A self-anchored self-compensating reinforcing device and method of SMA plate-negative poisson's ratio combination

Abstract

The application discloses a self-anchoring and self-compensating reinforcing device and method of SMA plate-negative Poisson's ratio combination, which comprises at least two groups of adapter steel plates, negative Poisson's ratio anchoring blocks and SMA plates; the interior of the adapter steel plates is provided with wedge-shaped grooves; the two ends of the SMA plates are respectively arranged in the wedge-shaped grooves of the two groups of adapter steel plates; the negative Poisson's ratio anchoring blocks are clamped between the side edges of the SMA plates and the side walls of the wedge-shaped grooves; when a thermal excitation is applied to the SMA plates, the SMA plates generate axial shape recovery and shrinkage force, and drive the negative Poisson's ratio anchoring blocks to move along the wedge-shaped grooves to the center of the cracks under the action of interface friction, so that the negative Poisson's ratio anchoring blocks expand in the transverse section under the axial tension, are locked with the groove walls of the wedge-shaped grooves and the SMA plates, and the self-anchoring of the SMA plates is realized; when the prestress of the SMA plates relaxes in long-term service, the axial tension of the negative Poisson's ratio anchoring blocks is reduced and the self-adaptive reverse springback deformation is generated, the axial relaxation deformation of the SMA plates is compensated, and the prestress self-compensation is realized.

Description

Technical Field

[0001] This invention belongs to the field of steel structure reinforcement technology, specifically relating to a self-anchoring and self-compensating reinforcement device and method of SMA plate-negative Poisson's ratio combination. Background Technology

[0002] Existing methods for reinforcing steel structures using SMA (Surface Mounted Abrasive) typically involve directly bonding SMA components to the surface of the steel structure members and applying thermal excitation to the SMA components to introduce prestress, thereby strengthening the steel structure. However, the operating excitation temperature of SMA is generally too high. High temperatures can easily cause aging of the adhesive layer, deterioration of bonding performance, and reduction of interfacial bonding reliability, thus significantly weakening the overall reinforcement effect.

[0003] Furthermore, SMA material itself has poor processing performance. If drilling, grooving, or other structural treatments are directly applied to the SMA component, not only is the processing procedure cumbersome and the manufacturing efficiency low, but stress concentration is also easily generated at the opening and groove locations, damaging the component's mechanical properties and shape memory effect. Currently, conventional anchoring solutions mostly use external mechanical anchors, which have a complex overall structure, require many on-site installation procedures, and have poor construction convenience, hindering their widespread application in engineering projects.

[0004] On the other hand, under long-term service conditions, the SMA reinforcement system is prone to prestress relaxation due to the coupled effects of environmental temperature cycles and continuous reciprocating loads, resulting in a gradual decline in reinforcement effectiveness. Traditional prestress compensation methods mostly rely on secondary thermal excitation tensioning or direct replacement of SMA components, which not only have high maintenance costs and long construction cycles, but also affect the normal use of the structure, making it difficult to meet the requirements of long-term service in actual engineering projects.

[0005] Therefore, there is an urgent need in engineering to develop an SMA reinforcement device that can achieve stable and reliable anchoring without cutting, drilling, or damaging the SMA component itself, while also having a prestress adaptive compensation function, in order to overcome many shortcomings of existing technologies. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a self-anchoring and self-compensating reinforcement device for SMA plates and negative Poisson's ratio combinations. This self-anchoring and self-compensating reinforcement device is used to solve the problems of thermal excitation affecting the performance of the adhesive layer, insufficient anchoring reliability, and difficulty in maintaining prestress over a long period of time in existing SMA reinforcement technologies.

[0007] The second objective of this invention is to provide a self-anchoring and self-compensating reinforcement method for SMA plate-negative Poisson's ratio combination.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0009] A self-anchoring and self-compensating reinforcement device based on an SMA plate and a negative Poisson's ratio combination includes a transition steel plate, a negative Poisson's ratio anchor block, and an SMA plate. At least two sets of transition steel plates are provided, each set fixed to both sides of the potential propagation path of a crack tip on the surface of the reinforced steel structure member. Each set of transition steel plates has a wedge-shaped groove inside, the width of which gradually increases along the direction away from the crack tip on the surface of the steel structure member. Both ends of the SMA plate are respectively inserted into the wedge-shaped grooves of the two sets of transition steel plates. The negative Poisson's ratio anchor block is sandwiched between the side of the SMA plate and the inclined sidewall of the wedge-shaped groove.

[0010] When thermal excitation is applied to the SMA plate, the SMA plate generates axial shape recovery shrinkage force, and under the action of interface friction, it drives the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center, so that the negative Poisson's ratio anchor block undergoes transverse cross-sectional expansion under axial tension, and interlocks with the groove wall of the wedge groove and the SMA plate to achieve self-anchoring of the SMA plate;

[0011] When the SMA plate experiences prestress relaxation during long-term service, the axial tensile force on the negative Poisson's ratio anchor block decreases and an adaptive reverse rebound deformation is generated, which compensates for the axial relaxation deformation of the SMA plate, maintains the pre-tightened stress state of the system, and realizes prestress self-compensation.

[0012] Preferably, the effective bonding area between the transition steel plate and the steel structure component is greater than the projected area of ​​the SMA plate in the direction of force.

[0013] Preferably, the effective bonding area is not less than 50mm × 300mm, and the thickness of the adapter steel plate is 4-6mm.

[0014] Preferably, the angle between the sidewall of the wedge groove and the longitudinal axis of the SMA plate is no greater than 45°.

[0015] Preferably, on the adapter steel plate, the local bending stiffness of the wedge-shaped groove opening area is less than the bending stiffness of the ungrooved area in the adapter steel plate.

[0016] Preferably, the length of the cavity reserved in the wedge groove for the adaptive retraction and sliding of the negative Poisson's ratio anchor block is less than 0.5 mm.

[0017] Preferably, the thickness of the SMA plate is less than the depth of the wedge-shaped groove.

[0018] Preferably, the cross-sectional dimension of the negative Poisson's ratio anchor block in the unloaded state is smaller than the assembly gap between the SMA plate and the sidewall of the wedge groove.

[0019] Preferably, it also includes a temporary fixing component; the temporary fixing component is a detachable structure, which is bridging between the two sets of transition steel plates, and is used to temporarily position and constrain the relative positions of the SMA plate, the negative Poisson's ratio anchor block and the transition steel plate before applying thermal excitation to the SMA plate, and is removed after the SMA plate completes thermal excitation and forms stable self-anchoring.

[0020] A self-anchoring and self-compensating reinforcement method for SMA plate-negative Poisson's ratio combination includes the following steps:

[0021] S1: Sandblast the bonding interface of the transition steel plate, the inner wall of the wedge groove, and the contact surface of the negative Poisson's ratio anchor block to remove the surface oxide layer and impurities, and improve the bonding and friction performance of the interface.

[0022] S2: At least two sets of transition steel plates are fixed to both sides of the potential propagation path of the crack tip on the surface of the reinforced steel structure component by adhesive bonding. The transition steel plates are provided with wedge-shaped grooves, and the width of the wedge-shaped grooves gradually increases along the direction away from the crack tip on the surface of the steel structure.

[0023] S3: Place both ends of the SMA plate into the wedge grooves of the two sets of transition steel plates respectively, so that the SMA plate is kept horizontal and in contact with the surface of the steel structure component.

[0024] S4: Embed the negative Poisson's ratio anchor block between the side of the SMA plate and the side wall of the wedge groove, and ensure that the negative Poisson's ratio anchor block is in close contact with the SMA plate and the side wall of the wedge groove;

[0025] S5: Apply thermal excitation to the SMA plate to generate axial shape recovery and retraction force, and drive the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center until the negative Poisson's ratio anchor block expands laterally under axial tension, and locks itself with the groove wall of the wedge groove and the SMA plate to achieve self-anchoring of the SMA plate.

[0026] S6: When prestress relaxation occurs during the long-term service of the SMA plate, the negative Poisson's ratio anchor block generates adaptive reverse rebound deformation as the axial tensile force decreases, and undergoes slight slippage along the wedge groove in the direction away from the crack center to compensate for the axial relaxation deformation of the SMA plate, maintain the pre-tightened stress state of the system, and realize prestress self-compensation.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. When the self-anchoring and self-compensating reinforcement device of the present invention applies thermal excitation to the SMA plate, the SMA plate generates an axial shape recovery retraction force, which drives the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center through interfacial friction. Under axial tension, the negative Poisson's ratio anchor block undergoes transverse cross-sectional expansion due to its own negative Poisson's ratio effect, locking itself with the sidewall of the wedge groove and the SMA plate, thus achieving hole-free self-anchoring of the SMA plate. When the SMA plate experiences prestress relaxation during long-term service, the axial tensile force on the negative Poisson's ratio anchor block decreases synchronously and generates adaptive reverse springback deformation, compensating for the axial relaxation deformation of the SMA plate, maintaining the pre-tightened stress state of the reinforcement system, and achieving passive prestress self-compensation.

[0029] 2. The self-anchoring and self-compensating reinforcement device of the present invention does not require drilling or grooving of the SMA base material, thus avoiding the risk of weakening of the base material cross section and stress concentration. At the same time, it significantly reduces the thermal impact of the thermal excitation process on the performance of the adhesive layer between the transfer steel plate and the steel structure component, effectively avoiding the problems of adhesive layer aging and debonding failure, and can significantly improve the long-term service stability and anchoring reliability of the SMA reinforcement system.

[0030] 3. The self-anchoring and self-compensating reinforcement device of the present invention utilizes the inherent characteristics of the negative Poisson's ratio anchor block under axial tension and lateral expansion, and with the gradual structure of the wedge groove, achieves self-locking self-anchoring with the greater the tension and the stronger the locking force. No additional anchoring components are required, the structure is simple and the anchoring reliability is high.

[0031] 4. The self-anchoring and self-compensating reinforcement device of the present invention can also achieve adaptive prestress self-compensation when the prestress of the SMA plate relaxes through the force-deformation coupling effect between the SMA plate and the negative Poisson's ratio anchor block. It can maintain the prestress of the system without manual secondary tensioning, thereby effectively suppressing the prestress attenuation and thus greatly improving the long-term service stability of the SMA reinforcement system.

[0032] 5. The self-anchoring and self-compensating reinforcement device of the present invention does not require any damaging treatment such as drilling or welding on existing steel structure components. The construction process is simple and can be adapted to various steel structure crack reinforcement and prestressing strengthening scenarios such as steel components of factories, steel structures of bridges, and steel supports of buildings. It has strong engineering applicability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the installation of the self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention.

[0034] Figure 2 This is a perspective view of the self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention.

[0035] Figure 3This is a front view of the self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention.

[0036] Figure 4 This is a force analysis diagram of the self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention during the initial reinforcement stage.

[0037] Figure 5 This is a stress analysis diagram of the self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention during the prestress loss stage.

[0038] In the figure: 1 is a self-anchoring and self-compensating reinforcement device; 2 is the crack tip of a steel structure component; 3 is a steel structure component; 101 is a transition steel plate; 102 is a negative Poisson's ratio anchor block; 103 is an SMA plate. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0040] See Figures 1-3 The self-anchoring and self-compensating reinforcement device of the SMA plate-negative Poisson's ratio combination of the present invention includes a transition steel plate, a negative Poisson's ratio anchor block, and an SMA plate. At least two sets of transition steel plates are provided, each set fixed to both sides of the potential propagation path of the crack tip on the surface of the reinforced steel structure member, serving to support the SMA plate and isolate its thermal excitation from the adhesive layer performance. Each set of transition steel plates has a wedge-shaped groove inside, the width of which gradually increases along the direction away from the crack tip on the steel structure surface. Both ends of the SMA plate are respectively inserted into the wedge-shaped grooves of the two sets of transition steel plates, and the thickness of the SMA plate (e.g., 1.5-5 mm) is smaller than the wedge shape. The groove depth ensures that the SMA plate does not rigidly contact the bottom of the wedge-shaped groove in the assembled state, thus reserving space for subsequent anchoring and deformation compensation. Furthermore, the cross-sectional dimension of the negative Poisson's ratio anchor block is smaller than the assembly gap between the SMA plate and the sidewall of the wedge-shaped groove when unloaded, and expands under load to form surface contact with the SMA plate and the sidewall of the wedge-shaped groove. The negative Poisson's ratio anchor block is sandwiched between the side of the SMA plate and the inclined sidewall of the wedge-shaped groove. In the unloaded state, the cross-sectional dimension of the negative Poisson's ratio anchor block is smaller than the assembly gap between the SMA plate and the sidewall of the wedge-shaped groove, facilitating installation and initial positioning.

[0041] When thermal excitation is applied to the SMA plate, the SMA plate undergoes a phase change upon heating, generating an axial shape recovery retraction force. Under the action of interfacial friction, this force drives the negative Poisson's ratio anchor block to move along the wedge-shaped groove towards the crack center. This causes the negative Poisson's ratio anchor block to undergo transverse cross-sectional expansion under axial tension, locking itself with the groove wall of the wedge-shaped groove and the SMA plate, thus achieving self-anchoring of the SMA plate. When the SMA plate experiences prestress relaxation during long-term service, the axial tensile force on the negative Poisson's ratio anchor block decreases, and an adaptive reverse springback deformation occurs, compensating for the axial relaxation deformation of the SMA plate and maintaining the pre-tightened stress state of the system, thus achieving prestress self-compensation.

[0042] In the above process, the dimensions of the transition steel plate, the negative Poisson's ratio anchor block, and the SMA plate are matched with each other, so that when the prestress of the SMA plate is relaxed, the negative Poisson's ratio anchor block can preferentially deform and absorb the axial deformation of the SMA plate.

[0043] See Figures 1-3 The transition steel plate is bonded to the surface of the steel structure component using structural adhesive. The effective bonding area between the transition steel plate and the steel structure component can be designed according to the prestress level applied to the SMA plate, so that the adhesive layer is within the allowable stress range during thermal excitation and long-term service of the SMA plate, thereby ensuring the reliability and durability of the connection. For example, the effective bonding area between the transition steel plate and the steel structure component is greater than the projected area of ​​the SMA plate in the stress direction. In this embodiment, the effective bonding area is not less than 50mm × 300mm, the thickness of the transition steel plate is 4-6mm, and the angle between the inclined sidewall of the wedge groove and the longitudinal axis of the SMA plate is not greater than 45°.

[0044] See Figures 1-3 On the transition steel plate, the local bending stiffness of the wedge-shaped groove area is less than that of the ungrooved area. This allows the wedge-shaped groove area to generate controlled elastic deformation throughout the entire process of SMA plate thermal excitation anchoring and prestress self-compensation during service life. This not only accommodates the wedge-locking action of the negative Poisson's ratio anchor block towards the crack center but also coordinates with the adaptive retraction and sliding of the negative Poisson's ratio anchor block during prestress relaxation. This ensures that the inner wall of the wedge-shaped groove remains tightly fitted to the negative Poisson's ratio anchor block, effectively alleviating local stress concentration and reducing the risk of slippage and jamming of the negative Poisson's ratio anchor block, thereby ensuring the stability and reliability of the device's self-anchoring and prestress self-compensation functions. In this embodiment, the cavity length reserved in the wedge-shaped groove for the adaptive retraction and sliding of the negative Poisson's ratio anchor block is less than 0.5 mm.

[0045] See Figures 1-3Before applying thermal excitation to the SMA plate, a detachable temporary fixing component can be installed on the outside of the transition steel plate, the negative Poisson's ratio anchor block, and the SMA plate. The temporary fixing component spans between two sets of transition steel plates and is used to accurately position and temporarily limit the components during the construction and installation stage to prevent the components from shifting or loosening before thermal excitation, thus ensuring installation accuracy. After the thermal excitation of the SMA plate is completed and the negative Poisson's ratio anchor block forms a stable self-locking anchor with the groove wall of the wedge-shaped groove and the SMA plate, the temporary fixing component can be removed. It does not participate in the long-term service stress of the reinforcement system, does not affect the prestressing application and prestress self-compensation function of the SMA plate, and can be reused to reduce construction costs.

[0046] See Figures 1-3 The prestress self-compensation function of this invention does not rely on the coordinated deformation between multiple sets of SMA plates, but is achieved through the force-deformation coupling effect between the SMA plate and the negative Poisson's ratio anchor block. In the initial thermal excitation stage, the SMA plate generates an axial shape recovery retraction force after being thermally excited. This axial shape recovery retraction force drives the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center. Under axial tension, the negative Poisson's ratio anchor block undergoes lateral expansion due to its own negative Poisson's ratio effect, thereby increasing the contact pressure and interface friction between it and the SMA plate and the sidewall of the wedge groove, forming a stable, hole-free self-anchoring. After entering the long-term service stage, when the prestress of the SMA plate decreases due to the cyclical changes in ambient temperature and the decay of the material shape memory effect, the axial tensile force and lateral contact pressure on the negative Poisson's ratio anchor block decrease synchronously, and then a small reverse backslip occurs along the wedge groove, accompanied by lateral adaptive retraction deformation. This backslip and retraction deformation can preferentially absorb the axial relaxation displacement generated by the SMA plate, thereby effectively slowing down or even offsetting the prestress decay, and achieving prestress self-compensation without manual intervention.

[0047] Furthermore, the self-anchoring and self-compensating reinforcement device of the present invention can be arranged near the crack tip of a steel structural member, or in other areas of the steel structural member that require active prestressing. Through the axial retraction force of the SMA plate, the self-anchoring and self-compensating reinforcement device of the present invention can actively apply compressive stress to the crack tip region of the steel structural member, thereby effectively inhibiting the initiation and propagation of cracks, and thus significantly improving the load-bearing capacity and long-term durability of the steel structural member.

[0048] See Figures 1-3 The self-anchoring and self-compensating reinforcement method of SMA plate-negative Poisson's ratio combination of the present invention includes the following steps:

[0049] S1: Sandblast the bonding interface of the transition steel plate, the inner wall of the wedge groove, and the contact surface of the negative Poisson's ratio anchor block to remove the surface oxide layer and impurities, and improve the bonding and friction performance of the interface.

[0050] S2: At least two sets of transition steel plates are fixed to both sides of the potential propagation path of the crack tip on the surface of the reinforced steel structure component by adhesive bonding. The transition steel plates are provided with wedge-shaped grooves, and the width of the wedge-shaped grooves gradually increases along the direction away from the crack tip on the surface of the steel structure.

[0051] S3: Place both ends of the SMA plate into the wedge grooves of the two sets of transition steel plates respectively, so that the SMA plate is kept horizontal and in contact with the surface of the steel structure component.

[0052] S4: Embed the negative Poisson's ratio anchor block between the side of the SMA plate and the side wall of the wedge groove, and ensure that the negative Poisson's ratio anchor block is in close contact with the SMA plate and the side wall of the wedge groove;

[0053] S5: Apply thermal excitation to the SMA plate to cause a phase change and generate axial shape recovery shrinkage force. This axial shape recovery shrinkage force is transmitted through the friction between the SMA plate and the negative Poisson's ratio anchor block, causing the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center. As the negative Poisson's ratio anchor block is under tension, it undergoes transverse cross-sectional expansion under axial tension and gradually forms surface contact with the SMA plate and the sidewall of the wedge groove, thereby establishing a reliable self-anchoring structure between the SMA plate and the transition steel plate.

[0054] S6: During the long-term service of SMA plates, when the SMA plates tend to relax prestress due to temperature changes or material properties, the negative Poisson's ratio anchor block generates adaptive reverse rebound deformation as the axial tension decreases, and slightly retreats in the wedge groove in the direction away from the crack center. Its deformation preferentially absorbs the axial deformation of the SMA plate, thereby achieving self-compensation of the prestress of the SMA plate and delaying or inhibiting the attenuation of the reinforcement effect.

[0055] See Figures 4-5 The prestressed self-compensation mechanical principle and design verification embodiment of the self-anchoring and self-compensation reinforcement method of SMA plate-negative Poisson's ratio combination of the present invention are as follows:

[0056] (1): Derivation of axial stiffness

[0057] Geometric relationships (small transformations) include:

[0058] ;

[0059] In the formula: In response, This is the amount of deformation. This is the original length.

[0060] Material constitutive properties (linear elasticity) include:

[0061] ;

[0062] In the formula: For stress, It is the elastic modulus.

[0063] The balance relationships are:

[0064] ;

[0065] In the formula: This represents the cross-sectional area in the stretching direction.

[0066] Combining the above equations, we get:

[0067] ;

[0068] Standard form of force-displacement relationship:

[0069] ;

[0070] The axial stiffness can be obtained according to Hooke's law. for:

[0071] ;

[0072] (2) Material parameters

[0073] Elastic modulus, cross-sectional area, and effective length of SMA plate , and The axial equivalent stiffness of the SMA is:

[0074] ;

[0075] In the formula: This is the axial equivalent stiffness of the SMA.

[0076] Negative Poisson's ratio anchor block: equivalent axial stiffness (Equivalent stiffness along the direction of wedge groove movement), equivalent negative Poisson's ratio The characteristic thickness is ;

[0077] Wedge groove: half angle (or equivalent wedge angle) The coefficient of friction between the negative Poisson's ratio anchor block and the sidewall / SMA plate of the wedge groove. ;

[0078] Contact equivalent stiffness: (The relationship between "lateral expansion of negative Poisson's ratio anchor block → contact pressure" is linearized; it can be regarded as an "equivalent parameter" jointly determined by the geometry of the anchor block (negative Poisson's ratio elements such as honeycomb / re-entry structure), material and local flexibility of the trench wall. It can be kept symbolic in the example.)

[0079] (3) Friction

[0080] The axial strain of the negative Poisson's ratio anchor block along the wedge groove direction is: The transverse strain of a negative Poisson's ratio material satisfies:

[0081] ;

[0082] because When a negative Poisson's ratio anchor block is under tension, the lateral strain is greater than 0, i.e., lateral expansion.

[0083] Take the equivalent "interference" (or indentation) in the lateral direction:

[0084] ;

[0085] The contact normal force (or equivalent contact pressure multiplied by area) is linearized as follows:

[0086] ;

[0087] because- Therefore, the tension will increase. .

[0088] The anti-slip frictional bearing capacity of the negative Poisson's ratio anchor block is:

[0089] ;

[0090] Let the displacement of the negative Poisson's ratio anchor block along the wedge groove be... The characteristic length of the negative Poisson's ratio anchor block is ,but:

[0091] ;

[0092] (4) Prestress relaxation

[0093] Assume that the SMA plate experiences prestress relaxation during service, which is equivalent to "force source attenuation," i.e.:

[0094] ;

[0095] That is, if no structural redistribution occurs, the axial tensile force of the SMA plate will decrease. .

[0096] To analyze only the relationship between the SMA plate and the negative Poisson's ratio anchor block, a "transfer coefficient of anchorage retraction displacement to SMA axial compensation" is introduced, namely:

[0097] ;

[0098] In the formula: The equivalent axial deformation increment when the SMA is re-tightened; This is the geometric transfer coefficient (determined by wedge angle, contact position, etc.). In the simplest case, it can be taken as... Therefore, the amount of force recovery generated by the SMA plate due to retraction is:

[0099] ;

[0100] (5) Force / deformation of anchor block after relaxation

[0101] After relaxation occurs, the system will revert to a new equilibrium point: the negative Poisson's ratio anchor block reverts to a point where the available frictional anchoring force matches the end constraint force required by the current SMA plate.

[0102] After relaxation, the axial tensile force of the SMA plate decreases as follows:

[0103] ;

[0104] The strain of the negative Poisson's ratio anchor block changes due to its retraction:

[0105] ;

[0106] The friction anchoring force becomes:

[0107] ;

[0108] At the new equilibrium point, the end slip resistance requirement is compatible with the friction capability, which can be expressed in the simplest equivalent matching form as follows:

[0109] ;

[0110] That is, the gap caused by relaxation is closed by both anchoring friction and displacement adjustment. Substituting, we get:

[0111] ;

[0112] The retraction displacement of the negative Poisson's ratio anchor block is obtained as follows:

[0113] ;

[0114] Therefore, the force compensation amount of the SMA plate is:

[0115] ;

[0116] The following are specific calculation examples:

[0117] Parameter assumptions:

[0118] (1) SMA plate parameters: elastic modulus cross-sectional area ,length Negative Poisson's ratio anchoring block parameters: height ,thickness Poisson's ratio ;

[0119] (2) Friction and contact parameters: coefficient of friction Equivalent contact stiffness ;

[0120] (3) Prestress relaxation amount: Geometric transfer coefficient is taken ;

[0121] (4) Basic mechanical relationships:

[0122] Axial equivalent stiffness of SMA plate: ;

[0123] The resilience of SMA plates: ;

[0124] Frictional force of negative Poisson's ratio anchor blocks: ;

[0125] (5) Force balance equation:

[0126] After the prestress is relaxed, the system satisfies the following in the new equilibrium state: ;

[0127] (6) Calculation of displacement and compensation force:

[0128] Axial displacement adjustment of a single negative Poisson's ratio anchor block: ;

[0129] Prestress recovery of SMA slab: ;

[0130] Frictional anchoring force: (The end constraint force provided by friction anchoring).

[0131] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A self-anchoring and self-compensating reinforcement device for SMA plate-negative Poisson's ratio combination, characterized in that, The system includes a transition steel plate, a negative Poisson's ratio anchor block, and an SMA plate. At least two sets of transition steel plates are provided, each set fixed to both sides of the potential propagation path of a crack tip on the surface of the reinforced steel structure member. Each set of transition steel plates has a wedge-shaped groove inside, the width of which gradually increases in the direction away from the crack tip on the surface of the steel structure member. Both ends of the SMA plate are respectively inserted into the wedge-shaped grooves of the two sets of transition steel plates. The negative Poisson's ratio anchor block is sandwiched between the side of the SMA plate and the inclined sidewall of the wedge-shaped groove. When thermal excitation is applied to the SMA plate, the SMA plate generates axial shape recovery shrinkage force, and under the action of interface friction, it drives the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center, so that the negative Poisson's ratio anchor block undergoes transverse cross-sectional expansion under axial tension, and interlocks with the groove wall of the wedge groove and the SMA plate to achieve self-anchoring of the SMA plate; When the SMA plate experiences prestress relaxation during long-term service, the axial tensile force on the negative Poisson's ratio anchor block decreases and an adaptive reverse rebound deformation is generated, which compensates for the axial relaxation deformation of the SMA plate, maintains the pre-tightened stress state of the system, and realizes prestress self-compensation.

2. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, The effective bonding area between the adapter steel plate and the steel structure component is greater than the projected area of ​​the SMA plate in the direction of force.

3. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 2, characterized in that, The effective bonding area is not less than 50mm × 300mm, and the thickness of the adapter steel plate is 4-6mm.

4. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, The angle between the sidewall of the wedge-shaped groove and the longitudinal axis of the SMA plate is no greater than 45°.

5. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, On the adapter steel plate, the local bending stiffness of the wedge-shaped groove opening area is less than the bending stiffness of the ungrooved area in the adapter steel plate.

6. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, The length of the cavity reserved in the wedge-shaped groove for the adaptive retraction and sliding of the negative Poisson's ratio anchor block is less than 0.5 mm.

7. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, The thickness of the SMA plate is less than the depth of the wedge-shaped groove.

8. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, The cross-sectional dimension of the negative Poisson's ratio anchor block in the unloaded state is smaller than the assembly gap between the SMA plate and the sidewall of the wedge groove.

9. The self-anchoring and self-compensating reinforcement device of SMA plate-negative Poisson's ratio combination according to claim 1, characterized in that, It also includes a temporary fixing component, which is a detachable structure used for temporary positioning and fixing of the SMA plate before thermal excitation is applied.

10. A self-anchoring and self-compensating reinforcement method for a self-anchoring and self-compensating reinforcement device for an SMA plate-negative Poisson's ratio combination as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Sandblast the bonding interface of the transition steel plate, the inner wall of the wedge groove, and the contact surface of the negative Poisson's ratio anchor block to remove the surface oxide layer and impurities, and improve the bonding and friction performance of the interface. S2: At least two sets of transition steel plates are fixed to both sides of the potential propagation path of the crack tip on the surface of the reinforced steel structure component by adhesive bonding. The transition steel plates are provided with wedge-shaped grooves, and the width of the wedge-shaped grooves gradually increases along the direction away from the crack tip on the surface of the steel structure. S3: Place both ends of the SMA plate into the wedge grooves of the two sets of transition steel plates respectively, so that the SMA plate is kept horizontal and in contact with the surface of the steel structure component. S4: Embed the negative Poisson's ratio anchor block between the side of the SMA plate and the side wall of the wedge groove, and ensure that the negative Poisson's ratio anchor block is in close contact with the SMA plate and the side wall of the wedge groove; S5: Apply thermal excitation to the SMA plate to generate axial shape recovery and retraction force, and drive the negative Poisson's ratio anchor block to move along the wedge groove towards the crack center until the negative Poisson's ratio anchor block expands laterally under axial tension, and locks itself with the groove wall of the wedge groove and the SMA plate to achieve self-anchoring of the SMA plate. S6: When prestress relaxation occurs during the long-term service of the SMA plate, the negative Poisson's ratio anchor block generates adaptive reverse rebound deformation as the axial tensile force decreases, and undergoes slight slippage along the wedge groove in the direction away from the crack center to compensate for the axial relaxation deformation of the SMA plate, maintain the pre-tightened stress state of the system, and realize prestress self-compensation.

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