U.S. patent number 3,916,592 [Application Number 05/518,861] was granted by the patent office on 1975-11-04 for structural members for buildings and buildings constructed therefrom.
Invention is credited to Takashi Morohashi, Yuji Morohashi.
United States Patent |
3,916,592 |
Morohashi , et al. |
November 4, 1975 |
Structural members for buildings and buildings constructed
therefrom
Abstract
A reinforced concrete structural member for buildings or the
like which has notably excellent resistance to earthquake, heat and
explosion, and is organic in structure, comprising: a concrete
column including a plurality of special-type extra coarse-laid wire
ropes embedded in the concrete column in a three-dimensional array,
longitudinally vertically extending substantially straight through
the concrete column but under untensioned or unstrained state and
further including an open-work wrapping of steel wires or the like
disposed around the steel wires to reinforce the concrete column; a
concrete beam including a plurality of special-type extra
coarse-laid wire ropes longitudinally, horizontally embedded
substantially straight in the concrete beam but under untensioned
or unstrained state, in a fashion intersecting the wire ropes of
the column at right angles; and connecting means integrally
fastening the wire ropes of the column to the wire ropes of the
beam at the intersecting points, thereby instantly dispersing the
external forces applied to the structural member which thus has
toughness and flexibility, throughout the whole structure where
they are employed.
Inventors: |
Morohashi; Takashi (Sagamihara,
Kanagawa-Prefecture, JA), Morohashi; Yuji
(Sagamihara, Kanagawa-Prefecture, JA) |
Family
ID: |
27298485 |
Appl.
No.: |
05/518,861 |
Filed: |
October 29, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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298641 |
Oct 18, 1972 |
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53137 |
Jul 8, 1970 |
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Foreign Application Priority Data
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Aug 16, 1969 [JA] |
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44-64467 |
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Current U.S.
Class: |
52/252; 52/263;
52/414; 52/857; 52/649.4 |
Current CPC
Class: |
E04B
1/21 (20130101); E04C 5/0618 (20130101); E04H
9/04 (20130101); E04H 9/02 (20130101); E04C
5/162 (20130101) |
Current International
Class: |
E04B
1/21 (20060101); E04C 5/16 (20060101); E04H
9/02 (20060101); E04H 9/04 (20060101); E04C
5/06 (20060101); E04C 5/01 (20060101); E04B
1/20 (20060101); E04B 001/04 () |
Field of
Search: |
;52/724,263,251,252,736,600,602,414,653,723 ;57/144-148 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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19,050 |
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Feb 1905 |
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SW |
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321 |
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Aug 1876 |
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IT |
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Primary Examiner: Purser; Ernest R.
Assistant Examiner: Raduazo; Henry
Attorney, Agent or Firm: Cushman, Darby & Cushman
Parent Case Text
This is a continuation-in-part application of our pending parent
application Ser. No. 298,641, filed Oct. 18, 1972; now abandoned;
and which is a continuation of our grandparent application Ser. No.
53,137 filed July 8, 1970; now abandoned.
Claims
What we claim is:
1. A reinforced concrete structural member adapted for buildings
and the like, comprising:
a concrete column;
a plurality of extra coarse-laid wire ropes each comprising a
plurality of strands each incorporating a plurality of wires laid
helically in the same angular sense to provide a built-up lay, at
least two strands each incorporating a plurality of wires, said at
least two strands each being of at least as great diameter as the
first-mentioned strands and being helically wound in two angularly
opposite senses upon said built-up lay so as to cross one another
at a phase angle of about 180.degree., the at least two strands
being spaced to expose said lay exteriorly of the wire rope,
between the at least two strands so the wire rope has a
substantially greater diameter at the crossings of said at least
two strands than where said lay is exposed exteriorly of the wire
rope;
said extra coarse-laid wire ropes directly embedded in said
concrete column in a three-dimensional array, in a fashion
longitudinally vertically extending straight through the concrete
column, but is an unstrained but unloosened stated, to reinforce
the concrete column;
an open-work wrapping of steel wires or wire gauze or the like
directly disposed about said array in a wrapped or wound
fashion;
a concrete beam unitary with said concrete column;
a plurality of extra coarse-laid wire ropes having a structure the
same as said first-mentioned extra coarse-laid wire ropes, directly
embedded in said concrete beam near the upper and lower extent
thereof, in a fashion longitudinally horizontally extending through
the concrete beam, but under an unstrained but unloosened state, to
reinforce the concrete beam;
an open-work wrapping of steel wires, or wire gauze, or the like
directly disposed about said second-mentioned extra coarse-laid
wire ropes;
the extra coarse-laid wire ropes of the column and beam crossing
one another where the column and beam join one another; and
connecting means fastening the extra coarse-laid wire ropes of the
column to the wire ropes of the beam where these wire ropes cross
one another.
2. The reinforced concrete structural member as claimed in claim 1,
wherein said connecting means essentially consists of a body of
tubular shape formed with a plurality of through holes over the
surface thereof in random arrangement, the extra coarse-laid wire
ropes of the columns and beamd each having an end portion thereof
inserted through at least two said through holes in random
directions, in a fashion that the end portion has acute turns of
such an extent as to permit the wire rope end portion to be
urgingly and frictionally caughted by the mouth edge of the through
holes.
3. The reinforced concrete structural member as claimed in claim 1,
wherein said connecting means essentially consists of a body of
spheric shape formed with a plurality of through holes over the
surface thereof in random arrangement, the extra coarse-laid wire
ropes of the columns and beams each having an end portion thereof
inserted through at least two said through holes in random
directions, in a fashion that the end portion has acute turns of
such an extent as to permit the wire rope and portion to be
urgingly and frictionally caughted by the mouth edge of the through
holes.
4. A reinforced concrete structural member adapted for buildings
and the like, comprising:
a concrete column;
a plurality of extra coarse-laid wire ropes each comprising a
plurality of strands each incorporating a plurality of wires laid
helically in the same angular sense to provide a built-up lay, and
a plurality of transversely extending, axially regularly spaced
metallic cross pieces incorporated in said lay and having both ends
of each piece protruding substantially outwardly of said lay, and
ball means secured on the protruding end of each cross piece, said
extra coarse-laid wire ropes directly embedded in said concrete
column in a three-dimensional array, in a fashion longitudinally
vertically extending straight through the concrete column, but in
an unstrained but unloosened state, to reinforce the concrete
column;
an open-work wrapping of steel wires or wire gauze or the like
directly disposed about said array in a wrapped or wound
fashion;
a concrete beam unitary with said concrete column;
a plurality of extra coarse-laid wire ropes having a structure the
same as said first-mentioned extra coarse-laid wire ropes, directly
embedded in said concrete beam near the upper and lower extent
thereof, in a fashion longitudinally horizontally extending through
the concrete beam, but in an unstrained but unloosened state, to
reinforce the concrete beam;
an open-work wrapping of steel wires, or wire gauze, or the like
directly disposed about said second-mentioned extra coarse-laid
wire ropes;
the extra coarse-laid wire ropes of the column and beam crossing
one another where the column and beam join one another; and
connecting means fastening the extra coarse-laid wire ropes of the
column to the wire ropes of the beam where these wire ropes cross
one another.
5. The reinforced concrete structural member as claimed in claim 4,
wherein said connecting means essentially consists of a body of
tubular shape formed with a plurality of through holes over the
surface thereof in random arrangement, the extra coarse-laid wire
ropes of the columns and beams each having an end portion thereof
inserted through at least two said through holes in random
direction, in a fashion that the end portion has acute turns of
such an extent as to permit the wire rope end portion to be
urgingly and frictionally caughted by the mouth edge of the through
holes.
6. The reinforced concrete structural member as claimed in claim 3,
wherein said connecting means essentially consists of a body of
spheric shape formed with a plurality of through holes over the
surface thereof in random arrangement, the extra coarse-laid wire
ropes of the columns and beams each having an end portion thereof
inserted through at least two said through holes in random
direction, in a fashion that the end portion has acute turns of
such an extent as to permit the wire rope and portion to be
urgingly and frictionally caughted by the mouth edge of the through
holes.
Description
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates to a reinforced concrete structural
member well adapted, particularly, for use as column and beam in
high rise buildings, and in long span sections of highways or
bridges, and even for use in earthquake-proof dams or earthquake
resistant hanger walls for atomic reactors. The structural member
according to the invention essentially comprises a concrete column
reinforced by a plurality of special extra coarse-laid wire ropes,
to be described hereinafter, longitudinally vertically embedded
directly in the column concrete in a fashion straight but without
special tension being applied thereto, and further reinforced by
steel wires, steel bars or the like wrapped around the wire ropes;
a concrete beam also reinforced by a plurality of special extra
coarse-laid wire ropes longitudinally horizontally embedded in the
beam concrete in a fashion straight but without tension being
applied thereto and further reinforced by steel wires or the like
wrapped around the wire ropes; and special-type connecting means
integrally fastening together the wire ropes of both the column and
the beam at the intersecting points, thus to integrally connect
together the column and beam. As described, the above-mentioned
vertical and horizontal extra coarse-laid wire ropes thus mutually
joined together are provided throughout the whole structure of a
building or the like which, therefore, results in that when the
external forces are applied to the structural members, they are
instantly transmitted via the straight wire ropes to any other
places in the whole structure thus to be dispersed in all
directions and effectively damped. Accordingly, the structural
member according to the invention exhibits excellent
characteristics particularly in earthquake resistance, heat
resistance and explasion resistance. The above-described extra
coarse-laid wire rope used in the present invention was invented by
the inventors of the instant invention to highly enhance the
adhesive power of wire ropes to concrete, and is now patented in
the United States under U.S. Pat. No. 3,716,982. This extra
coarse-laid wire rope, when used in place of conventional
reinforcing steel bar or steel frame, exhibits so extremely higher
adhesion with respect to concrete that the wire ropes and the
concrete become integrally joined enough to avoid rubbing of the
wire ropes against the concrete when they expand and contract, and
to make moderately flexible the structural body in which they are
used. As another merit, the extra coarse-laid wire rope has much
increased mechanical strength, which results in reduced cross
sectional area of the column or the beam where it is used. Thus, a
concrete structure which chiefly employs the extra coarse-laid wire
rope is lightweight as a whole, and is easy and simple to build up,
which may lead to a shortened period of construction of the
building constructed of such structures.
b. Description of the prior art
Conventional structures particularly for buildings include a
reinforced concrete structure (RC), a steel framed reinforced
concrete structure (SRC), a pre-stressed concrete structure (PS),
or a steel framed simple fire-proof covered structure (SPC), etc.
Choice of these structures depends upon the sorts of buildings to
be built. For instance, for high-rise buildings which have recently
been increasing in number also in Japan is particularly required a
earthquake-resistant and fire-proof structure. Most suitable for
this purpose are RC or SRC structures which are based upon the
theory of rigid construction. But, since these structures are more
or less short of flexibility and toughness, their
earthquake-resistance is doubtful. Further, they are heavy in
weight, and therefore regarded as unfit for high-rise buildings. In
the earthquake which happened off the coast of Tokachi of Hokkaido,
Japan in 1968, many buildings constructed of the RC structure fell
down. The building of Hakodate College, which was a four-story
building of RC structure became known for having fallen down in
that earthquake. Its collapse was due to the ill adhesion between
the reinforcing bars and the concrete which caused rubbing of the
reinforcing bars against the concrete when the shocks were given to
them. Further, in the earthquake which took place in Los Angeles,
the United States in 1971, the building of Olive View Hospital made
of RC structure fell down for almost the same reason as that for
the earthquake of the Tokachi offing. Particularly the column
portions of the building where no spiral hoops were used showed far
more violent collapse than the other column portions where spiral
hoops were used. This was also caused by the ill adhesion between
the reinforcing bars and the concrete which prevented the building
structure from having sufficient strength in compression, and
shearing. Nowadays, in consideration of the above-mentioned
technical problems, particularly, in earthquake resistance and
economy, the SPC structure is mainly adopted for high-rise
buildings, which differs completely from the two precedings in that
it is based upon the theory of flexible construction. This SPC
structure has a merit that its columns and beams may be made more
slender than those of the precedings, and, it has been, therefore,
most adopted for construction of high rise buildings. However,
since the steel frame is covered with a fire-proof material with
the aid of an adhesive or by spraying, the adhesive loses its
function if fire should happen (the upper limit of temperature at
which the adhesive still acts effectively is about 200.degree. C
according to the present level of technology) and thus the covering
is separated from the steel frame, thus being inferior in fire
resisting property. Thus, this structure is not a completely
fire-proof structure, though it is rather noninflammable.
Conventional steel frame and reinforcing bar used in the RC SRC
structure have low restitution coefficient so that they are weak
against larger external forces caused, for instance, by
earthquake.
Besides, steel frame and reinforcing bars have remarkably high
conduction of heat owing to nonpresence of internal air-gaps, and
has little internal air gaps for heat to be absorbed in as
possessed by wire ropes and further there is a large difference in
coefficient of thermal expansion, between the steel bar and the
concrete, so that their rubbing against the concrete becomes
intensified in the event of a fire. For these reasons, the
high-rise buildings of RC or SRC structures are limited in height
to have sufficient safety, specially in a country like Japan where
earthquakes take place frequently which may cause fires, while the
SRC structure exclusively adopted for construction of high-rise
buildings are limited in safety and may not be completely free from
danger as yet, for the aforestated reson.
Besides the preceding structures, there is also employed a
pre-stressed concrete structure. This structure is intended to
eliminate the demerit of much inferior tensile strength common to
the conventional concrete structures, by previously applying
compressive stress to those portions where there may occur tensile
stress by means of PC steel wires, so as to increase apparent
tensile strength of the concrete used. For this PC structure are
now employed two methods called "Pre-tensioning Method" and
"Post-tensioning Method."
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide a
structural member which is organic in structure, and excellent in
earthquake resistance and explosion resistance by virtue of its
construction comprising a plurality of extra coarse-laid wires (to
be described in detail hereinafter), in place of steel frame or
reinforcing bars, which wires are laid in columns and beams
throughout the whole building or the like in a fashion straight,
untensioned and unloosened, and special connecting means integrally
fastening the wires of the columns and beams to one another, thus
forming a wire rope concrete structure (hereinafter called "WRRC").
With this arrangement, when an external force, for instance, by
earthquake is applied to the structural members which thus already
have toughness and flexibility, the force is instantly transmitted
to any other places through the extra coarse-laid wire ropes of the
columns or beams provided throughout the building or the like.
A further object of the invention is to provide a thermally
insulated structural member which employs, in place of steel frame
or reinforcing bars, extra coarse-laid wire ropes which are
abundant in internal air-gaps apt to absorb heat energy, so that
there may be a much smaller difference in coefficient of thermal
expansion between the wire ropes and the concrete, thus effectively
preventing rubbing of the wire ropes against the concrete.
Another object of the invention is to provide an economical
structural member which is free from rubbing of wire ropes against
the concrete, and has higher tenacity and consequently increased
mechanical strength, by virtue of its construction comprising a
plurality of extra coarse-laid wire ropes in place of steel frame
or reinforcing bars which wires have much higher adhesion with the
adjacent concrete, thus being able to be made considerably smaller
in sectional area.
A still further object of the invention is to provide a structural
member which is lighter in weight by employing extra coarse-laid
wire ropes in place of steel frame or reinforcing bars.
Still another object of the invention is to provide a structural
member which is unlikely to cause cracking, collapsing or shearing
and breaking of the concrete used by employment of steel wires,
steel bars or the like wrapped around the extra coarse-laid wire
ropes in the columns and the beams for reinforcement of the
latter.
BRIEF DESCRIPTION OF THE DRAWING
The above objects and other features and advantages of the present
invention will be better understood upon consideration of the
following detailed explanation in connection with the accompanying
drawing, in which:
FIG. 1 is a partially sectional view showing an example of the
structural member according to the present invention,
FIGS. 2 and 3 are partially fragmentary front elevations showing
examples of the connecting means adapted for use in the structural
member according to the present invention, and embedded in concrete
structures,
FIG. 4 is a front elevation showing an example of the extra
coarse-laid wire rope to be used in the structural member according
to the present invention,
FIG. 5 is a cross sectional view taken along line V -- V of FIG.
4,
FIG. 6 is a front elevation showing another example of the extra
coarse-laid wire rope,
FIG. 7 is a cross sectional view taken along line VII -- VII of
FIG. 6,
FIG. 8 is a schematic representation showing a test piece of mortar
for use in a compressive strength test to be described
hereinafter,
FIG. 9 (A) and (B) are graphs showing results on the compressive
strength properties of an extra coarse-laid wire rope and a
deformed bar, obtained by a compressive strength test employing
test pieces as shown in FIG. 8,
FIG. 10 is a schematic representation showing a test piece for use
in a simple beam bending test to be described hereinafter,
FIGS. 11 and 12 are graphs showing results on the bending strength
of an extra coarse-laid wire rope and a deformed bar, obtained by a
bending test employing test pieces as shown in FIG. 10,
FIG. 13 is a diagrammatic view showing a test piece for use in a
sleeve beam test to be described hereinafter,
FIGS. 14 and 15 are graphs showing, respectively, .tau. - .theta.
and .sigma. - .epsilon. envelopes obtained by a sleeve beam test
employing test pieces as shown in FIG. 13,
FIG. 16 is a diagrammatic view showing a test piece for use in a
beam adhesive strength test to be described hereinafter,
FIG. 17 is a graph showing results obtained by a beam adhesive
strength test,
FIG. 18 is a diagrammatic view showing a test piece for use in a
beam bending strength test to be described hereinafter,
FIG. 19 is a diagrammatic view showing the direction in which the
load is applied to the test piece as shown in FIG. 18,
FIG. 20 is a graph showing load-deformation curve obtained by the
beam bending strength test,
FIG. 21 is a diagrammatic view showing a test piece for use in a
column center compressive strength test to be described
hereinafter,
FIG. 22 is a cross sectional view showing diagonal hoops for use in
the same column center compressive test,
FIG. 23 is a graph showing the effects by main reinforcement and
diagonal hoops upon the column yield strength, resulting from the
column center compressive test,
FIG. 24 is a diagrammatic view showing compressive stress block
factor of extreme concrete fiber referred to in the formula as will
be described later,
FIG. 25 is a diagrammatic view explaining change of stress
distribution referred to in the formulas,
FIG. 26 is a diagrammatic view showing strain distribution referred
to in the formulas,
FIG. 27 is a graph showing a stress-strain curve of an extra
coarse-laid wire rope referred to in the formulas,
FIG. 28 is a cross sectional view showing an example of extra
coarse-laid wire rope,
FIG. 29 is a cross sectional view showing another example of extra
coarse-laid wire rope,
FIG. 30 is a schematic plan view showing an example of structure in
actual designing,
FIG. 31 is a longitudinally sectional schematic view showing the
same example,
FIG. 32 is an explanatory view for comparison in column design
between the WRRC structure and the conventional one, and
FIG. 33 is a similar view to FIG. 32 for comparison in beam
design.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, description is hereinbelow made with
respect to the fundamental structure of the present invention. FIG.
1 shows a partly sectional view of a structural member according to
the invention, in which reference numeral 1 designates a column
having three sides of which the interior contains three extra
coarse-laid wire ropes 2 near the surfaces of the column. As
mentioned above, the extra coarse-laid wire rope as herein used was
invented by the present inventors in order to obtain reinforcing
members having higher stickiness to the concrete. The number of the
extra coarse-laid wire rope to be arranged in the column is
optional (but at least plural) depending upon the mechanical
strength required for the structural member.
These three extra coarse-laid wire rope 2 are respectively
longitudinally laid in the column 1 in a manner straight, and
unloosened without being particularly tensioned. The phrase
"without being particularly tensioned" does not mean that previous
wire tensioning as employed in the pre-stressed concrete structure
is not adopted for a special purpose, but merely means that the
wire ropes are laid straight under little tension of such an extent
as to remain unloosened. All the extra coarse-laid wire ropes
having the above-mentioned purposes are arranged in the structural
member in the above-explained manner. Reference numeral 3
represents a beam extending horizontally, the interior of which
includes, as in the case of the column 1, three extra coarse-laid
wire ropes 2 (In this specification like reference numbers
designate like or corresponding parts having the same functions)
which are longitudinally laid straight near the surfaces of the
beam without being particularly tensioned, respectively. Thus,
longitudinally arranged in the column and beam in the vertical and
horizontal directions, the extra coarse-laid wire ropes 2 are
disposed in a fashion intersecting one another at the cojoining
points of the column and beam, with the intersecting points
fastened by special connecting means (fastening means) 6, 7. In
this manner, all the extra coarse-laid wire ropes of the column are
joined to the corresponding extra coarse-laid wire ropes of the
beam, but are not joined with non-corresponding extra coarse-laid
wire ropes of the beam. That is, there are no extra coarse-laid
wire ropes which are not joined with any corresponding extra
coarse-laid wire ropes and in a so-called floating state. Reference
numeral 4 represents reinforcing spiral hoops of wire disposed in a
fashion wound around the plural extra coarse-laid wire ropes
disposed within the column or the beam. In place of such spiral
hoops of wire, there may be used wire gauzes or the like as such
reinforcing members. Reference numeral 5 designates ordinary
reinforcing bars which are of conventional type. Since prevention
is effectively made of cracking of the concrete, these members 4, 5
also effectively serve to prevent collapsing or shearing and
breaking of the concrete thereby to enhance the mechanical strength
of the structural member according to the invention.
Also the above-described fastening means 6, 7 were invented by the
inventors of the present invention for the purpose of improving the
connection between the wire ropes embedded in the concrete, for
which a patent application was filed Dec. 16, 1969 under Japanese
application Ser. No. 44-101075, and is still pending. FIGS. 2 and 3
show details of such fastening means. The fastening means 6 shown
in FIG. 2 has a hollow spheric body, and has its surface formed, at
random, with a plurality of wire insertion through holes 100 for
insertion of end portions of the extra coarse-laid wire ropes
therethrough. In the present embodiment, the wire ropes of the
column and beam are inserted through the respective corresponding
insertion holes 100, in such a fashion that, for instance, an end
of the wire rope is first inserted optionally into a first hole and
pulled out of a second hole, and then again inserted through third
and fourth holes, to be followed by further inserting the same end
through fifth and sixth holes. In this case, the wire ropes are
inserted in any optional holes so as to be acutely curved in random
directions according to the holes, so that the curved portions of
the wire rope may be brought into urging and frictional engagement
with the mouth edges of the individual holes by resilient force of
the wire rope. Thus, the wire rope thus inserted through the
various holes may not so easily extracted therefrom.
As an advantage of this fastening means, merely by altering the
diameters of the holes, various wire ropes with different diameters
may be used for this fastening means, thus dispensing with the need
of using other ones of such fastening means with different body
sizes. Further, there is no need of untieing the ends of the wire
ropes, since the ends of the wire ropes need not be tied to each
other, according to this fastening means. The fastening means 6 may
be made of metal or hard synthetic resin, or any other suitable
materials.
Shown in FIG. 3 is another type of fastening means 7. This
fastening means 7 represents a hollow tubular configuration, and
may be made of a material similar to that of the fastening means 6.
Over the surface of the fastening means 7 are formed a plurality of
wire insertion holes for receiving therethrough the respective
corresponding wire ropes 2 of the column and beam which are to be
fastened to one another. Thus, by means of the fastening means
having various configurations such as spheric or tubular ones, the
wire ropes 2 in the column and beam are connected to one another in
a rigid and stable manner. Further, such fastening means enable the
fastening operation to be simply and quickly effected.
The above-mentioned are the main component elements of the present
invention. Now, description is made more in detail with respect to
the extra coarse-laid wire ropes. As stated above, this extra
coarse-laid wire rope, which is of a quite novel structure, was
invented by the inventors of the present invention with the
intention of largely improving the connection between the wire
ropes and the concrete, and is already patented under U.S. Pat. No.
3,716,982 in the United States. The present wire rope, as distinct
from the conventional wire ropes, has its surfaces formed in
special configurations so as to possess much higher adhering power
to the concrete adjacent to the wire ropes. In the embodiment as
shown in FIGS. 4 and 5, the extra coarse-laid wire rope comprises,
for instance, a lay 201 which is built up of strands 204, 205, 206,
each incorporating a plurality of wires laid helically in the same
angular sense; and at least two strands 202, 203, each
incorporating a plurality of wires, the at least two strands 202,
203, each being of at least as great diameter as the
first-mentioned strands and being helically wound in two angularly
opposite senses upon said built-up lay so as to cross one another
at a phase angle of about 180.degree.; the at least two strands
being spaced to expose said lay exteriorly of the wire rope,
between the at least two strands so the wire rope has a
substantially greater diameter at the crossings of said at least
two strands than where said lay is exposed exteriorly of the wire
rope, thereby forming the extremely coarse-laid surface of the wire
rope 1.
FIGS. 6 and 7 show another example of extra coarse-laid wire rope.
In this example, in place of the at least two strands 202, 203,
there are used a plurality of metallic cross pieces 210 which are
incorporated in the lay 201 in a fashion transversely extending,
axially regularly spaced from one another, and having both ends of
each piece protruding substantially outwardly of the lay 201. On
the protruding ends of each cross piece are securred ball means
211.
Several tests were conducted to compare the adhesive strength of
the extra coarse-laid wire rope with respect to the concrete and
that of the conventional deformed bars with respect to the
concrete, of which the results are introduced in the following:
Incidentally, in a series of tests to be described in the following
were used deformed bars, reinforcing steel bars, and extra
coarse-laid wire ropes which are in accordance with the below
stated standards:
Table 1 ______________________________________ Symbol Yield point
Tensile strength Remark ______________________________________ SR24
2400 kg/cm.sup.2 3900-5300 kg/cm.sup.2 JIS* G3112, or more or more
1964 SR30 3000 kg/cm.sup.2 4900-6300 kg/cm.sup.2 " or more or more
SD30 3000 kg/cm.sup.2 4900-6300 kg/cm.sup.2 " or more or more SD35
3500 kg/cm.sup.2 5000 kg/cm.sup.2 " or more or more SD40 4000
kg/cm.sup.2 5700 kg/cm.sup.2 " or more or more WD120 12200
kg/cm.sup.2 16500 kg/cm.sup.2 or more or more
______________________________________ SR: reinforcing steel bar
SD: deformed bar WD: extra coarse-laid wire rope *: JIS= Japanese
Industrial Standard
First, description is made of the results of a comparison test on
the compressive strength of mortar incorporating an extra
coarse-laid wire rope and a mortar incorporating a steel-made
deformed bar. Pieces of mortar each of a shape as designated at 21
in FIG. 8 was put to the test, and the mortar had a water - cement
ratio of 65%, a specific gravity of 3.17, and a compressive
strength of 413 kg/cm.sup.2 after the lapse of 28 days after
mixing. Each mortar piece 21 assumed a cylindrical shape having a
diameter of 68mm, a height of 34mm, with an extra coarse-laid wire
rope or a deformed bar longitudinally embedded in the center 22
thereof. Compressive force was added to the test pieces, the
results of which are shown in FIG. 9 in which (A) shows the
resulting compressive strength of the extra coarse-laid wire rope
mortar, and (B) that of the deformed bar mortar. Here, symbol
.sigma.C represents applied compressive pressure, .epsilon.
deformation. These figures (A), (B) show, respectively, the
strength ranges within which the test pieces are able to endure the
compressive force applied thereon. As seen in the two figures, it
was found that as regards the deformed bar mortar, the deformed bar
may not adhere to the mortar, and may be easily separated from the
mortar, while in the extra coarse-laid wire rope mortar, the extra
coarse-laid wire rope may adhere to the mortar so closely as not to
be easily separated therefrom.
Next, a simple beam test was run under the following conditions:
Lightweight sand of a grain size smaller than 2.5mm, and
lightweight gravel of a grain size smaller than 15mm were mixed
with cement and water into a slurry having a slump of 21cm. Then,
the slurry was water cured at a temperature of 20.degree. .+-.
3.degree.C, to obtain a test piece 24 (simple beam) as shown in
FIG. 10 which had a mixing strength of 180kg/cm.sup.2, a sectional
area of 10cm .times. 10cm, and a length of 40cm, having an extra
coarse-laid wire rope or a deformed bar vertically inserted through
the center 25 thereof. The test pieces were subjected to bending.
FIGS. 11 and 12 show the test results. In FIG. 11, M represents
momentum (ton .times. meter), and .epsilon. deformation. In FIG.
12, Q means shearing force (ton). From these tests, it was found
that the extra coarse-laid wire rope concrete beam is smaller in
strain and larger in yield strength: Since the adhesion area
between the extra coarse-laid wire rope and the concrete is larger,
they may cooperate so as to better exhibit their respective
properties.
Explanation is now made with respect to the results of a sleeve
beam test conducted on beams incorporating an extra coarse-laid
wire rope or a deformed bar, under the following conditions:
The test piece sleeve beams were made of concrete from a slurry of
a slump of 19mm and had a 28 day post-mixing compressive strength
of 28Fc = 180kg/cm.sup.2 and an air volume of 5%, and also having a
central through bore. The extra coarse-laid wire rope embedded in
the sleeve beam had a size of 3 .times. 7 - 18.phi., while the
deformed bar to be used as a stirrup had a size of SD - 19.phi.,
and a stirrup size of 2 - 9 .phi. at 200. The sleeve beam 26, which
is shown in FIG. 13, had a sectional area of 280mm .times. 150mm,
with a central through bore of a diameter of 70mm. The extra
coarse-laid wire rope had no hook, while the deformed bar had
hooks. P denotes a direction in which the pressure is applied to
the test beams. Shown in FIGS. 14, 15 are the results of the
present test on the extra coarse-laid wire rope sleeve beam and the
deformed bar sleeve beam. In FIG. 14, .tau. represents shearing
unit stress, and .theta. joint translation angle (kg/cm.sup.2). In
FIG. 15, .sigma. means stress (kg/cm.sup.2), and .epsilon.
deformation. From the obtained results, it could be concluded that
the extra coarse-laid wire rope sleeve beam showed remarkably
excellent properties in restitution coefficient, stress-strain
development curve, joint translation angle, residual unit strain,
and toughness.
Lastly, a pull-out test was conducted on concrete blocks
respectively incorporating an extra coarse-laid wire rope and a
deformed bar. The same concrete was used for all the test piece
concrete blocks, as that used in the preceding tests. In testing
under the tensile force of 3.6 ton/cm.sup.2, the deformed bar was
easily extracted from the concrete block. While, the extra
coarse-laid wire rope was not extracted from the concrete block
until the later became fractured. This shows more excellent
adhesion of the extra coarse-laid wire rope with respect to the
concrete.
Besides a series of tests as introduced above, further tests were
conducted on actual applications of the extra coarse-laid wire rope
according to the present invention to columns and beams for
buildings, in respect of the adhesive strength of the extra
coarse-laid wire rope, the bending strength of the beams, or the
compressive strength of the columns in comparisons with the
deformed bar applications. The present series of tests were made in
accordance with the testing methods described in the below-listed
publications:
______________________________________ 1) Issue date: August, 1971
Writer: Hajime Umemura et al Title: Methods of Designing Deformed
Bar Concrete Structures Publisher: The Kozaikurabu (a corporation)
2) Issue date: August, 1971 Writer: Yuji Morohashi et al Title:
Wire Rope Concrete Structures (a treatise) Publisher: R.I.L.E.M.
Israel International Symposium 3) Issue date: January, 1972 Writer:
Yuji Morohashi et al Title: Methods of Designing Extra Coarse-laid
Rope Concrete Structures Publisher: Universal Consulting
Engineering, Inc. 4) Issue date: December, 1973 Writer: Yuji
Morohashi Takashi Morohashi S. Saeed Mirza Title: Extra Coarse-laid
Wire Rope Concrete Struc- tures (a treatise) Publisher: Canada
Institution of McDill University 5) Issue date: December, 1961
Writer: John A. Blume Nathan M. Newmark Leo H. Corning Title:
Design of Multistory Reinforced Concrete Buildings for Earthquake
Motions Publisher: Portland Cement Association
______________________________________
1. Adhesive strength tests
The following three kinds of tests are generally adopted as typical
ones for testing adhesive strength:
a. Pull-Out Test
b. Bilateral Pull Test
c. Beam Adhesive Strength Test
Here in this specification is described only the test of the item
(c). This test consisted of the steps of applying shearing force to
test pieces of a beam-like shape to cause adhesive stress in the
shared span portion of the pulled deformed bar or extra coarse-laid
wire rope, and determining the relationship between the adhesive
strength and an amount slipping of the loaded end or of the free
end of the test piece with respect to the concrete. FIG. 16 shows a
test piece in which the test piece size and the directions in which
the test piece receives loads. The test conditions were provided as
follows: The concrete was used which had a compressive strength of
Fc = 220kg/cm.sup.2. The extra coarse-laid wire rope had a strength
corresponding to class WD 120 having a diameter of 22.4mm whose
yield point was .sigma.r = 12.2ton/cm.sup.2, and whose tensile
strength was .sigma.max = 16.5ton/cm.sup.2, and the deformed bar
had a strength corresponding to Class SD 35 having a diameter of
22mm whose yield point was .sigma.r = 3.8ton/cm.sup.2, and tensile
strength was .sigma.max = 5.7ton/cm.sup.2. The test results are
shown in FIG. 17, and in which the adhesive stress was determined
by the following formula: ##EQU1## or ##EQU2## where Q: shearing
force (ton),
j: distance between centers of tension and compression,
.phi.: circumferential length of tension deformed bar or tension
wire rope (cm),
T: tensile strength of the loaded end of deformed bar or extra
coarse-laid wire rope (to be determined by measuring the stress of
the exposed portion of deformed bar or extra coarse-laid wire
rope),
l: length of the sheared span portion.
As seen from the test results, the extra coarse-laid wire rope
concrete exhibited about 150% of the adhesive strength of the
conventional deformed bar concrete, enough to effectively prevent
the rubbing of the wire ropes against the concrete.
2. Beam bending strength test
Now, described in the following are the results of the bending
strength test. This bending strength test comprised a step of
repeatedly applying positive and negative forces with respect to
the test pieces of an extra coarse-laid wire rope concrete beam and
a deformed bar concrete beam. The test conditions were as
follows:
The test pieces were constituted by a deformed bar concrete beam
(25.phi.) and an extra coarse-laid wire rope concrete beam
(25.phi.), each having a size of 25.4cm (10 inches) width .times.
50.8cm (20 inches) height. The test pieces were repeatedly given
concentrated positive and negative forces at three predetermined
equi-interval points thereof. The deformed bar and the extra
coarse-laid wire rope embedded in the concrete beams had the
following sizes:
Tension bar or wire rope Concrete Dia. sAt.(wAt) s.sigma.tY
(w.sigma.tY) s.sigma.max c.sigma.u c.epsilon.u E* (mm) (cm.sup.2)
(t/cm.sup.2) (t/cm.sup.2) (kg/cm.sup.2) (%) (.times.10.sup.5
kg/cm.sup.2)
__________________________________________________________________________
Test piece of deformed 25 5.07 3.25 4.90 242 180 2.58 bar con-
crete Test piece of extra coarse- 25 5.07 12.20 16.50 242 180 2.58
laid concrete
__________________________________________________________________________
Note: Mark* represents second modulus at point 1/4 c.sigma.s.
where,
sAt: sectional area of tension reinforcing bar wAt: sectional area
of tension wire rope s.sigma.tY: yield point of tension main
reinforcement w.sigma.tY: yield point of tension main wire rope
c.sigma.u: concrete strength c.epsilon.u: strain of concrete at the
ultimate load E*: modulus of elasticity (Young's modulus)
FIG. 18 shows the size of the test piece, FIG. 19 shows how to
apply loads to the test piece, and FIG. 20 indicates the
load-deformation curve (by applying forces in plus and minus
directions) which represents the relationship between the total
loads P and the deformation .sigma. of the center of the beam
relative to the supporting point. In the figure, the dotted lines
show values in accordance with the theoretical calculation. These
theoretical values are approximately in conformity to the
enveloping lines corresponding to the measured values.
The theoretical formula (by Hayato Umemura): Mc = (4.2 + 3.7 Pt)
bD.sup.2, ##EQU3## where At: sectional area of tension bar or wire
rope (cm.sup.2),
b: width of beam (cm),
D: height of beam (cm), and
Mc: cracking moment (kg/cm).
Remark: The deformation of the central portion of the beam is
expressed in coefficient of elasticity and rigidity obtained from
the test piece with a built-in deformed bar or wire rope.
From the test results shown in FIG. 20, it was found that the test
piece of extra coarse-laid wire rope beam had four to six times as
much bending strength as the test piece of deformed bar concrete
beam, per the same deformation .delta. (mm). This is of course,
considered to be attributable to the higher strength or higher
adhesive power of the extra coarse-laid wire rope.
From the foregoing, it is to be noted that the extra coarse-laid
wire rope concrete structure (WRRC structure) according to the
invention is structurally more advantageous than the conventional
RC structure.
3. Column center compressive strength test
Next, a further similar comparison test was carried out, which
consisted of a step of applying compressive strength to the centers
of the test piece columns composed of deformed bar concrete or
extra coarse-laid wire rope concrete.
The test conditions were as follows:
The sectional area of the test piece: B .times. D = 20 .times. 20
cm.sup.2
Main Reinforcement: SD40 (13mm in dia.)--s.sigma.r = 4.20
t/cm.sup.2 ; WD120 (12.5mm in dia.)--s = 12.20t/cm.sup.2
Hoop--SR30 (6mm in dia.) s.sigma.r = 3.85t/cm.sup.2
Concrete--c.sigma.u = 153kg/cm.sup.2
The configuration of the test piece is shown in FIG. 21.
The following test pieces were used:
______________________________________ Main reinforcement Extra
coarse- Hoop Deformed bar laid wire rope
______________________________________ 4 - 13.phi. 4 - 12.5.phi.
6.phi. at 50 O.C (P.sub.f = 0.54%) (Pm = 1.27%) (Pm = 0.77%) 6.phi.
at 100 O.C (P.sub.f = 0.27%) 6.phi. at 150 O.C (P.sub.f = 0.18%) 8
- 13.phi. 8 - 12.5.phi. (Pm = 2.54%) (Pm = 1.54%) Ditto 12 -
13.phi. 12 - 12.5.phi. (Pm = 3.81%) (Pm = 2.30%) Ditto
______________________________________
where
Pm: ratio of main reinforcement or ratio of main wire rope
Pf: hoop bar ratio or hoop wire rope ratio
FIG. 22 bears the test results concerning the yield strength of the
columns. As a consequence of the test, the ultimate yield strength
of the columns in the case of compressive force being given to the
centers thereof is expressed by the following formula:
PT = (s.sigma.r .times. sA + 0.85 c.sigma.B .times. cA).alpha.,
where,
s.sigma.r, sA are yielding point stress or sectional area of the
deformed bar or the wire rope respectively
c.sigma.B, cA are maximum stress or sectional area of the concrete
respectively and
.alpha. is function of the hoop ratio Pw (approx. 0.9 - 1.2).
In the above formula, if .alpha. is let to be 1, it will conform to
the ultimate strength formula of the U.S. AC1 standards. In FIG.
22, the dotted lines show the values obtained with .alpha. equal to
1.
From FIG. 22, it is found that the extra coarselaid wire rope
concrete increases in column yield strength in proportion to its
increase in (i) main reinforcement ratio and (ii) hoop ratio.
It is due to the higher strength of the extra coarse-laid wire rope
that the extra coarse-laid wire rope concrete is higher in ultimate
yield strength P.sub.T of the centrally compressed column than the
deformed bar concrete, though the former is smaller than the latter
both in main reinforcement ratio and hoop ratio. A diagonal hoop
(seen in dotted lines in FIG. 23) is effective for increasing the
yield strength of the column. This is due to that the spiral hoop
does not only bind the concrete for itself, but also binds the main
reinforcement of the non-corner portions which are apt to swell
outwardly, as well as increases the binding effect of the concrete.
While, even with the same hoop ratio, it was found more effective
to arrange smaller diameter hoops closely at narrower intervals
than to arrange larger diameter hoops roughly at wider intervals.
Further more effective is to arrange hoops parallel with one
another.
For these reasons, in the WRRC structure according to the present
invention, hoop wire ropes are provided in spiral arrangement thus
elevating the binding effect of the concrete.
Next, there are presented just for reference, some sample
calculations by the fundamental equations specially derived for
determining actual reinforcement employing the WRRC structure
according to the invention:
"Fundamental Equations on Wire Rope Concrete Members." By Yuji
Morohashi; Takashi Morohashi; M. Saeed Mirza
1. Introduction
Studies on the use of wire rope in structural concrete have
concentrated on application of the technique to structural members
in highway bridges and tall buildings.
Authors derived the fundamental equations for the ultimate
flextural strength and other mechanical properties to determine the
most economical wire reinforcement required.
The following describes the development of these fundamental
equations and presents some sample culculations.
2. Notation
a: difference of strain at yield point
b: breadth
cCu: ultimate compressive strength of concrete
wCu: ultimate tensile strength of wire rope
d: depth
E: Young's modulus
cEc: compressive Young's modulus of concrete
cEt: tensile Young's modulus of concrete
wEc: compressive Young's modulus of wire rope
uEt: tensile Young's modulus of wire rope
Fc.sup.kg/ cm.sup.2 : flextural compressive strength of
concrete
Ft.sup.kg/ cm.sup.2 : flextural tensile strength of concrete
j: distance of strength between compression and tension
ku: compressive stress block factor at the extreme concrete fiber
(See FIG. 24)
m: moment
Mc: flextural compressive moment
cM: moment of concrete resistance
wM: moment of wire rope resistance
n: Young's modular ratio ##EQU4## Pt: tensile area ratio of wire
rope at the reinforced concrete Ptb: balanced tensile area ratio of
wire rope at the reinforced concrete
Pt: tensile area ratio of wire rope at the reinforced concrete
r: ratio at the wire rope reinforcement ##EQU5## Pc: compressive
area ratio of wire rope at the reinforced concrete Xnu: depth of
neutral axis at the ultimate
Xnul: ratio of neutrol axis at the ultimate
Xnulb: balanced ratio of neutral axis at the ultimate
.epsilon.: strain
c.epsilon.cu: strain at the ultimate compression of concrete
c.epsilon.cy: strain at the yielding compression of concrete
c.epsilon.tu: strain at the ultimate tension of concrete
c.epsilon.ty: strain at the yielding tension of concrete
w.epsilon.cu: strain at the ultimate compression of wire rope
w.epsilon.tu: strain at the ultimate tension of wire rope
w.epsilon.ty: strain at the yielding tension of wire rope
w.epsilon.y: strain at the yield of wire rope
(1/.rho.): curvature
.sigma.: stress
c.sigma.c: compressive stress of concrete resistance
w.sigma.t: tensile stress of wire rope resistance
w.sigma.tu: ultimate tensile stress of wire rope resistance
w.sigma.y: yielding stress of wire rope
c.phi.cu: half-diameter of curvature at the ultimate compression of
concrete
w.phi.ty: half-diameter of curvature at the yielding tension of
wire rope
.mu.: ductility factor
T: tensile strength
Tu: tensile strength of ultimate
K: parameter
s: suffix indicating wire rope
c: suffix indicating concrete
y: suffix indicating yielding
u: suffix indicating ultimate
.phi.: rotation strain
3. Assamptions
1. Plane section remain plane after loading (assumption of
Bernoulli or Navier)
2. Maximum compressive strain at the extreme concrete fiber of slit
tending to close at ultimate flexural moment is 0.003.
3. Stress-strain curve of wire rope is as shown in FIG. 27.
4. Values of ku are taken as follows:
Fc kg/cm.sup.2 Ku Fc kg/cm.sup.2 Ku
______________________________________ 250 0.8 400 0.7 300 0.76 500
0.63 ______________________________________
5. Concrete cover to wire rope on both tension and compression
faces shall be as follows:
dc = 0.1d, dt = 0.1D
FIG. 25 shows the change of stress distribution with load increse
up to the ultimate flexural moment.
FIG. 26 shows strain distribution.
FIG. 27 shows stress-strain curve of an extra coarse-laid wire
rope, where a is a difference of strain at yield point (a case of
compressive strain)
4. Derivation of Fundamental Equations
4.1--Ultimate flexural moment cut neglecting the tensile stress in
concrete
Where
Therefore the neutral axis ratio Xnul can be expressed as follows
##EQU7##
Considering equations (9) and (10), the balanced neutral axis ratio
will be given by equation (13) as ##EQU8##
Balanced ratio of wire rope reinforcement can also be obtained from
equations (9) and (10) ##EQU9##
Replacing Fc in equation (11) by stress of resistance c.sigma.c,
can be expressed as equaton (15). ##EQU10##
Equations (2) and (11) give
Replacing s.sigma.y in equation (16) by s.sigma.t, we obtain the
following equation for s.sigma.t ##EQU11## 4.2-At ultimate flexural
moment considering the concrete tensile stress ##EQU12##
It is assumed that
Let's suppose Xnul = 0.3, d = 40 K value varies in the interval off
equation (FIG. 1) according to the following condition.
Let's take value of K = 0.1, then the value of .phi.will be given
as fallows. ##EQU14## 4.3--K value at ultimate flexural moment
neglecting the concrete tensile stress is given by the equation.
##EQU15##
Supposing that d = 40cm, then Xnul is 12cm, Therefore, ##EQU16##
4.4--Equations at ultimate flexural moment considering the concrete
tensile stress are as follows ##EQU17##
Modular ratio ##EQU19## Therefore, ##EQU20## Ex. 2--Calculation of
ultimate flexural moment assuming that Fc = 300, Ft = 30, and n =
18, respectively.
The value of K varies in the interval of
1 .gtoreq. K .gtoreq. 0.9 Xnul
If we assume K = 0.3, equation (30) become ##EQU21##
Therefore, if a wire rope of size No. 6 .times. 7 (See FIG. 28) is
selected, it gives w.sigma.tu
4.5--the case in which the concrete tensile stress is nealy equal
to zero
Ex. 3--Assuming K = 0.28, and substitute it into the equation
##EQU22##
In this case, if we select the wire rope No. 3 .times. 9 (See FIG.
29) it gives w.sigma.tu
4.6--the value of x.sigma.t is below its ultimate strength
In this case we obtain the value of s.sigma.t by selecting K = 1
under the condition of
Each value of ductility factor can be obtained by substituting
equation (35) into ##EQU27## 5.2--The ductility factor for Xnulb
and Ptb can be obtained in the same manner as shown above, each
value can be obtained by substituting the of equation (35) into
##EQU28## 6. In Conclusion
Various design charts are now under preparation, and N values will
be decided from the data from preliminary tests.
Next, described are actual examples of designs of the conventional
deformed bar concrete structure (RC structure) (Case 1) and the
WRRC structure (Case 2):
The buildings of both the structures Case 1 and Case 2 were
designed under the same conditions, for comparison's sake. The
outlines and conditions of the buildings to be constructed of such
structures are as follows: FIGS. 30 and 31 are rough plan and
sectional views of the building to be designed, respectively. This
building is intended for a multi-story appartment house having
eight stories above and one floor under the ground, and also having
a penthouse with two stories above. It is constructed to have an
underground parking place, a restaurant on part of the first floor,
dwellings on the second through the eight floors, a penthouse, a
machinery room, an attic floor water tank, etc. The size of the
reinforcing bar to be used in Case 1 is SD40 (JIS G 3112, 1964 see
Page 14, Table 1 of this specification), and the size of the extra
coarse-laid wire rope for Case 2 is WD120 (see Page 14, Table 1 of
this specification), the concrete for both Cases having a 28 day
post-mixing compressive strength of 28Fc = 270kg/cm.sup.2.
Cases 1 and 2 were designed under the above-mentioned same
conditions. New description is made with respect to the typical
column of the first floor (FIG. 32), and the beam of the second
floor (FIG. 33). As seen from FIG. 32, the column of the first
floor of the WRRC structure was reduced by 64% in sectional area
ratio, and by 43% in steel ratio. Of course, similar results were
obtained by the column of the second floor or above. As evident
from FIG. 33, the beam of the present invention could be reduced by
61% in sectional area ratio, and 18% in steel ratio. Similar
results were obtained by the beam of the third floor or above.
As a whole of the building, the column and the beam of the WRRC
structure according to the invention were reduced by 35 - 55% and
20 - 40% in sectional area ratio, respectively. In steel ratio,
they were reduced by 55 - 65% and 65 - 85%, respectively.
The building employing the present invention may advantageously be
constructed in the following sequence:
First, a temporary work, an earthwork, and a foundation and
foundation slub work are effected in the mentioned order. Following
these series of works, a reinforcing work is executed which
comprises the step of arranging wire ropes and hoop steel wires or
wire gauze so as to form concrete moulds. Usually this work is done
for columns, walls, beams, and slubs in said order. Then, concrete
works in the order of columns, walls, beams, and slubs, to be
followed by a waterproofing work, and a finish work in a
conventional manner.
According to the WRRC structure, large simplification of the
reinforcing work is feasible, as compared with the conventional RC
structure, particularly in respect of the construction term. In
addition, assembly of the columns and beams may be speeded up
because of employment of the special connecting means as
aforementioned.
As will be learned from the aforementioned structure of the present
invention and the various test data, in place of steel frame, and
reinforcing bars as mainly used in the conventional structures such
as RC, SRC, SPC, PS, or dam structures, extra coarse-laid wire
ropes are embedded in concrete columns and beams of the present
invention, to be followed by mutually fastening of the wire ropes
of the columns and beams at the intersecting points by means of
special fasteners. Thus, in the columns and beams throughout the
whole building are provided extra coarse-laid wire ropes mutually
integrally connected together at their associated ends.
In conventional structures employing steel frames and/or
reinforcing bars, compressive strength and bending stress are
mainly undertaken by the concrete itself, and tensile strength and
bending stress by the steel frames and/or reinforcing bars. Whilst,
in the present invention, as evident from the above-mentioned test
results, the extra coarse-laid wire ropes, used in lieu of steel
frame or reinforcing bars, the adhesive power between the extra
coarse-laid wire ropes and the concrete is outstandingly excellent
relative to the steel frame or the reinforcing bar, by virtue of
their specially configurated surfaces and unique properties, thus
being free from their rubbing against the concrete. Further, as
compared with the steel frame or reinforcing bars, the extra
coarse-laid wire rope has higher restitution coefficient per se,
enough to be more easily restituted into a pre-deformation state
shortly after the load is released. For these reasons, the WRRC
structure according to the present invention always acts in one
body smoothly coping with all directional external forces applied
to the structuree, thus exhibiting tenacity (or toughness). In
addition, it may have a higher critical breaking stress, thus being
excellent in mechanical strength. As mentioned before, the column
and beam according to the invention, if they are given the same
strength, may have reduced sectional areas by 35 - 55% and 20 -
40%, respectively. Therefore, more efficient use may be feasible of
a given site or a dwelling space. As for the amount of steel (or
material) required, large reduction may be possible, i.e., by 55 -
65% for columns, and by 65 - 85% for beams, which may lead to large
curtailment of costs and considerable reduction in the weight of
the whole structure.
Further, with the above-mentioned construction that the extra
coarse-laid wire ropes arranged straight throughout the whole
building or the like are all integrally joined together, the
external forces applied to the structure are instantly transmitted
from the force applied part of the wire rope to any other parts
thereof or other wire ropes through the wire ropes to be thus
dispersed. Thanks to the presence of air-gaps in the interior of
the wire rope as unseen in steel frame of reinforcing bars,
internal forces generated by external forces applied to the wire
rope are absorbed into the air-gaps and consequently well damped.
Therefore, partial destruction of the structure may be effectively
avoided. Further, in the event of the building or the like
employing the present structure being inclined, the whole building
or the like is supported by the groups of extra coarse-laid wire
ropes on the opposite side thereof to the direction of inclination,
thus being prevented from falling down (In this moment, the
concrete acts as a supporting rod). Thus, it is to be noted that
the structure according to the invention is largely improved also
in earthquake resistance. Also in the event of a fire, the heat
energy may be more efficiently absorbed into the air-gaps existent
in the extra coarse-laid wire ropes, in a similar manner. Thus, it
has superior fire-resistance as well.
In addition, the extra coarse-laid wire ropes may be incorporated
into the columns or beams of the structure in a more simple manner
than the conventional steel framed structure, thus resulting in a
shortened term of construction of the buildings or the like
constructed according to the invention.
As stated in the foregoing, the WRRC structure according to the
present invention is a novel organic structure which provides
better resistance to earthquake, explosion, and fire, as compared
with the conventional ones.
While a few particular embodiments have been described to the
better understanding of the invention, it is to be understood that
the present invention is applicable to any other structure without
departing from the scope of the appended claims.
* * * * *