A fire-resistant stay cable and a method for manufacturing the same

Abstract

The present invention discloses a fire-resistant cable-stayed structure and a manufacturing method thereof, comprising the following structure: a combined structure of steel wire bundle + wrapping tape + (high polyethylene sheath) + fire-resistant heat insulation layer (waterproof coating coated on the outer surface) + hot-melt wrapping tape + (fiber cloth high polyethylene sheath); that is, the inner layer is steel wire bundle + wrapping tape + (high polyethylene sheath), the middle layer is fire-resistant heat insulation layer + (waterproof coating), and the outer layer is hot-melt wrapping tape + (fiber cloth high polyethylene sheath). The present invention achieves the purposes of waterproofing, weather resistance, flame retardancy and fire-resistant heat insulation through the cable structure.

Description

Technical Field

[0001] The invention relates to the technical field of bridge cables, and in particular to a fire-resistant inclined cable and a manufacturing method thereof. Background Art

[0002] In recent years, bridge fire accidents have occurred frequently, and some fire accidents have caused huge economic losses and social impacts. For cable-stayed bridges whose main force-bearing structure is cables, they are severely affected by fire. The strength of cables is reduced and they fail in the high temperature environment of fire, which may cause the structural damage of the entire cable-stayed bridge. Therefore, it is of great practical significance to develop a high-temperature resistant cable-stayed cable.

[0003] At present, most of the cables on the market use high polyethylene to protect the cable steel bundles. Polyethylene has good water-tightness and weather resistance, but it is easy to ignite in the high temperature environment of the fire, which makes the cable more seriously affected by the fire. And the polyethylene protective layer is easily damaged mechanically during the construction process, thereby reducing its water-tightness and weather resistance. Chinese Patent 201920138763.0 discloses a flame-retardant bridge cable, which uses an adhesive to stick a fire-resistant cloth on the surface of the original high polyethylene protective layer to achieve the purpose of fire prevention. This method is more cumbersome to construct and is more suitable for high-temperature upgrades of existing cables. Chinese patent application 201811612472.7 discloses a flame-retardant cable, which has developed a protection system that is completely different from the original high-polyethylene protection, including: an outer fire-resistant rubber layer, an inner insulation layer composed of raw materials such as water-based resin, polyphosphate amine, vermiculite, expanded graphite, perlite and water. Judging from the composition of its insulation layer, its construction and installation after production is not convenient. During the construction process, the insulation layer is easily damaged mechanically, which not only affects the insulation effect, but also may cause damage to the steel wire bundle. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a fire-resistant cable-stayed cable and a method for manufacturing the same, which, without changing the water-tightness and weather-resistant properties of the current polyethylene protection system of the cable-stayed cable, composites fire-proof, heat-preserving, thermal-insulating and other functional layers into polyethylene during the production process of the cable-stayed cable, thereby forming a new type of fire-resistant cable-stayed cable.

[0005] The present invention provides the following technical solutions:

[0006] A method for manufacturing a fire-resistant cable-stayed structure comprises the following steps:

[0007] S1. Wire bundle fastening and forming:

[0008] After drawing and tightening the steel wire bundles with the designed specifications and quantity as required, use the wrapping machine to wrap the steel wire bundles with wrapping tape at a certain angle and overlapping width to tighten them into shape;

[0009] S2. Wrapping fire-resistant thermal insulation layer:

[0010] Use a wrapping machine to wrap the fire-resistant thermal insulation layer;

[0011] S3. Wrapping hot melt wrapping tape:

[0012] Use a wrapping machine to wrap the hot-melt wrapping tape on the surface of the fire-resistant thermal insulation layer;

[0013] S4. Carry out surface treatment of the cable-stayed structure to resist wind, rain and vibration.

[0014] Preferably, a polyethylene sheath of designed thickness is formed by hot-melt extrusion on the surface of the formed steel wire bundle.

[0015] Preferably, the fire-resistant thermal insulation layer is a composite thermal insulation laminate, which is formed by alternatingly stacking a plurality of base fabrics and needle-punched felts.

[0016] Preferably, the base fabric is made of one or a blend of two or more of high-silica fabric, basalt fiber fabric, glass fiber fabric, polyester, nylon, polyimide, and aramid; the needle-punched felt is made of one or a blend of two or more of basalt fiber felt, high-silica felt, glass fiber felt, polyester, polyimide, and aramid.

[0017] Preferably, in step S2, a high temperature resistant metal clamp is used to fix the fire resistant thermal insulation layer.

[0018] Preferably, in step S3, the material is wrapped around the surface of the fire-resistant thermal insulation layer at an angle of 15 to 50 degrees and fastened into shape.

[0019] Preferably, in step S3, an outer fiber cloth polyethylene sheath is formed after wrapping with the hot-melt wrapping tape, and the specific steps are: the fiber cloth required by the design is fully attached to the inner layer of the extrusion machine, the hot-melt polyethylene material is injected into the test mold, and the extrusion machine is started to extrude the fiber cloth onto the surface of the hot-melt polyethylene, and at the same time, the polyethylene material is extruded onto the surface of the wrapping tape; preferably, the fiber cloth is high-silica cloth, basalt fiber cloth, glass fiber cloth or carbon fiber cloth.

[0020] Preferably, the exterior of the fire-resistant thermal insulation layer is also coated with a waterproof coating.

[0021] The present invention also provides a fire-resistant cable-stayed structure prepared by the method.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention uses fiber and polyethylene as the main materials, and adopts the combined structure of "steel wire bundle + wrapping tape + (polyethylene sheath) + fire-resistant thermal insulation layer (waterproof coating coated on the outer surface) + hot-melt wrapping tape + (fiber cloth polyethylene sheath)", so as to improve the waterproof, flame-retardant, heat-insulating and weather-resistant properties of the bridge cable, extend the service life of the bridge cable, and ensure safe use.

[0024] (2) The manufacturing process of the cable-stayed structure of the present invention is simple, and only the steps of making a fire-resistant thermal insulation layer and a wrapping tape need to be added to the original cable-stayed production steps, which is suitable for large-scale factory production.

[0025] (3) The functions of each layer of the cable-stayed cable of the present invention are clear. On the one hand, the polyethylene sheath can be isolated from the fire source to prevent the polyethylene sheath from being ignited in a small or medium-sized fire environment; on the other hand, the built-in flexible thermal insulation layer can ensure that the steel wire bundle will not fail due to high temperature in a large fire environment.

[0026] (4) The cable-stayed cable of the present invention can be applied to different fire risk scenarios by eliminating the thermal insulation layer or adjusting the thickness and position of the thermal insulation layer, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a composite thermal insulation laminate according to Example 1 of the present invention;

[0028] Figure 2 This is a graph of internal and external temperature of fire resistance performance of Example 1 of the present invention;

[0029] Figure 3 is a schematic structural diagram of a composite thermal insulation laminate according to Example 2 of the present invention;

[0030] Figure 4 This is a graph of internal and external temperature of fireproof performance of Example 2 of the present invention;

[0031] Figure 5 It is a graph of internal and external temperature of the fireproof performance of Example 3 of the present invention.

[0032] In the figure: 1-base fabric, 2-needle felt. DETAILED DESCRIPTION

[0033] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0034] Example 1

[0035] A method for manufacturing a fire-resistant cable-stayed structure, wherein the structure is a combination of a steel wire bundle + a wrapping tape + a basalt fire-resistant thermal insulation layer (with a waterproof coating on the outer surface) + a hot-melt wrapping tape, and the preparation process comprises the following steps:

[0036] S1. Steel wire bundles are tightened and formed. After the steel wire bundles of the designed specifications and quantity are drawn and tightened as required, a wrapping machine is used to wrap the steel wire bundles with wrapping tape at a certain angle and overlapping width to tighten them into shape.

[0037] S2. Wrap the basalt fiber refractory insulation layer. Use a wrapping machine to tightly wrap the basalt refractory insulation layer on the surface of the inner wrapping tape, and use a high-temperature resistant metal clamp to fix the refractory insulation layer. The basalt refractory insulation layer is made of basalt fiber base cloth and needle felt alternately stacked, such as Figure 1 shown.

[0038] S3. Use a wrapping machine to wrap the hot-melt wrapping tape directly on the surface of the fire-resistant insulation layer at an angle of 30° and tighten it into shape; apply a waterproof coating on the outer surface.

[0039] S4. Anti-wind and rain vibration surface treatment of the cable. After the hot-melt extrusion of the outer sheath is completed, the anti-wind and rain vibration surface treatment of the cable is immediately carried out, and the cable is completed. The measures currently adopted mainly include mechanical measures (damper), structural measures (auxiliary cables) and pneumatic measures (winding spiral wires on the cable surface, pressing pits, etc.). The principle of mechanical measures is to control vibration by increasing the damping of the structure; structural measures, such as the principle of setting auxiliary cables, are to reduce the effective length of the cable and increase the natural frequency of the cable, thereby achieving the purpose of suppressing vibration; pneumatic measures are to achieve the purpose of controlling vibration by hindering the formation of the waterline and changing the wind speed and degree of the Reynolds number effect.

[0040] Studies have shown that when the steel strand is heated below 400 degrees Celsius, the organizational changes are not obvious and the mechanical properties do not decay much; above 400 degrees Celsius, crystallization and phase change occur successively, the strength and hardness decay significantly, and the plasticity increases significantly. Figure 2 The average temperature inside the test piece did not reach 400 degrees Celsius, and the fire caused by the vehicle lasted for about 30 to 120 minutes. Therefore, the structure used in this test basically met the fireproof and heat insulation requirements of bridge cables, leaving ample time for fire rescue and meeting the needs of bridge fire rescue.

[0041] Figure 2 This is the internal and external temperature curve of the fire resistance performance of the fire-resistant cable-stayed structure. The combustion test lasted for 30 minutes. As can be seen from the figure, the flame temperature rose to about 900°C within 300 seconds, while the temperature inside the specimen rose slowly and basically stabilized below 8090°C after 1200 seconds. The material meets the requirements of fireproofing and heat insulation.

[0042] Example 2

[0043] A method for manufacturing a fire-resistant cable-stayed structure, wherein the structure is a combination of a steel wire bundle + a wrapping tape + a polyethylene sheath + a fire-resistant thermal insulation layer (with a waterproof coating on the outer surface) + a hot-melt wrapping tape, and the preparation process is basically the same as that of Example 1, except that the base fabric of the fire-resistant thermal insulation layer is made of high-silica fabric, and the needle-punched felt is made of high-silica needle-punched felt, such as Figure 3 shown.

[0044] like Figure 4 As shown in the figure, the combustion test lasted for 30 minutes, the flame temperature rose to about 900°C within 300 seconds, and the temperature inside the specimen rose slowly, basically stabilizing below 150°C after 1200 seconds. The material meets the requirements of fireproofing and heat insulation.

[0045] Example 3

[0046] A method for manufacturing a fire-resistant cable-stayed structure, the structure of which is a combination of a steel wire bundle + a wrapping tape + a polyethylene sheath + a fire-resistant thermal insulation layer (with a waterproof coating on the outer surface) + a hot-melt wrapping tape + a fiber cloth polyethylene sheath. The preparation process is basically the same as that of Example 2, except that: the fiber cloth required by the design is fully attached to the inner layer of the extrusion machine, hot-melt polyethylene material is injected into the test mold, the extrusion machine is started to extrude the fiber cloth onto the surface of the hot-melt polyethylene, and at the same time, the polyethylene material is extruded onto the surface of the wrapping tape, and the fiber cloth is basalt fiber cloth.

[0047] like Figure 5 As shown in the figure, the combustion test lasted for 30 minutes, the flame temperature rose to about 900°C within 300 seconds, and the temperature inside the specimen rose slowly, basically stabilizing below 120°C after 1200 seconds. The material meets the requirements of fireproofing and heat insulation.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a fire-resistant cable-stayed structure, characterized in that: The steps include: S1. Wire bundle fastening and forming: After drawing and fastening the steel wire bundles with designed specifications and quantity as required, use a wrapping machine to wrap the steel wire bundles with wrapping tape at a certain angle and overlapping width to fasten them into shape; hot-melt extrude a polyethylene sheath of designed thickness on the surface of the formed steel wire bundles; S2. Wrapping fire-resistant thermal insulation layer: A fire-resistant thermal insulation layer is wound by a wrapping machine, and a waterproof coating is applied on the outside; the fire-resistant thermal insulation layer is a composite thermal insulation laminate, which is formed by alternating stacking of a plurality of base fabrics and needle felts; S3. Wrapping hot melt wrapping tape: A wrapping machine is used to wrap the hot-melt wrapping tape on the surface of the fire-resistant heat-insulating layer; then an outer fiber cloth polyethylene sheath is formed, and the specific steps are: the fiber cloth required by the design is fully attached to the inner layer of the extrusion machine, and the hot-melt polyethylene material is injected into the test mold, and the extrusion machine is started to extrude the fiber cloth onto the hot-melt polyethylene surface, and at the same time, the polyethylene material is extruded onto the surface of the wrapping tape; the fiber cloth is high-silica cloth, basalt fiber cloth, glass fiber cloth or carbon fiber cloth; S4. Carry out surface treatment of the cable-stayed structure to resist wind, rain and vibration.

2. The method according to claim 1, characterized in that: The base fabric is made of one or a blend of two or more of high-silica fabric, basalt fiber fabric, glass fiber fabric, polyester, nylon, polyimide, and aramid; the needle-punched felt is made of one or a blend of two or more of basalt fiber felt, high-silica felt, glass fiber felt, polyester, polyimide, and aramid.

3. The method according to claim 1, characterized in that: In step S2, a high temperature resistant metal clamp is used to fix the fire resistant heat insulation layer.

4. The method according to claim 1, characterized in that: In step S3, the laminate is wrapped around the surface of the fire-resistant heat-insulating layer at an angle of 15 to 50 degrees and fastened into shape.

5. A fire-resistant cable-stayed structure prepared according to the manufacturing method according to any one of claims 1 to 4.

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