Anti-ultraviolet aging durable easy-to-apply and replaceable cable-stayed cable flame-retardant structure

Abstract

The application relates to a durable anti-ultraviolet aging and easy-to-replace cable-stayed cable flame-retardant structure, and belongs to the technical field of cable-stayed cable flame-retardant technology. The durable anti-ultraviolet aging and easy-to-replace cable-stayed cable flame-retardant structure comprises an intumescent fire-retardant coating, the intumescent fire-retardant coating is arranged on the outer periphery of a steel wire bundle, a polyester fiber layer, a double-layer sheath and a protection pipe are arranged between the steel wire bundle and the intumescent fire-retardant coating, the polyester fiber layer, the double-layer sheath and the protection pipe are sequentially arranged from inside to outside, and an outer protective layer is arranged on the outer periphery of the intumescent fire-retardant coating.

Description

Technical Field

[0001] This invention relates to a UV-resistant, durable, easy-to-construct, and easy-to-replace flame-retardant structure for cable stays, belonging to the field of flame-retardant technology for cable stays. Background Technology

[0002] Stay cables are the main load-bearing components of cable-stayed bridges. In the event of a fire, the high temperatures during combustion cause the outer polyethylene protective layer of the stay cables to burn and become damaged. Annealing of the high-strength materials that bear the main load leads to a decrease in their mechanical properties, and in severe cases, fracture, posing safety hazards to the construction and operation of the bridge. In recent years, the technical approach of using fire-retardant coatings for the fire protection of stay cables has been proposed, but the following problems need to be addressed: 1) Insufficient adhesion between the high-density polyethylene of the stay cables and the fire-retardant coating, making the coating prone to detachment during operation and creating new safety hazards; 2) Poor durability of the fire-retardant coating, which is prone to aging under ultraviolet radiation at the bridge site; 3) Direct application of fire-retardant coatings to stay cables results in poor aesthetics. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a UV-resistant, durable, easy-to-construct and easy-to-replace flame-retardant cable-stayed structure that is simple in structure, easy to construct and replace, and has UV resistance and durability.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: a UV-resistant, durable, easy-to-construct and easy-to-replace cable-stayed structure, comprising an intumescent fire-retardant coating, wherein the intumescent fire-retardant coating is disposed on the outer periphery of the steel wire bundle, and a polyester fiber layer, a double sheath and a protective tube are disposed between the steel wire bundle and the intumescent fire-retardant coating, wherein the polyester fiber layer, the double sheath and the protective tube are arranged sequentially from the inside to the outside, and an outer protective layer is provided on the outer periphery of the intumescent fire-retardant coating.

[0005] The polyester fiber layer is formed by winding polyester fiber tape, which is wrapped around the outer periphery of the steel wire bundle, and the thickness of the polyester fiber layer is 1-2 mm.

[0006] The double-layer sheath is made of high-density polyethylene and has a thickness of 7-11 mm.

[0007] The protective tube is made of 316 or 304 stainless steel and has a thickness of 0.5 to 2.0 mm.

[0008] The thickness of the intumescent fire-retardant coating is 2-5 mm.

[0009] The outer protective layer includes a polyvinyl fluoride wrapping layer and an outer polyester fiber layer. The outer polyester fiber layer is wrapped around the outer periphery of the intumescent fire-retardant coating, and the polyvinyl fluoride wrapping layer is disposed around the outer periphery of the outer polyester fiber layer.

[0010] The thickness of the polyvinyl fluoride wrapping layer is 0.2–1.0 mm, and the thickness of the outer polyester fiber layer is 0.1–0.5 mm.

[0011] A construction method for a UV-resistant, durable, easy-to-construct, and easily replaceable cable-stayed flame-retardant structure, the construction method comprising the following steps:

[0012] Step 1: Wrap a polyester fiber tape around the outer periphery of the steel wire bundle to form a polyester fiber layer;

[0013] Step 2: Hot-extrude a double-layer sheath onto the wire bundle;

[0014] Step 3: After the stay cables are anchored, an over-tension test is conducted; the over-tensioned stay cables are then coiled up and transported to the construction site for installation, and the installed stay cables are then tensioned.

[0015] Step 4: After tensioning is completed, weld protective pipes to the area between the stay cables and the beam ends, sandblast the surface of the protective pipes, and then clean the surface of the protective pipes.

[0016] Step 5: Apply an intumescent fire-retardant coating to the surface of the protective pipe by brushing or spraying to form an intumescent fire-retardant coating.

[0017] Step Six: After the intumescent fire-retardant coating has dried completely, first wrap it with polyester fiber tape to form an outer polyester fiber layer, and then wrap it with PVC wrapping tape to form a PVC wrapping layer.

[0018] The steel wire bundle in step one is made of twisted zinc-aluminum alloy coated steel wire or zinc-aluminum rare earth multi-element alloy coated steel wire.

[0019] The base material of the intumescent fire-retardant coating in step five is organic resin, and it also contains foaming agent, flame retardant and charring agent.

[0020] In step five, an arc-shaped spring brush is used for brushing. The arc-shaped spring brush includes a spring support and multiple wool brushes. The two ends of the spring support are fixed to the working handle, and the multiple wool brushes are spaced apart on the spring support, so that the multiple wool brushes are arc-shaped as the spring support deforms.

[0021] Compared with existing technologies, the advantages of this invention are: a UV-resistant, durable, easy-to-construct, and easily replaceable flame-retardant structure for cable stays. When the cable stays are pre-fired, in the initial stage, the PVC wrapping tape and high-strength polyester fiber tape melt and burn first. When the temperature reaches above 200 degrees Celsius, the foaming component in the intumescent fire-retardant coating causes the coating to expand rapidly, forming a porous carbonized layer, thereby preventing heat penetration into the substrate. After the fire, the residues of the intumescent fire-retardant coating, PVC wrapping layer, and outer polyester fiber layer need to be cleaned. The intumescent fire-retardant coating is then applied again to the stainless steel protective pipe, and an outer protective layer is wrapped around it. This application features a simple structure, UV resistance, and durable flame-retardant design; the secondary treatment scheme eliminates the need to replace the cable stays and protective pipes, making it easy to construct and replace. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed structure according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of an arc-shaped spring brush.

[0024] Figure 3 This is a schematic diagram of a UV-resistant, durable, easy-to-construct, and easy-to-replace flame-retardant cable-stayed structure according to an embodiment of the invention.

[0025] The diagram shows: 1. Steel wire bundle, 2. Polyester fiber layer, 3. Double sheath, 4. Stainless steel protective tube, 5. Fireproof and flame-retardant coating layer, 6. Outer protective layer, and 7. Arc-shaped spring brush. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] like Figure 1 As shown in the figure, a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed structure in this embodiment includes an intumescent fire-retardant coating. The intumescent fire-retardant coating is disposed on the outer periphery of the steel wire bundle. Between the steel wire bundle and the intumescent fire-retardant coating, there is a polyester fiber layer, a double sheath, and a protective tube. The polyester fiber layer, the double sheath, and the protective tube are arranged sequentially from the inside to the outside. An outer protective layer is wrapped around the outer periphery of the intumescent fire-retardant coating.

[0028] The polyester fiber layer is made of high-strength polyester fiber tape wound around the outer periphery of the steel wire bundle. The number of polyester fiber tape winding layers is not less than 3, so that the thickness of the polyester fiber layer is 1-2 mm, which shapes the steel wire bundle.

[0029] The double-layer sheath is made of high-density polyethylene with a thickness of 7-11mm. It is used to protect the steel wire bundle from corrosion and prevent external moisture and other harmful substances from directly corroding the cable-stayed cable wire bundle.

[0030] The protective tube is made of 316 or 304 stainless steel with a thickness of 0.5 to 2.0 mm. It serves as the base for the intumescent fire-retardant coating and also acts as a flame isolateer.

[0031] The thickness of the intumescent fire-retardant coating is 2-5mm. It is applied by brushing or spraying with intumescent fire-retardant paint. The base material of this paint is organic resin, and the formula contains foaming agents, flame retardants, and charring agents. Upon exposure to fire, it foams and expands, forming a porous carbonaceous layer several to tens of times thicker than its original thickness. This porous carbonaceous layer blocks heat transfer from external heat sources to the protective pipe, acting as an insulation barrier. In the event of a fire, it expands rapidly, isolating flames and temperature, preventing polyethylene from burning and the steel wire from overheating.

[0032] The outer protective layer comprises a polyvinyl fluoride (PVC) wrapping layer and an outer polyester fiber layer. The outer polyester fiber layer is wrapped around the periphery of the intumescent fire-retardant coating, and the PVC wrapping layer is wrapped on top of the outer polyester fiber layer. The thickness of the PVC wrapping layer is 0.2–1.0 mm, and the thickness of the outer polyester fiber layer is 0.1–0.5 mm. The outer polyester fiber layer is made of high-strength polyester fiber tape to prevent the intumescent fire-retardant coating from detaching during operation due to factors such as cable vibration. The PVC wrapping layer, made of PVC wrapping tape, is used to block ultraviolet radiation, preventing aging and detachment of the intumescent fire-retardant coating under UV exposure, thus improving the durability of the coating. Additionally, the PVC wrapping tape also enhances the aesthetic appeal.

[0033] When a fire occurs on the bridge deck, the intumescent fire-retardant coating, under high temperature and flame conditions, can expand to 10 to 50 times its original size upon reaching a certain temperature. This forms a sponge-like carbonized layer between the coated surface and the fire source, preventing heat conduction to the substrate and simultaneously generating non-combustible gases, significantly reducing the combustion rate and temperature of the flammable substrate. The foaming agent plays a significant role in this process. The foaming agent is an additive that decomposes into a large amount of non-combustible gases when the intumescent fire-retardant coating is heated, causing the coating to expand and form a sponge-like micro-bubble structure. The foaming agent mainly contains melamine, dicyandiamide, oxidized paraffin, ammonium polyphosphate, ammonium borate, and dicyandiamide-formaldehyde resin. Its flame-retardant mechanism refers to the intumescent fire-retardant coating decomposing into flame-retardant gases upon heating, diluting the concentration of flammable gases released from the combustible material, delaying or inhibiting combustion, and also diluting the oxygen concentration in the combustion zone, making it difficult to burn or reducing the intensity of combustion, thereby achieving the purpose of flame retardancy. When heated, ammonium polyphosphate first decomposes to produce NH3, which dilutes the concentration of flammable gases in the mixed gas around the material and also reduces the oxygen content in the mixed gas, forming a gas protective layer around the flammable material. Zinc borate hydrate, melamine, melamine cyanurate, etc., will generate water vapor, NH3, N2 and other non-flammable gases when heated, which also play the role of diluting the concentration of flammable gases and oxygen.

[0034] However, these chemicals are prone to aging, so the intumescent fire-retardant coating should be sealed and protected. This application achieves durability of the flame-retardant structure by wrapping high-strength polyester fiber tape and UV-resistant polyvinyl fluoride wrapping tape sequentially around the outer periphery of the intumescent fire-retardant coating from the inside out.

[0035] A construction method for a UV-resistant, durable, easy-to-construct, and easily replaceable cable-stayed flame-retardant structure includes the following steps:

[0036] Step 1: Twist zinc-aluminum alloy coated steel wire or zinc-aluminum rare earth multi-element alloy coated steel wire into a steel wire bundle, and wrap a high-strength polyester fiber tape around the outer periphery of the steel wire bundle to form a polyester fiber layer.

[0037] Step 2: A double-cavity co-extrusion extruder hot-extrudes a double-layer sheath of high-density polyethylene with a thickness of 7mm to 11mm onto the surface of the steel wire bundle.

[0038] Step 3: After the stay cables are anchored, an over-tension test is conducted; the stay cables that have passed the over-tension test are then coiled up and transported to the construction site for stay cable erection, and tensioning is performed on the erected stay cables.

[0039] Step 4: After tensioning, the stay cables are welded with protective tubes by argon arc welding in an area 8 meters above the beam end, and the surface of the protective tubes is sandblasted and then cleaned to improve the adhesion of the intumescent fire-retardant coating.

[0040] Step 5: Apply an intumescent fire-retardant coating to the surface of the protective pipe by brushing or spraying to form an intumescent fire-retardant coating.

[0041] Based on the fire resistance time requirements, the thickness control and number of coating coats for intumescent fire-retardant coatings are as follows:

[0042] The fire resistance time is 1.5 to 2.0 hours, the coating thickness is 2.0 mm to 2.5 mm, and 7 to 8 coats are applied.

[0043] The fire resistance time is 1.0 to 1.5 hours, the coating thickness is 1.5 mm to 2.0 mm, and 6 to 7 coats are applied.

[0044] 1) Requirements for the base layer: Remove rust and oil stains to ensure the adhesion between the intumescent fire-retardant coating and the stainless steel protective pipe.

[0045] 2) Environmental requirements: The ambient temperature during construction should be 10–30℃, and the relative humidity should be <85%.

[0046] 3) After the previous coat of paint has dried, apply the next coat until the required thickness is achieved.

[0047] 4) Application requirements for intumescent fire-retardant coatings: Before application, the intumescent fire-retardant coating should be thoroughly mixed using a handheld automatic mixer. If the intumescent fire-retardant coating is applied in multiple layers, the application sequence should be: spray (brush) the primer, spray the intermediate coat, and brush the topcoat. It is important to ensure that the next coat is completely dry before applying the primer or intermediate coat.

[0048] 5) Application of the final coat of intumescent protective flame retardant coating: The final coat of intumescent protective flame retardant coating should be applied using an arc-shaped spring-loaded brush that can adapt to the cylindrical outer surface of the cable-stayed bridge to ensure the uniformity and aesthetic appeal of the fire-retardant coating. For example... Figure 2 As shown, the aforementioned arc-shaped spring-loaded brush consists of three parts: a stainless steel spring bracket to adapt to the cylindrical surface of the cable-stayed bridge, 4 to 6 wool rollers, and a working handle. The two ends of the spring bracket are fixed to the working handle with bolts. During brushing, the wool rollers are fixed to the spring bracket, causing the multiple wool rollers to deform with the spring bracket, forming a semi-circular arc or a partial arc, thus adapting to the cylindrical surface of the cable-stayed bridge and ensuring uniform coating and surface quality.

[0049] The above-mentioned arc-shaped spring brush can be operated manually or used in conjunction with a cable robot.

[0050] Step Six: After the intumescent fire-retardant coating is completely dry, first wrap high-strength polyester fiber tape to form an outer polyester fiber layer, then wrap PVC wrapping tape on the outer polyester fiber layer to form a PVC wrapping layer. The high-strength polyester fiber tape should overlap by at least 1 / 3, and the thickness after wrapping should be 0.1mm to 1.0mm. The UV-resistant PVC wrapping tape should overlap by at least 1 / 25, and the thickness after wrapping should be 0.1mm to 0.5mm.

[0051] like Figure 3 The cable section with flame-retardant structure and the ordinary cable section are connected by flexible materials such as butyl rubber. A high-strength polyester fiber layer and a polyvinyl fluoride wrapping layer are wrapped around the flexible material to prevent moisture from entering the intumescent fire-retardant coating and avoid affecting durability.

[0052] After the stay cables are pre-fired, in the initial stage, the PVC wrapping tape and high-strength polyester fiber tape melt and burn first. When the temperature reaches above 200 degrees Celsius, the foaming component in the intumescent fire-retardant coating causes it to expand rapidly, forming a porous carbonized layer, thereby preventing heat penetration into the substrate. The heat insulation and fire-retardant effect of the intumescent fire-retardant coating is achieved by the porous carbonized layer formed by the fire, which is dozens of times thicker than the original intumescent fire-retardant coating. After the fire, the residue of the intumescent fire-retardant coating, PVC wrapping layer, and outer polyester fiber layer needs to be cleaned. Then, the intumescent fire-retardant coating is brushed onto the stainless steel protective pipe again, and the outer protective layer is wrapped around it. This application has a simple structure, is resistant to ultraviolet aging, and has a durable flame-retardant structure; the secondary treatment scheme does not require replacement of the stay cables and protective pipes, and is easy to construct and replace.

[0053] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A construction method for a UV-resistant, durable, easy-to-construct, and easily replaceable flame-retardant cable-stayed structure, characterized in that: The construction method produces a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed structure. The cable-stayed structure includes an intumescent fire-retardant coating. The intumescent fire-retardant coating is applied to the outer periphery of the steel wire bundle. Between the steel wire bundle and the intumescent fire-retardant coating, there is a polyester fiber layer, a double sheath, and a protective tube. The polyester fiber layer, the double sheath, and the protective tube are arranged sequentially from the inside to the outside. An outer protective layer is provided around the outer periphery of the intumescent fire-retardant coating. The protective tube is made of 316 or 304 stainless steel, and the thickness of the protective tube is 0.5~2.0mm; The outer protective layer includes a polyvinyl fluoride wrapping layer and an outer polyester fiber layer. The outer polyester fiber layer is wrapped around the outer periphery of the intumescent fire-retardant coating, and the polyvinyl fluoride wrapping layer is disposed around the outer periphery of the outer polyester fiber layer. The thickness of the polyvinyl fluoride wrapping layer is 0.2~1.0 mm, and the thickness of the outer polyester fiber layer is 0.1~0.5 mm; The construction method includes the following steps: Step 1: Wrap a polyester fiber tape around the outer periphery of the steel wire bundle to form a polyester fiber layer; Step 2: Hot-extrude a double-layer sheath onto the wire bundle; Step 3: After the stay cables are anchored, an over-tension test is conducted; the over-tensioned stay cables are then coiled up and transported to the construction site for installation, and the installed stay cables are then tensioned. Step 4: After tensioning is completed, weld protective pipes to the area between the stay cables and the beam ends, sandblast the surface of the protective pipes, and then clean the surface of the protective pipes. Step 5: Apply an intumescent fire-retardant coating to the surface of the protective pipe by brushing or spraying to form an intumescent fire-retardant coating. Step 6: After the intumescent fire-retardant coating has dried completely, first wrap it with polyester fiber tape to form an outer polyester fiber layer, and then wrap it with polyvinyl fluoride wrapping tape to form a polyvinyl fluoride wrapping layer. The outer polyester fiber layer prevents the intumescent fire-retardant coating from cracking or peeling off due to cable vibration during operation; the polyvinyl fluoride wrapping layer is used for UV aging resistance and durability protection. The cable section with flame-retardant structure and the ordinary cable section are transitioned by a flexible material; and a polyester fiber layer and a polyvinyl fluoride wrapping layer are wrapped around the flexible material.

2. The construction method of the UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed flame-retardant structure according to claim 1, characterized in that: The polyester fiber layer is formed by winding polyester fiber tape, which is wrapped around the outer periphery of the steel wire bundle, and the thickness of the polyester fiber layer is 1~2mm.

3. The construction method of the UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed flame-retardant structure according to claim 1, characterized in that: The double-layer sheath is made of high-density polyethylene and has a thickness of 7-11 mm.

4. The construction method of a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed fire-retardant structure according to claim 1, characterized in that: The thickness of the intumescent fire-retardant coating is 2~5mm.

5. The construction method of a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed flame-retardant structure according to claim 1, characterized in that: The steel wire bundle in step one is made of twisted zinc-aluminum alloy coated steel wire or zinc-aluminum rare earth multi-element alloy coated steel wire.

6. The construction method of a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed flame-retardant structure according to claim 1, characterized in that: The base material of the intumescent fire-retardant coating in step five is organic resin, and it also contains foaming agent, flame retardant and charring agent.

7. The construction method of a UV-resistant, durable, easy-to-construct, and easy-to-replace cable-stayed flame-retardant structure according to claim 1, characterized in that: In step five, an arc-shaped spring brush is used for brushing. The arc-shaped spring brush includes a spring support and multiple wool brushes. The two ends of the spring support are fixed to the working handle, and the multiple wool brushes are spaced apart on the spring support, so that the multiple wool brushes are arc-shaped as the spring support deforms.

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