Cable structure with thermal protection performance and design method thereof

Abstract

The invention discloses a cable structure with thermal protection performance and a design method thereof, the cable structure comprises a cable body and a material 1, a material 2 and a material 3 which are sequentially arranged on the outer side of the cable body, and the cable structure with the thermal protection performance is formed. The material 1 is a low-heat-conductivity material, the material 2 and the material 3 are selected according to the structural size, the selection range of the heat conduction materials is widened by adjusting the radius R1 of the material 1, the radius R2 and the heat conductivity coefficient k2 of the material 2 and the radius R3 and the heat conductivity coefficient k3 of the material 3, the cable with the heat protection performance is suitable for cable bodies with different radiuses, and the fireproof effect of the cable with the heat protection performance is adjusted. According to the design method of the cable structure with the thermal protection performance, the structure is simple, manufacturing is easy, a new way is provided for heat transmission control, the influence of external high temperature on the cable body is effectively reduced, a brand new thought is provided for fire protection of bridges and other cable systems, and good application prospects are achieved.

Description

Technical Field

[0001] The invention relates to a design method of a cable structure with heat protection performance, belonging to the technical field of cable fire protection. Background Art

[0002] Cable-stayed bridges and suspension bridges have the characteristics of large spans and beautiful shapes. They are widely used in bridge construction. While the traffic volume has increased significantly, the risk of vehicle fire accidents has also increased. Among the extreme loads that bridges may bear, fire and explosion will cause immeasurable losses to bridges. Cables are important load-bearing components of cable-supported bridges. When a fire accident occurs on the bridge deck (especially a tanker fire), the cable system will be affected by heat convection and heat radiation, which can easily cause the PE sheath of the suspension cable to burn, the temperature of the steel wire continues to rise, and then the anti-corrosion layer will fall off, the performance of the steel wire will deteriorate, and other fire damage diseases will occur. The elastic modulus and ultimate bearing capacity of the cable will also decrease with the increase in temperature, posing a serious threat to the safe operation of the bridge.

[0003] At present, relevant specifications for fire protection of cable components have not yet been formulated. The fire protection design of cable components mainly refers to the relevant achievements in the field of building steel structures. By using fireproof materials with high temperature resistance, heat resistance and flame retardant properties, the damage caused by fire to bridges can be reduced. However, existing fireproof materials have problems such as low fire resistance level, insufficient high temperature resistance and thermal conductivity. New ways are needed to control heat transfer near the cables and reduce the impact of fire accidents on the cable body. Summary of the invention

[0004] Technical issues:

[0005] The present invention aims to solve at least one of the technical problems existing in the related art to a certain extent. To this end, the purpose of the present invention is to propose a design method for a cable structure with thermal protection performance. By arranging low thermal conductivity material 1, material 2 with different thermal conductivity coefficients, and material 3 on the outside of the cable body, a cable structure with thermal protection performance is formed. The structure is simple and easy to make, which provides a new way to control heat transfer, effectively reduces the influence of external high temperature on the cable body, and provides a new idea for fire protection of bridges and other cable systems, and has good application prospects.

[0006] Technical solution:

[0007] A cable structure with thermal protection performance comprises a protected cable body and a first material, a second material and a third material sequentially arranged outside the cable body; the first material is a low thermal conductivity material, and the thermal conductivity k1 is 0.001-0.1 W / (m·K); the relationship between the thermal conductivity and radius of the three materials is given by the following formula:

[0008]

[0009] Among them, β=k2 / k3, R1, R2, R3 are the outer diameters of the first material, the second material, and the third material respectively, k is the environmental thermal conductivity, k2 is the thermal conductivity of the second material, and k3 is the thermal conductivity of the third material.

[0010] Preferably, the protected cable body is a steel cable or a CFRP cable.

[0011] Preferably, the first material is polystyrene, ceramic fiber, rock wool or aerogel composite material.

[0012] Preferably, the second material and the third material are carbon fiber, polycarbonate or rainproof neoprene.

[0013] Preferably, when β=1, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material are given by the following formula:

[0014]

[0015] The present invention also provides a design method for a three-layer cable structure, comprising the following steps:

[0016] Step 1: Determine the environmental thermal conductivity k, select the first material, the second material and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material, and calculate β;

[0017] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material;

[0018] Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (1).

[0019] The present invention also provides a design method for a two-layer cable structure, comprising the following steps:

[0020] Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and take β=1;

[0021] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material;

[0022] Step 3: Determine the outer diameter R1 of the first material, and calculate the outer diameter R2 of the second material according to formula (2).

[0023] Beneficial effects:

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The cable structure with thermal protection performance proposed in the present invention can reduce the impact of external high temperature on the cable body to a large extent. In a continuous high temperature environment, heat is transmitted around the cable body, and the temperature of the cable body remains basically unchanged, providing a new way to control heat transmission and a new idea for cable fire prevention.

[0026] (2) The cable structure with thermal protection performance proposed in the present invention can broaden the selection range of thermal conductive materials by changing the radius R1 of material 1, the radius R2 and thermal conductivity k2 of material 2, and the radius R3 and thermal conductivity k3 of material 3, so as to flexibly construct cable structures suitable for different cable body radii.

[0027] (3) The cable structure with thermal protection performance proposed by the present invention has a simple structure and is easy to prepare.

[0028] (4) The cable structure with thermal protection performance proposed in the present invention can be applied to, but not limited to, cable structures in bridges, and is also applicable to other cable systems that require protection, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a three-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0030] Figure 2 Schematic diagram of a two-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0031] Figure 3 The temperature variation curve of the cable body of the two-layer cable structure with thermal protection performance according to an embodiment of the present invention is shown as follows:

[0032] Figure 4 It is the isotherm of the cable body of the two-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0033] Figure 5 Graphs 1 and 2 show the temperature fields of the cable body of a two-layer cable structure with thermal protection performance according to an embodiment of the present invention at different times. DETAILED DESCRIPTION

[0034] The present invention will be described in more detail below in conjunction with the schematic diagram, wherein the preferred embodiment of the present invention is shown, and it should be understood that those skilled in the art can modify the present invention described herein, and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0035] A design method of a cable structure with heat protection performance according to an embodiment of the present invention will be further described below with reference to the accompanying drawings.

[0036] like Figure 1As shown, a cable structure with thermal protection performance is proposed according to an embodiment of the present invention. The three-layer cable structure includes: a cable body, and material 1, material 2, and material 3 arranged in sequence on the outside of the cable body. The radius of the cable body is R0, the outer diameter of material 1 is R1, the outer diameter of material 2 is R2, and the outer diameter of material 3 is R3.

[0037] When the outer side of the cable body in the cable structure is made of three materials, the design method includes the following steps:

[0038] Step 1: Determine the environmental thermal conductivity k, select the first material, the second material and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material, and calculate β;

[0039] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material;

[0040] Step 3: Determine the outer diameter R1 of the first material, and calculate the outer diameter R2 of the first material according to formula (1).

[0041]

[0042] When the outer side of the cable body in the cable structure is made of two materials, the design method includes the following steps:

[0043] Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and take β=1;

[0044] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material;

[0045] Step 3: Determine the outer diameter R1 of the first material, and calculate the outer diameter R2 of the second material according to formula (2).

[0046]

[0047] like Figure 2 As shown, this embodiment provides a two-layer cable structure, including a cable body, material 1, and material 2, and constructs a finite element model of a cable structure with thermal protection performance. The radius of the cable body is R0 = 0.1m, and the radius of material 1 is R1 = 0.125m. Among them, the cable body is selected as a steel cable with a density of ρ0 = 7850kg / m 3 , thermal conductivity k0 = 44.5W / (m·K), constant pressure heat capacity C p0 =475J / (kg·K); Material 1 is polystyrene, density ρ1=40kg / m 3 , thermal conductivity k1 = 0.04W / (m·K), constant pressure heat capacity C p1=1300J / (kg·K); Material 2 is carbon fiber, density ρ2=1500kg / m 3 , thermal conductivity k2 = 0.2326W / (m·K), constant pressure heat capacity C p2 =800 J / (kg·K). A temperature load of 1000°C was applied to the bottom of the model, the initial temperature was set to 30°C, and the thermal conductivity of the environment was k=0.076 W / (m·K).

[0048] Substituting the above related parameters into formula (2), the radius of material 2 is calculated to be R2 = 0.1375m.

[0049] like Figure 3 As shown in the figure, the cable body temperature change curve within 2 hours of temperature load application. The initial temperature of the cable body is 30°C. After the temperature load is applied for 1 hour, the cable body temperature is 30.07°C, and the cable body temperature changes relatively slowly; after the temperature load is applied for 2 hours, the cable body temperature is 30.56°C. Within 1 to 2 hours of temperature load, the cable body temperature changes relatively greatly. Considering the actual needs, the temperature of the cable body is reasonable after the temperature load is applied for 2 hours. Therefore, the cable structure with thermal protection performance effectively reduces the impact of external high temperature on the cable body.

[0050] like Figure 4 As shown in the figure, the isotherms of the cable structure model with thermal protection performance after burning for 2 hours. The temperature of material 1 is in the range of 535-584℃, the temperature of material 2 is in the range of 584-633℃ on the side close to the temperature load, and in the range of 486-535℃ on the side away from the temperature load. The temperature of the cable body is relatively low at around 30℃.

[0051] like Figure 5 As shown in the figure, the temperature field of the cable structure model with thermal protection performance when burning for 30 minutes, 60 minutes, 90 minutes, and 120 minutes respectively. As time goes by, the ambient temperature gradually rises, and the temperature around the cable gradually rises. The cable temperature is relatively low at around 30°C, and the heat is transmitted around the cable body, realizing the control of heat transfer near the cable.

[0052] Finally, it should be noted that the drawings are only for illustrative purposes and represent only schematic diagrams rather than physical drawings, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted. The examples of the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by engineers and technicians in this field to the technical solution of the present invention should fall within the scope of protection of the present invention.

Claims

1. A cable structure with thermal protection performance, characterized in that: It includes a protected cable body and a first material, a second material, and a third material arranged in sequence on the outer side of the cable body; the first material is a low thermal conductivity material, and the thermal conductivity k1 is 0.001-0.1 W / (m·K); the relationship between the thermal conductivity and radius of the three materials is given by the following formula: Among them, β=k2 / k3, R1, R2, R3 are the outer diameters of the first material, the second material, and the third material respectively, k is the environmental thermal conductivity, k2 is the thermal conductivity of the second material, and k3 is the thermal conductivity of the third material.

2. A cable structure with heat protection performance according to claim 1, characterized in that: The protected cable body is a steel cable or a CFRP cable.

3. A cable structure with heat protection performance according to claim 1, characterized in that: The first material is polystyrene, ceramic fiber, rock wool or aerogel composite material.

4. A cable structure with heat protection performance according to claim 1, characterized in that: The second material and the third material are carbon fiber, polycarbonate or rainproof chloroprene rubber.

5. A cable structure with heat protection performance according to claim 1, characterized in that: When β=1, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material are given by the following formula:

6. The design method of the cable structure according to claim 1, characterized in that: The steps include: Step 1: Determine the environmental thermal conductivity k, select the first material, the second material and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material, and calculate β; Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material; Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (1).

7. The design method of the cable structure according to claim 5, characterized in that: The steps include: Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and take β=1; Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material; Step 3: Determine the outer diameter R1 of the first material, and calculate the outer diameter R2 of the second material according to formula (2).

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