A rusted cold-bent thin-walled C-shaped steel reinforcing structure and a construction method thereof

Abstract

This invention belongs to the field of civil engineering structural reinforcement and corrosion protection technology, and discloses a reinforcement structure and construction method for rusted cold-formed thin-walled C-shaped steel. The structure includes grouting concrete, a reinforcing steel plate, an end sealing plate, a fiber-reinforced composite material retaining layer, and an epoxy resin pre-coating layer. The epoxy resin pre-coating layer is applied to the dense rust layer surface of the rusted C-shaped steel. The reinforcing steel plate is placed at the opening of the rusted C-shaped steel, and the end sealing plate is placed at the end of the rusted C-shaped steel. The rusted C-shaped steel, the reinforcing steel plate, and the end sealing plate together form a closed cavity. Grouting concrete fills the closed cavity. The fiber-reinforced composite material retaining layer covers the outside of the rusted C-shaped steel and the reinforcing steel plate. This invention enables efficient and reliable rust-bearing reinforcement of rusted cold-formed thin-walled C-shaped steel, effectively ensuring the long-term durability of the reinforced component.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering structure reinforcement and corrosion protection technology, and specifically relates to a reinforcement structure for rusted cold-formed thin-walled C-shaped steel and its construction method. Background Technology

[0002] Cold-formed thin-walled C-shaped steel has outstanding advantages such as light weight, high cross-sectional utilization efficiency, and the ability to be prefabricated in factories and assembled on-site. It is often used as purlins, wall beams, secondary beams, and various load-bearing and secondary load-bearing components, and is widely used in industrial plants, public buildings, light steel structure houses, and various infrastructure projects. However, during long-term service, cold-formed thin-walled C-shaped steel is often exposed to harsh corrosive environments such as high humidity, high salt spray, acidic media, high-temperature steam, and corrosive dust. Its surface anti-corrosion coating is prone to aging, damage, and even peeling, which in turn causes corrosion damage to the steel substrate. Compared with conventional thick-walled steel structures, cold-formed thin-walled C-shaped steel has a smaller wall thickness, and there are geometric abrupt changes and stress concentration problems at the rolled edges and inner corners of the components. Under the coupled effect of the corrosive environment, local accelerated corrosion is prone to occur, which ultimately leads to a significant reduction in the load-bearing capacity, overall stiffness, and service durability of the components, affecting the overall safety of the steel structure.

[0003] Currently, the main methods for repairing and reinforcing corroded thin-walled steel sections include welding reinforcement, mechanical connection reinforcement, steel cladding reinforcement, and grouting reinforcement. Among them, welding reinforcement uses molten metal welding to reinforce and repair the corroded and damaged parts of the steel section; mechanical connection reinforcement uses mechanical connectors such as bolts to splice and reinforce damaged components; steel cladding reinforcement improves the overall load-bearing performance of the component by wrapping a steel plate around the outside of the corroded steel section; and grouting reinforcement repairs structural defects and strengthens the overall structure by injecting filling material into the cavity or gap of the component.

[0004] However, in practical engineering applications, the versatility and adaptability of existing reinforcement technologies are poor, making it difficult to meet the reinforcement and repair needs of cold-formed thin-walled C-shaped steel, especially the commonly used double-section C-shaped steel, and failing to guarantee the long-term service durability of the reinforced components. Specifically, welding reinforcement will generate residual welding stress and heat-affected zones, changing the original stress state of the component and damaging the original anti-corrosion coating, causing secondary structural damage. Mechanical connection reinforcement requires drilling holes in the thin-walled steel to install connectors, which not only weakens the effective stress section of the component but also creates new corrosion channels at the hole locations, accelerating the corrosion of the component. Subsequent corrosion and aging; when steel reinforcement and closed cavity grouting reinforcement are applied to thin-walled components, the grouting process is prone to generating internal pressure, causing local bulging deformation of the steel section, and quality problems such as grout leakage, internal hollowing, and incomplete sealing are prone to occur at component splices and around connection holes, resulting in insufficient reliability in long-term service; in addition, it is difficult to achieve thorough rust removal and complete continuous coating in the narrow gaps, inner corners, and obstructions of cold-formed thin-walled C-shaped steel through conventional construction methods, and dense rust layers are prone to remain on the surface of the components, which seriously affects the interface force transmission effect, long-term bonding stability and overall sealing durability of the reinforced structure. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a reinforcement structure for rusted cold-formed thin-walled C-shaped steel and its construction method, in order to solve the technical problems that existing reinforcement technologies have poor versatility and adaptability, making it difficult to meet the requirements of cold-formed thin-walled C-shaped steel and ensuring the long-term service durability of the reinforced components.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a reinforcement structure for rusted cold-formed thin-walled C-shaped steel, comprising grouting concrete, a reinforcing steel plate, an end sealing plate, a fiber-reinforced composite material sheathing layer, and an epoxy resin pre-coating layer. An epoxy resin pre-coating is applied to the dense rust layer surface of the rusted C-shaped steel; a reinforcing steel plate is applied to the opening of the rusted C-shaped steel, and an end sealing plate is applied to the end of the rusted C-shaped steel; wherein, the rusted C-shaped steel, the reinforcing steel plate, and the end sealing plate together form a closed cavity; Grouting concrete is used to fill the sealed cavity; Fiber-reinforced composite material sheathing is wrapped around the outside of the rusted C-shaped steel and the reinforcing steel plate.

[0007] Furthermore, the epoxy resin pre-coating covers all exposed surfaces of the dense rust layer and penetrates into the pores of the dense rust layer.

[0008] Furthermore, a reinforcing steel plate is fastened to the opening of the rusted C-shaped steel, and the shape of the reinforcing steel plate is adapted to the shape of the opening of the rusted C-shaped steel; wherein, the two sides of the reinforcing steel plate contact the rolled edge of the rusted C-shaped steel and are fixedly connected by fasteners.

[0009] Furthermore, the end sealing plate is snapped onto the end of the rusted C-shaped steel; wherein, the end sealing plate includes a sealing end plate and four sealing side plates, the four sealing side plates are respectively located on the four sides of the sealing end plate, and all extend vertically toward the outward direction of the sealing end plate. The sealing end plate is set at the end of the rusted C-shaped steel, and all four sealing side plates are inserted into the opening of the rusted C-shaped steel; among them, the outer surface of one sealing side plate is tightly fitted with the inner surface of the reinforcing steel plate, and the outer surfaces of the remaining three sealing side plates are tightly fitted with the inner wall of the rusted C-shaped steel.

[0010] Furthermore, the reinforcing steel plate is provided with at least one grouting port; wherein, the grouting concrete is injected into the closed cavity through the grouting port.

[0011] Furthermore, the reinforcing steel plate is also provided with vents or overflow outlets; or, one or more of the grouting outlets may also serve as vents or overflow outlets.

[0012] Furthermore, the grouting concrete is a self-compacting micro-expansion grouting concrete.

[0013] Furthermore, the fiber-reinforced composite sheath layer is a sheath layer formed by adhesively bonded carbon fiber cloth.

[0014] Furthermore, the epoxy resin pre-coating layer is a continuous interface layer formed by curing low-viscosity epoxy resin; wherein, at 25°C, the rotational viscosity of the low-viscosity epoxy resin is 50-150 mPa·s.

[0015] Secondly, the present invention provides a construction method for reinforcing a rusted cold-formed thin-walled C-shaped steel structure, comprising: Apply an epoxy resin pre-coating to the dense rust layer on the surface of the corroded C-shaped steel; The end sealing plate is snapped onto the end of the rusted C-shaped steel and then fixedly connected to the rusted C-shaped steel. A reinforcing steel plate is placed at the opening of the rusted C-shaped steel and fixedly connected to the rusted C-shaped steel; at the same time, an end sealing plate is fixedly connected to the reinforcing steel plate so that the rusted C-shaped steel, the reinforcing steel plate and the end sealing plate together form a closed cavity. A fiber-reinforced composite material sheath is wrapped around the outside of the corroded C-shaped steel and the reinforcing steel plate; Grouting concrete is poured into the sealed cavity.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The reinforcement structure for rusted cold-formed thin-walled C-shaped steel provided by this invention can achieve efficient and reliable rust-bearing reinforcement of rusted cold-formed thin-walled C-shaped steel, effectively ensuring the long-term durability of the reinforced component. Specifically, an epoxy resin pre-coating is applied to the surface of the dense rust layer of the rusted C-shaped steel. Utilizing the permeability and adhesion of the epoxy resin pre-coating, the difficult-to-remove dense rust layer is transformed into a bonding transition layer, thus avoiding the problem of traditional rust removal processes failing to completely remove rust in hidden areas such as crevices and inner corners, ensuring reliable interface force transmission and long-term bonding stability. Secondly, the opening of the C-shaped steel is sealed by a reinforcing steel plate, and the ends are sealed by an end sealing plate, forming a closed cavity with the rusted C-shaped steel. Concrete is then poured into the cavity, so that the grouting process is rigidly bounded, avoiding local damage to the thin-walled steel due to grouting pressure. This method addresses the issue of bulging and deformation, while also eliminating potential quality problems such as joint leakage and internal hollowing. Furthermore, the fiber-reinforced composite material sheathing layer is integrally wrapped around the outer side of the steel profile and reinforcing steel plate to provide continuous circumferential restraint. This not only inhibits shrinkage cracking and compressive expansion of the grouting concrete but also effectively prevents the intrusion of external corrosive media. The fiber-reinforced composite material sheathing layer, along with the epoxy resin pre-coating and grouting concrete, works synergistically to form a multi-layered protective barrier for the entire reinforcement system. The construction of the reinforced structure requires no welding, avoiding residual welding stress, heat-affected zone damage, or section weakening. This effectively ensures the structural integrity and long-term service durability of the reinforced components, significantly improving the versatility and adaptability of the reinforced structure, making it particularly suitable for corroded thin-walled components with complex cross-sections, such as double-section C-shaped steel.

[0017] Furthermore, an epoxy resin pre-coating is applied to cover all exposed surfaces of the dense rust layer and penetrates into the pores of the dense rust layer. Through capillary penetration curing, the loose and porous dense rust layer is bonded into a dense resin-rust composite, eliminating the risk of micro-cracks and interlayer peeling within the rust layer, blocking the diffusion path of corrosive media along the capillary channels of the rust layer to the steel substrate, and eliminating the hidden danger of closed blind areas becoming sites for later corrosion initiation from the source.

[0018] Furthermore, the shape of the opening of the reinforcing steel plate is adapted to the shape of the rusted C-shaped steel and the two sides are in close contact with the rolled edge, so that the fastener only undertakes the function of binding and fixing rather than transmitting the internal force of the section, which significantly reduces the opening diameter and the section weakening effect; at the same time, the rolled edge is effectively restricted by the lateral constraint of the steel plate to limit the distortion buckling, so that the reinforcing steel plate participates in the stress during the grouting construction stage, improving the temporary stability of the component during construction.

[0019] Furthermore, the end sealing plate engages with the inner wall of the C-shaped steel and the inner surface of the reinforcing steel plate through multi-directional contact via four sealing side plates, forming a directionally coupled clamping force with the grouting pressure. The greater the grouting pressure, the tighter the contact, ensuring pressure maintenance and dense filling throughout the entire grouting process of the sealed cavity.

[0020] Furthermore, by setting vents or overflow ports, the combination of grouting ports and vents or overflow ports allows the grouting concrete to orderly replace the air in the closed cavity, avoiding the accumulation of air bubbles and filling voids at geometric abrupt changes. The grouting port also serves as a vent or overflow port, which can prevent the increased internal air pressure in the later stages of grouting from causing outward expansion of the flanges and webs of the corroded C-shaped steel, thus preventing local bulging deformation.

[0021] Furthermore, self-compacting micro-expansion grouting concrete can fill all the tiny gaps in the closed cavity without vibration by its own weight, avoiding segregation and incomplete filling caused by limited vibration. The micro-expansion characteristics of self-compacting micro-expansion grouting concrete apply uniform extrusion prestress to the inner wall of the closed cavity during the hardening process, eliminating the micro-gaps at the interface caused by grout shrinkage and ensuring coordinated deformation under long-term load.

[0022] Furthermore, the fiber-reinforced composite material retaining layer is formed by adhesive carbon fiber cloth. The initial circumferential pretension is generated by circumferential winding and curing, which suppresses the local buckling of the flange and web in the compression zone. At the same time, it restrains the lateral expansion of the internal grouted concrete, putting it in a triaxial compression state and improving compressive strength and ductility. The adhesive carbon fiber cloth and the epoxy resin pre-coating are both epoxy system, with good interfacial chemical compatibility and guaranteed long-term bonding durability.

[0023] Furthermore, the low-viscosity epoxy resin adhesive is in a balance range between good wetting and penetration and sufficient thixotropic anti-sagging, which can effectively penetrate into the microcapillaries of the dense rust layer and cure into a penetration-reinforcing layer with sufficient rigidity; at the same time, the low-viscosity epoxy resin adhesive with a rotational viscosity of 50-150 mPa·s has good tolerance and replacement ability for trace amounts of moisture and chloride salts remaining on the rust surface, effectively reducing the difficulty of on-site construction and environmental dependence.

[0024] The construction method for reinforcing rusted cold-formed thin-walled C-shaped steel provided by this invention possesses all the advantages of the aforementioned reinforcing structure for rusted cold-formed thin-walled C-shaped steel. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the overall structure of the reinforcement structure for the rusted cold-formed thin-walled C-shaped steel provided in the embodiment; Figure 2 This is a schematic diagram illustrating the effect of applying an epoxy resin pre-coating to the surface of a dense rust layer in the embodiment. Figure 3 This is a schematic diagram of the end sealing plate in the embodiment.

[0027] Among them, 1. Rusted C-shaped steel; 2. Grouting concrete; 3. Reinforcing steel plate; 4. End sealing plate; 5. Fiber-reinforced composite material binding layer; 6. Fasteners; 7. Fixing holes; 8. Grouting port; 9. Dense rust layer; 10. Epoxy resin pre-coating layer. Detailed Implementation

[0028] To make the technical problems solved, technical solutions, and beneficial effects of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Before describing specific embodiments of the present invention, some technical terms involved in the embodiments of the present invention are explained as follows: Cold-formed thin-walled C-shaped steel refers to open cold-formed steel with a C-shaped cross section and a wall thickness of no more than 6mm, made from hot-rolled or cold-rolled steel plates through a continuous roll bending process at room temperature. It includes, but is not limited to, C-shaped cross-section steel composed of web, flange and rolled edge, as well as double C-shaped steel composite cross-section members formed by splicing two C-shaped steels together.

[0030] Fiber-reinforced polymer / plastic (FRP) refers to composite material plates, sheets, or profiles formed by impregnating, molding, and curing high-strength continuous fibers (including but not limited to carbon fiber, glass fiber, basalt fiber, and aramid fiber) as reinforcing materials and synthetic resins (including but not limited to epoxy resin, polyester resin, and vinyl ester resin) as matrix materials, resulting in a strong bond between the fiber and matrix interfaces. In this invention, it specifically refers to flexible fiber cloth-like FRP material that is applied or wrapped on the surface of the reinforced component using adhesive methods, forming a continuous wrapping layer after curing with structural adhesive.

[0031] Epoxy resin adhesive refers to a thermosetting polymer adhesive material made primarily of epoxy resin, combined with curing agents, diluents, toughening agents, and other additives. It possesses excellent metal adhesion, low shrinkage, high chemical stability, and good resistance to corrosion media penetration. In this invention, it specifically refers to room-temperature curing epoxy resin adhesives. Its low-viscosity specifications can be used to penetrate and seal rust layers to form a pre-coating layer, while its conventional viscosity specifications can be used for bonding and impregnating fiber-reinforced composite materials.

[0032] A confinement layer is a fiber-reinforced composite material layer that surrounds and continuously encloses the outer periphery of a reinforced component. Through the continuous circumferential arrangement of fibers, it forms a circumferential constraint effect on the internal components, which can effectively suppress the lateral expansion deformation and local buckling of the compressed components, while also serving as an external protective barrier.

[0033] Pre-coating refers to a functional thin layer that is applied to the surface of the substrate of the reinforced component before the main reinforcement construction (such as grouting or steel plate wrapping) and fully cured. In this invention, it specifically refers to a continuous and dense interface layer formed by applying low-viscosity epoxy resin to the dense rust layer surface of rusted C-shaped steel and allowing it to penetrate and cure. It has the dual functions of sealing and isolation as well as interface bonding and transition.

[0034] Self-compacting micro-expansion grouting concrete refers to an inorganic cementitious material-based grouting material that simultaneously possesses self-compacting and micro-expansion properties. Self-compacting means that in its freshly mixed state, it can flow under its own weight, pass through the gaps between reinforcing bars, and fill all the spaces within the formwork, achieving good compaction without the need for external vibration. Micro-expansion refers to the grouting material that produces stable and controllable volume expansion during hydration and hardening (with the expansion rate controlled at 0.02%-0.05%), enabling it to apply uniform extrusion prestress to the confined boundary, compensate for grout shrinkage, and eliminate interfacial micro-cracks.

[0035] This invention provides a reinforcement structure for rusted cold-formed thin-walled C-shaped steel, comprising grouting concrete 2, reinforcing steel plate 3, end sealing plate 4, fiber-reinforced composite material binding layer 5, and epoxy resin pre-coating layer 10; the epoxy resin pre-coating layer 10 is applied to the surface of the dense rust layer 9 of the rusted C-shaped steel 1; the reinforcing steel plate 3 is applied to the opening of the rusted C-shaped steel 1, and the end sealing plate 4 is applied to the end of the rusted C-shaped steel 1; wherein, the rusted C-shaped steel 1, the reinforcing steel plate 3, and the end sealing plate 4 together form a closed cavity; the grouting concrete 2 fills the closed cavity; and the fiber-reinforced composite material binding layer 5 covers the outside of the rusted C-shaped steel 1 and the reinforcing steel plate 3.

[0036] In the above embodiments, an epoxy resin pre-coating layer 10 is applied to the surface of the dense rust layer 9 to penetrate, cure, and seal the dense rust layer 9, thereby transforming the rust interface of the rusted C-shaped steel 1 into a stable load-bearing base layer, effectively overcoming the problems of interface bonding failure and continuous deterioration under rusted conditions. Secondly, a closed cavity is constructed by using a reinforcing steel plate 3 and an end sealing plate 4 in conjunction with the rusted C-shaped steel 1, avoiding thermal damage and weakening of the openings in the thin-walled section of the rusted C-shaped steel 1 caused by traditional welding or extensive mechanical connections. Grouting concrete 2 is then injected into the closed cavity, utilizing the flow and filling characteristics of the grouting concrete 2 to achieve dense filling of the complex internal cavity. Furthermore, a fiber-reinforced composite material binding layer 5 is wrapped around the outside of the rusted C-shaped steel 1 and the reinforcing steel plate 3. The grouting concrete 2 is injected using the external wrapping constraint of the fiber-reinforced composite material binding layer 5. During the process, the risk of thin-walled bulging caused by the lateral pressure of concrete is transformed into prestressed confinement, changing the component from a pressure-bearing bulging state to a constrained and coordinated stress state, effectively suppressing local buckling and internal pressure failure. In addition, the fiber-reinforced composite confinement layer 5 and the corroded C-shaped steel 1 are physically isolated by the epoxy resin pre-coating layer 10, blocking the direct contact between the fiber-reinforced composite confinement layer 5 and the steel substrate, fundamentally eliminating the risk of galvanic corrosion in the electrolyte environment. Furthermore, the circumferential constraint provided by the fiber-reinforced composite confinement layer 5 significantly improves the compressive strength and ductility of the grouted concrete 2, forming a combined stress system of steel-concrete-fiber-reinforced composite material, which greatly improves the load-bearing capacity, stiffness and long-term service durability of the reinforced component. It is especially suitable for complex cross-section forms such as double-section C-shaped steel and space-constrained conditions, and has significant advantages such as convenient construction, controllable quality and strong adaptability.

[0037] The following specific embodiments further explain and illustrate the reinforcement structure and construction method for rusted cold-formed thin-walled C-shaped steel provided by the present invention: Example As attached Figure 1-3 As shown, this embodiment provides a reinforcement structure for rusted cold-formed thin-walled C-shaped steel, used for rusted reinforcement of rusted C-shaped steel 1; wherein, the rusted C-shaped steel 1 is a single cold-formed thin-walled C-shaped steel, or a double C-shaped steel formed by two cold-formed thin-walled C-shaped steels arranged opposite each other and combined.

[0038] It should be noted that a dense rust layer 9 is retained on the surface of the corroded C-shaped steel 1; the dense rust layer 9 is a firmly adhered rust layer that remains on the surface of the corroded C-shaped steel 1 after the removal of loose rust and floating rust; preferably, the adhesion strength between the dense rust layer 9 and the steel substrate of the corroded C-shaped steel 1 is greater than 4.5 MPa, and the adhesion strength is measured by the pull-off method.

[0039] Specifically, the reinforcement structure of the rusted cold-formed thin-walled C-shaped steel includes grouting concrete 2, reinforcing steel plate 3, end sealing plate 4, fiber-reinforced composite material binding layer 5, and epoxy resin pre-coating layer 10; the epoxy resin pre-coating layer 10 is applied to the surface of the dense rust layer 9 of the rusted C-shaped steel 1; the reinforcing steel plate 3 is applied to the opening of the rusted C-shaped steel 1, and the end sealing plate 4 is applied to the end of the rusted C-shaped steel 1; wherein, the rusted C-shaped steel 1, the reinforcing steel plate 3, and the end sealing plate 4 together form a closed cavity; the grouting concrete 2 fills the closed cavity; and the fiber-reinforced composite material binding layer 5 covers the outside of the rusted C-shaped steel 1 and the reinforcing steel plate 3.

[0040] Explained, an epoxy resin pre-coating 10 is applied to the surface of the dense rust layer 9 to penetrate, cure, and seal the dense rust layer 9, thereby transforming the rust interface of the dense rust layer 9 into a stable load-bearing base layer; a closed cavity is constructed using a reinforcing steel plate 3 and end sealing plates 4 in conjunction with the rusted C-shaped steel 1; wherein, the closed cavity is formed by the inner wall of the groove of the rusted C-shaped steel 1, the inner surface of the reinforcing steel plate 3, and the inner surfaces of the end sealing plates 4 at both ends, providing a stable filling space for the grouting concrete 2 and effectively preventing Local bulging caused by uncontrolled internal pressure during the grouting process; in particular, for double-section C-shaped steel, the closed cavity is formed by the inner cavity of two rusted C-shaped steels 1 joined together, the reinforcing steel plate 3 and the end sealing plate 4; secondly, by using the outer winding constraint of the fiber-reinforced composite material binding layer 5, the risk of thin-wall bulging caused by the side pressure of concrete during the grouting of concrete 2 is transformed into binding prestress, so that the component changes from pressure-bearing bulging to a constrained and coordinated stress state, effectively suppressing local buckling and internal pressure failure.

[0041] In one possible implementation, the epoxy resin pre-coating 10 covers the entire exposed surface of the dense rust layer 9 and penetrates into the pores of the dense rust layer 9, as shown in the attached figure. Figure 2 As shown; specifically, the epoxy resin pre-coating layer 10 is applied to all exposed surfaces of the dense rust layer 9 by brushing, rolling or spraying; before application, ensure that the surface of the dense rust layer 9 is dry, clean and free of oil and dust; the amount of epoxy resin pre-coating layer 10 applied should be sufficient to allow the epoxy resin to fully wet the surface pores and microcracks of the dense rust layer 9. Explained, since the epoxy resin pre-coating layer 10 covers all exposed surfaces of the dense rust layer 9, forming a continuous and complete closed covering layer, it can effectively isolate external corrosive media from contact with the dense rust layer 9 and prevent further rust development; after the epoxy resin penetrates into the pores of the dense rust layer 9, it interlocks with the rust particles during the curing process to form a mechanically interlocked structure. At the same time, the active groups in the epoxy resin chemically bond with the rust surface to form a chemical bonding force, thereby significantly improving the interfacial bonding strength between the dense rust layer 9 and the subsequent reinforcement layer.

[0042] In this embodiment, the epoxy resin pre-coating 10 fully covers and penetrates the pores of the dense rust layer 9, achieving comprehensive stabilization and sealing of the residual rust layer. This transforms the originally loose and porous rust layer into a continuous and dense interface transition layer, providing a reliable interface foundation for subsequent reinforcement construction. Secondly, by covering the entire exposed surface of the dense rust layer 9 with the epoxy resin pre-coating 10 and penetrating into the pores, a rust-adhesive fused composite interface layer is formed. This rust-adhesive fused composite interface layer has both high cohesive strength and high adhesion to the steel substrate, effectively solving the key technical problem of weak interface force transmission in rusted reinforcement.

[0043] In one possible implementation, the epoxy resin pre-coating layer 10 is a continuous interface layer formed by curing low-viscosity epoxy resin, which achieves deep penetration curing of the dense rust layer 9 and improves the interface performance. It is worth noting that since it is difficult to completely remove rust from the slits, inner corners and obstructed areas of cold-formed thin-walled C-shaped steel, in this embodiment, it is not necessary to completely remove rust from the areas where it is difficult to completely remove rust. Only the loose rust and loose rust layer need to be removed, and the firmly attached dense rust layer 9 is retained. The epoxy resin pre-coating layer 10 can improve the interface stability and force transmission continuity of the residual rust layer, so that the residual rust layer is transformed from a potentially weak layer into an interface transition layer that can participate in the bonding force transmission, which significantly improves the stability of the rusted interface.

[0044] Specifically, the low-viscosity epoxy resin adhesive is formulated with epoxy resin matrix, reactive diluent, curing agent, and additives; wherein, the epoxy resin matrix is ​​bisphenol A type epoxy resin or bisphenol F type epoxy resin; the reactive diluent is a glycidyl ether reactive diluent, used to reduce the viscosity of the system and participate in the curing reaction; the curing agent is an amine curing agent, which undergoes a cross-linking curing reaction with the epoxy resin to form a three-dimensional network structure; the additives include coupling agents, accelerators, and defoamers.

[0045] Specifically, at 25℃, the rotational viscosity of the low-viscosity epoxy resin adhesive is 50-150 mPa·s, ensuring good fluidity and permeability, which can fully wet the pores and microcracks of the dense rust layer 9, while avoiding flow and waste of adhesive due to excessively low viscosity; the gel time of the low-viscosity epoxy resin adhesive is controlled within the range of 30-90 min to meet the time requirements of on-site construction operations; the tensile strength of the cured low-viscosity epoxy resin adhesive is not less than 30 MPa, and the bonding strength with the steel substrate is not less than 15 MPa, ensuring a strong bond between the dense rust layer 9 and the epoxy resin pre-coating layer 10.

[0046] For example, the low-viscosity epoxy resin adhesive is formulated with the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 20-30 parts of butyl glycidyl ether reactive diluent, 2-5 parts of γ-aminopropyltriethoxysilane coupling agent, 0.5-1.0 parts of nano zinc phytate, 0.01-0.10 parts of multi-walled carbon nanotubes, 30-40 parts of polyetheramine curing agent, 0.2-0.5 parts of accelerator, and 0.1-0.3 parts of defoamer; wherein, the nano zinc phytate has a particle size of 20-40 nanometers and is spherical, used to complex with iron ions to promote rust layer stability; multi-walled carbon nanotubes are used to improve the tensile strength and structural integrity of the cured adhesive.

[0047] Preferably, the low-viscosity epoxy resin adhesive is prepared using the following raw materials in the indicated weight ratios: 100 parts bisphenol A type epoxy resin, 20 parts butyl glycidyl ether reactive diluent, 3 parts γ-aminopropyltriethoxysilane coupling agent, 0.75 parts nano zinc phytate, 0.03-0.08 parts multi-walled carbon nanotubes, 33 parts polyetheramine curing agent, 0.3 parts accelerator, and 0.2 parts defoamer. The different proportions and performance parameters of the low-viscosity epoxy resin adhesive are shown in Tables 1-2 below.

[0048] Table 1 Different proportions of low-viscosity epoxy resin adhesive

[0049] Table 2 Performance parameters of low-viscosity epoxy resin adhesive

[0050] It should be noted that in Table 1 above, E-51 represents bisphenol A type epoxy resin, BGE represents butyl glycidyl ether reactive diluent, KH-560 represents γ-aminopropyltriethoxysilane coupling agent, CNT represents multi-walled carbon nanotubes, D-23 represents polyetheramine curing agent, DMP-30 represents accelerator, and BYK represents defoamer.

[0051] In one possible implementation, the reinforcing steel plate 3 is fastened to the opening of the rusted C-shaped steel 1, and the shape of the reinforcing steel plate 3 is adapted to the shape of the opening of the rusted C-shaped steel 1; wherein, the two sides of the reinforcing steel plate 3 contact the rolled edge of the rusted C-shaped steel 1 and are fixedly connected by fasteners 6.

[0052] Specifically, the reinforcing steel plate 3 is a rectangular flat plate structure. The width of the rectangular flat plate structure matches the width of the opening of the rusted C-shaped steel 1, and the length of the rectangular flat plate structure is equal to the length of the rusted C-shaped steel 1. After the reinforcing steel plate 3 is fastened to the opening of the rusted C-shaped steel 1, the two sides of the reinforcing steel plate 3 are in close contact with the inner sides of the two rolled edges of the rusted C-shaped steel 1.

[0053] Fixing holes 7 are provided around the perimeter of the reinforcing steel plate 3, and anchoring holes matching the fixing holes 7 are provided on the flange or rolled edge of the rusted C-shaped steel 1. The fasteners 6 are self-tapping screws that pass through the fixing holes 7 on the reinforcing steel plate 3 and the anchoring holes on the rusted C-shaped steel 1 in sequence to seal and fix the reinforcing steel plate 3 and the rusted C-shaped steel 1 together. The fasteners 6 are evenly arranged at a certain interval along the length of the reinforcing steel plate 3 to ensure the uniformity and reliability of the fixed connection.

[0054] Explained, the reinforcing steel plate 3 and the rusted C-shaped steel 1 are mechanically connected by fasteners 6, eliminating the need for welding and avoiding the adverse effects of welding heat and residual stress on the thin-walled section. At the same time, after the reinforcing steel plate 3 is fastened to the opening of the rusted C-shaped steel 1, it forms a closed section with the original web, flange and rolled edge of the rusted C-shaped steel 1, which significantly improves the bending stiffness and torsional stiffness of the section.

[0055] In this embodiment, by adapting the shape of the reinforcing steel plate 3 to the shape of the opening of the rusted C-shaped steel 1, and by using fasteners 6 to fix the two sides of the reinforcing steel plate 3 to the rolled edge of the rusted C-shaped steel 1, a tight fit and reliable fixation between the reinforcing steel plate 3 and the rusted C-shaped steel 1 are achieved, ensuring the structural integrity and sealing of the closed cavity. Secondly, the spacing and number of fasteners 6 can be adjusted according to the length of the component and the stress requirements to meet the connection strength and rigidity requirements under different engineering conditions.

[0056] In one possible implementation, the reinforcing steel plate 3 is provided with at least one grouting port 8; wherein, the grouting concrete 2 is injected into the closed cavity through the grouting port 8, making the grouting construction operation of the grouting concrete 2 simple and the quality controllable.

[0057] Specifically, the grouting port 8 is a through hole penetrating the thickness direction of the reinforcing steel plate 3. The diameter of the hole is determined according to the size of the grout outlet of the grouting equipment and the fluidity of the grouting material. The number of grouting ports 8 is determined according to the length and cross-sectional dimensions of the component. For components with a large length, multiple grouting ports 8 can be set at intervals along the length of the component on the reinforcing steel plate 3 to ensure that the grouting concrete 2 can uniformly fill the entire closed cavity. The position of the grouting port 8 can be optimized according to the construction conditions and grouting path. It is usually set in the longitudinal middle or near the end of the reinforcing steel plate 3. A connecting pipe joint can be set at the grouting port 8 for quick connection with the grout outlet pipe of the grouting equipment.

[0058] Explained, the grouting port 8 allows the grouting concrete 2 to be directly poured into the closed cavity through the reserved channel on the reinforcing steel plate 3, realizing convenient grouting operation after the closed cavity is formed; the arrangement of multiple grouting ports 8 allows for uniform filling of the grouting concrete 2 through multi-point grouting for long-distance components or components with complex internal cavities, avoiding the problems of incomplete filling or excessively long grouting distance that may be caused by single-point grouting. Explained, in this embodiment, by setting grouting ports 8 on the reinforcing steel plate 3, a convenient grouting channel is provided for the grouting concrete 2.

[0059] In one possible implementation, the reinforcing steel plate 3 is also provided with an exhaust port or an overflow port; or, one or more of the grouting ports 8 may also serve as exhaust ports or overflow ports.

[0060] Specifically, the vent is a through hole that penetrates the thickness of the reinforcing steel plate 3, used to expel air from the closed cavity during the grouting process of the grouting concrete 2, preventing air from accumulating inside the cavity and forming voids or air bubbles; the overflow port is also a through hole that penetrates the thickness of the reinforcing steel plate 3, used as an outlet for the grout to overflow when the grouting concrete 2 has filled the closed cavity, thus serving as a mark of completion of grouting.

[0061] The vent or overflow port can be independently set on the reinforcing steel plate 3 at a different position from the grouting port 8, or one or more of the grouting ports 8 can be used as vents or overflow ports. When the grouting port 8 is used as a vent or overflow port, it serves as a grouting channel in the early stage of grouting. In the later stage of grouting, when the grout flows out from the grouting port 8, it indicates that the closed cavity has been filled and compacted. At this time, the grouting port 8 is closed to complete the grouting operation. The diameter of the vent or overflow port can be smaller than the diameter of the grouting port 8. The vent or overflow port is usually set at both ends or the highest point of the longitudinal direction of the reinforcing steel plate 3 to facilitate the smooth discharge of air and the filling of grout.

[0062] Explanation: The setting of vents or overflow outlets allows air in the cavity to be discharged in a timely manner during the grouting process, ensuring the compactness of the grouting concrete 2. By observing the discharge of grout from the overflow outlet, it is possible to intuitively and accurately determine whether the grouting is complete, avoiding the problems of insufficient or excessive grouting. This achieves visual control of the grouting process and reliable judgment of grouting quality, improving the controllability of construction and the reliability of grouting quality.

[0063] In one possible implementation, the end sealing plate 4 is snapped onto the end of the rusted C-shaped steel 1; wherein, the end sealing plate 4 includes a sealing end plate and four sealing side plates, the four sealing side plates are respectively located on the four sides of the sealing end plate and all extend vertically toward the outward direction of the sealing end plate; the sealing end plate is disposed at the end of the rusted C-shaped steel 1, and the four sealing side plates are all inserted into the opening of the rusted C-shaped steel 1; wherein, the outer surface of one sealing side plate is tightly fitted with the inner surface of the reinforcing steel plate 3, and the outer surfaces of the remaining three sealing side plates are tightly fitted with the inner wall of the rusted C-shaped steel 1 respectively.

[0064] For details, see attached. Figure 3 As shown, the end sealing plate 4 has a box-shaped structure with one open end, and its shape matches the cross-sectional shape of the rusted C-shaped steel 1. The sealing end plate is a rectangular flat plate, and its outer dimensions are slightly larger than the outer dimensions of the end of the rusted C-shaped steel 1 so as to completely cover the end opening of the rusted C-shaped steel 1. The four sealing side plates are the upper side plate, the lower side plate, the left side plate, and the right side plate, which are located on the four sides of the sealing end plate and extend vertically toward the same side of the sealing end plate. When the end sealing plate 4 is snapped into the end of the rusted C-shaped steel 1, the sealing end plate is located outside the end of the rusted C-shaped steel 1, and the four sealing side plates are inserted into the opening of the rusted C-shaped steel 1 along the longitudinal direction of the rusted C-shaped steel 1.

[0065] Among them, a sealing side plate that is closely connected to the inner surface of the reinforcing steel plate 3 is located on one side of the opening of the rusted C-shaped steel 1. The outer surface of the sealing side plate is closely attached to the inner surface of the reinforcing steel plate 3 and is fixedly connected by fasteners 6. The outer surfaces of the remaining three sealing side plates are closely attached to the inner wall of the web and the inner wall of the flange of the rusted C-shaped steel 1, respectively, and are fixedly connected by fasteners 6. A sealing gasket or sealant can be provided between the sealing end plate and the end flange and web end face of the rusted C-shaped steel 1 to further improve the end sealing performance.

[0066] Explained, the four sealing side plates of the end sealing plate 4 are all inserted into the opening of the rusted C-shaped steel 1, forming a labyrinth-like sealing structure, which effectively extends the penetration path of the corrosive medium and improves the reliability and durability of the end seal; the tight fit between the sealing side plates and the inner wall of the rusted C-shaped steel 1 and the inner surface of the reinforcing steel plate 3 ensures the complete closure of the end of the closed cavity, preventing grout leakage and intrusion of external corrosive media during the grouting process of the grouting concrete 2.

[0067] In this embodiment, the box-shaped structure design of the end sealing plate 4 and the snap-fit ​​connection with the end of the rusted C-shaped steel 1 enable rapid installation and reliable sealing of the end without the need for complex welding or extensive mechanical connections, making construction simple and quick. The four sealing side plates of the end sealing plate 4 are tightly connected to the inner wall of the rusted C-shaped steel 1 and the inner surface of the reinforcing steel plate 3, forming multiple sealing barriers that effectively ensure the overall sealing performance of the closed cavity.

[0068] In one possible implementation, the grouting concrete 2 is a self-compacting micro-expansion grouting concrete.

[0069] Specifically, self-compacting micro-expansion grouting concrete is a special concrete material with high fluidity, high filling performance, and micro-expansion characteristics. Under its own weight, it can flow and fill every corner of a closed cavity, achieving dense filling without vibration. During the hardening process, it exhibits a micro-expansion effect, with an expansion rate controlled within the range of 0.02%-0.05%, generating expansion compressive stress on the inner wall of the closed cavity, further enhancing the tight bond between the grouting concrete and the cavity's inner wall. Its 28-day compressive strength is not less than 40 MPa, effectively compensating for cross-sectional weakening caused by corrosion and improving the load-bearing capacity of the component. With a fluidity of not less than 250 mm, it can fully fill complex areas such as slits, folds, and inner corners within the cavity of the corroded C-shaped steel.

[0070] Explained, the excellent fluidity of self-compacting micro-expansion grouting concrete allows it to fill various parts of a closed cavity without vibration, making it particularly suitable for working conditions where the internal space of cold-formed thin-walled C-shaped steel is narrow and vibration is not possible; the micro-expansion characteristic allows the grouting concrete 2 to form a tight contact with the inner wall of the cavity after hardening, eliminating the interface gaps caused by shrinkage, ensuring the synergistic working performance between the grouting concrete 2, the corroded C-shaped steel 1, and the reinforcing steel plate 3, achieving dense filling of the closed cavity and tight bonding of the interface, effectively improving the integrity and load-bearing capacity of the reinforced component.

[0071] In one possible implementation, the fiber-reinforced composite sheath 5 is a sheath formed of adhesive carbon fiber cloth.

[0072] Specifically, the bonded carbon fiber cloth is a composite material layer formed by bonding carbon fiber cloth to the outer surfaces of the rusted C-shaped steel 1 and the reinforcing steel plate 3 using epoxy resin adhesive. The carbon fiber cloth is a unidirectional carbon fiber woven fabric with high strength, high modulus, and corrosion resistance. During construction, epoxy resin adhesive primer is first applied to the outer surfaces of the rusted C-shaped steel 1 and the reinforcing steel plate 3. Then, the carbon fiber cloth is wrapped around the component circumferentially, and a top coat is applied to the surface of the carbon fiber cloth to ensure a firm bond between the carbon fiber cloth and the component surface. The number of layers of carbon fiber cloth is determined according to the required reinforcement strength, usually 1-3 layers. The winding direction of the carbon fiber cloth is arranged circumferentially along the component cross-section to provide effective circumferential restraint. The fiber-reinforced composite material sheathing layer 5 reserves an operating area at the grouting port 8 for subsequent grouting and sealing operations. After the grouting port 8 is sealed, a local reinforcing carbon fiber cloth layer is bonded to the outside of the sealed area to form a local reinforcing layer.

[0073] To explain, the adhesive carbon fiber cloth is lightweight and high-strength. When wrapped around the outside of the component, it can provide a strong circumferential constraint force to the component, effectively suppressing the lateral bulging deformation and local buckling of the component during grouting and in service. The composite material layer formed by the carbon fiber cloth and epoxy resin adhesive has good corrosion resistance and can serve as an external protective layer to isolate the intrusion of corrosive media, achieving circumferential constraint on the combined section of the corroded C-shaped steel 1 and the reinforced steel plate 3, which significantly improves the overall stability and load-bearing capacity of the component. At the same time, the carbon fiber cloth and the steel substrate are physically isolated by the epoxy resin pre-coating 10, avoiding the risk of galvanic corrosion.

[0074] This embodiment also provides a construction method for reinforcing a rusted cold-formed thin-walled C-shaped steel structure, which can be used to realize the above-mentioned reinforcing structure for rusted cold-formed thin-walled C-shaped steel, including: S1. Apply an epoxy resin pre-coating 10 to the dense rust layer 9 of the corroded C-shaped steel 1.

[0075] S2. Attach the end sealing plate 4 to the end of the rusted C-shaped steel 1 and fix the end sealing plate 4 to the rusted C-shaped steel 1.

[0076] S3. Place the reinforcing steel plate 3 at the opening of the rusted C-shaped steel 1 and fix the reinforcing steel plate 3 to the rusted C-shaped steel 1; at the same time, fix the end sealing plate 4 to the reinforcing steel plate 3 so that the rusted C-shaped steel 1, the reinforcing steel plate 3 and the end sealing plate 4 together form a closed cavity.

[0077] S4. A fiber-reinforced composite material sheathing layer 5 is wrapped around the outside of the corroded C-shaped steel 1 and the reinforcing steel plate 3.

[0078] S5. Pour grouting concrete into the closed cavity 2.

[0079] Specifically, in S1, an epoxy resin pre-coating 10 is applied to the surface of the dense rust layer 9 of the corroded C-shaped steel 1. First, the loose rust and loose rust layer on the surface of the corroded C-shaped steel 1 are removed, leaving the firmly attached dense rust layer 9. The removal can be carried out by manual tools, power tools, or sandblasting, with the control standard being that the loose rust on the surface is removed while the firmly attached rust layer is retained. Then, a low-viscosity epoxy resin is applied to the surface of the dense rust layer 9 and cured to form the epoxy resin pre-coating 10. The low-viscosity epoxy resin is applied by brushing, rolling, or spraying, and the amount applied should ensure that it fully covers all exposed surfaces of the dense rust layer 9 and penetrates into its pores. After the low-viscosity epoxy resin coating is applied, it is left to stand to allow the low-viscosity epoxy resin to fully penetrate and initially cure, forming a continuous interface layer.

[0080] In step S2, the end sealing plate 4 is snapped onto the end of the rusted C-shaped steel 1, and the end sealing plate 4 is fixedly connected to the rusted C-shaped steel 1. Specifically, the four sealing side plates of the end sealing plate 4 are aligned with the end opening of the rusted C-shaped steel 1, and the four sealing side plates are inserted longitudinally into the opening of the rusted C-shaped steel 1, so that the sealing end plates are flush with the end of the rusted C-shaped steel 1. Then, the remaining three sealing side plates of the end sealing plate 4 are fixedly connected to the inner wall of the web and the inner wall of the flange of the rusted C-shaped steel 1 respectively using fasteners 6. The fasteners 6 are self-tapping screws, which pass through the fixing holes 7 on the sealing side plates and are driven into the web or flange of the rusted C-shaped steel 1 to achieve a firm connection. The connection between the end sealing plate 4 and the rusted C-shaped steel 1 can be coated with sealant or a sealing gasket can be set to improve the sealing performance.

[0081] In step S3, a reinforcing steel plate 3 is placed at the opening of the rusted C-shaped steel 1 and fixedly connected to the rusted C-shaped steel 1. Simultaneously, an end sealing plate 4 is fixedly connected to the reinforcing steel plate 3, so that the rusted C-shaped steel 1, the reinforcing steel plate 3, and the end sealing plate 4 together form a closed cavity. Specifically, the reinforcing steel plate 3 is fastened and placed at the opening of the rusted C-shaped steel 1, so that both sides of the reinforcing steel plate 3 contact the rolled edges of the rusted C-shaped steel 1, and the end of the reinforcing steel plate 3 is flush with the outer surface of the sealing end plate of the end sealing plate 4. Then, fasteners 6 are used to secure the reinforcing steel plate 3 to the rusted C-shaped steel 1. The rolled edge and flange of the steel section 1 are fixedly connected; at the same time, fasteners 6 are used to fix a sealing side plate in the end sealing plate 4 that is connected to the reinforcing steel plate 3 to the inner surface of the reinforcing steel plate 3; the fasteners 6 are self-tapping screws, which penetrate through the fixing hole 7 on the reinforcing steel plate 3 and then drive into the rolled edge or flange of the rusted C-shaped steel 1, and penetrate through the fixing hole 7 on the reinforcing steel plate 3 and the fixing hole 7 on the sealing side plate to fix the two together; the connection between the reinforcing steel plate 3 and the end sealing plate 4 and the rusted C-shaped steel 1 is coated with sealant or a sealing gasket is set to ensure the sealing of the closed cavity.

[0082] In S4, a fiber-reinforced composite material binding layer 5 is wrapped around the outside of the rusted C-shaped steel 1 and the reinforcing steel plate 3. Specifically, firstly, an epoxy resin adhesive primer is applied to the outer surface of the rusted C-shaped steel 1 and the reinforcing steel plate 3. Then, carbon fiber cloth is wrapped around the outside of the rusted C-shaped steel 1 and the reinforcing steel plate 3 in the circumferential direction along the component cross-section to form the main binding layer. The number of layers of carbon fiber cloth is determined according to the reinforcement strength required by the design. After the carbon fiber cloth is wrapped, an epoxy resin adhesive topcoat is applied to the surface of the carbon fiber cloth to make the carbon fiber cloth firmly bonded to the surface of the component. An operating area is reserved at the grouting port 8 to facilitate subsequent grouting and sealing operations.

[0083] In S5, grouting concrete 2 is injected into the closed cavity. Specifically, self-compacting micro-expansion grouting concrete is injected into the closed cavity through the grouting port 8 on the reinforcing steel plate 3. During the injection process, a low-pressure injection method is preferred to reduce the adverse effects of grouting pressure on the local deformation of thin-walled components. When the reinforcing steel plate 3 is provided with an exhaust port or overflow port, the grout flowing out of the exhaust port or overflow port is used as the criterion for determining the completion of the grouting of the closed cavity. When the grouting port 8 also serves as an exhaust port or overflow port, the grout flowing out of the grouting port 8 in the later stage of the injection is used as the criterion for determining the completion of the injection. After the injection is completed, after the grouting concrete 2 has hardened to the design requirements, the grouting port 8 is sealed, and a local reinforcement layer is formed on the outside of the grouting port 8. The local reinforcement layer is formed by bonding carbon fiber cloth to the outside of the sealed area of ​​the grouting port 8.

[0084] The construction method for reinforcing rusted cold-formed thin-walled C-shaped steel described in this embodiment first stabilizes the rusted interface by removing loose rust and applying an epoxy resin pre-coating 10, eliminating the need for thorough rust removal in difficult-to-treat areas such as slits and inner corners. Then, a closed cavity is formed by the snap-fit ​​fixing of the end sealing plate 4 and the fastening fixing of the reinforcing steel plate 3, avoiding complex cavity-forming construction. Next, the outer side of the fiber-reinforced composite material binding layer 5 provides circumferential constraint to the component and isolates direct contact between the carbon fiber and the steel matrix. Finally, grouting concrete 2 is injected into the closed cavity to effectively compensate for the weakened cross-section and significantly improve the component's load-bearing capacity. This construction method is systematic, easy to operate, and has controllable quality, applicable to various cross-sectional forms such as single C-shaped steel and double C-shaped steel, as well as complex working conditions in existing projects where operating space is limited and the component is heavily obstructed.

[0085] It should be noted that, in this embodiment, the rusted C-shaped steel 1 can be divided into rusted cold-formed thin-walled C-shaped steel components mainly subjected to bending, rusted cold-formed thin-walled C-shaped steel components mainly subjected to compression, or double-section C-shaped steel components; among them, rusted cold-formed thin-walled C-shaped steel components mainly subjected to bending are, for example, purlins, wall beams, or similar thin-walled bending members in a building; rusted cold-formed thin-walled C-shaped steel components mainly subjected to compression are, for example, cold-formed thin-walled structural columns, vertical supports, or other similar compression members; double-section C-shaped steel components are, for example, purlins, wall beams, secondary beams, and other lightweight steel structure components commonly found in existing projects.

[0086] The reinforcement structure and construction method for rusted cold-formed thin-walled C-shaped steel described in this invention retains a firmly attached dense rust layer 9 after only removing surface rust and loose rust layers. An epoxy resin pre-coating layer 10 is applied to the surface of the dense rust layer 9, which helps to improve the state of the rusted interface and enhance the interface continuity between the reinforcement structure and the rusted C-shaped steel 1, thereby improving the adaptability of reinforcement construction under rusted conditions. By forming a closed cavity through the cooperation of the rusted C-shaped steel 1 with the end sealing plate 4 and the reinforcement steel plate 3, compared with the treatment method that relies on large-scale replacement or complex formwork support, it is more suitable for construction environments in existing projects where the working space is limited and the components are heavily obstructed, and has better engineering implementation convenience.

[0087] In this invention, by injecting grouting concrete 2 into a closed cavity and setting a fiber-reinforced composite material binding layer 5 on the outside, a composite reinforcement form combining internal filling support and external binding is formed. This is beneficial to improving the overall working performance of the corroded C-shaped steel 1 and suppressing the local bulging and instability trend during the injection and service of the grouting concrete 2. By setting an injection port 8, and combining it with an exhaust port or overflow port to complete low-pressure injection, it is beneficial to improve the compactness of the filling in the closed cavity and the controllability of construction. After the injection is completed, the injection port 8 is sealed, and a local reinforcement layer is formed on the outside of the injection port 8, which is beneficial to maintaining the integrity of the injection port 8 and the stability of subsequent use.

[0088] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A reinforcement structure for rusted cold-formed thin-walled C-shaped steel, characterized in that, It includes grouting concrete (2), reinforcing steel plate (3), end sealing plate (4), fiber reinforced composite material binding layer (5) and epoxy resin pre-coating layer (10). An epoxy resin pre-coating layer (10) is applied to the surface of the dense rust layer (9) of the corroded C-shaped steel (1); a reinforcing steel plate (3) is applied to the opening of the corroded C-shaped steel (1), and an end sealing plate (4) is applied to the end of the corroded C-shaped steel (1); wherein the corroded C-shaped steel (1), the reinforcing steel plate (3) and the end sealing plate (4) together form a closed cavity; Grouting concrete (2) fills the closed cavity; A fiber-reinforced composite sheath (5) is wrapped around the outside of the corroded C-shaped steel (1) and the reinforcing steel plate (3).

2. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, An epoxy resin pre-coating (10) covers all exposed surfaces of the dense rust layer (9) and penetrates into the pores of the dense rust layer (9).

3. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, The reinforcing steel plate (3) is fastened to the opening of the rusted C-shaped steel (1), and the shape of the reinforcing steel plate (3) is adapted to the shape of the opening of the rusted C-shaped steel (1); wherein, the two sides of the reinforcing steel plate (3) are in contact with the rolled edge of the rusted C-shaped steel (1) and are fixedly connected by fasteners (6).

4. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, The end sealing plate (4) is snapped onto the end of the rusted C-shaped steel (1); wherein, the end sealing plate (4) includes a sealing end plate and four sealing side plates, the four sealing side plates are located on the four sides of the sealing end plate respectively, and all extend vertically toward the outward direction of the sealing end plate. The sealing end plate is set at the end of the rusted C-shaped steel (1), and the four sealing side plates are inserted into the opening of the rusted C-shaped steel (1); among them, the outer surface of one sealing side plate is closely attached to the inner surface of the reinforcing steel plate (3), and the outer surfaces of the remaining three sealing side plates are closely attached to the inner wall of the rusted C-shaped steel (1).

5. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, At least one grouting port (8) is provided on the reinforcing steel plate (3); wherein, the grouting concrete (2) is injected into the closed cavity through the grouting port (8).

6. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 5, characterized in that, The reinforcing steel plate (3) is also provided with an exhaust port or an overflow port; or, one or more of the grouting ports (8) are also used as exhaust ports or overflow ports.

7. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, Grouting concrete (2) is self-compacting micro-expansion grouting concrete.

8. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, The fiber-reinforced composite sheath (5) is a sheath formed by adhesive carbon fiber cloth.

9. The reinforcement structure for rusted cold-formed thin-walled C-shaped steel according to claim 1, characterized in that, The epoxy resin pre-coating layer (10) is a continuous interface layer formed by curing low-viscosity epoxy resin; wherein, at 25°C, the rotational viscosity of the low-viscosity epoxy resin is 50-150 mPa·s.

10. A construction method for a reinforcement structure of rusted cold-formed thin-walled C-shaped steel as described in any one of claims 1-9, characterized in that, include: Apply an epoxy resin pre-coating (10) to the dense rust layer (9) of the corroded C-shaped steel (1); The end sealing plate (4) is snapped onto the end of the rusted C-shaped steel (1), and the end sealing plate (4) is fixedly connected to the rusted C-shaped steel (1); The reinforcing steel plate (3) is placed at the opening of the rusted C-shaped steel (1) and the reinforcing steel plate (3) is fixedly connected to the rusted C-shaped steel (1); at the same time, the end sealing plate (4) is fixedly connected to the reinforcing steel plate (3) so that the rusted C-shaped steel (1), the reinforcing steel plate (3) and the end sealing plate (4) form a closed cavity. A fiber-reinforced composite material sheath (5) is wrapped around the outside of the corroded C-shaped steel (1) and the reinforcing steel plate (3); (2) Grouting concrete is poured into the closed cavity.

Images