SYNTHETIC FIBER CABLE

Abstract

A carbon fiber cable includes a core member having multiple thermosetting-resin-impregnated carbon fibers bundled together, and multiple side members each having multiple thermosetting-resin-impregnated synthetic fibers bundled together in each side member. The thermosetting resin is in a cured state and each of the multiple side members has been shaped utilizing curability of the resin. The shaped multiple side members are each in such a state that they are twisted together around the core member.

Claims

1. A synthetic fiber cable comprising: a core member having multiple synthetic fibers impregnated with a resin, the fibers being bundled together; and multiple side members each having multiple synthetic fibers impregnated with the resin, the fibers being bundled together in each side member; wherein the resin is in a cured state and each of the multiple side members has been shaped utilizing curability of the resin; each of said shaped multiple side members being in such a state that they are twisted together around said core member.

2. A synthetic fiber cable according to claim 1, wherein with regard to said core member and each of said multiple side members, along the longitudinal direction thereof, each have contact portions where said side member is in contact with said core member and non-contact portions where said side member is not in contact with said core member.

3. A synthetic fiber cable according to claim 1, wherein each of said multiple side members has, along the longitudinal direction thereof, contact portions in contact with mutually adjacent side members, and non-contact portions not in contact with the mutually adjacent side members.

4. A synthetic fiber cable according to claim 2, wherein the contact portion and non-contact portion are present repeatedly along the longitudinal direction thereof.

5. A synthetic fiber cable according to claim 3, wherein the contact portion and non-contact portion are present repeatedly along the longitudinal direction thereof.

6. The synthetic fiber cable set forth in claim 1 wherein the synthetic fiber cable has been embedded in concrete of a concrete structure.

7. The synthetic fiber cable set forth in claim 1 wherein the synthetic fiber cable is used as reinforcement of an elongated object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a front view of a carbon fiber cable;

[0016] FIG. 2 is an exploded perspective view of the carbon fiber cable;

[0017] FIG. 3 is an enlarged sectional view taken along line of FIG. 1;

[0018] FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. 1;

[0019] FIG. 5 is an enlarged sectional view taken along line V-V of FIG. 1; and

[0020] FIG. 6 is a graph illustrating results of a concrete pull-out test.

DETAILED DESCRIPTION OF THE INVENTION

[0021] FIG. 1 illustrates the external appearance of a carbon fiber cable. FIG. 2 is an exploded perspective view of the carbon fiber cable. FIGS. 3 to 5 are enlarged sectional views of the carbon fiber cable taken along lines IV-IV and V-V, respectively, of FIG. 1.

[0022] A carbon fiber cable 1 is constituted by a single core member 2 as well as six side members 3 (3a to 3f) (a 17 structure) placed in such a state that the side members are twisted together around the core member. When viewed in cross section, the carbon fiber cable 1, core member 2 and side members 3 all have a substantially circular shape. Further, when viewed in cross section, the carbon fiber cable 1 is such that the core member 2 is placed at the center thereof while the six side members 3 are situated so as to surround the core member 2. The carbon fiber cable 1 has a diameter of 5 to 20 mm, by way of example.

[0023] The core member 2 and side members 3 each comprise a large number, e.g., tens of thousands, of long carbon fibers 4 impregnated with a thermosetting resin (epoxy resin, for example) 5 and bundled into a shape having a circular cross section. The overall carbon fiber cable 1 includes on the order of several hundred thousand of the carbon fibers 4. Each of the carbon fibers 4 is very slender and has a diameter of 5 to 7 m, by way of example. The core member 2 and side members 3 may each be formed by bundling together the large number of carbon fibers 4 impregnated with the thermosetting resin 5 and twisting together a plurality of these bundles of carbon fiber. The core member 2 and side members 3 can also be referred to carbon fiber reinforced plastics (CFRP).

[0024] In this embodiment, the core member 2 and side members 3 employed have the same thickness (cross-sectional area). The side members 3 used may of course be thinner or thicker than the core member 2. The thickness of the core member 2 and of each of the side members 3 can be adjusted at will depending upon the number of carbon fibers 4.

[0025] The core member 2 and side members 3 constituting the carbon fiber cable 1 are all used in a state in which the thermosetting resin 5 has been heated and cured in advance. Specifically, the carbon fiber cable 1 is produced by placing the side members 3, hardened by utilizing the thermal curability of the thermosetting resin 5, in such a state that they are disposed and twisted together around the core member 2 which, similarly, has been hardened by utilizing the thermal curability of the thermosetting resin 5. Since the thermosetting resin 5 of the core member 2 and of each of the side members 3 has cured, suitable slippage is allowed between the core member 2 and surrounding side members 3 and between the side members 3 that are adjacent each other.

[0026] With reference to FIG. 2, the six side members 3 that will be placed in a state in which they are twisted together around the core member 2 are all shaped into a helical configuration beforehand; the core member 2, on the other hand, does not undergo helical shaping. It goes without saying that the side members 3 are shaped into the helical configuration before the thermosetting resin 5 is thermally cured. The pitch of the helix of each of the helically shaped side members is substantially the same, and the inner diameter of the helix of each of the side members 3 is substantially equal to the diameter of the core member 2.

[0027] Each of the side members 3 partially has portions (referred to as bulged portions below) shaped so as to bulge slightly outward. Bulged portions 3A to 3D at four locations are illustrated in somewhat emphasized form on the carbon fiber cable 1 shown in FIG. 1.

[0028] Referring now to FIG. 3, when the portion having the bulged portion 3A is viewed in cross section, it will be seen that one side member (side member 3a) among the six side members 3a to 3f around the core member 2 is not in contact with the core member 2 but is positionally displaced outwardly away from the core member 2. The pre-shaping of the side member 3a is carried out so as to give rise to this positional displacement. Owing to the fact that the side member 3a is spaced away from the core member 2, an internal space (non-contact portion) 11 is assured between the core member 2 and side member 3a.

[0029] Since the core member 2 and side members 3 all have a circular cross section, portions of non-contact inevitably exist between the core member 2 and side members 3. [For example, in FIG. 3, an approximately triangular space (indicated at reference numeral 20), when viewed in cross section, is formed by the core member 2, the side member 3c and the side member 3d]. However, the internal space 11 referred to in this specification does not mean the space 20 having the approximately triangular cross section but rather signifies the space between the core member 2 and each of the core members 3, this internal space being assured by the pre-shaping of the core members 3. By assuring the internal space 11, the two spaces 20 having the approximately triangular cross section are connected.

[0030] In FIG. 3, the side member 3a situated between the two side members 3b, 3f on either side is in contact with the one side member 3f but is not in contact with the other side member 3b and is positionally displaced away from the side member 3b (shaping of the side member 3a being performed in advance so as to give rise to this positional displacement). A gap 12 is assured between the side member 3a and the side member 3b owing to the fact that the side member 3a is spaced away from the side member 3b.

[0031] Referring now to FIG. 4, when a portion having the other bulged portion 3B is viewed in cross section, it will be seen that two side members (side members 3e, 3f) among the six side members 3a to 3f around the core member 2 are not in contact with the core member 2. Instead, internal spaces 11 are assured between the core member 2 and the side members 3e, 3f. Since the side members 3e, 3f are adjacent each other, the two internal spaces 11 are connected, resulting in the formation of a large internal space. Further, although the other side member 3c is in contact with the core member 2, it is situated spaced away from both of the two side members 3b, 3d situated on either side of the side member 3c. Thus the gaps 12 are assured on both sides of the side member 3c.

[0032] In FIG. 4, the internal spaces 11 are illustrated as closed spaces. However, the internal spaces 11 are not spaces completely cut off from the outside but rather are open spaces in communication with the outside. Specifically, the internal spaces 11 assured between the core member 2 and side members 3 are connected to the above-mentioned gaps 12 that are assured by the fact that two mutually adjacent side members are spaced away at other locations along the longitudinal direction of the carbon fiber cable 1. The internal spaces 11 are in communication with the outside through the gaps 12.

[0033] Referring now to FIG. 5, when the portion having the bulged portions 3C, 3D is viewed in cross section, it will be seen that four side members (side members 3b, 3c, 3e, 3f) among the six side members 3a to 3f around the core member 2 are not in contact with the core member 2, thereby assuring internal spaces 11. Further, gaps 12 are assured between side members 3a and 3b, between side members 3c and 3d, between side members 3e and 3f, and between side members 3f and 3a.

[0034] Thus, the carbon fiber cable 1 is such that the locations and numbers of internal spaces 11 and gaps 12 differ depending upon the location where the cross section is taken. Naturally, depending upon where the cross section is taken, there will be instances where the internal spaces 11 and gaps 12 do not appear at all and, conversely, there can be instances where the six side members 3 will not be in contact with the core member 2 over its entire circumference. Further, as illustrated in FIGS. 3 to 5, the sizes of the internal spaces 11 and gaps 12 (the distances between the core member 2 and side members 3 and the distances between mutually adjacent side members 3) that appear in a cross section will vary. This means that the extent of the multiple bulged portions 3A to 3D varies. It should be noted that extremely large bulged portions (internal spaces 11 and gaps 12) do not exist in the carbon fiber cable 1 and, hence, the essentially twisted state is not impaired.

[0035] The bulged portions mentioned above are formed repeatedly along the longitudinal direction of the carbon fiber cable 1. That is, with regard to the core member 2 and each of the multiple side members 3, contact portions where the side members 3 are in contact with the core member 2 (portions where the internal spaces 11 do not exist) and non-contact portions where the side members 3 are not in contact with the core member 2 (portions where the internal spaces 11 do exist) appear repeatedly along the longitudinal direction. Similarly, with regard to side members 3 that are adjacent each other, contact portions (portions where the gaps 12 do not exist) and non-contact portions (portions where the gaps 12 do exist) appear repeatedly along the longitudinal direction.

[0036] The bulged portion may be provided at prescribed intervals, or provided randomly, on each side member along the longitudinal direction thereof. Although the bulged portion may be provided at identical intervals on all of the side members 3 along the longitudinal direction thereof, the intervals of the bulged portions along the longitudinal direction may be made different for every side member 3. The bulged portions thus are provided on the carbon fiber cable 1 in dispersed fashion and the internal spaces 11 and gaps 12 along the longitudinal direction of the carbon fiber cable 1 are present in dispersed fashion.

[0037] As set forth above, since the carbon fiber cable 1 is such that the thermosetting resin 5 on the core member 2 and on each of the side members 3 has cured, slippage is allowed between the core member 2 and side members 3 and between side members 3 that are adjacent each other. Furthermore, since the cable has the internal spaces 11 and gaps 12, it undergoes suitable flexing when bent and excels in handling ease. The cable can be put into compact form by being wound upon a small-diameter reel, thereby making handling easy at the workplace. For example, the carbon fiber cable 1 is suitable for use as the core material of a long object such as a power transmission line.

[0038] Further, the carbon fiber cable 1 can be used as reinforcement for concrete structures, by way of example. When the carbon fiber cable 1 is embedded in concrete before the concrete sets (fresh concrete), the concrete penetrates into interior of the carbon fiber cable 1 with the gaps 12 between mutually adjacent side members 3 serving as entrances. Concrete that has entered into the interior of the carbon fiber cable 1 from the gaps 12 enters the internal spaces 11 assured between the core member 2 and side members 3, resulting in greater area of contact between the carbon fiber cable 1 and the concrete. Naturally, depending upon such factors as the viscosity of the fresh concrete and the sizes of the internal spaces 11 and gaps 12, the concrete may not fill the internal spaces 11 completely. However, in addition to the fact that the concrete comes into contact with the outer periphery (surface) of the carbon fiber cable 1, contact with the concrete also occurs in the interior of the carbon fiber cable 1 as well. Hence an increase in the area of contact between the concrete and the carbon fiber cable 1 is achieved. As a consequence, adhesion stress can be improved greatly in comparison with iron reinforcing bars and the carbon fiber cable 1 can be fixed inside the concrete with a high degree of fixing efficiency. Concrete structures include bridge beams, piers, bridge rails, protective barriers and the like.

[0039] FIG. 6 is a graph illustrating results of a concrete pull-out test in which the horizontal axis is a plot of slip displacement (mm) and the vertical axis a plot of adhesion stress (N/mm.sup.2). The solid line in the graph indicates the result of testing the above-described carbon fiber cable 1, and the broken line indicates the result of testing a carbon fiber cable that does not have the internal spaces 11 and gaps 12. The diameters of the core members, side members, number and structure thereof, as well as the length embedded (the length fixed) in concrete were measured under identical conditions.

[0040] The concrete pull-out test was conducted in line with the Method of Testing Adhesion Strength between Continuous Fiber Reinforcing Material and Concrete by Pull-out Test of the Japan Society of Civil Engineers. According to this test, a concrete block in which the intermediate portion of a carbon fiber cable has been embedded with both ends of the cable exposed to the outside is fabricated. By using a tensile testing machine, a tensile load is applied at a prescribed loading rate to the carbon fiber cable projecting to the outside from one end of the concrete block, and a displacement gauge is used to measure the amount of displacement (slip displacement) of the carbon fiber cable projecting to the outside from the other end of the concrete block.

[0041] Adhesion stress (N/mm.sup.2) was calculated using the following equation:

Adhesion stress =P/u.Math.L

where P represents tensile load (kN), u the nominal circumference (mm) of the carbon fiber cable and L the adhesion length (mm) with respect to the concrete block.

[0042] As a result of the concrete pull-out test, it was confirmed that, in comparison with the adhesion stress (the broken line) of the carbon fiber cable devoid of the internal spaces 11 and gaps 12, the adhesion stress (the solid line) of the above-described carbon fiber cable 1 is greatly improved and exhibits a high concrete fixation efficiency.

[0043] The degree of shaping of the side members 3 (the degree of constraint due to the side members 3) in the carbon fiber cable 1 can be expressed by D/(.sub.1A+.sub.2)100(%) (referred to as shaping ratio below) using diameter D of the cable 1 and diameters .sub.1 and .sub.2 of the core member 2 and side members 3, respectively, that constitute the cable 1. If the shaping ratio is on the order of 100.1 to 105(%), the carbon fiber cable 1 will undergo suitable flexing when bent, and the concrete adhesion efficiency will rise as well. In cases where the emphasis is placed on concrete adhesion efficiency and the concrete adhesion efficiency is to be raised, the multiple side members 3 may be shaped so as to take on a shaping ratio on the order to 110%, by way of example.

[0044] In the embodiment set forth above, an example is described in which bundles of the multiple carbon fibers 4 are impregnated with the thermosetting resin 5 and the carbon fiber cable 1 is constructed from the core member 2 and side members 3 hardened by applying heat to the thermosetting resin 5. However, a thermoplastic resin (polyamide, for example) may used instead of the thermosetting resin 5. Further, instead of carbon fiber, glass fiber, boron fiber, aramid fiber, polyethylene fiber and PBO (polyp-phenylenebenzobisoxazole) fiber, as well as other synthetic fibers, can be used.