Note: Descriptions are shown in the official language in which they were submitted.
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Patent Specification
Fibrous Composite RoPe and Method of M~nufacturing the Same ` .
Technical Field
The Present invention relates to a fibrous composite roPe for use in
prestressing members of PC (prestressed concrete) structures in the civil
engineering and construction industry or strengthening or reinforcing members -
for power or communication cables, etc., and more particularly to such a fibrous
roPe which is obtained bY stranding a PluralitY of fibrous cores or strands
impregnated with a thermosetting resin. The "rope" herein referred to is a
generic term including in its meaning all ropes, cords and the like stranded
materials.
Background Arts ~ ~-
Heretofore, an overwhelmingly maior part of Prestressing members for PC
structures has been shared bY steel in the civil engineering and construction
industrY.' ~ '' !; `'~.
Many improvements have been proposed in such steel-based structural
prestressing members, among which Japanese Patent Publication No. Hei 3-28,551
typically discloses one of the most advanced one. NamelY, it discloses a
prestressing member featuring a high corrosion resistance, good anchorage and ~ ~`
workability due to its synthetic resin coating.
Honever, since such a Prestressing member comprises stranded steel wires
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as its base material, it is heavY in weight and cannot be free from problems
caused by magnetism, and if its resin coating is damaged the stranded wires
will corrode, resulting in the loss of required mechanical proPerties.
Meanwhile, there are known various cords and ropes fabricated of fibers
or fibrous YarnS. Among those, the fibrous composite ropes disclosed in
Japanese Patent Publication No. Sho 62-18,679 is known as having a high tensile
strength. The disclosed fibrous composite rope is obtained by imPregnating a
fiber core with a thermosetting resin, covering the outer PeripherY of the
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impregnated core with a fiber braid after applying drYing powder onto the
periphery, and subsequentlY heating the covered core to cure the $hermosetting
resin.
In the technique disclosed in Japanese Patent Publication cited
immediately above, in which drying powder is used to prevent the thermosetting
resin impregnated into the fiber core from leaking therefrom, the drYing Powder
must be applied uniformly in a well controlled quantity, thus renderir,g the
process or production control difficult. If such leakage of the thermosetting
resin cannot be prevented, the leaked thermosetting resin will cause such fiber
cores to be adhesivelY bonded to each other when theY are brought together in a
later stranding or twisting process, consequentlY to suPpress their relative
movements, resulting in reduced mechanical strength and flexibility of the
resultant rope. Further, the existence of the drying powder will not have a
desirable effect on integral adhesion of the thermosetting resin of the fiber
core to the fibrous yarns of the braid covering the core. Besides, the
thermosetting resin of the fiber core will substantially lose its plasticity
when cured, rendering the twisting difficult. and so that a roPe stranded of
such rigidified cores would have its cores loosened when cut for use.
D i sc I osure of the I nvent i on
With a view to solving the aforementioned problems of the prior art, the
inventors aimed at forming a prestressing material by usin~ fiber-based
materials having a high tensile strength and low elongation such as carbon
fiber, glass fiber and aramid fiber, instead of using. as base material,
stranded steel wires which is not only heavY in weight but poor in corrosion
resistance.
The inventors have undertook a series of experiments and research
works to successfullY obtain a fibrous comPOsite roPe having sufficient
mechanical proPerties and satisfiable anchorage to mortar. resins or other
anchoring bodies to which the roPe is embeddedlY anchored.
Namely, according to one aspect of the present invention, there is
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provided a fibrous composite rope comprising a pluralitY of fiber cores stranded
together, each of said cores being impre~nated with a thermosetting resin and
having a fiber bundle wrapped around the ~eripherY thereof in one winding
direction without clearance between the sides of adjacent turns of the bundle,
namely, without wrapping clearance.
Preferably, the present fibrous comPOSite rope may be fabiricated bY
first heating the thermosetting resin-imPregnated fiber cores so as to semicure
the resin, then wrapping said fiber bundle around the periphery of each said
fiber core in one winding direction without wrapping clearance, stranding a
plurality of the resultant fiber cores together into a rope form, and
subsequentlY heating the stranded rope to finalize the curing.
For preventin~ leakage of the thermosetting resin from the fiber core
without semicuring the resin but merelY by wrapping the fiber bundle around its
periPherY in such a manner that no clearance remains between the sides of
adjacent turns of the bundle, it would be necessarY to strictly control the
manufacturing conditions by for examPle thickening the fiber bundle and
controlling its winding force within an appropriate range during the wrapping
process. Too thick fiber bundle will increase the diameter of the resultant
rope, resulting in reduced tensile strength Per cross-sectional area.
According to another aspect of the present invention, there is provided
a fibrous composite rope comprising a PluralitY of fiber cores stranded
together, each of said cores being imPregnated with a thermosetting resin and
having as a primary wrapping member said fiber bundle wrapped around the
Periphery thereof in one winding direction without wrapPing clearance and
further having as a secondarY WraPPing member a fiber bundle wrapPed around the
periphery of said primary wrapping member in the oppsite winding direction
thereto without wrapping clearance.
Preferebly, the fibrous comPosite rope according to the second aspect of
the present invention maY be fabiricated bY first heating the thermosetting
resin-impregnated fiber cores so as to semicure the resin, then wrapping said
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fiber bundle of said PrimarY wrapping member around the peripherY of each saidfiber core in one winding direction without clearflnce between the sides of
adjacent turns of the bundle, further wrapPing said fiber bundle of said
secondary wrapping member around the periPherY of said PrimarY wrappin8 member
in the opposite winding direction thereto without wrapping clearance, stranding
a PluralitY of the resultant fiber cores together into a roPe form. and
subsequently heating the stranded rope to finalize the curing.
Either of the aforementioned methods may be modified to ioprove integral
adheshion of the fiber core to the fiber bundle wrapping the same, for
example, by applying a thermosetting resin to the wrapping fiber bundle
internally thereof, or by controlling the semicured state of the thermosetting
resin-impregnated fiber core so as to cause the resin to Penetrate into the the
wrapping fiber bundle.
Instead of applying drying Powder onto the periPheral surface of fiber
core for preventing the thermosetting resin impregnated into the core as in the
prior art, the method of the present invention first semicure the thermosetting
resin and then wrap the fiber bundle around the core in one winding direction
without clearance between the sides of adiacent turns of the fiber bundle.
Since it is impossible to prevent the thermosetting resin from leaking in its
liquid state and since application of the drying powder is not preferable for
the aforementioned reason. the thermosetting resin is first semicured to obtain
a highly viscous state which facilitates working. In addition, wraPPing the
fiber bundle around the fiber core ensures the prevention of resin leakage.
Further, according to the present invention, wrapping the secondarY
fiber bundle around the foregoing wrapping fiber bundle in the opPosite winding
direction thereto produces a bidirectionally wrapped fiber core, which allows
fabrication of a fibrous composite rope from torsion-free fiber cores. That is
to say, wraPping the fiber bundle around the fiber core only in one direction
will rather tends to give rotation to the core, leaving a torsion therein. Such
a torsion would act to impede even and uniform elongation of constituent fibers
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and consequentlY deteriorate mechanical Properties of the resultant roPe.However, according to the second aspect of the present invention. the secondarY
wrapping fiber bundle is wrapped around the PrimarY fiber bundle in the opposite
winding direction thereto without clearance bet~een the sides of adiacent turns
of the fiber bundle, therebY to give counterrotation to the core so as to
offset the torsion.
In any of the foregoing two aspects of the invention, the present
fibrous comPosite roPe is fabricated bY stranding together a plurality of
fibrous cores impregnated with a thermosetting resin around which is wrapped a
fiber bundle without wrapping clearance, so that spiral peripheral grooves of
the roPe formed between adiacent cores thereof would not be slackened . Thus,
when used as a prestressing member, the Present roPe will exhibit strong
adhesion to anchoring bodies.
If a wedge and a wedge support are used for anchoring a rope end, a
fibrous composite rope exhibiting Poor adhesion tends to slide on the wedge
surface and, in some cases, maY slip off the wedge. Even if such a roPe
exhibiting poor adhesion is anchored by inserting its end in a pipe, Pouring a
mortar or resin into the pipe to fill the surrounding space of the rope end and
curing the mortar or resin, the end tends to slide against such a mortar or
resin to occasionallY slip off the anchoring Pipe. Thus, it is difficult to
anchor such a rope with a practicably short anchoring length. Meanwhile,
regarding the individual fiber cores constituting the roPe which are poor in
adhesion, relative slippage may occur between their Primary and secondary
wrapping members or between the wrapping members and the base core, occasionallY
resulting in complete slipping off.
Further, according to still another aspect of the present invention, for
far improving the adhesion of roPe to anchoring bodies, either of the primary
or secondary wraPPing member maY be wound so as to follow a screw thread-like
pattern, namelY, with a wrapping clearance between adiacent turns of the
wrapping member or fiber bundle for obtaining rugged surfaces.
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In this manner. wrapping either of the PrimarY or secondarY fiber bundle
with adiacent turns of the bundle spaced apart from each other brings about a
rugged peripheral surface, increasing the pullout resistance at anchoring means
to the extent that the rope end can be securely prevented from slipping off when
the rope is used as ~ prestressing member for PC structures.
For the aspect of the present invention described last hereinabove,
which of the primary and secondarY wrapping members or fiber bundles may be
wound with adjacent turns of the fiber bundle spaced apart from each other. For
example, the primarY wrapping member (inside) may be wound without wraPPing
clearance, followed by the secondary wrappin~ member (outside) which is wound
ujth adjacent turns thereof sPaced apart from each other, and vice versa. In
either case, the resultant fiber core can have a rugged PeriPheral surface.
Further according to the lastly aspect of the invention. since one of
the primary or secondary fiber bundles is wrapped without clearance between the
sides of adiacent turns of thereof in the opposite winding direction to that of
the other bundle, leakage of the thermosetting resin as well as torsion can be
effectively prevented in the resultant fiber core. Any such residual torsion
existing in the fiber core would impede even and uniform longitudinal elongation
of the constituent fibers and lead to deteriorated mechanical proPerties of the
resultant rope. The present invention can successfully solve these problems.
Brief DescriPtion of the Dra~ings
FIG. I is a schematic diagram showing a manufacturing process used in a
Preferred example of the Present invention, with FIG. I(A) showing the former
half of the Process and FIG. I(B) the latter half;
FIG. 2 is a perspective view showing a state in which a fiber bundle is
RraPPed around the peripherY of a fiber core in one winding direction without
clearance between the sides of adjacent turns of the bundle according to the
Prefeferred example of the Present invention;
FIG. 3 is a schematic drawing showing a manufacturing Process used in a
second and third examples of the present invention, with FIG. 2(A) showing the
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former half of the process and FIG. 2(B) the latter half;
FIG. 4(A) is a perspective view showing a state in which a primary and a
secondary fiber bundles are wrapped around the Periphery of a fiber core in two
opposite winding directions, respectivelY, without clearance between the sides
of adjacent turns of the respective bundles according to the second preferred
example of the present invention, while FIG. 4(B) is a like PersPeCtiVe view
showing a state in which the PrimarY fiber bundle is wrapped around the
periphery of the fiber core in one winding direction without wrapping clearance,
followed by wrapping the secondary fiber bundle in the opposite direction with
adjacent sides theleof spaced apart from each other, according to the third
preferred example of the present invention.
FIG. 5 is a drawing showing partially in section a tensile tester used
for tesiting the fibrous composite rope according to the present invention to
mesure pullout resistance (adhesion) to an anchoring body.
Best Mode CarrYing out the Invention
ExamPle I
When using the fibrous composite rope of the Present invention as a
prestres sing member for PC structures, the third example to be described herein
later is most preferable for securing sufficient adhesion with a shorter
anchoring length. However, the description will be made in the order of the
first, second and third examples, because such order would be appropriate for
exactly understanding the present invention.
~ ith reference to FIG. 1, especially to FIG. I(A), showing a
manufacturing process according to the first preferred examPle, initiallY a
PluralitY of aramid resin fibers or Yarns of such fibers having a high tensile
strength and low elongation are unwound from the respective feed reels I and
bundled into a fiber core A. The fiber core A is then fed into a thermosetting
resin bath 2 to be impregnated with a thermosetting resin (e.g., unsaturated
polYester or epoxy resin). The impregnated fiber core is then passed through a
die (or forming mold) 3 to be reduced to a Predetermined outside diameter and to
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remove excess resin, and is subsequentlY fed into a heater 4. In the heater,the fiber core is heated at about 90C for about 30 seconds to cure the
thermosetting resin, and then fed into a wrapping machine 5, where a fiber
bundle or bunndled yarn 10 (FIG. 2) is wrapped around the periPheral surface of
the fiber core A in one windin~ direction ~ithout clearance between the sides of
adjacent turns of the bundle. A thermosetting resin. which may be the same or
different from the aforesaid thermosetting resin, may be apPlied onto the fiber
bundle 10 on its side coming inside when wraPPed, for furthering integral
adhesion to the core A. In FIG. 2, is shown the fiber core A wraPped with the
fiber bundle 10 without clearance between the sides of its aiacent turns,
namely, without ~raPping clearance. The resultant fiber core is wound up on a
take-up reel 6.
Thereafter, as shown in FIG. I(B), a plurality of such wrapped fiber
cores A are un~ound from the respective reel 6 to be fed into a stranding
machine 7, where theY are stranded together. The resultant stranded roPe A is
then heated in a heater 8 to finalaize or comPlete the curing of the semicured
thermosetting resin, and is subsequently wound uP on a take-up reel 9.
Thus, by wrapping the fiber core with the fiber bundle without clearance
between its adjacent turns while the thermoseting resin being still in its
seeicured state, it is Possible according to the present invention to surely
prevent leakage of the thermosetting resin without using a drying Powder as in
the prior art and to Prevent adiacent fiber cores from directlY bonding to each
other during the stranding Process also as in the prior art. Further,
protuberances on the rope surface or like unseemlY external appearance caused b
leaked resin can be eliminated according to the Present invention.
ExamPle 2
Now ~3ith reference to FIG. 3, esPeciallY to FIG. 3(A), showing a
manufacturing process according to the first Preferred example, initiallY a
plurality of aramid resin fibers or yarns of such fibers having a high.tensile
strength and low elongation are unNound from the resPective feed reels 1 and
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bundled into a fiber core A. The fiber core A is then fed into a thermosetting
resin bath 2 to be impregnated with a thermosetting resin (e.g., unsaturated
polyester or epoxy resin). The impregnated fiber core is then passed through a
die (or forming mold) 3 to be reduced to 8 Predetermined outside diameter and to
re~ove excess resin, and is subsequentlY fed into a heater 4. In the heater,
the fiber core is heated at about 90~C for about 30 seconds to cure the thermo
setting resin, and then fed into a urapping machine 5A, where a fiber bundle or
bundled yarn 10 is wraPPed AS a PrimarY ~rapPing member around the peripheral
surface of the fiber core A in one winding direction uithout clearance between
the sides of adjacent turns of the bundle. Then, the fiber core A is fed into
another wrapping machine 5B, where another fiber bundle 10, as a secondary
wrapping member, is wrapped around the fiber core A also without wrapping
clearance but in the winding direction opposite to that of the primary wrappin~
member. A thermosetting resin, which may be the same or different froo the
aforesaid thermosetting resin, maY be aPPlied onto the fiber bundle 10 on its
side coming inside when wrapped, for furthering integral adhesion to the core
A.ln FIG. 4(A), is shown the fiber core A urapped with the primarY and secondarY
fiber bundles 10 without clearance between the sides of its aiacent turns. The
resultant fiber core is wound up on a take-up reel 6.
Thereafter, as shown in FIG. 3(B~. a plurality of such wrapped fiber
cores A are unwound from the respective reel 6 to be fed into a strandin
machine 7, where they are stranded together. The resultant stranded rope A is
then heated in a heater 8 to finalaize or comlete the curing of the semicured
thermosetting resin, and is subsequently wound up on a take-up reel 9.
Thus, bY wraPPing the fiber core uith the fiber bundle without wraPPing
clearance while the thermoseting resin being still in its semicured state, it
is possible according to the present invention to surely prevent leakage of the
thersosetting resin to Prevent adjacent iiber cores from directly bonding to
each other during the stranding Process as in the prior art. Further, in this
preferred examPle, the bidirectional wrapPing effectively eliminates torsion of
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the fiber core.
As a material for the fiber core of the Present invention, carbon fiber,
glass fiber or the like may be used in addition to the aforementioned aramid
resin fiber. Also, the wrapping fiber bundle used for the present invention may
be made of an aramid resin fiber, vinylon fiber or polYester fiber. For a
prestressing member for PC structures. it is preferable to use an aramide fiber
to improve alkali resistance of the resultant rope.
ExamPle 3
In the similar manner, the Process of the aforementioned Example 2 shown
in FIG . 3 is repeated. except that a secondary wrapping fiber bundle is wound
by the wrapping machine 5B with its adjacent turns spaced apart from each other
on a primarY wrapping fiber bundle wound by the wrapping machine 5A without
clearance between the sides of adjacent turns of the bundle in the windin
direction opposite to that of the secondary wrapping member. In this example,
the resultant core has a rugged peripheral surface.
In FIG. 4(B), is shown the resultant fiber core of Example 3 comprising
the primary wrapPing fiber bundle IOA wound inside without wrapping clearance
and the secondary wrapping fiber bundle IOB wound around the periphery of the
PrimarY fiber bundle in the oPposite direction thereto with its adjacent turns
spaced aPart from each other. Either one of the wrapping fiber bundles which is
wound with wrapping clearance (fiber bundle IOB in the instant example) may
vary from the other bundle which is wound without clearance (bundle IOA in the
instant example) in at least one of a grouP of items including the number of
fibers or yarns, shaPe, Pitch, or wrapping tension of the bundle.
Like the aforementioned Exaples I and 2, a thermosetting resin, which
maY be the same or different from the aforesaid thermosetting resin, maY be
applied onto these fiber bundles IOA and/or IOB on their sides coming inside
when wrapped, for furtherin8 integral adhesion to the core A.
Further, the mode of winding the primarY and secondary wrapping members
may be reversed from Example 3, namerY, the Primary member disPosed inside may
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be wound with wrapping clearance, followed by winding the secondarY member
without ~rapping clearance. In addition, a third fiber bundle may be ~raPPed
around the PeriPherY of such a fiber core that is bidirectionallY wrapped with
fiber bundles as in Example 2. In such a case, the resultant fiber core would
have an increased diameter.
In the same manner as in the aforementioned Examples I and 2, a
plurality of resultant fiber cores having a rugged PeriPheral surface are then
stranded together and heated to be formed into a fibrous composite material
havin~ a rugged outer peripheral surface and exhibiting good adhesior. to
anchoring means, as intended bY the present invention. Differential height
between the top and bottom of the rugged PeriPheral suraface of the wrapped
fiber core, as viewed in its cross section, is apploximatelY 0.5 mm in Example
3, although it may preferably ranges from approximately 0.3 to 0.8 mm.
Tensile Test
By using the processes of the aforementioned Examples I and 2, 7 wrapped
fiber cores, each 4.2 mm across, were stranded together to fabricate samples of
fibrous composite roPes of the respective preferred examples. The base fiber
core was PrePared bY bundling 18 aramid resin fibers of 6,000 deniers, and the
core was impregnated with a thermosetting resin, the Proportion of fiber to
thermosetting resin being 65 ~ by volume of fiber. As the thermosetting resin,
a vinyl ester resin was used, and an arami resin fiber as the wrapping fiber.
Each sPecimen of the fibrous composite ropes has its oPPosite ends
secured to a tensile tester and its tensile load was measured. The tensile -
tester used is shown in FIG. 5. As shown in the drawing, the tester had a pair
of cylindrical anchoring iigs or fixtures, in which the oPPosite ends of the
specimen 13 was inserted and mortar 11 was filled to fix the respective ends.
Then, the tester exerted a tension on the sPecimen bY Pulling the same in the ~
opposite directions, and the maximum tensile load was measured for evaluation. ;``
In FIG. 5, the reference numeral 14 denotes a crosshead, 15 a Plate, and 16 a
rubber plug, respectively. ~ ~
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As described hereinabove, the specimen of Example 1 was prepared by
using fiber cores each wrapped with onlY a primarY fiber bundle wound in one
direction therearound without winding clearance, and the sPecimen of ExamPle 2
~as prepared bY using fiber cores which are obtained by further wrapping a
secondary fiber bundle around the resultant fiber core of Example 1 in the
opposite winding direction without wrapping clearance. For comparison, another
specimen was prepared, as a comparative example. bY wrapping only a primary
fiber bundle in one winding direction without wrapping clearance around a
thermosetting resin-imPregnated base fiber core without semicuring the resin,
and stranding together a pluralitY of such wrapped fiber cores with the resin
leaked out to the surfaces.
Each specimen was set on the tester under the following conditions and
tested for tensile load.
Anchoring iig size: 30 mm l.D., SOO mm long
Jig filler: mortar cured for 5 daYs
The test results are given below. The specimens of the preferred
examples all showed a significantily higher tensile load than the comparative
example. This evidently shows good applicabilitY of the preferred examples of
the Present invention to a prestressing member for PC structures and to
reinforcing members for power and communication cables.
Specimens Tensile load (kN)
Example 1 165
Example 2 175
Comparative examPle 100
This improvement achieved in the preferred examPles of the present
invention would be attributable to positive prevention of the resin leakage by
wrappin~ the peripherY of the thermosetting resin-imPregnated fiber core with
the fiber bundle in the semicured state of the resin and to prevention of
slackening of the periPheral spiral grooves of the rope by completing the curing
of the semicured resin after stranding. EspeciallY, in Example 2 emPloYing
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bidirectional wrapping, torsion of the fiber cores is prevented to effectively
further the improvement.
Adhesion Test
Except the anchorin~ 12 had a shorter length, the same equipment as
that in the aforementioned tensile test was used to measure a tensile load, as a
allo~able tensile load, at which the specimen had its end slipped off the
anchoring jig. In this test. were used a sPecimen of Example 3-1, as one
Preferred example, prepare by using fiber cores IYrapPed with a PrimarY fiber
bundle without wrapping clearance and a secondary fiber bundle with wraPPin
clearance, and a specimen of Example 3-2, as another preferred example, prepared
in a manner reverse to Example 3-1, namely, bY using fiber cores wrapped with a
PrimarY fiber bundle with wrapping clearance, followed by a secondary fiber
bundle wrapped without clearance~ Besides, a comparative example was prePared
in the same manner as in the preceding tensile test, namely, wrapping only a
primary fiber bundle in one winding direction without wrapping clearance around
a thermosetting resin-impregnated base fiber core without semicuring the resin,
and stranding together a pluralitY of such wrapped fiber cores~
The anchorin~ s were set as follows:
Jig size: 30 mm l.D., 200 mm long
Jig filler: mortar cured for 5 daYs
The test results are as shown below, where the allowable tensile load is
given in terms of index based on the allowable tensile load of the comparative
example taken as the reference index 100. The preferred examples, particularly,
Example 3-1 adoPting the secondary fiber bundle wound with wrapping clearance
exhibits excellent adhesion.
SPecimens Allowable tensile load ~1
Example 3-1 180
Example 3-2 140
Comparative examPle 100
Industrial APPI icabi I ity
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As fullY described hereinbefore, lhe Present invention provides a
fibrous composite roPe having superior mechanical Properties, fabricated bY &
novel method in which leakage of the thermopsetting resin imPregnated in the
fiber core can be Prevented without fail, so that adjacent cores are prevented
from being directlY bonded to each other in the subsequent stranding stage.
Particularly, in the present invention, the drying Powder used in the Prior art
for preventing leakage of the thermosetting resin impregnated in the fiber core
can be eliminated together v,ith the process steP for its application to the
fiber core.
Furthermore, bidirectional w.apping of the fiber bundles can PreVent
torsion of wrapPed fiber cores, resulting in a fibrous composite rope having
more excellent mechanical properties. Besides, if either the primarY or
secondary wrapping member is wound with wrapping clearance in the bidirectional
wrapping configuration, high adhesion can be assured to anchoring means.
Heretofore, an overwhelmin81y major part of Prestressing members for PC
structures has been shared bY steel. Meanv,hile, the fibrous composite roPe
according to the Present invention has a high tensile strength comparable with
PC steel members in addition to such features as high corrosion resistance,
nonmagnetizability and light weight which are not provided by PC steel members.
Thus, the Present invention has expectedly an increasinglY wide applications,
including :grine structures, PC structures for linegr :otors. etc.
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