Additive manufacturing-based open-section profile steel reinforced structure wound by optimized structure filling blocks and FRP fibers as well as construction method and application

Abstract

The invention relates to the technical field of steel structure reinforcement, in particular to an opening section steel reinforcement structure wound by optimized structure filling blocks and FRP fibers based on additive manufacturing and a construction method and application, and aims to solve the problems of poor FRP fitness and low reinforcement efficiency caused by limitation of geometrical characteristics of opening section steel. The reinforcing structure comprises an optimized structure filling block which is prepared by adopting additive manufacturing and is fixed at the concave surface of the profile steel; the optimized structure filling block has an optimized geometry based on a preset performance objective, such as an optimized internal cross section (such as a honeycomb or lattice structure) and / or an optimized longitudinal layout (such as functional gradient or topological optimization); and the FRP fiber winding layer is continuously wound on the outer surfaces of the optimized structure filling block and the profile steel. The optimized structure filling blocks convert the open cross section into a closed cross section beneficial to winding, and the closed cross section and the FRP fiber winding layer form a cooperative stress system. The FRP fiber winding layer provides circumferential constraint to restrain local buckling, and the FRP fiber winding layer and the FRP fiber winding layer jointly enhance the mechanical property of the section. The method is particularly suitable for repairing and reinforcing open-section profile steel members bearing complex loads, such as power transmission towers and bridge supports.

Description

Technical Field

[0001] This invention belongs to the field of steel structure reinforcement technology, specifically relating to an open-section steel reinforcement structure based on the continuous winding of an optimized structural filler block using additive manufacturing (3D printing) and fiber-reinforced polymer (FRP), as well as its construction method and application. Background Technology

[0002] Open-section steel sections (such as angle steel, channel steel, and I-beams) are widely used in engineering structures such as transmission towers and bridge supports due to their simple manufacturing process and high load-bearing efficiency. However, their inherent open sections and asymmetrical geometry make reinforcement difficult and compromise the reliability of the reinforcement, thus affecting structural safety. Traditional welded steel plate reinforcement methods can improve structural strength, but they are complex to construct, add significant weight, and residual welding stress may pose hidden dangers, which is not conducive to lightweighting and durability requirements. In recent years, fiber-reinforced polymers (FRPs) have become an important research direction in the field of steel structure reinforcement due to their significant advantages such as high strength, lightweight, corrosion resistance, and flexible construction.

[0003] In existing technologies, the typical approach to reinforcing open-section steel sections with FRP is to directly bond FRP fabric or FRP sheets along the outer surface of the component. For example, multiple layers of unidirectional FRP fabric are often used to wrap the outer surface of angle steel to improve its bending capacity. However, this method does not fully consider the geometric characteristics of the concave surface of the steel section, which can easily lead to loose bonding of the FRP on the concave surface, resulting in stress concentration and interface delamination. In addition, this type of reinforcement method usually relies on manual bonding, which makes it difficult to form a standardized and automated process, resulting in low efficiency and high labor costs.

[0004] Given the anisotropy of FRP materials, and the fact that most FRP fabrics and sheets are unidirectional fiber products, the bonding layer is prone to interfacial delamination when the reinforced steel member buckles. Studies have shown that while increasing the number of longitudinal FRP layers can improve the bending performance of the member, it easily induces local buckling of the fiber layers in the absence of lateral restraint, and its effect on improving torsional stiffness is relatively limited. Furthermore, unidirectional fiber reinforcement fails to fundamentally address the low torsional stiffness of open-section steel, making the reinforced structure still prone to lateral instability under large lateral loads or dynamic wind loads.

[0005] The limitations of the aforementioned technologies are mainly reflected in two aspects: First, due to the concave geometry of open-section steel, FRP is difficult to adhere evenly on the concave surface, easily leading to stress concentration and the formation of weak areas at the interface; second, current performance improvements for open sections mainly rely on the wrapping of FRP in a single direction, which is insufficient to suppress buckling and torsion. Therefore, there is an urgent need to develop an efficient reinforcement method targeting the geometric characteristics of open-section steel to improve the bonding strength and construction efficiency of FRP on the concave surface of the open section, and to enhance the overall mechanical properties of the reinforced structure. Summary of the Invention

[0006] This invention addresses the problems of poor concave surface fit and low construction efficiency when using FRP to reinforce open-section steel in the prior art. It provides a reinforcement structure based on additive manufacturing, consisting of an optimized structural filler block and FRP fiber winding, as well as a construction method and application.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides an open-section steel reinforcement structure based on an additively manufactured optimized structural filler block and FRP fiber winding, comprising: an open-section steel, an additively manufactured optimized structural filler block, and an FRP fiber winding layer. The cross-sectional shape of the additively manufactured optimized structural filler block is a closed cross-section; The additively manufactured optimized structural filler block is fitted to the concave surface of the open-section steel, and the FRP fiber winding layer is continuously wound around the outer surface of the additively manufactured optimized structural filler block and the open-section steel.

[0008] In this invention, the additively manufactured optimized structural filler block prioritizes the longitudinal force transmission and longitudinal stiffness requirements, while the FRP fiber winding layer prioritizes providing circumferential constraints and suppressing local buckling, forming a synergistic force-bearing system.

[0009] In this invention, the cross-sectional form of the additively manufactured optimized structural filler block is a closed cross-section. The closed cross-section refers to a geometric shape with a completely closed cross-sectional profile and no openings, such as a circle or a rectangle.

[0010] In additive manufacturing of optimized structural filler blocks, using a closed cross-section offers the following advantages: Improved winding fit: Transform the open section into a closed section that facilitates winding, eliminate geometric discontinuities, and enable the FRP fiber winding layer to fit tightly, reducing stress concentration.

[0011] Optimized force transmission: Closed sections provide a continuous force transmission path, enhancing longitudinal stiffness and circumferential constraint effects, forming a synergistic force-bearing system.

[0012] Suppressing local buckling: The overall stability of the cross section is improved through a closed design, and the FRP fiber winding layer effectively suppresses local buckling instability.

[0013] This design is suitable for components such as angle steel for transmission towers and channel steel for bridges that need to withstand bending and shear loads, and is particularly effective in improving the fit of concave surfaces and construction efficiency.

[0014] Optionally, the additively manufactured optimized structural filler block may be made of thermoplastic plastics such as carbon fiber reinforced polyamide 12 (PA12-CF), polyetherimide (PEI), or polyether ether ketone (PEEK), or cement-based composite materials, or metal materials such as aluminum alloys; the material selection should meet the requirements of longitudinal force transmission and longitudinal stiffness, and be compatible with the adhesive system.

[0015] Optionally, the fibers of the FRP fiber winding layer can be glass fibers, carbon fibers, or aramid fibers, preferably having high tensile strength and tensile modulus to provide circumferential restraint.

[0016] For applications where carbon fiber is selected as the FRP fiber winding layer, in order to prevent galvanic corrosion between carbon fiber and steel in a humid environment, an insulating isolation layer (such as a glass fiber layer or an insulating coating) needs to be set, and epoxy resin should be used for secondary sealing at the ends or damaged areas.

[0017] Optionally, the matrix resin of the FRP fiber winding layer may be epoxy resin, vinyl ester resin or unsaturated polyester resin, preferably a type that is compatible with the open section steel and the additively manufactured optimized structural filler block and has good durability.

[0018] The additively manufactured optimized structure filler block is fixed to the concave surface of the open section steel; the FRP fiber winding layer is continuously wound around the additively manufactured optimized structure filler block and the outer surface of the open section steel.

[0019] The shape of the additively manufactured optimized structural filler block is designed to fit closely to the concave surface of the open section steel, and to give the fitted section a smooth outer contour, thereby transforming the open section into a closed section that is conducive to winding, so as to reduce stress concentration.

[0020] Preferably, in the cross-section after the additively manufactured optimized structural filler block is fitted to the concave surface of the open-section steel, the edge of the additively manufactured optimized structural filler block is arc-shaped, and the arc sagitta is not less than 1 / 20 of the corresponding side length. By rounding the edge, the open section is transformed into a smoothly transitioned closed section, effectively reducing stress concentration during FRP fiber winding and improving structural integrity and force transmission efficiency. The use of this radius of curvature ensures a sufficient curvature transition.

[0021] The additively manufactured optimized structural filler block has a geometric shape optimized based on preset performance targets. This geometric shape is reflected in both the internal cross-sectional shape and the longitudinal layout. The internal cross-sectional shape is a lightweight, high-strength porous structure, preferably a honeycomb or lattice structure. The longitudinal layout can be a variable-density structure, with its internal density varying spatially, and the material distribution matching the stress field under preset load conditions, determined through functional gradient or topology optimization. Functional gradient refers to achieving continuous changes in mechanical properties through a gradual transition in material density; topology optimization refers to generating an optimal material distribution scheme based on finite element analysis, increasing material density in critical stress areas and reducing material usage in non-critical areas.

[0022] The selection of the internal cross-sectional shape and the longitudinal layout is determined comprehensively based on the dominant stress conditions, local buckling risk locations, shape constraints, and construction accessibility of the target component during the design reference period.

[0023] Furthermore, the internal cross-sectional shape can be selected from porous structures such as honeycomb and lattice, and its applicable scenarios and advantages are as follows: (1) Honeycomb structure: suitable for components such as angle steel of transmission towers and channel steel of bridge support, which are mainly coupled by bending and shear, and need to take into account out-of-plane stability and specific stiffness.

[0024] The reason is that the honeycomb structure is approximately isotropic in the plane, has continuous nodes, and a short force path, which can uniformly transmit longitudinal stress. For example, the angle steel of the transmission tower needs to withstand repeated bending and shearing under wind load. The honeycomb filler blocks can reduce the additional self-weight through lightweight design and use their high specific stiffness to ensure longitudinal force transmission efficiency.

[0025] (2) Lattice structure (such as body-centered or truss type): suitable for scenarios that require high specific strength and internal functional integration (such as wiring and sensing) such as crane beams and I-beams in industrial plants and support components of offshore platforms, or for parts that need directional reinforcement in the peak bending moment region.

[0026] The reason is that the lattice bars can be arranged according to the principal stress direction, which facilitates the implementation of functional gradients along the length direction and achieves strength-weight matching. For example, high-density lattice filling can be used in the mid-span bending moment concentration area of ​​crane beam I-beams, while low-density lattice can be used near the supports. This not only improves the stiffness of key sections, but also reserves internal space for laying fiber optic sensors to achieve structural health monitoring.

[0027] Furthermore, the vertical layout can adopt a variable density structure, the applicable scenarios and advantages of which are as follows: Suitable for components that bear complex dynamic loads, such as the I-beams supporting the bottom of wind turbine towers (to withstand wind vibration and equipment vibration) and the angle steel of rail transit bridge supports (to withstand train impact loads).

[0028] The reason is that by optimizing the topology, high-density filling (e.g., increasing the lattice rod diameter) can be used in areas with significant vibration response, while low-density filling can be used in stable stress areas, thus improving the structure's vibration resistance. For example, the H-beams at the bottom of wind turbine towers use body-centered cubic lattices in the peak bending moment region and face-centered cubic lattices in other regions to achieve an optimized match between stiffness and damping.

[0029] Preferably, the additively manufactured optimized structural filler block is firmly bonded to the concave surface of the open section steel by adhesive bonding and / or mechanical connection.

[0030] Epoxy resin adhesive is preferably used for bonding, and mechanical connection can be used as a supplement; wherein, the mechanical connection is preferably a snap-fit ​​connection to achieve rapid on-site assembly, and a locking component is provided to prevent loosening; or bolt or stud connection is used according to the stress and durability requirements, and anti-corrosion and electrochemical isolation treatment is provided when necessary.

[0031] The constituent materials of the FRP fiber winding layer are selected from any one or a combination of the following: (1) wet-wound fiber bundle: dry fiber bundle that is impregnated in the resin bath during the winding process; (2) thermoplastic prepreg tape: fiber tape impregnated with a thermoplastic resin matrix and melted and cured in situ during the winding process.

[0032] The FRP fiber winding layer can provide a multi-directional reinforcement solution. Its winding angle and number of layers can be optimized according to requirements to provide circumferential constraints to suppress local buckling and enhance the mechanical properties of the cross section.

[0033] In sections where local buckling needs to be suppressed or circumferential cracking prevented, a near-circumferential winding layer is provided, with the fiber winding angle being 75° to 90° relative to the longitudinal axis of the member; in sections where flexural-torsional coupling stiffness or shear resistance needs to be enhanced, an oblique cross-winding layer is provided, with the fiber winding angle being ±30° to ±60°, preferably ±45°; in sections where longitudinal bearing capacity needs to be synergistically improved, an inner layer is a small-angle spiral layer with a winding angle of ±10° to ±30°, and an outer layer covers the near-circumferential winding layer to form a closed constraint.

[0034] A second aspect of the present invention provides a construction method for an open-section steel reinforcement structure based on an optimized additive manufacturing filler block and FRP fiber winding, comprising the following steps: Step 1: Pre-treatment of the open-section steel. Preferably, the open-section steel is first geometrically corrected, and then surface cleaning and rust removal are performed. More preferably, surface roughening treatment is performed to improve the interfacial bonding performance between the open-section steel and the reinforcement system.

[0035] Step 2: Optimization design and fabrication of the additively manufactured optimized structural filler block.

[0036] (2.1) Geometric and operational condition data acquisition: The surface three-dimensional point cloud data of the section of the open-section steel to be reinforced is obtained using a non-contact three-dimensional scanning device; A digital model reflecting the true geometric features and deformation state of the open section steel is reconstructed based on the three-dimensional point cloud data. A virtual envelope with a preset closed outer contour is constructed, i.e., the reinforced structure, and the digital model is subtracted from the virtual envelope by Boolean subtraction operation; Based on the preset adhesive layer thickness, the normal offset compensation is performed on the contact surface after Boolean operation to generate the outer contour of the manufacturing model of the optimized structure filling block. (2.2) Structural optimization design: Based on the geometric features and working conditions (such as expected load and constraints), a three-dimensional numerical model of the optimized structure infill block of the additive manufacturing is generated by using methods such as finite element analysis, topology optimization or biomimetic design, so that it has an optimized internal cross-sectional shape and / or optimized longitudinal layout. (2.3) Additive manufacturing: Input the three-dimensional numerical model into the additive manufacturing equipment to add an optimized structural filler block.

[0037] Step 3: Fixing the additively manufactured optimized structural filler block. The additively manufactured optimized structural filler block is firmly bonded to the concave surface of the open-section steel profile using adhesive bonding and / or mechanical connection. The contact surfaces should be as close as possible to reduce interface gaps and enhance overall integrity.

[0038] Step 4: FRP fiber winding layer deployment. The FRP fiber winding layer is completed on the outer surface of the bonded section using automated continuous fiber winding technology. The fiber winding angle, number of layers, and reinforcement section length are determined according to design requirements, and the rotation speed, movement speed, and reciprocating distance and number of passes of the fiber feeding head are controlled by a CNC program.

[0039] Preferably, the peak value of the interfacial shear stress is controlled within 60% of the shear strength of the epoxy resin to prevent peeling failure.

[0040] For reinforcement sections exceeding 2m in length, segmented filling and wrapping are recommended. Overlapping sections in the filling process should be connected using mortise and tenon joints, and should be staggered from the overlapping sections in the wrapping process as much as possible. The overlap length should be no less than 100 mm.

[0041] Optionally, fiber optic sensors can be embedded in the FRP fiber winding layer for structural health monitoring.

[0042] Step 5: Curing and post-treatment of the FRP fiber winding layer. Preferably, after the resin has fully cured at room temperature, the edges, seams, and ends of the FRP fiber winding layer are sealed with epoxy resin paste to prevent moisture intrusion. After the entire FRP system has fully cured, a durable protective topcoat is applied to all exposed surfaces.

[0043] Preferably, the durable protective topcoat is an aliphatic polyurethane coating or a fluoropolymer coating to provide long-term protection against UV degradation and weather resistance.

[0044] A third aspect of the present invention provides an application of the optimized structural filler block based on additive manufacturing and the open section steel reinforcement structure wound with FRP fibers, as described in the present invention, in transmission towers, bridge supports, crane beams of industrial plants, and support components of offshore platforms.

[0045] Beneficial effects: Geometric morphology optimization: By customizing the additive manufacturing optimization structure filler block, the concave surface of the open section is transformed into a closed shape (such as a smooth closed shape) that is conducive to winding. This can reduce the dead corners and geometric discontinuities generated when FRP fibers are wound, and improve the fit between the fiber and the open section profile and the stress transfer efficiency.

[0046] Controllability of failure modes: By optimizing the layup of the FRP fiber winding layer, traditional buckling instability can be transformed into controllable progressive material failure, thereby enhancing the safety and reliability of the structure.

[0047] Multidirectional Fiber Synergistic Reinforcement: The FRP fiber winding layer design of this invention abandons the traditional single-angle approach and instead adopts a functionalized zoning configuration based on classical laminate theory. By controlling the angle and number of layers of the FRP fiber winding layer, it forms a synergistic force-bearing system with the additively manufactured optimized structural filler block, achieving a synergistic improvement in the bending, compressive, and torsional properties of the cross-section, and providing circumferential constraints to suppress local buckling, thereby improving the interfacial bond strength between the FRP fiber winding layer and the open-section steel, as well as the interfacial bond strength between the additively manufactured optimized structural filler block and the open-section steel. For the buckling-resistant layer, near-circumferential winding at 85°-89° is used in areas prone to local buckling, such as the tips of angle steel limbs. This fiber layer acts like numerous restraining stirrups, providing continuous elastic lateral support for the thin-walled steel plate and effectively suppressing the generation of wavy buckling. For the torsional layer, considering the inherent torsional tendency caused by the deviation of the shear center of the open section, a ±45° cross-winding layer is configured in the middle of the reinforcement layer. According to Saint-Venant's torsional theory, the ±45° direction is the main path for shear flow transmission in a closed thin-walled section, and this layer significantly improves the torsional constant of the section. For the longitudinal reinforcement layer, in the mid-span region where a significant increase in flexural bearing capacity is required, a small-angle spiral layer with a ±15° angle is configured as the inner layer. To prevent these longitudinally stressed fibers from breaking off outward under compression, the aforementioned buckling-resistant layer must be tightly wrapped around their outer side, forming a synergistic system of "internal bearing and external restraint".

[0048] Lightweight materials: Both FRP and the additively manufactured optimized structural filler block have lightweight and high strength characteristics, which can reduce transportation costs and installation difficulty during the construction phase, and reduce the additional self-weight caused by reinforcement during the service phase.

[0049] Lifecycle cost optimization: The excellent corrosion resistance of FRP materials, combined with the durable protective coating on their surface, can improve the long-term durability of the reinforced area, extend the service life of the structure, and reduce the maintenance cost throughout the entire lifecycle.

[0050] Automated construction system: This invention combines 3D scanning, structural optimization design, additive manufacturing and automated continuous fiber winding process to improve on-site construction efficiency and ensure construction quality and stability. Attached Figure Description

[0051] Figure 1 A cross-sectional schematic diagram of the angle steel reinforcement structure based on additive manufacturing and FRP fiber winding provided by the present invention; Figure 2 This is a schematic diagram of the finished product cross-section of the angle steel reinforcement structure based on additive manufacturing and FRP fiber winding in Embodiment 1 of the present invention; Figure 3 This is a real photograph of the surface treatment step (1.1) in the construction method of Embodiment 1 of the present invention; Figure 4 This is a photograph of the angle steel after preprocessing in step one in Embodiment 1 of the present invention; Figure 5 The image shows a real-life photograph of the geometry and working conditions in step (2.1) of the construction method in Embodiment 1 of the present invention. Figure 6 The screenshot shows the structural optimization design software in step (2.2) of the construction method in Embodiment 1 of the present invention. Figure 7 This is a real-life photograph of additive manufacturing in step (2.3) of the construction method in Embodiment 1 of the present invention; Figure 8 This is a physical image of the additively manufactured optimized structure filler block in Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the mortise and tenon connection of the optimized additive manufacturing structure filler block in Embodiment 1 of the present invention; Figure 10 This is a photograph of the additively manufactured optimized structural filler block after mortise and tenon joint connection in Embodiment 1 of the present invention; Figure 11 This is a photograph of the actual application of adhesive in step (3.1) of the construction method in Embodiment 1 of the present invention; Figure 12 This is a real-life photo of equipment debugging in step (4.1) of the construction method in Embodiment 1 of the present invention; Figure 13 This is a photograph of step (4.2) winding in the construction method of embodiment 1 of the present invention; Figure 14 This is a finished product image of the angle steel reinforcement structure based on additive manufacturing and FRP fiber winding, as shown in Embodiment 1 of the present invention. Figure 15 This is a cross-sectional schematic diagram of the high-stress zone of the angle steel reinforcement structure based on the additive manufacturing optimized structural filler block and FRP fiber winding in Embodiment 2 of the present invention; Figure 16 This is a cross-sectional schematic diagram of the low-stress zone of the angle steel reinforcement structure based on the additive manufacturing optimized structural filler block and FRP fiber winding in Embodiment 2 of the present invention; Figure 17 This is a cross-sectional schematic diagram of the high-density lattice region of the I-beam reinforced structure based on additive manufacturing of the optimized structural filler block and FRP fiber winding in Embodiment 3 of the present invention. Figure 18 This is a cross-sectional schematic diagram of the low-density lattice region of the I-beam reinforced structure based on additive manufacturing of the optimized structural filler block and FRP fiber winding in Embodiment 3 of the present invention.

[0052] In the diagram, 1-Angle steel; 2-Additively manufactured optimized structural filler block; 3-FRP fiber winding layer; 4-Torch and tenon structure; 5-Adhesive; 6-Adhesive layer; 7-Snap-fit ​​structure; 8-Durable protective topcoat; 9-I-beam. Detailed Implementation

[0053] This invention provides an optimized structural filler block based on additive manufacturing and an open-section steel reinforcement structure with FRP fiber winding, along with its construction method and application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0054] Example 1: Combination Figures 1-14 As shown, laboratory sample preparation and finished product display. The application scenario of this embodiment is small-batch preparation in a controlled laboratory environment, which aims to demonstrate the core component composition of the present invention and provide standard samples for subsequent mechanical performance testing.

[0055] The reinforcing base is a section of open-section steel, specifically a hot-rolled equilateral angle steel 1 with specifications L 45×45×5 mm and a cut length of 500 mm.

[0056] The additively manufactured optimized structural filler block 2 is made of a common thermoplastic, polylactic acid (PLA). Its internal cross-sectional shape is a honeycomb structure to showcase lightweight design features. The FRP fiber-wound layer 3 uses continuous glass fiber and epoxy resin matrix (GFRP). This sample clearly demonstrates the synergistic stress system composed of angle steel 1, the additively manufactured optimized structural filler block 2, and the FRP fiber-wound layer 3, making it suitable for basic mechanical testing to evaluate its ability to suppress local buckling, such as... Figure 2 As shown.

[0057] The specific construction method in this embodiment is as follows: Step 1: Pretreatment of open-section steel.

[0058] (1.1) Surface treatment: such as Figure 3 As shown, a handheld angle grinder equipped with a wire brush wheel or louvers is used to mechanically remove rust from the surface of angle steel 1, removing oxide scale and rust until a clean, shiny metal substrate is revealed.

[0059] (1.2) Cleaning: Wipe the polished surface with a clean cotton cloth soaked in acetone to thoroughly remove oil and dust. The treated angle steel 1 is as follows: Figure 4 As shown.

[0060] Step 2: Optimization design and fabrication of the additively manufactured optimized structural filler block.

[0061] (2.1) Geometric and operational condition data acquisition: such as Figure 5 As shown, the geometric dimensions of angle steel 1 were measured using a high-precision digital vernier caliper and a radius gauge.

[0062] (2.2) Structural optimization design: such as Figure 6 As shown, a 3D numerical model of the additively manufactured optimized structural infill block 2 was created in SolidWorks software based on the measured geometric information. The outer contour of the additively manufactured optimized structural infill block 2 was designed as a quarter-circle cross-section with a chamfered center to closely fit the concave angle of the angle steel 1. Inside the additively manufactured optimized structural infill block 2, a honeycomb structure (composed of periodic hexagonal units) was designed, with each unit having a side length of 6 mm and a wall thickness of 1 mm, thereby optimizing its stiffness-to-weight ratio.

[0063] (2.3) Additive Manufacturing: The three-dimensional numerical model is imported into a fused deposition modeling (FDM) additive manufacturing system, and the optimized structure filler block 2 is fabricated using PLA filament printing, such as... Figure 7 As shown. The printed product is as follows. Figure 8 As shown. Figure 8 The finished end of the component uses a mortise and tenon structure 4 to achieve the overlapping function of the additive manufacturing optimized structure filler block 2. A schematic diagram of the overlapping is shown below. Figure 9 As shown, the finished product after overlapping is as follows Figure 10 As shown.

[0064] Step 3: Fixing the additively manufactured optimized structure filler block.

[0065] This step uses adhesive bonding.

[0066] (3.1) Applying adhesive: such as Figure 11 As shown, use a brush to evenly apply the newly mixed two-component, room-temperature curing epoxy resin adhesive 5 to the L-shaped concave contact surface of the angle steel 1.

[0067] (3.2) Installation and clamping: Position and press the additively manufactured optimized structure filler block 2 onto the L-shaped concave surface of the angle steel 1 coated with adhesive. Apply uniform pressure (about 0.1 MPa) using a clamp to ensure that the adhesive 5 overflows to achieve a tight fit and firm bond, and maintain the clamping state until the adhesive 5 is initially cured.

[0068] Step 4: The FRP fiber winding layer is laid out.

[0069] (4.1) Equipment debugging: such as Figure 12The clamped and fixed sample is mounted on the spindle of a small CNC fiber winding machine used in the laboratory, so that it can act as a mandrel.

[0070] (4.2) Winding: After the continuous E-glass fiber roving is drawn from the yarn rack, it is passed through the resin impregnation tank containing the epoxy resin matrix, fully impregnated, and then wound onto the sample surface, such as... Figure 13 As shown. The fiber winding angle is designed to be ±80°, with a total of 2 layers wound.

[0071] Step 5: Curing and post-treatment of the FRP fiber winding layer.

[0072] (5.1) Curing: Allow to stand at room temperature (20~25 °C) for about 6 hours until the epoxy resin matrix hardens.

[0073] (5.2) Trimming and Finished Product Display: After curing, trim excess fibers and resin burrs at both ends of the sample using scissors or a cutter equipped with a diamond wheel. Since the sample does not require durability, no durable protective topcoat is applied. The completed sample is shown below. Figure 14 As shown. This sample can be directly used for subsequent axial compression tests or three-point bending tests to verify the effectiveness of the reinforcement scheme of the present invention in improving the load-bearing capacity of the component and suppressing local buckling.

[0074] Example 2: Combination Figures 15-16 As shown, the reinforcement of transmission tower angle steel based on functional gradient and cellular structure This embodiment is applied to tall outdoor structures, particularly the main or diagonal members of transmission towers. These components are exposed to the natural environment for extended periods, enduring repeated bending and shearing forces caused by wind loads and icing, resulting in fatigue damage and localized corrosion. Therefore, there is an urgent need to improve their out-of-plane stability and buckling resistance.

[0075] The reinforcing base is a single equilateral angle steel 1 with a length of 150×150×12 mm. The reinforcement area is mainly concentrated in the middle section of the component and the inter-joint area sensitive to wind vibration. The specific structural form of this embodiment is as follows: Figure 15 As shown, it includes an angle steel 1, an additively manufactured optimized structural filler block 2 fixed to the outer surface of the L-shaped angle steel, and an FRP fiber winding layer 3 continuously wound around the outside of the reinforced section.

[0076] The additively manufactured optimized structural filler block 2 is made of PA12-CF material to achieve a lightweight design. Its internal cross-sectional shape is a honeycomb structure, the same as in Example 1. The honeycomb structure is chosen because of its near isotropic properties in the plane, continuous nodes, and short stress paths, which can uniformly transmit longitudinal stress and is very suitable for resisting repeated bending and shearing under wind loads.

[0077] The longitudinal layout of the additively manufactured optimized structural filler block 2 adopts a variable density layout determined based on the functional gradient algorithm. The design method is as follows: First, through finite element (FEA) modal analysis combined with wind engineering computational fluid dynamics (CFD) simulation, the high stress zone (such as near the connection node) and high vibration response zone (such as the mid-span of the inter-segment) of the angle steel 1 under the design wind load are determined. Then, based on this stress / vibration field distribution, the functional gradient of the honeycomb is designed: the aperture of the honeycomb unit (e.g., the diameter of the inscribed circle) remains constant at 10 mm, but its wall thickness varies along the length of the component. In areas with significant wind vibration response, the wall thickness is increased to 2.0 mm, such as... Figure 15 As shown; in the low-stress region, the wall thickness is reduced to 1.0 mm, as... Figure 16 As shown. This design utilizes its high specific stiffness to ensure longitudinal force transmission efficiency while minimizing additional self-weight.

[0078] The FRP fiber winding layer 3 is made of GFRP, which has excellent mechanical properties, weather resistance and cost advantages.

[0079] The core reinforcement objective of this embodiment is to suppress local buckling. The design method of the reinforced structure is based on steel structure stability theory (such as Eurocode 3 or AISC). The circumferential constraint provided by the FRP fiber winding layer 3 is equivalent to providing elastic support for the limbs of the angle steel 1, and its required minimum stiffness is determined according to plate buckling theory. To maximize the circumferential constraint stiffness while taking into account a certain torsional performance, the ply design (from the inside to the outside) in this embodiment is: [±89° / ±89° / ±45° / ±45° / ±89° / ±89°]. Among them, the dominant near-circumferential (near 90°) ply provides strong circumferential constraint; the ±45° ply is used to enhance the torsional stiffness and shear performance of the section.

[0080] The additively manufactured optimized structural filler block 2 is bonded to the L-shaped surface of the angle steel 1 via adhesive bonding and mechanical connection. This embodiment preferably employs a combination of adhesive bonding and snap-fit ​​connection, such as... Figure 15 As shown. The design method is based on the principles of rapid assembly and synergistic force distribution. During the additive manufacturing of the optimized structural filler block 2, a snap-fit ​​structure 7 is integrally formed on its edge that mates with the inner side of the angle steel 1 limb. During on-site installation, this snap-fit ​​connection enables rapid positioning and temporary fixation of the additively manufactured optimized structural filler block 2, greatly improving on-site rapid assembly efficiency. Subsequently, high-strength epoxy resin adhesive 5 is injected into the gap between the additively manufactured optimized structural filler block 2 and the L-shaped surface of the angle steel 1 through pre-reserved grouting holes. After the adhesive 5 cures, it forms a bonded body that can transmit the shear force between the additively manufactured optimized structural filler block 2 and the angle steel 1, achieving a synergistic force distribution system.

[0081] The construction method of this embodiment includes the following specific steps: Step 1: Substrate treatment.

[0082] (1.1) Geometric Correction: The initial deformation of angle steel 1 was detected using a laser collimator. For high-altitude operations, slight deformation ( L Within 500 mm, the leveling can be achieved by using adhesive 5 in the subsequent step three. L The calculated length of angle steel 1 is equal to the net span or effective length of angle steel 1 between the two longitudinal constraint / support points.

[0083] (1.2) Surface treatment: Since it is a high-altitude operation, it is preferred to use a portable handheld electric wire brush to remove rust and roughen the surface of angle steel 1 and the FRP winding area. The surface should reach ST3 level (very thorough manual and power tool cleaning) or equivalent roughness (Rz>60 μm).

[0084] (1.3) Cleaning: Use high-pressure air to blow and then use a clean cotton cloth soaked in acetone or anhydrous ethanol to degrease and wipe.

[0085] Step 2: Optimization design and fabrication of the additively manufactured optimized structural filler block.

[0086] (2.1) Geometric and Operating Condition Data Acquisition: For the angle steel main material of the transmission tower, which has been in service for many years, considering the uneven corrosion and slight torsional deformation on its surface, traditional standard-sized filler blocks cannot guarantee the uniformity of the adhesive layer. Therefore, a digital reverse engineering process was introduced. A handheld 3D laser scanner was used to perform high-precision scanning of the surface of the section of angle steel 1 to be reinforced, acquiring 3D point cloud data. Operating condition data such as wind load and icing level were collected. After denoising and registration, the acquired three-dimensional point cloud data is encapsulated into an STL mesh model that reflects the true geometric features and deformation state of the angle steel 1. In CAD software, a virtual envelope with a smooth fan-shaped outer contour is defined, which is the reinforced structure. Then, a Boolean subtraction operation is performed to subtract the angle steel model. To allow for the optimal bonding thickness of the structural adhesive, a uniform outward expansion of 0.8 mm is performed on the inner surface generated by the calculation to generate the outer contour of the manufacturing model of the optimized structural filler block.

[0087] (2.2) Structural optimization design: A model is established in the finite element analysis software, and the functional gradient analysis is run according to the above design method to generate a three-dimensional numerical model of the variable density honeycomb of the additive manufacturing optimized structural filler block 2.

[0088] (2.3) Additive manufacturing: The three-dimensional numerical model is input into an industrial-grade fused deposition modeling (FDM) 3D printer, and the optimized structure filler block 2 of the additive manufacturing is prepared by printing using PA12-CF filament.

[0089] Step 3: Fixing the additively manufactured optimized structure filler block.

[0090] (3.1) Trial assembly and positioning: Using its one-piece snap-fit ​​structure 7, the additively manufactured optimized structure filler block 2 is fixed to the surface of the angle steel 1 to complete the rapid positioning.

[0091] (3.2) Adhesion: Using a high-pressure injection pump, inject the two-component epoxy resin adhesive 5 into the gap between the additively manufactured optimized structure filler block 2 and the angle steel 1 through the reserved injection hole until the adhesive overflows from the vent hole, ensuring tight adhesion and firm bonding.

[0092] (3.3) Segmented Filling: When the length of the reinforced section exceeds 2 m, a segmented filling process is adopted. The entire section is divided into several working segments according to the design, preferably 1.5 to 2.0 m, taking into account the production size of the additive manufacturing equipment and the cost of transportation. The overlapping segments are connected using mortise and tenon structure 4, supplemented by adhesive bonding. The overlapping segments in the filling process should generally be staggered from the overlapping segments of the segmented winding in step four.

[0093] Step 4: The FRP fiber winding layer is laid out.

[0094] (4.1) Equipment commissioning: For high-altitude complex nodes such as transmission towers, it is preferable to use portable, on-site deployable automated continuous fiber winding robots, or to use CNC program-controlled fiber feeding heads in feasible sections.

[0095] (4.2) Winding: The winding machine is started, and after the glass fiber bundles are impregnated with vinyl ester resin, multiple layers are wound in accordance with the designed [±89° / ±89° / ±45° / ±89° / ±89°] layup, for a total of 5 layers.

[0096] (4.3) Segmented winding: For reinforcement sections with a length exceeding 2m, in order to facilitate construction and control resin curing, segmented winding and overlapping processes are adopted, with an overlap length of not less than 100 mm (or 60 times the FRP layer thickness, whichever is larger) to avoid stress accumulation along the length direction.

[0097] First, complete the main body winding section by section, leaving an overlap section between adjacent sections. Using a portable automated winding device, first complete the laying of the FRP fiber winding layer 3 in the first working section (e.g., 1.5m to 2.0m), and leave an overlap area of ​​not less than 100 mm at its end; perform the same operation on subsequent working sections.

[0098] After the resin in the working section has initially set, the overlapping section can be wound. Each overlapping section should be wound with the same strength as the stronger constraint section in its adjacent working section. To avoid stress concentration at both ends of the overlapping section due to abrupt changes in thickness, after the main body of the overlapping section is wound, two additional layers of ±45° oblique transition layers should be wound, with a width that covers the overlapping section and extends 50 mm to each side.

[0099] Step 5: Curing and post-treatment of the FRP fiber winding layer.

[0100] (5.1) Curing: Allow to cure naturally for 24 hours at room temperature (e.g., 25°C to 35°C).

[0101] (5.2) Trimming and Sealing: After curing, trim the edges of the FRP fiber winding layer 3 using a hand-held grinder. Apply epoxy resin paste to the start and end points and edges of the FRP fiber winding layer 3 using a scraper to thoroughly seal it and prevent moisture intrusion.

[0102] (5.3) Coating protection: After the entire FRP system has been fully cured, apply two coats of fluoropolymer coating to all exposed FRP surfaces by brushing or rolling as a durable protective topcoat (8) to provide long-term protection against UV degradation and weather resistance.

[0103] Example 3: Reinforcement of Crane Beams in Industrial Plants Based on Topology Optimization and Lattice Structure This embodiment corresponds to Figure 17 and Figure 18 The I-beam reinforcement structure shown.

[0104] This embodiment applies to heavy-duty bridge crane beams in industrial plants. Due to upgrades in plant processes, the rated lifting capacity of the cranes has increased, causing the original crane beams' bending capacity and local stability to no longer meet the new specifications. The reinforcement base is a single HW 300×300×10×15 mm open-section I-beam 9. The reinforcement area is mainly concentrated in the mid-span region of the component, i.e., the peak positive bending moment region caused by the crane load.

[0105] The specific structural form of this embodiment is as follows: Figure 17 As shown, it includes an I-beam 9 as the base, an additively manufactured optimized structural filler block 2 fixed to the concave surface between its flanges, and an FRP fiber winding layer 3 continuously wound around the surface of the reinforced section.

[0106] Because crane beams have extremely high requirements for stiffness and fatigue resistance, and the added weight is strictly limited, this invention uses a topology-optimized lightweight lattice structure additive manufacturing optimized structural filler block 2 and a multi-angle FRP fiber winding layer 3 to form an efficient synergistic force-bearing system, which maximizes the improvement of cross-sectional stiffness and local stability while minimizing the added weight.

[0107] The additively manufactured optimized structural filler block 2 is made of PEEK. Its external dimensions are matched to the concave surface of the section of the I-beam 9 to be reinforced using 3D scanning to ensure a tight fit. The internal structure design of the additively manufactured optimized structural filler block 2 is determined using a topology optimization algorithm, the specific design method of which is as follows: First, a finite element analysis model of the crane beam is established, and the most unfavorable load conditions specified in the relevant structural design code are applied. Then, the design domain occupied by the additively manufactured optimized structural filler block 2 is taken as the optimization object, the design objective is to maximize the total structural stiffness (i.e. minimize strain energy), and the material volume (e.g., reduced by 60%) is taken as the constraint condition. The solid isotropic material penalty model (SIMP) method is used to perform topology optimization calculation.

[0108] The internal cross-sectional shape is selected from a body-centered cubic lattice (e.g. Figure 17 As shown), the lattice unit size is fixed at 20×20×20mm. The diameter of the lattice bars is varied according to the density obtained by topology optimization: in the mid-span bending moment peak region where maximum stiffness is required (corresponding to the high-density lattice region, such as...), Figure 17 As shown), the rod diameter is the largest, designed to be 5.0 mm; in the region with lower stress, near the support (corresponding to the low-density lattice region, such as...), Figure 18 As shown in the diagram, the rod diameter gradually decreases to 2.0 mm. This variable density structural design distributes the material where it is most needed, achieving a strength-weight match.

[0109] The FRP fiber winding layer 3 is made of high-strength continuous carbon fiber and epoxy resin matrix. To simultaneously enhance the bending, shear, and flexural-torsional coupling properties of the cross-section, the FRP fiber winding layer 3 adopts a multi-angle composite layup. Its design method is based on the theory of composite laminates and relevant design guidelines (such as GB 50608 or ACI 440.2R).

[0110] First, the required increase in bearing capacity is calculated based on the target bearing capacity after the crane beam is reinforced and the existing bearing capacity. The nominal thickness of the required FRP fiber winding layer 3 is determined through iterative calculation to ensure that the ultimate state of the reinforced section meets the requirements for the increase in bearing capacity. At the same time, it is checked that the strain of the FRP does not exceed its design ultimate strain (usually taken as 0.004 ~ 0.006) and that the adhesive layer 6 does not peel off.

[0111] To balance circumferential restraint, longitudinal stiffness, and torsional stiffness, the ply design (from inside to outside) in this embodiment is: [±89° / ±45° / ±45° / ±89° / ±45° / ±45° / ±89°]. The near-circumferential (±89°) ply primarily provides strong circumferential restraint, effectively suppressing local buckling of the I-beam's 9th flange; the ±45° ply is mainly used to resist shear and torsion.

[0112] In this embodiment, the additively manufactured optimized structural filler block 2 is firmly bonded to the web of the I-beam 9 through a hybrid connection method combining adhesive bonding and bolting.

[0113] The design methodology is based on load sharing and failure protection principles. Under normal service loads, shear force is primarily transmitted through the high-strength adhesive layer 6 (e.g., a two-component epoxy structural adhesive with a shear strength >20 MPa). High-strength connecting bolts at this stage primarily provide strong clamping force, ensuring the adhesive layer 6 is under compressive stress and inhibiting peeling. When crane impact loads or fatigue cause localized failure or yielding of the adhesive layer, the connecting bolts are activated, bearing shear force through bolt hole pressure and friction, acting as a second line of defense to prevent catastrophic, brittle peeling failure of the reinforced system, significantly improving the ductility and reliability of the connection.

[0114] M12 grade 10.9 high-strength bolts are used. The bolts are arranged in two rows along the height of the web of the I-beam 9, with a spacing of no more than 300 mm along the length of the member. During calculation, the shear stress of the adhesive layer 6, the shear and bearing capacity of the bolts must be checked separately to ensure that, under ultimate conditions, the total bearing capacity of the combined connection is greater than the design shear force.

[0115] The construction method of this embodiment includes the following specific steps: Step 1: Substrate treatment.

[0116] (1.1) Geometric Correction: The initial deformation of the I-beam 9 was detected using a laser collimation measuring instrument. For deformations exceeding limits (such as...), ... L The section with a diameter of 500 mm was straightened using hydraulic jacks and local heating. L The calculated length of I-beam 9 is equal to the net span or effective length of I-beam 9 between two longitudinal constraint / support points.

[0117] (1.2) Surface treatment: Use a sandblasting machine equipped with an air compressor to remove rust and roughen the concave surface and FRP winding area of ​​the I-beam 9. The surface should reach Sa 2.5 grade (near white metal grade) as specified in GB / T 8923.1.

[0118] (1.3) Cleaning: Use an industrial vacuum cleaner to remove dust, and then use a clean cotton cloth soaked in acetone to thoroughly degrease and wipe.

[0119] Step 2: Optimization design and fabrication of the additively manufactured optimized structural filler block.

[0120] (2.1) Geometric and operational data acquisition: A handheld 3D laser scanner was used to perform high-precision scanning of the concave surface of the section of the I-beam 9 to be reinforced, and 3D point cloud data was acquired to establish a digital model. Simultaneously, operational data such as crane load were collected. A digital model reflecting the true geometric features and deformation state of the I-beam 9 is reconstructed based on the three-dimensional point cloud data. A virtual envelope with a preset closed outer contour is constructed, i.e., the reinforced structure, and the digital model is subtracted from the virtual envelope by Boolean subtraction operation; Based on the preset adhesive layer thickness, the normal offset compensation is performed on the contact surface after Boolean operation to generate the outer contour of the manufacturing model of the optimized structure filler block.

[0121] (2.2) Structural optimization design: A model is established in the finite element analysis software, and topology optimization is performed according to the above design method to generate a variable density lattice numerical model of the additive manufacturing optimized structure filler block 2.

[0122] (2.3) Additive Manufacturing: The numerical model is input into an industrial-grade high-temperature fused deposition modeling (FDM) 3D printer. The nozzle temperature (>400°C) and chamber temperature (>120°C) are set, and the optimized additive structure filler block 2 is prepared by printing using PEEK material. After printing, the optimized additive structure filler block 2 is subjected to necessary annealing treatment to eliminate internal stress.

[0123] Step 3: Fixing the additively manufactured optimized structure filler block.

[0124] (3.1) Drilling: According to the design drawings, use a magnetic drill to drill M12 bolt holes at the corresponding positions on the web of the I-beam 9. The corresponding bolt holes were pre-drilled during the 3D printing of the additive manufacturing optimized structural infill block 2.

[0125] (3.2) Surface treatment of PEEK: Due to the inertness of the PEEK material surface, the bonding surface needs to be sandblasted or plasma treated before applying adhesive to improve its surface energy and bonding strength.

[0126] (3.3) Applying adhesive and installation: Using a two-component glue gun, apply the uniformly mixed epoxy structural adhesive to the concave surface of the I-beam (9) and the bonding surface of the treated additively manufactured optimized structural filler block 2 to form an adhesive layer (6).

[0127] (3.4) Tightening: Immediately install the additively manufactured optimized structure filler block 2 into place and insert the high-strength bolts. Use a torque wrench to tighten the bolts symmetrically to the designed torque (e.g., 80 N·m for M12 10.9 grade bolts) to ensure that the adhesive layer 6 cures under pressure and achieves a tight fit.

[0128] Step 4: The FRP fiber winding layer is laid out.

[0129] (4.1) Equipment debugging: A multi-axis robot fiber winding equipment is used, which integrates a fiber tension control system, a resin impregnation tank and a CNC program.

[0130] (4.2) Insulation layer winding: In order to prevent galvanic corrosion between carbon fiber and steel substrate, the winding machine is started first. The automated continuous fiber winding technology is used to wind a layer of glass fiber tape impregnated with thermoplastic resin matrix into the entire reinforced area (including the exposed surface of the additive manufacturing optimized structure filler block 2 and I-beam 9) after in-situ heating and melting during the winding process, forming a glass fiber insulation layer with a thickness of about 0.5 mm.

[0131] (4.3) Structural Layer Winding: After the initial gelation of the insulating layer, the CNC program automatically switches to carbon fiber bundles and performs multi-layer reciprocating winding according to the designed layup angles [±89° / ±45° / ±45° / ±89° / ±45° / ±45° / ±89°], completing a total of 7 fiber winding layers. During the winding process, the fiber tension is kept constant (e.g., 20 N) to ensure sufficient impregnation and proper compaction.

[0132] (4.4) Segmented wrapping: For reinforcement sections with a length exceeding 2m, segmented wrapping and overlapping processes are adopted to facilitate construction. The overlap length is not less than 100 mm (or 60 times the FRP layer thickness, whichever is larger). The process is the same as step (4.3) in Example 2.

[0133] Step 5: Curing and post-treatment of the FRP fiber winding layer.

[0134] (5.1) Curing: Thermoplastic resin matrix is ​​usually automatically laid out and solidified in situ, and can be continuously wound without waiting for curing.

[0135] (5.2) Trimming and Sealing: After curing, use scissors or an angle grinder with a fine grinding wheel to trim excess fibers and resin burrs from the edges of the FRP fiber-wound layer 3. Then, use a scraper to apply epoxy resin paste to the start and end points and edges of the FRP fiber-wound layer 3 to thoroughly seal it and prevent moisture intrusion.

[0136] (5.3) Coating protection: After the entire FRP system has been fully cured, use an airless sprayer to uniformly coat all exposed FRP surfaces with two coats of aliphatic polyurethane coating (total dry film thickness of about 100 μm) as a durable protective topcoat 8 to provide long-term protection against UV degradation and weather resistance.

[0137] In summary, this invention provides a method for reinforcing open-section steel profiles by continuously winding an optimized structural filler block and fiber-reinforced polymer (FRP) using additive manufacturing (3D printing). This method aims to solve the problems of poor FRP adhesion and low reinforcement efficiency caused by the geometric limitations of open-section steel profiles. The reinforcement structure of this invention includes: an optimized structural filler block prepared by additive manufacturing and fixed to the concave surface of the steel profile; the optimized structural filler block has a geometry optimized based on preset performance targets, such as an optimized internal cross-section (e.g., honeycomb or lattice structure) and / or an optimized longitudinal layout (e.g., functional gradient or topology optimization); and an FRP fiber winding layer continuously wound around the optimized structural filler block and the outer surface of the steel profile. The optimized structural filler block transforms the open section into a closed section that facilitates winding, forming a synergistic force-bearing system with the FRP fiber winding layer. The FRP fiber winding layer provides circumferential constraints to suppress local buckling, and both together enhance the mechanical properties of the section. This invention is particularly suitable for the repair and reinforcement of open-section steel components subjected to complex loads, such as transmission towers and bridge supports.

[0138] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A reinforced steel structure with an open section and an optimized structural filler block based on additive manufacturing and FRP fiber winding, characterized in that, include: Open-section steel, additively manufactured optimized structural filler blocks, and FRP fiber winding layer; The cross-sectional shape of the additively manufactured optimized structural filler block is a closed cross-section; The additively manufactured optimized structural filler block is fitted to the concave surface of the open-section steel, and the FRP fiber winding layer is continuously wound around the outer surface of the additively manufactured optimized structural filler block and the open-section steel.

2. The open-section steel reinforcement structure based on additive manufacturing and FRP fiber winding, as described in claim 1, is characterized in that... The cross-section of the additively manufactured optimized structural filler block, after being fitted with the concave surface of the open-section steel, has a smooth outer contour.

3. The open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 1, characterized in that, The internal cross-sectional shape of the additively manufactured optimized structural filler block is a honeycomb structure or a lattice structure. The longitudinal layout of the additively manufactured optimized structural filler block is a variable density structure, and the material distribution matches the stress field under the preset load conditions, which is determined through functional gradient or topology optimization.

4. The open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 1, characterized in that, The additively manufactured optimized structural filler block is bonded to the concave surface of the open section steel by adhesive bonding and / or mechanical connection; The constituent material of the FRP fiber winding layer is selected from any one or a combination of the following: (1) wet-wound fiber bundle: dry fiber bundle that has been impregnated in a resin bath during the winding process; (2) Thermoplastic prepreg tape: a fiber tape impregnated with a thermoplastic resin matrix, which is heated and melted in situ during the winding process.

5. The open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 1, characterized in that, The FRP fiber winding layer adopts a layered multi-angle configuration system; in sections where local buckling needs to be mainly suppressed or circumferential cracking needs to be prevented, a near-circumferential winding layer is configured, with the fiber winding angle relative to the longitudinal axis of the component being 75° to 90°; in sections where bending-torsional coupling stiffness or shear resistance needs to be enhanced, an oblique cross winding layer is configured, with the fiber winding angle being ±30° to ±60°; in sections where longitudinal bearing capacity needs to be synergistically improved, an inner layer is configured as a small-angle spiral layer with a winding angle of ±10° to ±30°, and an outer layer covers the near-circumferential winding layer to form a closed constraint.

6. A construction method for an open-section steel reinforcement structure based on additive manufacturing of an optimized structural filler block and FRP fiber winding, as described in any one of claims 1 to 5, characterized in that, include: Step 1: Pre-treat the open-section steel section; Step 2: Additive manufacturing of optimized structural filler blocks; Step 3: The additively manufactured optimized structural filler block is bonded to the concave surface of the pretreated open section steel by adhesive bonding and / or mechanical connection; Step 4: The FRP fiber winding layer is completed on the outer surface of the additively manufactured optimized structural filler block and the open section steel using automated continuous fiber winding technology; Step 5: Curing and post-processing the FRP fiber winding layer to obtain the open section steel reinforcement structure.

7. The construction method of the open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 6, characterized in that, Step one specifically includes: firstly, geometrically correcting the open-section steel, and then performing surface cleaning and rust removal treatment on the open-section steel.

8. The construction method of the open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 6, characterized in that, Step two specifically includes: The surface three-dimensional point cloud data of the section of the open-section steel to be reinforced is obtained using a non-contact three-dimensional scanning device; A digital model reflecting the true geometric features and deformation state of the open section steel is reconstructed based on the three-dimensional point cloud data. Construct a virtual envelope with a preset closed outer contour, and subtract the digitized model from the virtual envelope using Boolean subtraction operations; Based on the preset adhesive layer thickness, the normal offset compensation is performed on the contact surface after Boolean operation to generate the outer contour of the manufacturing model of the optimized structure filling block. A three-dimensional numerical model of the optimized additive manufacturing structure filler block is generated using finite element analysis, topology optimization, or biomimetic design. The three-dimensional numerical model is input into the additive manufacturing equipment to produce an additive manufacturing optimized structural filler block.

9. The construction method of the open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in claim 6, characterized in that, Step five specifically includes: after the FRP fiber winding layer has fully cured, sealing the edges, seams and ends of the FRP fiber winding layer with epoxy resin paste; after curing, applying a durable protective topcoat to the exposed surface.

10. The application of the open-section steel reinforcement structure based on additive manufacturing optimized structural filler block and FRP fiber winding as described in any one of claims 1 to 5 in transmission towers, bridge supports, crane beams of industrial plants, and support components of offshore platforms.

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