Self-anchored self-compensating reinforcing device and method for multi-layer composite sma
By using a multi-layer composite SMA plate structure, the prestress loss of the reinforcing SMA plate is automatically compensated by the self-locking and self-compensating SMA plate, which solves the problem of high temperature excitation affecting the adhesive layer and shape memory effect attenuation in the existing technology. This achieves self-anchoring and self-compensating reinforcement without secondary thermal excitation, improving the safety and service performance of the steel structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGZHOU UNIVERSITY
- Filing Date
- 2026-05-11
- Publication Date
- 2026-06-09
AI Technical Summary
Existing SMA reinforcement technology suffers from the performance of the adhesive layer under high temperature excitation, is difficult to process and easily introduces stress concentration, and the shape memory effect is weakened due to changes in ambient temperature, making it difficult to achieve continuous and automatic prestress compensation.
The structure employs a multi-layer composite SMA plate, including a self-locking and self-compensating SMA plate and a reinforcing SMA plate. Through pre-stretching and thermal excitation shaping treatment, the self-locking and self-compensating SMA plate automatically compensates for the prestress loss of the reinforcing SMA plate under changes in ambient temperature, achieving self-anchoring and self-compensation without the need for secondary thermal excitation.
Without relying on secondary thermal excitation, automatic compensation and long-term maintenance of prestress in SMA plates are achieved, improving the safety and long-term service performance of steel structure reinforcement systems, simplifying the construction process and reducing the risk of stress concentration.
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Figure CN122169651A_ABST
Abstract
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 for multi-layer composite SMA. Background Technology
[0002] With the widespread application of steel structures in bridges and large-scale engineering structures, they are inevitably affected by fatigue loads, environmental corrosion, and temperature changes during long-term service. This makes them prone to cracks in critical stress areas, which can gradually propagate and threaten the overall safety of the structure. To suppress crack propagation and restore or improve the structural load-bearing capacity, the reinforcement method of introducing active prestress using shape memory alloys (SMA) has attracted widespread attention.
[0003] Existing SMA (Surface Mounted Abrasive) reinforcement techniques typically involve directly bonding or anchoring SMA components to the surface of a steel structure. After heating and excitation, the shape memory effect of the SMA applies compressive stress to the structure, thereby reducing the stress intensity factor at the crack tip. However, this method still has several shortcomings in engineering applications. Firstly, the excitation temperature of SMA is usually high, which can easily cause degradation of the adhesive layer when applied directly, thus affecting long-term bond reliability. Secondly, to achieve reliable anchoring of SMA components, it is often necessary to drill holes, cut grooves, or install complex mechanical anchors on the SMA body. This is not only difficult to process but also prone to introducing stress concentration, weakening the mechanical properties of the SMA component.
[0004] Furthermore, shape memory alloys are inevitably affected by sunlight, seasonal changes, and structural temperature fluctuations in engineering service environments. Their shape memory effect and strain recovery capacity will decrease to varying degrees with long-term exposure to ambient temperature. When SMA components are excited and under constraint, the attenuation of this memory effect will directly manifest as a gradual reduction in active prestress.
[0005] Existing technologies for addressing the memory effect loss caused by ambient temperature typically rely on re-thermal excitation or replacement of SMA components for repair. This makes it difficult to achieve continuous and automatic prestress compensation without interrupting structural service. Therefore, there is an urgent need for an SMA reinforcement device that can separate and coordinate the reinforcement function with the self-anchoring and self-compensation functions without manual excitation or replacement of the SMA component itself, in order to improve the safety and long-term service performance of steel structure reinforcement systems. Summary of the Invention
[0006] In order to overcome the shortcomings of the prior art, the present invention provides a self-anchoring and self-compensating reinforcement device for multilayer composite SMA. The self-anchoring and self-compensating reinforcement device can automatically compensate for and maintain the prestress loss of SMA plate for a long time without relying on secondary thermal excitation.
[0007] The second objective of this invention is to provide a self-anchoring and self-compensating reinforcement method for multilayer composite SMA.
[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 for multi-layer composite SMA includes at least two sets of transition steel plates, a multi-layer composite SMA plate, and connecting components for mounting the two ends of the multi-layer composite SMA plate onto the two sets of transition steel plates respectively. The transition steel plates are mounted on the surface of the steel structure member being reinforced, and are respectively located on both sides of the potential crack propagation path of the steel structure. The multi-layer composite SMA plate includes a self-locking and self-compensating SMA plate, a reinforcing SMA plate, and mounting components for mounting the self-locking and self-compensating SMA plate onto the reinforcing SMA plate. The self-locking and self-compensating SMA plate is a shape memory composite material that has undergone pre-stretching and preheating excitation shaping treatment. The SMA plate, which has a pre-stored shape memory recovery deformation capability, is fixed at one end to the reinforcing SMA plate via the mounting assembly, and at the other end to the adapter steel plate. The reinforcing SMA plate is a shape memory alloy plate that is thermally excited after assembly, used to generate active prestress for closing cracks in the crack tip region of the steel structure. When the reinforcing SMA plate experiences prestress loss during service, the self-locking and self-compensating SMA plate compensates for the axial deformation loss of the reinforcing SMA plate through its pre-stored shape memory recovery deformation capability, achieving prestress self-compensation without secondary thermal excitation.
[0010] Preferably, the self-locking and self-compensating SMA plate is disposed at one or both ends of the multilayer composite SMA plate, and there are at least two sets of the self-locking and self-compensating SMA plates.
[0011] Preferably, the self-locking and self-compensating SMA plate is disposed at one end of the multi-layer composite SMA plate. There are two sets of self-locking and self-compensating SMA plates, which are respectively disposed on the upper and lower sides of the reinforcing SMA plate. One end of the upper self-locking and self-compensating SMA plate is fixed to the reinforcing SMA plate by a mounting assembly, and the upper and lower sides of a portion of the other end are respectively fixed to the transition steel plate and the reinforcing SMA plate. One end of the lower self-locking and self-compensating SMA plate is fixed to the reinforcing SMA plate by a mounting assembly, and the upper and lower sides of a portion of the other end are respectively fixed to the reinforcing SMA plate and the transition steel plate.
[0012] Preferably, the width of the self-locking and self-compensating SMA plate is greater than the width of the reinforcing SMA plate.
[0013] Preferably, the mounting assembly includes pins for connecting the self-locking and self-compensating SMA plate to the reinforcing SMA plate as a whole.
[0014] Preferably, the transition steel plate is fixed to the surface of the reinforced steel structure member by an adhesive, and the transition steel plate includes a first transition steel plate and a second transition steel plate; the connecting assembly includes a first connecting assembly and a second connecting assembly, wherein the first transition steel plate is fixed to the multilayer composite SMA plate by the first connecting assembly; and the second transition steel plate is fixed to the multilayer composite SMA plate by the second connecting assembly.
[0015] Preferably, the first connecting assembly includes a mounting groove disposed on the first transition steel plate, and the second connecting assembly includes a steel column disposed on the second transition steel plate; wherein, the end of the self-locking and self-compensating SMA plate in the multi-layer composite SMA plate is embedded in the mounting groove, one end of the self-locking and self-compensating SMA plate located on the lower side of the multi-layer composite SMA plate is fixed to the reinforcing SMA plate by the mounting assembly, and the upper side of a portion of the other end is fixed to the reinforcing SMA plate; the other end of the multi-layer composite SMA plate is provided with a mounting hole that mates with the steel column, and the mounting hole is disposed on the reinforcing SMA plate.
[0016] Preferably, when the reinforcing SMA plate is thermally excited, the self-locking and self-compensating SMA plate is also heated simultaneously, and undergoes lateral expansion deformation perpendicular to the axial direction in the preset mounting groove. The two side walls of the self-locking and self-compensating SMA plate form a full-fit surface contact with the inner wall of the mounting groove, and the lateral compressive force generated by the increased cross-section forms a lateral locking effect, thereby achieving self-locking anchoring in the mounting groove.
[0017] Preferably, it also includes a magnetic fastener, which is used to temporarily fix the reinforcing SMA plate during the construction phase to limit its lateral off-center loading and axial slippage during thermal excitation.
[0018] Preferably, the diameter of both the pin and the steel column is 4-6 mm.
[0019] Preferably, the self-locking and self-compensating SMA plate and the reinforcing SMA plate use the same material system and are subjected to separate excitation timing control to form different initial memory states and working functions. Specifically, the self-locking and self-compensating SMA plate generates a shape memory effect through thermal excitation before assembly; the reinforcing SMA plate generates a shape memory effect through thermal excitation after assembly, so that the shape memory effect of both decreases synchronously under the influence of service environment temperature, thereby achieving automatic compensation of the prestress loss of the reinforcing SMA through the non-bonded deformation zone in the multilayer composite SMA plate; wherein, in the initial reinforcement stage, the axial recovery of the reinforcing SMA plate... Force drives the self-locking and self-compensating SMA plate to move relative to the excitation center through the connecting components, forming a self-locking anchor. During long-term service, the reinforcing SMA plate experiences prestress loss due to temperature, manifested as an increase in axial relaxation deformation. Since the self-locking and self-compensating SMA plate and the reinforcing SMA plate are mechanically connected in parallel through pins and the non-bonded deformation zone, when the reinforcing SMA plate experiences axial relaxation, the total prestress previously borne independently by the reinforcing SMA plate will be redistributed between them according to stiffness: the tensile force of the reinforcing SMA plate decreases, while the tensile force of the self-locking and self-compensating SMA plate increases due to passive tension. The additional tensile deformation generated by the self-locking and self-compensating SMA plate in the non-bonded deformation zone precisely compensates for the prestress loss of the reinforcing SMA plate caused by axial relaxation. The mechanical premise of this compensation mechanism is that the self-locking and self-compensating SMA plate and the reinforcing SMA plate use the same material system and have similar shape memory effect attenuation laws under the same service environment temperature. However, due to differences in their initial memory states and constraint conditions, their instantaneous axial stiffness in the structural system does not decrease synchronously—the self-locking and self-compensating SMA plate maintains a higher apparent stiffness reserve in the compensation direction. Therefore, without applying secondary thermal excitation, continuous compensation of the reinforcing prestress is achieved through the automatic redistribution of internal forces.
[0020] A self-anchoring and self-compensating reinforcement method for multilayer composite SMA includes the following steps:
[0021] S1. Attach the two sets of transition steel plates to both sides of the potential propagation path of the crack in the steel structure, and ensure that the total effective bonding area is not less than 6000mm².
[0022] S2. Install the self-locking and self-compensating SMA plate, which has been pre-stretched and preheated to set shape, onto the reinforcing SMA plate to form a multi-layer composite SMA plate, and install both ends of the multi-layer composite SMA plate onto two sets of transition steel plates.
[0023] S3. Apply thermal excitation to the reinforcing SMA plate to generate active prestress on the crack tip of the steel structure and drive the self-locking and self-compensating SMA plate to achieve self-locking anchorage; when the reinforcing SMA plate experiences prestress loss, the self-locking and self-compensating SMA plate compensates for the axial deformation loss of the reinforcing SMA plate through its pre-stored shape memory recovery deformation capability, thereby achieving prestress self-compensation without secondary thermal excitation.
[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0025] 1. This invention applies thermal excitation to a reinforcing SMA plate, generating active prestress at the crack tip region of the steel structure, thereby inhibiting crack propagation. Simultaneously, under the action of connecting components and a multi-layered composite structure, the self-locking and self-compensating SMA plate moves towards the excitation center. In the mounting groove of the transfer steel plate, the self-locking and self-compensating SMA plate forms a self-locking anchor by contacting the groove wall through cross-sectional expansion. When the reinforcing SMA plate experiences prestress loss due to temperature changes or material properties during long-term service, the self-locking and self-compensating SMA plate compensates for the axial deformation of the reinforcing SMA plate through its own deformation, achieving prestress self-compensation. Specifically, the self-locking and self-compensating SMA plate is pre-excited by thermal excitation to generate an initial shape memory effect before assembly and maintains this memory state at room temperature. Thermal excitation is then applied to the reinforcing SMA plate after assembly to introduce active prestress at the crack tip region of the steel structure.
[0026] 2. The self-anchoring and self-compensating reinforcement device of the present invention can automatically compensate for and maintain the prestress loss of the reinforcement SMA plate in the long term by constructing a collaborative working system of reinforcement SMA and self-locking and self-compensating SMA without relying on secondary thermal excitation. It actively utilizes the synchronous attenuation characteristics of the shape memory effect of the two under the action of ambient temperature. It also has the advantages of simple structure, strong construction adaptability and broad engineering application prospects. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the installation of the self-anchoring and self-compensating reinforcement device for multilayer composite SMA of the present invention.
[0028] Figure 2 This is a perspective view of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention.
[0029] Figure 3 This is a front view of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention.
[0030] Figure 4 This is a left view of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention.
[0031] Figure 5 This is a top view of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention.
[0032] Figure 6 This is a stress analysis diagram of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention during the initial reinforcement stage.
[0033] Figure 7 This is a stress analysis diagram of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention during the prestress loss stage.
[0034] Figure 8 This is a stress analysis diagram of the self-anchoring and self-compensating reinforcement device of the multilayer composite SMA of the present invention after prestress compensation.
[0035] In the figure: 1 is a self-anchoring and self-compensating reinforcement device, 2 is the tip of a crack in the steel structure, 3 is the steel structure component being reinforced, 101 is the first transition steel plate, 102 is the second transition steel plate, 103 is a self-locking and self-compensating SMA plate, 104 is a reinforcement SMA plate, 105 is a pin, and 106 is a steel column. Detailed Implementation
[0036] 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.
[0037] See Figures 1-5 The self-anchoring and self-compensating reinforcement device 1 for multi-layer composite SMA of the present invention includes at least two sets of transition steel plates, a multi-layer composite SMA plate, and a connecting assembly for mounting both ends of the multi-layer composite SMA plate onto the two sets of transition steel plates respectively.
[0038] The transition steel plate is installed on the surface of the reinforced steel structure member 3 and is located on both sides of the potential propagation path of the steel structure crack.
[0039] The multi-layer composite SMA plate includes a self-locking and self-compensating SMA plate 103, a reinforcing SMA plate 104, and a mounting assembly for mounting the self-locking and self-compensating SMA plate 103 onto the reinforcing SMA plate 104. The mounting assembly connects the self-locking and self-compensating SMA plate 103 and the reinforcing SMA plate 104 along their length to form a multi-layer composite structure. The self-locking and self-compensating SMA plate 103 is a shape memory alloy plate that has undergone pre-stretching and preheating excitation shaping treatment, and it has pre-stored shape memory recovery deformation capability. One of the self-locking and self-compensating SMA plates 103... One end is fixed to the reinforcing SMA plate 104 by the mounting assembly, and the other end is fixed to the transition steel plate; the reinforcing SMA plate 104 is a shape memory alloy plate that is thermally excited after assembly, used to generate active prestress for closing cracks in the region of the crack tip 2 of the steel structure; when the reinforcing SMA plate 104 experiences prestress loss during long-term service, the self-locking and self-compensating SMA plate 103 compensates for the axial deformation loss of the reinforcing SMA plate 104 through its pre-stored shape memory recovery deformation capability, thereby achieving prestress self-compensation without secondary thermal excitation.
[0040] See Figures 1-5 The thickness of the self-locking and self-compensating SMA plate 103 and the reinforcing SMA plate 104 is preferably 1.5-3mm.
[0041] See Figures 1-5 The self-locking and self-compensating SMA plate 103 is disposed at one or both ends of the multilayer composite SMA plate, and there are at least two sets of the self-locking and self-compensating SMA plate 103. In this embodiment, the self-locking and self-compensating SMA plate 103 is disposed at one end of the multilayer composite SMA plate, and there are two sets of the self-locking and self-compensating SMA plate 103, which are respectively disposed on the upper and lower sides of the reinforcing SMA plate 104. One end of the self-locking and self-compensating SMA plate 103 located on the upper side is installed via... The component is fixed to the reinforcing SMA plate 104, and the upper and lower sides of a portion of the other end are respectively fixed to the adapter steel plate and the reinforcing SMA plate 104; one end of the self-locking and self-compensating SMA plate 103 located on the lower side is fixed to the reinforcing SMA plate 104 by the mounting component, and the upper and lower sides of a portion of the other end are respectively fixed to the reinforcing SMA plate 104 and the adapter steel plate, and the width of the self-locking and self-compensating SMA plate 103 is greater than the width of the reinforcing SMA plate 104.
[0042] See Figures 1-5Along the length of the multilayer composite SMA plate, a portion of the self-locking and self-compensating SMA plate 103 is coupled between the multilayer SMA plates through an adhesive, while the remaining portion forms a non-adhesive deformation zone. This ensures that during service, the self-locking and self-compensating SMA plate 103 can preferentially absorb the axial deformation of the reinforcing SMA plate 104, thereby achieving prestressed self-compensation.
[0043] See Figures 1-5 The mounting assembly includes pins 105, which are used to connect the self-locking and self-compensating SMA plate 103 and the reinforcing SMA plate 104 into a whole to form an integrated collaborative working system. In this embodiment, the pins 105 are as close as possible to the adapter steel plate, and the diameter of each pin 105 is 4-6mm.
[0044] See Figures 1-5 The transition steel plate is fixed to the surface of the reinforced steel structure member 3 by an adhesive. The transition steel plate includes a first transition steel plate 101 and a second transition steel plate 102. The connecting assembly includes a first connecting assembly and a second connecting assembly. The first transition steel plate 101 is fixed to the multilayer composite SMA plate by the first connecting assembly. The second transition steel plate 102 is fixed to the multilayer composite SMA plate by the second connecting assembly.
[0045] See Figures 1-5 The first connecting component includes a mounting groove disposed on the first transition steel plate 101, and the second connecting component includes a steel column 106 disposed on the second transition steel plate 102; wherein, the end of the self-locking and self-compensating SMA plate 103 in the multi-layer composite SMA plate is embedded in the mounting groove, one end of the self-locking and self-compensating SMA plate 103 located on the lower side of the multi-layer composite SMA plate is fixed to the reinforcing SMA plate 104 by the mounting component, and the upper side of a portion of the other end is fixed to the reinforcing SMA plate 104; the other end of the multi-layer composite SMA plate is provided with a mounting hole that mates with the steel column 106, and the mounting hole is disposed on the reinforcing SMA plate 104. With the above settings, when the reinforcement SMA plate 104 is thermally excited, the self-locking and self-compensating SMA plate 103 is simultaneously heated and undergoes lateral expansion deformation perpendicular to the axial direction within the preset mounting groove. Its two side walls form a full-fit surface contact with the inner wall of the mounting groove, and the lateral compressive force generated by the increased cross-section forms a lateral locking effect, achieving self-locking anchoring within the mounting groove. The steel column 106 is used to limit the lateral slippage of the multi-layer composite SMA plate during thermal excitation and service, so that the multi-layer composite SMA plate forms a stable anchoring under axial action. In this embodiment, the diameter of the steel column 106 is 4-6mm.
[0046] In addition, in this embodiment, the mounting groove of the first adapter steel plate 101 can simultaneously embed three SMA plates of different widths (all with a thickness of 1.5-3mm). The wider one is the self-locking and self-compensating SMA plate 103 (with a width of 35-55mm), and the narrower one is the reinforcing SMA plate 104 (with a width of 30-50mm). The self-locking and self-compensating SMA plate 103 forms a surface contact with the inner wall of the mounting groove of the first adapter steel plate 101, and generates a locking effect with an increased cross-section when driven by thermal excitation.
[0047] See Figures 1-5 The self-anchoring and self-compensating reinforcement device 1 of the multilayer composite SMA of the present invention also includes a magnetic fastener, which is used to temporarily fix the reinforcement SMA plate 104 during the construction stage to limit its lateral off-center load and axial slippage during the thermal excitation process.
[0048] See Figures 1-5 The self-locking and self-compensating SMA plate 103 and the reinforcing SMA plate 104 perform different functions, mainly relying on the fact that they use the same material system to ensure similar phase transition temperature ranges and memory effect decay laws under the same service temperature conditions. The functional differences between the two mainly stem from differences in excitation timing, initial memory state, and boundary constraint conditions. Specifically, the self-locking and self-compensating SMA plate 103 undergoes pre-stretching and thermal excitation treatment before assembly to form a pre-stored recovery deformation capacity, and is in a constrained state with limited ends and local deformability after assembly; the reinforcing SMA plate 104 is thermally excited after assembly, and its recovery deformation mainly outputs axial restoring force along the potential propagation path of the steel structure crack. In the initial reinforcement stage, the axial restoring force of the reinforcement SMA plate 104 drives the self-locking and self-compensating SMA plate 103 to move relative to the excitation center through the pin 105 and the multi-layer composite connection relationship, thus completing the self-locking anchoring. In the long-term service stage, when the prestress of the reinforcement SMA plate 104 decreases due to the effect of ambient temperature and memory effect decay, the self-locking and self-compensating SMA plate 103 releases its pre-stored recovery deformation in the non-bonded deformation zone to compensate for the axial relaxation deformation of the reinforcement SMA plate 104, thereby forming a reverse adjustment process corresponding to the initial traction stage, and thus realizing automatic redistribution and long-term maintenance of prestress.
[0049] See Figures 1-5This invention applies thermal excitation to the reinforcing SMA plate 104, generating active prestress in the crack tip 2 region of the steel structure, thereby inhibiting crack propagation. Simultaneously, under the action of the connecting components and the multi-layer composite structure, the self-locking and self-compensating SMA plate 103 moves towards the excitation center (i.e., the crack center). In the mounting groove of the first transition steel plate 101, the self-locking and self-compensating SMA plate 103 forms a self-locking anchor by contacting the groove wall through cross-sectional expansion. When the reinforcing SMA plate 104 experiences prestress loss due to temperature changes or material properties during long-term service, the self-locking and self-compensating SMA plate 103 compensates for the axial deformation of the reinforcing SMA plate 104 through its own deformation, achieving prestress self-compensation. Specifically, the self-locking and self-compensating SMA plate 103 is pre-excited by thermal excitation to generate an initial shape memory effect before assembly and maintains this memory state at room temperature. The reinforcing SMA plate 104 is thermally excited again after assembly to introduce active prestress in the crack tip 2 region of the steel structure. Therefore, without considering the effects of external loads, the reinforced SMA plate and the self-locking and self-compensating SMA plate are affected by the same environmental temperature changes in the service environment, and their shape memory effect decay trends are consistent, thus providing a basis for subsequent synchronous prestress redistribution.
[0050] Because at least one steel column 106 is welded to the surface of the second transition steel plate 102, the steel column 106 provides geometric restraint and anti-slip constraint for the SMA plate, which can limit the lateral slippage of the SMA plate during thermal excitation and service, so that the multi-layer composite SMA plate can form a stable anchoring state under axial force. When the reinforcing SMA plate 104 experiences prestress loss during long-term service, the self-locking and self-compensating SMA plate 103 absorbs its axial deformation through the non-adhesive deformation zone, thereby achieving prestress self-compensation.
[0051] See Figures 1-5 The self-anchoring and self-compensating reinforcement method for multilayer composite SMA of the present invention includes the following steps:
[0052] S1. Attach the two sets of transition steel plates to both sides of the potential propagation path of the crack in the steel structure, and ensure that the effective bonding area meets the design requirements, such as ensuring that the total effective bonding area is not less than 6000mm².
[0053] S2. The self-locking and self-compensating SMA plate 103, which has undergone pre-stretching and preheating excitation shaping treatment, is installed on the reinforcing SMA plate 104 to form a multi-layer composite SMA plate. The two ends of the multi-layer composite SMA plate are respectively installed on two sets of transition steel plates. That is, one end of the multi-layer composite SMA plate is embedded in the mounting groove of the first transition steel plate 101, and the other end is arranged on the surface of the second transition steel plate 102, so that the mounting hole of the multi-layer composite SMA plate matches the steel column 106 to achieve lateral limiting. In addition, magnetic fasteners can be set on the outside of the reinforcing SMA plate 104 for temporary fixing and positioning during the construction stage to prevent relative misalignment of the multi-layer composite SMA plate during assembly and thermal excitation.
[0054] S3. Apply thermal excitation to the reinforcing SMA plate 104 to generate active prestress on the crack tip 2 of the steel structure, and drive the self-locking and self-compensating SMA plate 103 to achieve self-locking anchoring; when the reinforcing SMA plate 104 experiences prestress loss, the self-locking and self-compensating SMA plate 103 compensates for the axial deformation loss of the reinforcing SMA plate 104 through its pre-stored shape memory recovery deformation capability, and achieves prestress self-compensation without secondary thermal excitation.
[0055] In the above process, the self-locking and self-compensating SMA plate 103 needs to undergo thermal excitation to generate a shape memory effect and maintain its memory state before assembly; the reinforcing SMA plate 104 is thermally excited again after assembly, so that it generates active prestress in the region of the crack tip 2 in the steel structure, thereby inhibiting crack propagation. At the same time, under the driving action of the pin 105 and the multi-layer composite structure, the self-locking and self-compensating SMA plate 103 moves relative to the excitation center. After the self-anchoring and self-compensating reinforcement device 1 of the present invention enters the long-term service stage, the reinforcement SMA plate 104 and the self-locking and self-compensating SMA plate 103 are exposed to the same ambient temperature conditions. The shape memory effect of both will decrease synchronously with the long-term effect of ambient temperature. This decrease process, under constrained conditions, manifests as a simultaneous reduction in the free recovery strain capacity of both types of SMA plates, thereby inducing a redistribution of axial internal forces in the non-bonded deformation zone of the multilayer composite SMA plate. Since the self-locking and self-compensating SMA plate 103 is reliably anchored through the first transition steel plate 101, it will passively bear the increase in axial tensile force during the synchronous shape memory effect loss process, while the decrease in prestress of the reinforcement SMA plate 104 will be correspondingly offset. Thus, without the need for re-thermal excitation, the self-locking and self-compensating SMA plate 103 automatically compensates for the prestress loss of the reinforcement SMA plate 104 through the synchronous shape memory effect loss, thereby ensuring the prestress stability of the reinforcement system during long-term service.
[0056] Furthermore, within the mounting groove of the first transition steel plate 101, the self-locking and self-compensating SMA plate 103 expands laterally within the mounting groove, forming surface contact with the inner wall of the mounting groove and generating a locking effect with increased cross-section, thereby achieving self-locking anchoring within the mounting groove. In the second transition steel plate 102, located on one side of the steel column 106, the steel column 106 provides geometric restraint for the multi-layer composite SMA plate, limiting its lateral slippage during thermal excitation and service, ensuring a stable anchoring state for the multi-layer composite SMA plate under axial action. During long-term service, when the reinforcing SMA plate 104 experiences a tendency to lose prestress due to temperature changes or material properties, the self-locking and self-compensating SMA plate 103 undergoes relative deformation through the non-bonded deformation zone, preferentially absorbing the axial deformation of the reinforcing SMA plate 104, thereby compensating for the prestress loss of the reinforcing SMA plate 104 and achieving a self-compensation function.
[0057] See Figures 6-8 The following describes the working principle of the prestress self-compensation of the self-anchoring and self-compensating reinforcement device of the present invention:
[0058] Step 1: Derivation of axial stiffness;
[0059] Geometric relationships (small transformations) include:
[0060] ;
[0061] In the formula: In response, This is the amount of deformation. This is the original length.
[0062] Material constitutive properties (linear elasticity) include:
[0063] ;
[0064] In the formula: For stress, It is the elastic modulus.
[0065] The balance relationships are:
[0066] ;
[0067] In the formula: This represents the cross-sectional area in the stretching direction.
[0068] Combining the above equations, we get:
[0069] ;
[0070] Standard form of force-displacement relationship:
[0071] ;
[0072] The axial stiffness can be obtained according to Hooke's law. for:
[0073] ;
[0074] Step 2: Define material parameters;
[0075] The elastic modulus, cross-sectional area, and effective length of the SMA plate 104 used for reinforcement are as follows: , and Its axial stiffness The result derived in step 1 is shown in the following formula:
[0076] ;
[0077] The elastic modulus, single-piece cross-sectional area, and effective length of the self-locking and self-compensating SMA plate 103 are as follows: , , Its equivalent axial stiffness The result derived in step 1 is shown in the following formula:
[0078] ;
[0079] Step 3: Assuming that the long-term service reinforcement SMA plate 104 experiences prestress loss due to temperature influence, define the prestress generated by the reinforcement SMA plate 104 and the self-locking and self-compensating SMA plate 103 after excitation as follows: and Then we have:
[0080]
[0081] In the formula: The deformation of the SMA plate 104 used for front and rear reinforcement and the self-locking and self-compensating SMA plate 103 is the main source of prestress.
[0082] The prestress loss of the reinforcing SMA plate 104 due to shape memory effect decay under long-term environmental temperature is characterized by monitoring deformation. The deformation of the reinforcing SMA plate 104 is as follows: The prestress loss on the reinforcing SMA plate 104 is:
[0083] ;
[0084] The stress state changes after the prestress is lost. Assuming that the self-locking and self-compensating SMA plate 103 has not yet started compensating for the prestress loss, then:
[0085] ;
[0086] When the self-locking and self-compensating SMA plate 103 begins to compensate for prestress, then:
[0087] ;
[0088] To ensure that the compensated prestress matches the initial state, the cross-sectional area of the self-locking and self-compensating SMA plate 103 must be the same as that of the reinforcing SMA plate 104. Therefore, the cross-sectional area of a single self-locking and self-compensating SMA plate 103 is equal to... n represents the number of self-locking and self-compensating SMA plates; when the width of the self-locking and self-compensating SMA plate 103 is the same as that of the reinforcing SMA plate 104, its thickness should be [missing information]. .
[0089] 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 multilayer composite SMA, characterized in that, The system includes at least two sets of transition steel plates, a multi-layer composite SMA plate, and connecting assemblies for mounting the two ends of the multi-layer composite SMA plate onto the two sets of transition steel plates respectively. The transition steel plates are mounted on the surface of the steel structure member being reinforced, and are located on both sides of the potential crack propagation path of the steel structure. The multi-layer composite SMA plate includes a self-locking and self-compensating SMA plate, a reinforcing SMA plate, and mounting assemblies for mounting the self-locking and self-compensating SMA plate onto the reinforcing SMA plate. The self-locking and self-compensating SMA plate is a shape memory alloy plate that has undergone pre-stretching and preheating excitation shaping treatment, and its internal shape is pre-stored. The self-locking and self-compensating SMA plate has a shape memory recovery deformation capability. One end of the self-locking and self-compensating SMA plate is fixed to the reinforcing SMA plate via the mounting assembly, and the other end is fixed to the adapter steel plate. The reinforcing SMA plate is a shape memory alloy plate that is thermally excited after assembly. It is used to generate active prestress for closing cracks in the crack tip region of the steel structure. When the reinforcing SMA plate experiences prestress loss during service, the self-locking and self-compensating SMA plate compensates for the axial deformation loss of the reinforcing SMA plate through its pre-stored shape memory recovery deformation capability, thereby achieving prestress self-compensation without secondary thermal excitation.
2. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 1, characterized in that, The self-locking and self-compensating SMA board is disposed at one or both ends of the multilayer composite SMA board, and there are at least two sets of the self-locking and self-compensating SMA board.
3. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 2, characterized in that, The self-locking and self-compensating SMA plate is disposed at one end of the multi-layer composite SMA plate. There are two sets of self-locking and self-compensating SMA plates, which are respectively disposed on the upper and lower sides of the reinforcing SMA plate. One end of the self-locking and self-compensating SMA plate on the upper side is fixed to the reinforcing SMA plate by a mounting assembly, and the upper and lower sides of a portion of the other end are respectively fixed to the transition steel plate and the reinforcing SMA plate. One end of the self-locking and self-compensating SMA plate on the lower side is fixed to the reinforcing SMA plate by a mounting assembly, and the upper and lower sides of a portion of the other end are respectively fixed to the reinforcing SMA plate and the transition steel plate.
4. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 3, characterized in that, The width of the self-locking and self-compensating SMA plate is greater than the width of the reinforcing SMA plate.
5. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 4, characterized in that, The mounting assembly includes pins for connecting the self-locking and self-compensating SMA plate to the reinforcing SMA plate as a whole.
6. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 5, characterized in that, The transition steel plate is fixed to the surface of the reinforced steel structure component by an adhesive. The transition steel plate includes a first transition steel plate and a second transition steel plate. The connecting assembly includes a first connecting assembly and a second connecting assembly. The first transition steel plate is fixed to the multilayer composite SMA plate by the first connecting assembly. The second transition steel plate is fixed to the multilayer composite SMA plate by the second connecting assembly.
7. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 6, characterized in that, The first connecting assembly includes a mounting groove disposed on the first transition steel plate, and the second connecting assembly includes a steel column disposed on the second transition steel plate; wherein, the end of the self-locking and self-compensating SMA plate in the multi-layer composite SMA plate is embedded in the mounting groove, one end of the self-locking and self-compensating SMA plate located on the lower side of the multi-layer composite SMA plate is fixed to the reinforcing SMA plate by the mounting assembly, and the upper side of a portion of the other end is fixed to the reinforcing SMA plate; the other end of the multi-layer composite SMA plate is provided with a mounting hole that mates with the steel column, and the mounting hole is disposed on the reinforcing SMA plate.
8. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 7, characterized in that, When the SMA plate for reinforcement is thermally excited, the self-locking and self-compensating SMA plate is also heated simultaneously, and undergoes lateral expansion deformation perpendicular to the axial direction in the preset mounting groove. The two side walls of the self-locking and self-compensating SMA plate form a full-fit surface contact with the inner wall of the mounting groove. The lateral compressive force generated by the increased cross-section forms a lateral locking effect, and self-locking anchoring is achieved in the mounting groove.
9. The self-anchoring and self-compensating reinforcement device for multi-layer composite SMA according to claim 1, characterized in that, It also includes magnetic fasteners, which are used to temporarily fix the reinforcing SMA plate during the construction phase to limit its lateral off-center loading and axial slippage during thermal excitation.
10. A self-anchoring and self-compensating reinforcement method for a self-anchoring and self-compensating reinforcement device for a multilayer composite SMA according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Attach the two sets of transition steel plates to both sides of the potential propagation path of the crack in the steel structure, and ensure that the total effective bonding area is not less than 6000mm². S2. Install the self-locking and self-compensating SMA plate, which has been pre-stretched and preheated to set shape, onto the reinforcing SMA plate to form a multi-layer composite SMA plate, and install both ends of the multi-layer composite SMA plate onto two sets of transition steel plates. S3. Apply thermal excitation to the reinforcing SMA plate to generate active prestress on the crack tip of the steel structure and drive the self-locking and self-compensating SMA plate to achieve self-locking anchoring; when the reinforcing SMA plate experiences prestress loss, the self-locking and self-compensating SMA plate compensates for the axial deformation loss of the reinforcing SMA plate through its pre-stored shape memory recovery deformation capability, thereby achieving prestress self-compensation without secondary thermal excitation.