Anti-buckling system integrating stress-driven self-adjustment and cathode protection functions and design method

Abstract

The invention discloses an anti-buckling system integrating stress-driven self-adjustment and cathode protection functions and a design method. The anti-buckling system integrating the stress-driven self-adjustment and cathode protection functions comprises a composite rib, a power source and a sensing assembly, and the composite rib and the sensing assembly are installed on a steel structure column; the composite bars serve as a plurality of cable-stayed assemblies which are symmetrically distributed on the two sides of the steel structure column. Each cable-stayed component comprises a shape memory alloy inner core and a fiber reinforced composite material wire which are insulated from each other, the fiber reinforced composite material wire is arranged in a groove of the shape memory alloy inner core, and two ends of the shape memory alloy inner core corresponding to each cable-stayed component are respectively connected with a positive electrode and a negative electrode of a power supply; the fiber reinforced composite material wire corresponding to each cable-stayed assembly is connected with the positive electrode of the power supply, and the steel structure column is connected with the negative electrode of the power supply. The corrosion resistance of the steel structure column under the coastal environment and the seismic load and the buckling resistance of the steel structure column under the external load can be improved.

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 resistance devices, such as traditional stiffening components, external support frames and damping devices, have improved the stability of components to a certain extent, but they still have some shortcomings. For example, traditional stiffening devices have poor corrosion resistance, are particularly susceptible to damage in humid or corrosive environments, and have high maintenance costs; damping devices often cannot be restored to their original state after being hit by an earthquake, have limited energy dissipation characteristics, and are difficult to adapt to high-intensity external force impacts; and many devices have poor ductility and are prone to brittle failure under large deformation conditions.

[0003] Therefore, the prior art 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 integrating stress-driven self-adjustment and cathodic protection functions, aiming to solve the problem in the prior art that when the steel structure is anti-buckled by the anti-buckling device under coastal environment and seismic load, the corrosion resistance, impact resistance or ductility of the device is poor, resulting in poor corrosion resistance of the steel structure.

[0005] In a first aspect, an embodiment of the present application provides an anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions, the anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions comprises a composite rib, a power supply and a sensor assembly, the composite rib and the sensor assembly are mounted on a steel structure column; the composite rib comprises a plurality of inclined-stayed assemblies, and the plurality of inclined-stayed assemblies are symmetrically distributed on both sides of the steel structure column; each of the inclined-stayed assemblies comprises an insulated shape memory alloy structure and a fiber reinforced composite structure, the fiber reinforced composite structure is arranged in a groove of the shape memory alloy structure, the two ends of the shape memory alloy structure corresponding to each inclined-stayed assembly are respectively connected to the positive and negative electrodes of the power supply, and the fiber reinforced composite structure corresponding to each inclined-stayed assembly is connected to the positive electrode of the power supply, and the steel structure column is connected to the negative electrode 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 inclined-stayed assembly, so that the stretched inclined-stayed assembly is restored to a target length.

[0006] Optionally, in one embodiment of the present application, a first lateral support and a second lateral support are respectively provided on both sides of the steel structure column, and the plurality of inclined-stayed assemblies include a first inclined-stayed, a second inclined-stayed, a third inclined-stayed and a fourth inclined-stayed, the two ends of the first inclined-stayed are respectively connected to the top end of the steel structure column and the upper side end of the first lateral support, the two ends of the second inclined-stayed are respectively connected to the top end of the steel structure column and the upper side end of the second lateral support, the two ends of the third inclined-stayed are respectively connected to the bottom end of the steel structure column and the lower side end of the first lateral support, and the two ends of the fourth inclined-stayed are respectively connected to the bottom end of the steel structure column and the lower side end of the second lateral 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-tie, and the second strain sensor is arranged on the second inclined-tie; when the first strain sensor detects that the strain of the first inclined-tie is greater than a preset value, the power supply applies an excitation current to the first inclined-tie and the third inclined-tie to restore the first inclined-tie and the third inclined-tie to an initial length; when the first strain sensor detects that the strain of the second inclined-tie is greater than a preset value, the power supply applies an excitation current to the second inclined-tie and the fourth inclined-tie to restore the second inclined-tie and the fourth inclined-tie to an initial length.

[0008] Optionally, 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.

[0009] Optionally, in one embodiment of the present application, each of the cable-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.

[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 embodiments of the present application also provides an anti-buckling design method for an anti-buckling system that integrates stress-driven self-adjustment 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-stayed assembly, multiple diagonal-stayed assemblies are installed on a steel structure column, and if the stiffness of the steel structure column reaches the critical stiffness, the anti-buckling design of one diagonal-stayed 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; the 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: ; 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.

[0014] Optionally, in one embodiment of the present application, the critical stiffness is expressed as: ; in, is the critical stiffness, is the allowable stress of the cable-stayed assembly, 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.

[0015] Beneficial effect: The present application provides an anti-buckling system and a design method integrating stress-driven self-adjustment and cathodic protection functions. In the anti-buckling system, a cable-stayed assembly is formed by a memory alloy structure and a corresponding fiber-reinforced composite structure. Multiple cable-stayed assemblies are installed on a steel structure column. The strain is detected by a sensor 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 cable-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 cable-stayed assembly under a coastal environment and seismic load, thereby improving the corrosion resistance of the structure. The cable-stayed assembly can also perform self-adjustment to improve the recovery capacity of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A three-dimensional diagram of a preferred embodiment of the anti-buckling system of the present invention that integrates stress-driven self-adjustment and cathodic protection functions; Figure 2 A schematic plan view of an SMA-CFRP reinforcement in a preferred embodiment of the anti-buckling system of the present application that integrates stress-driven self-adjustment and cathodic protection functions; 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; Figure 4 It is a flow chart of a preferred embodiment of the anti-buckling design method of the present application; Figure 5 It is a SMA-CFRP stress-strain relationship curve diagram of a preferred embodiment of the anti-buckling design method of the present application; Figure 6 It 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.

[0018] Description of reference numerals: 11. First inclined pull; 12. Second inclined pull; 13. Third inclined pull; 14. Fourth inclined pull; 20. Steel structure column; 21. First transverse support; 22. Second transverse support.

[0019] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and effect of the present application clearer and more specific, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. The described embodiments are only possible technical implementations of the present application, not all possible implementations. Based on the embodiments in the present application, those skilled in the art can completely combine the embodiments of the present application to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of the present application.

[0021] First, the terms involved in the embodiments of the present application are introduced: shape memory alloy (Shape Memory Alloy, SMA for short), that is, the shape memory alloy structure of the present application is SMA tendon; carbon fiber reinforced composite material (Carbon Fiber Reinforced Polymer, CFRP for short), that is, the carbon fiber reinforced composite structure of the present application is CFRP fiber; the diagonal-stayed component of the present application is SMA-CFRP tendon, and multiple diagonal-stayed components constitute composite tendons.

[0022] The following describes the anti-buckling system and design method of the embodiment of the present application with reference to the accompanying drawings. In view of the problem that when the steel structure is buckled by the anti-buckling device under the coastal environment and seismic load in the above-mentioned related art, the corrosion resistance, impact resistance or ductility of the device is poor, resulting in poor corrosion resistance of the steel structure, the present application provides an anti-buckling system with stress-driven self-adjustment and cathodic protection functions, in which a diagonal-stayed assembly is formed by a memory alloy structure and a corresponding fiber-reinforced composite structure, and multiple diagonal-stayed assemblies are installed on the steel structure column, and the strain is detected by the sensor assembly on the surface of the steel structure column, so that the fiber-reinforced composite structure in the stretched diagonal-stayed assembly is applied with an excitation current through a power supply to restore to the original target length, so that the steel structure column is protected by each diagonal-stayed assembly under the coastal environment and seismic load, and the corrosion resistance of the structure is improved, and the diagonal-stayed assembly can be self-reset to improve the recovery ability of the structure. Thereby, the technical problem in the related art that when the steel structure is anti-buckling under coastal environment and seismic load through the anti-buckling device, the corrosion resistance, impact resistance or ductility of the device is poor, resulting in poor corrosion resistance of the steel structure.

[0023] The anti-buckling system of the present application has the advantages of high strength, high energy consumption and high ductility through the combination of fiber-reinforced composite materials and shape memory alloys (SMA). Fiber-reinforced composite materials have the advantages of high strength and corrosion resistance, and the self-resetting characteristics of SMA can help the device return to its original state after being deformed by force, thereby improving the self-recovery ability of the structure. In addition, winding fiber-reinforced composite materials such as CFRP on the surface of shape memory alloys can effectively inhibit the necking of SMA and significantly improve the strength and large plastic deformation capacity of SMA after yielding, which shows an excellent buffering effect when resisting large-scale buckling failure of components. That is, the present application can improve the corrosion resistance of steel structure columns under coastal environments and seismic loads and the anti-buckling performance under external loads.

[0024] The technical solution of the present application is described in detail with specific embodiments below. 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.

[0025] 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, the anti-buckling system with integrated stress-driven self-adjustment and cathodic protection functions comprises a composite rib, a power supply (not shown in the figure) and a sensor assembly (not shown in the figure), the composite rib and the sensor assembly are installed on a steel structure column 20; the composite rib comprises a plurality of inclined-stayed assemblies, and the plurality of inclined-stayed assemblies are symmetrically distributed on both sides of the steel structure column 20; each of the inclined-stayed assemblies comprises an insulated shape memory alloy structure (i.e., a shape memory alloy inner core) and a fiber-reinforced composite structure (i.e., a fiber-reinforced composite material wire), the fiber-reinforced composite structure being arranged in a groove of the shape memory alloy structure, the two ends of the shape memory alloy structure corresponding to each inclined-stayed assembly being respectively connected to the positive and negative electrodes of the power supply, and the fiber-reinforced composite structure corresponding to each inclined-stayed assembly being connected to the positive electrode of the power supply, and the steel structure column 20 being connected to the negative electrode 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 inclined-stayed assembly under tension, so that the inclined-stayed assembly under tension is restored to a target length.

[0026] The multiple inclined-stayed components (SMA-CFRP tendons) of the embodiment of the present application are divided into a part of inclined-stayed components under tension and another part of inclined-stayed components under compression. A stimulation current is applied to the SMA tendons corresponding to the inclined-stayed components under tension to restore the length to the target length (i.e., the original length, or other set length).

[0027] It should be noted that current is applied 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, an excitation current is applied to the shape memory alloy structure (SMA tendon) through a power supply to achieve self-resetting of the length of the SMA tendon. This is another self-recovery system with a self-resetting function, which can improve the recovery of the steel structure column 20 after buckling due to external loads (earthquake or impact). Therefore, the cooperation of these two systems can improve the service life and safety of the steel structure column 20.

[0028] It is understood that the 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 self-adjust the length, which can also be understood as applying current to the power supply to adjust the temperature.

[0029] This application aims to solve the problem that existing steel structures are susceptible to corrosion and lack self-reset function when buckled under coastal environments and seismic loads. In the embodiment of this application, spiral grooving (i.e. grooves) are performed on the surface of SMA tendons (i.e. shape memory alloy structures), and carbon fiber reinforced composite materials (CFRP) are embedded to form a fiber-reinforced composite structure to realize SMA-CFRP tendons (i.e. cable-stayed components) that integrate stress-driven self-reset and cathodic protection functions. The overall technical effect of the anti-buckling system of the embodiment of this application is: significantly improve the anti-buckling ability of steel structures, enhance corrosion resistance in coastal environments, and improve the recovery of structures after buckling under external loads (earthquakes or impacts). It significantly improves the service life and safety of steel structures, and is particularly suitable for coastal and earthquake-prone environments, reducing the maintenance cost of the structure.

[0030] In one embodiment of the present application, Figure 1 As shown, the first lateral support 21 and the second lateral 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 lateral 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 lateral 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 lateral 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 lateral support 22.

[0031] It can be understood that the plurality of inclined-stayed assemblies in this embodiment include four inclined-stayed assemblies, namely, a first inclined-stayed assemblies 11 , a second inclined-stayed assemblies 12 , a third inclined-stayed assemblies 13 and a fourth inclined-stayed assemblies 14 .

[0032] Specifically, in the embodiment of the present application, the SMA-CFRP reinforcement (camber-stayed assembly) is installed in the steel structure column 20 as an anti-buckling cable-stayed system, and an activation current is applied to generate a pre-tightening force.

[0033] like Figure 1As shown, the SMA-CFRP tendon 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 tendon 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, and these two sides are the two sides of the long side with smaller inertia. There is a lateral support made of stainless steel in the middle of the rectangular column, namely the first lateral support 21 and the second lateral support 22. The first diagonal 11 (SMA-CFRP tendon anti-buckling diagonal) and the second diagonal 12 are installed on the upper side of the first lateral support 21 and the second lateral support 22 respectively. The third inclined groove and the fourth diagonal 14 are installed on the lower side of the first lateral support 21 and the second lateral support 22. The angle between the first inclined brace 11, the second inclined brace 12, the third inclined brace 13 and the fourth inclined brace 14 and the steel structure column 20 (rectangular column) is q (the preset angle in this embodiment is 45 degrees), and the total length of the first inclined brace 11, the second inclined brace 12, the third inclined brace 13 and the fourth inclined brace 14 is L, then the length of the first lateral support 21 and the second lateral support 22 is sinqL.

[0034] In one embodiment of the present application, the sensing assembly includes a first strain sensor and a second strain sensor, wherein the first strain sensor is arranged on the first inclined rope 11, and the second strain sensor is arranged on the second inclined rope 12; when the first strain sensor detects that the strain of the first inclined rope 11 is greater than a preset value, the power supply applies an excitation current to the first inclined rope 11 and the third inclined rope 13, so that the first inclined rope 11 and the third inclined rope 13 are restored to their initial lengths; when the first strain sensor detects that the strain of the second inclined rope 12 is greater than a preset value, the power supply applies an excitation current to the second inclined rope 12 and the fourth inclined rope 14, so that the first inclined rope 11 and the third inclined rope 13 are restored to their initial lengths. The strain sensor realizes strain detection by sensing the resistance change of the inclined rope.

[0035] Specifically, in the self-recovery system with a self-reset function, the first strain sensor of the first inclined rope 11 and the second strain sensor of the second inclined rope 12 monitor the strain of the inclined rope to determine its buckling condition. 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 SMA-CFRP tendons, A b is the area of ​​the SMA-CFRP reinforcement section, q is the angle between the cable and the rectangular column), the rectangular column buckles toward the second lateral support 22, the second cable 12 and the fourth cable 14 are compressed, and the first cable 11 and the third cable 13 are stretched. At this time, an activation current can be applied to the stretched first cable 11 and the third cable 13 to restore them to their original length, realizing the self-adjustment function of the SMA-CFRP cable anti-buckling system. When the strain of the first cable 11 is less than 0 and the strain sensor strain of the second cable 12 is greater than the preset value (i.e. M y N d l / (12 EIE s A b sinq), the rectangular column is compressed toward the first lateral support 21, the first inclined cable 11 and the third inclined cable 13 are compressed, and the second inclined cable 12 and the fourth inclined cable 14 are tensile. At this time, an activation current can be applied to the second inclined cable 12 and the fourth inclined cable 14 to restore them to their original lengths, thereby realizing the self-adjusting function of the SMA-CFRP tendon anti-buckling inclined cable system.

[0036] In the present application, in a set of anti-corrosion cathodic protection system, the fiber reinforced composite structure (i.e., CFRP fiber) of the first inclined-stayed brace 11, the second inclined-stayed brace 12, the third inclined-stayed brace 13, and the fourth inclined-stayed brace 14 is connected to the positive pole of the power supply of the cathodic protection system, and the rectangular column is connected to the negative pole of the power supply of the cathodic protection system, so as to realize the cathodic protection function of the SMA-CFRP tendon anti-buckling system and effectively inhibit the corrosion of the rectangular column.

[0037] 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.

[0038] Specifically, a 0.2 mm thick insulating material, i.e., the insulating layer, is coated between the CFRP fiber and the SMA surface.

[0039] In one embodiment of the present application, each of the cable-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.

[0040] Specifically, Figure 2 and Figure 3 As shown, the SMA rib is divided into three areas along the length direction: the installation section, the variable section section and the reinforcement section. The two ends are installation sections with a length of 300 mm and a diameter of 30 mm, the inner part is a variable section section with a length of 50 mm, and the middle is a reinforcement section with a diameter of 12 mm. The length can be determined according to the actual design requirements. The embodiment of this application takes (1500 mm). The diameter ratio of the installation section to the reinforcement section is 2.5~3. Among them, the installation section is provided with an annular groove with a width of 2 mm and a depth of 4 mm at a distance of 20 mm from the variable section section. The equal-shaped grooves opened start from here, covering the variable section and the reinforcement section. The grooves at the cross section of the annular groove need to be chamfered to prevent cutting of the CFRP fibers.

[0041] 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%.

[0042] Specifically, the groove of the embodiment of the present application is at an angle of 45 degrees to the horizontal direction, but is 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).

[0043] In the embodiment of the present application, CFRP fibers are wound around the surface of the SMA-CFRP tendons to suppress the necking of the SMA tendons under large deformation, significantly improve the strength and ductility of the SMA tendons, and are suitable as energy-absorbing supports for structural buckling resistance under seismic loads. The CFRP fibers wound around the surface of the SMA-CFRP tendons can be used as auxiliary anodes for cathodic protection, suppress structural erosion, and increase the service life of coastal concrete structures. SMA has a stress-driven function, and can generate self-driven stress after structural buckling to make the structure self-adjusting.

[0044] See also Figure 2 The preparation method of the SMA-CFRP reinforcement (slant-stayed component) of the present application is as follows: Step K1: First, in order to ensure the self-resetting ability of the SMA-CFRP reinforcement, the SMA reinforcement needs to be pre-tensioned (5% to 6%) before preparation. The SMA reinforcement selected in this application is a plain round reinforcement.

[0045] Step K2, a plurality of grooves are provided on the surface of the metal SMA at a preset angle to the horizontal direction, and a plurality of the grooves are filled with fiber composite materials. Further, 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).

[0046] Step K3, the shapes of the grooves are the same, which can be circular or rectangular. Further, the grooves in this embodiment are circular. The grooves should be arranged at equal intervals in the cross section and length direction of the SMA. In this embodiment, 4 grooves are arranged at equal intervals in the cross section, and the spacing along the length is 100 mm. The width of the grooves is about 2.5~3 mm, and the volume of the grooves accounts for about 35% to 50% of the volume of the SMA.

[0047] Step K4, SMA is divided into three areas in the length direction: the installation section, the variable section section, and the reinforcement section. The two ends are installation sections with a length of 300 mm and a diameter of 30 mm, the inner part is a variable section section with a length of 50 mm, and the middle part is a reinforcement section with a diameter of 12 mm. The length can be determined according to the actual design requirements. The embodiment of this application takes (1500 mm). The diameter ratio of the installation section to the reinforcement section is 2.5~3. Among them, the installation section is provided with an annular groove with a width of 2 mm and a depth of 4 mm at a distance of 20 mm from the variable section section. The equi-shaped grooves opened start from here, covering the variable section and the reinforcement section. The grooves at the cross section of the annular groove need to be chamfered to prevent cutting of the CFRP fibers.

[0048] Step K5, the function of the annular groove is to anchor the CFRP. The CFRP is filled from the annular groove, and in order to ensure the anchoring effect, the fibers in the annular grooves at both ends need to be wound at least 2 times.

[0049] Step K6: Before filling the CFRP fibers, a 0.2 mm thick insulating material needs to be evenly coated on the SMA surface.

[0050] Step K7, each beam area is about 2 mm 2 The 2200 mm long CFRP fiber is soaked in epoxy resin and then wound in the annular groove at one end of the SMA. It is first wound twice in the annular groove and then wound along the spiral grooves opened in the SMA variable section and reinforcement section to the annular groove of the mounting section at the other end. After winding twice, the excess CFRP fiber is cut off.

[0051] Step K8, placing the SMA-CFRP reinforcement wrapped with CFRP fibers in a curing box at 45 degrees Celsius for 24 hours. The preset angle, CFRP dosage and stiffness of the obtained SMA-CFRP reinforcement (slant-stayed component) should satisfy the above relationship to prevent necking.

[0052] 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: 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.

[0053] In a possible implementation, the material properties include the axial strain at the necking of the shape memory alloy structure, the corresponding cross-sectional pressure, and the strengthening section modulus. The size of the shape memory alloy structure is determined based on the parameters of the steel structure column; the axial strain at the necking of the shape memory alloy structure, the corresponding cross-sectional pressure, and the strengthening section modulus are determined based on the stress-strain curve of the shape memory alloy structure.

[0054] In a possible implementation, the relationship between the fiber-reinforced composite structure and the shape memory alloy structure 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.

[0055] That is to say, 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.

[0056] Specifically, in the above relationship, , and The expression is as follows:

[0057]

[0058] It should be noted that see Figure 1 and Figure 5When the SMA-CFRP reinforcement (cable-stayed assembly) is in a state of 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, which can dissipate a large amount of energy through the characteristics of anti-necking, high strength and large deformation 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. .

[0059] exist Figure 5 In the stress-strain curve of the shape memory alloy structure, the arrow position of the SMA tendon 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 tendon are obtained from the curve.

[0060] 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 according to the local engineering stress-strain curve of the necking section corresponding to the SMA reinforcement.

[0061] 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 property and the relationship.

[0062] Specifically, determine the geometric dimensions of the SMA and basic material properties , , After that, 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 be determined according to the above relationship. After the CFRP fiber angle is determined, a spiral groove along the SMA axis direction is opened in the SMA variable section and the reinforcement section.

[0063] In step S103, after the shape memory alloy structure and the corresponding fiber reinforced composite structure are formed into a diagonal-stayed assembly according to the angle and the amount, a plurality of diagonal-stayed assemblies are installed on a steel structure column. If the stiffness of the diagonal-stayed assembly (i.e., the rectangular column) reaches a critical stiffness, the anti-buckling design of one diagonal-stayed assembly is completed.

[0064] 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.

[0065] The compressive buckling mechanism of SMA-CFRP reinforcement is Figure 6 The model shown. The rectangular column is simply supported, the self-restoring anti-buckling force is simplified to a concentrated force, and the resultant force of the SMA-CFRP reinforcement on the tension side acts on the rectangular column through the lateral support to resist the concentrated buckling force.

[0066] 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: ; (1) In the formula, is the area of ​​the SMA-CFRP reinforcement section, is the axial force in the SMA rod, is the stress at both ends.

[0067] Anti-buckling concentration , calculated as follows: ; (2) In the formula, 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 column and the rectangular column.

[0068] 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: ; (3) 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: ; (5) In the formula, is the stiffness of the rectangular column, is the height of the rectangular column.

[0069] Substituting formula (2) into formula (5) yields formula (6): ; (6) In the formula, 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 column and the rectangular column.

[0070] When the SMA-CFRP reinforcement is in a critical state, its axial stress reaches the design stress When the SMA-CFRP reinforcement has a plastic hinge, the mid-span displacement is considered to reach the maximum value. In order to prevent buckling, the self-adjusting moment at the end point should be greater than the bending moment, as shown in the following formula: ; (7) Substituting formula (6) into formula (7) yields formula (8): ; (8) The right side of formula (8) is the critical stiffness, and the critical stiffness of the anti-buckling system can be expressed as: .

[0071] 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 will do.

[0072] That is to say, in this application, firstly, a module is constructed according to the SMA-CFRP reinforcement design equation, that is, the design equation of the SMA-CFRP reinforcement is constructed by the relational expression, and 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 inclined tension in the 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.

[0073] This application improves the utilization rate of materials by preparing and designing SMA-CFRP bars, calculating the preset angle, CFRP dosage and stiffness of SMA-CFRP bars according to actual engineering conditions. The SMA-CFRP bars of this application can be used as the diagonal tension of the structural anti-buckling system, and a corresponding design method is established. A calculation formula for the critical stiffness of the rectangular column in the system when buckling is proposed, which ensures the effectiveness of the anti-buckling design.

[0074] In the description of this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0075] 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 referred device or element 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.

[0076] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0077] It should be noted that: in this application, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the 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 higher in level than the second feature. The first feature being "below", "below" and "below" the 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 lower in level than the second feature.

[0078] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be 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 of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0079] In the description of this specification, the description with reference to the terms "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 schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0080] 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 it. 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate 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 rib, a power supply and a sensor component, wherein the composite rib and the sensor component are installed on a steel structure column; The composite reinforcement includes a plurality of inclined-stayed components, and the plurality of inclined-stayed components are symmetrically distributed on both sides of the steel structure column; Each of the inclined-stayed components comprises an insulated shape memory alloy structure and a fiber reinforced composite structure, wherein the fiber reinforced composite structure is arranged in a groove of the shape memory alloy structure, and both ends of the shape memory alloy structure corresponding to each of the inclined-stayed components are respectively connected to the positive and negative electrodes of the power supply, and the fiber reinforced composite structure corresponding to each of the inclined-stayed components is connected to the positive electrode of the power supply, and the steel structure column is connected to the negative electrode 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 inclined-stayed component to restore the stretched inclined-stayed component to a target length.

2. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 1, characterized in that: A first transverse support and a second transverse support are respectively provided on both sides of the steel structure column, and the multiple inclined-stayed components include a first inclined-stayed, a second inclined-stayed, a third inclined-stayed and a fourth inclined-stayed. The two ends of the first inclined-stayed 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-stayed 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-stayed 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-stayed are respectively connected to the bottom end of the steel structure column and the lower side end of the second transverse support.

3. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 2 is characterized in that: The sensing assembly includes a first strain sensor and a second strain sensor, wherein the first strain sensor is arranged on the first inclined pulley, and the second strain sensor is arranged on the second inclined pulley; 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 an initial length; 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 an initial length.

4. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 1, 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.

5. 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.

6. The anti-buckling system integrating stress-driven self-adjustment and cathodic protection functions according to claim 1, characterized in that: The groove is an annular groove, the cross section of which is circular or rectangular, and 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%.

7. 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 6, 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 the angle of the shape memory alloy structure and the amount of the fiber reinforced composite structure according to the size, the material property 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-stayed assembly, a plurality of diagonal-stayed assemblies are installed on a steel structure column. If the stiffness of the steel structure column reaches a critical stiffness, the anti-buckling design of one diagonal-stayed assembly is completed.

8. The anti-buckling design method of the anti-buckling system according to claim 7, characterized in that: The material properties include the axial strain at the necking 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 point of the shape memory alloy structure, the corresponding cross-sectional pressure and the strengthening section modulus are determined.

9. The anti-buckling design method of the anti-buckling system according to claim 7, 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.

10. The anti-buckling design method of the anti-buckling system according to claim 7, characterized in that: The critical stiffness is expressed as: ； in, is the critical stiffness, is the allowable stress of the cable-stayed assembly, 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.

Images