plurality of diagonal components are symmetrically distributed on both sides of the steel structure column; Each of the inclined-stayed components includes an insulated shape memory alloy structure and a fiber-reinforced composite structure, the fiber-reinforced composite structure being disposed in a groove of the shape memory alloy structure, the two ends of the shape memory alloy structure corresponding to each of the inclined-stayed components being connected to the positive and negative poles of the power supply, respectively, and the fiber-reinforced composite structure corresponding to each of the inclined-stayed components being connected to the positive pole of the power supply, while the steel structure column being connected to the negative pole of the power supply; When the sensing component detects that the strain of the steel structure column reaches a preset condition, the power supply applies an excitation current to the shape memory alloy structure corresponding to the stretched oblique component, so that the stretched oblique component is restored to a target length; A first transverse support and a second transverse support are respectively provided on both sides of the steel structure column, and the plurality of inclined-bracing assemblies include a first inclined-bracing, a second inclined-bracing, a third inclined-bracing and a fourth inclined-bracing, two ends of the first inclined-bracing are respectively connected to the top end of the steel structure column and the upper side end of the first transverse support, two ends of the second inclined-bracing are respectively connected to the top end of the steel structure column and the upper side end of the second transverse support, two ends of the third inclined-bracing are respectively connected to the bottom end of the steel structure column and the lower side end of the first transverse support, and two ends of the fourth inclined-bracing are respectively connected to the bottom end of the steel structure column and the lower side end of the second transverse support; The sensing assembly includes a first strain sensor and a second strain sensor, wherein the first strain sensor is arranged on the first inclined pull and the second strain sensor is arranged on the second inclined pull; When the first strain sensor detects that the strain of the first inclined rope is greater than a preset value, the power supply applies an excitation current to the first inclined rope and the third inclined rope to restore the first inclined rope and the third inclined rope to their initial lengths; When the first strain sensor detects that the strain of the second inclined rope is greater than a preset value, the power supply applies an excitation current to the second inclined rope and the fourth inclined rope to restore the second inclined rope and the fourth inclined rope to their initial lengths; The steel structure column is a rectangular column, the first and third inclined cables are installed on one side of the long side with smaller inertia of the rectangular column, and the second and fourth inclined cables are installed on the other side of the long side with smaller inertia of the rectangular column; When the strain of the second strain sensor of the second oblique tension is less than 0 and the strain of the first strain sensor of the first oblique tension is greater than a preset value, the rectangular column is compressed toward the side of the second transverse support, the second oblique tension and the fourth oblique tension are compressed, the first oblique tension and the third oblique tension are tensioned, and an activation current is applied to the tensioned first oblique tension and the third oblique tension to restore them to their original lengths; when the strain of the first oblique tension is less than 0 and the strain sensor strain of the second oblique tension is greater than the preset value, the rectangular column is compressed toward the side of the first transverse support, the first oblique tension and the third oblique tension are compressed, the second oblique tension and the fourth oblique tension are tensioned, and an activation current is applied to the second oblique tension and the fourth oblique tension to restore them to their original lengths; wherein the preset value is M y N d l / (12 EIE s A b sinq ), M y is the buckling moment of the rectangular column, N d Design axial pressure for rectangular columns, l is the height of the rectangular column, EI is the stiffness of the rectangular column, E s is the elastic modulus of the SMA-CFRP reinforcement, A b is the area of the SMA-CFRP reinforcement section, q is the angle between the cable-stayed column and the rectangular column; The groove is an annular groove with a circular or rectangular cross section. The annular groove is used to anchor the fiber reinforced composite structure. The ultimate strain range of the fiber reinforced composite structure is 1.5%-2%.

2. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 1 is characterized in that: The groove is filled with an insulating layer, and the fiber-reinforced composite structure is insulated from the shape memory alloy structure by the insulating layer.

3. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 1, characterized in that: Each of the inclined-stayed components includes a reinforcement segment, two variable-section segments and two installation segments, the two installation segments are located at both ends, and the reinforcement segment is located in the middle. Each of the variable-section segments is respectively connected to one end of the reinforcement segment and one of the installation segments, and the diameter of the reinforcement segment is smaller than the diameter of the installation segment.

4. An anti-buckling design method for an anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to any one of claims 1 to 3, characterized in that: The anti-buckling design method comprises: Determining the size and material properties of the shape memory alloy structure, and constructing a relationship between the shape memory alloy structure and the corresponding fiber reinforced composite structure; determining an angle of the shape memory alloy structure and an amount of the fiber reinforced composite structure according to the size, the material properties, and the relationship; According to the angle and the amount, after the shape memory alloy structure and the corresponding fiber-reinforced composite structure are formed into a diagonal assembly, multiple diagonal assemblies are installed on the steel structure column. If the stiffness of the steel structure column reaches the critical stiffness, the anti-buckling design of one diagonal assembly is completed.

5. The anti-buckling design method of the anti-buckling system according to claim 4, characterized in that: The material properties include the axial strain at the necking point of the shape memory alloy structure, the corresponding cross-sectional pressure and the strengthening section modulus; Determining the size and material properties of the shape memory alloy structure specifically includes: Determining the size of the shape memory alloy structure based on the parameters of the steel structure column; Based on the stress-strain curve of the shape memory alloy structure, the axial strain at the necking portion of the shape memory alloy structure, the corresponding cross-sectional pressure, and the strengthening section modulus are determined.

6. The anti-buckling design method of the anti-buckling system according to claim 4, characterized in that: The relationship is as follows: ； in, is the area of the fiber reinforced composite structure, is the elastic modulus of the fiber-reinforced composite structure, is the winding angle of the fiber reinforced composite structure, is the strain of the necked section of the shape memory alloy structure, is the axial strain conversion coefficient corresponding to the necking strain of the shape memory alloy structure, is the radius of the shape memory alloy structure, is the distance from the center of the shape memory alloy structure section to the center of the fiber reinforced composite structure section, is the elastic modulus conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure, is the area conversion coefficient of the fiber reinforced composite structure corresponding to the necking strain of the shape memory alloy structure; is the cross-sectional area of the shape memory alloy structure, is the stress corresponding to the strain at the necking section of the shape memory alloy structure, is the strengthening section modulus of the shape memory alloy structure.

7. The anti-buckling design method of the anti-buckling system according to claim 4, characterized in that: The critical stiffness is expressed as: ； in, is the critical stiffness, is the allowable stress of the cable-stayed component, is the design stress at both ends of the cable-stayed assembly, is the height of the rectangular column, is the design axial pressure for the rectangular column.

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