|Publication number||US3916592 A|
|Publication date||Nov 4, 1975|
|Filing date||Oct 29, 1974|
|Priority date||Aug 16, 1969|
|Publication number||US 3916592 A, US 3916592A, US-A-3916592, US3916592 A, US3916592A|
|Inventors||Morohashi Takashi, Morohashi Yuji|
|Original Assignee||Morohashi Takashi, Morohashi Yuji|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Referenced by (25), Classifications (22)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Nov. 4, 1975 United States Patent [191 Morohashi et a].
52/725 52/723 Morohashi............................ 52/145 FOREIGN PATENTS OR APPLICATIONS  STRUCTURAL MEIVIBERS FOR BUILDINGS 3,421,271 l/l969 Whitfield N BUI CONSTRUCTED 3,472,031 10/1969 Kelso THEREFROM 3,716,982 2/1973  Inventors: Takashi Morohashi; Yuji Morohashi, both of Universal Corporation Engineering Consultant Co. Ltd., Sagamidai 1-15-9,
Primary ExaminerErnest R. Purser Assistant Examiner-J-Ienry Raduazo Attorney, Agent, or Firm-Cushman, Darby & Cushman Sagamihara, Kanagawa-Prefecture, Japan  Filed: Oct. 29, 1974 211 Appl. No.: 518,861
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 in the concrete column in a threedimensional 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 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 6 Claims, 33 Drawing Figures d e m w .m m. o m d C e e e d T. e d e m 1 m a 7 n y 5 m o e rL e C m 7 6 8 6346323555 @No 6 M Mfi 3523525444 4 1 7677676111 4 4 2 ru 6 L 2222222777 OS n m 5555555555 f 4 .7 5 nun. n u n u" 2/ "n" "u u" l n 3 E 7 n 4n n 2 n u be m m m a u m m a l2" .3 S n u 39% D m Q 51 n DZ W." n m n .l n .9 4 a m m omd n m 2 "n E m m e 0 m 5 m n n t. cm H n ..A m n m d m 2 G m m m n 5 4 S 0 n 0um D. a m n 1. ."n. i a" I4 mmTw A .1 H u n. t .V.. e muee h a a A an Odn O c H ""2 e eflm rmn Sm 7 vua "0 rTea uiai vim 6 mSLBMwTKHNsP e u n wn A 9 u 0 0 R m o 6 n u 0 E3772457767 t odlv.. @9 u n 6 900 566 ain 1 8999999999 6 MM fl h 2 6 HHHHHH R m M 6 U 0 mm 9 2252WWUW 1 l1 1 l uLn F d W3 we S LHM 2J 45638 3584 C 5 A U .mF 632 945694 11 1 574673311 06749630 3 m m Q flaw 15,3 rt [.l .l. 23 3 US. Patent Nov. 4, 1975 Sheet1of13 3,916,592
U.S. Patent Nov. 4, 1975 Sheet 2 of 13 3,916,592
U.S. Patent Nov. 4, 1975 Sheet 3 of 13 3,916,592
US. Patent Nov. 4, 1975 SheetSof 13 3,916,592
% B X i U.S. Patent NoV.4, 1975 Sheet60f13 3,916,592
FIGH FIG/2 M (ton,Meter) Q (ton) a of exrm coarse'bd area of extra coarse-laid I e rope concrete wire rope concrete 2%'??e I/ 0.5 I l l 1 2 3 I 2 3 FIG. I 3
26 1000mm 200mm T beam 6 e L E1 A t A D=280mm U y =--=7omm 400mm 400mm 400mm FIG.I4
extra coarse-laid wire rope concrete deformed bar concrete US. Patent NOV.4, 1975 Sheet70f13 3,916,592
F I 6. I5
deformed bar concrete extra coarse-laid wire rope concrete Kg/cm FIG.I6
\ lll rllu U.S. Patent Nov. 4, 1975 ADHESIVE STRESS (Kg/cm )'(a Sheet 8 of 13 FIG.I7
Xexfm coarse-laid wire rope concrete deformed bar concrete SLIPPING OF THE LOADED END (mm) US. Patent Nov. 4, 1975 Sheet90f13 3,916,592
IOOcm l IOOcm I US. Patent Nov. 4, 1975 YIELD STRENGTH OF THE COLUMN Sheet 10 of 13 Steel Ca 5 =4-mrn StCCL Cap FIG.23
HOOP RATIO extra coarse-laid wire rope concrete deformed bar concrete III STRUCTURAL MEMBERS FOR BUILDINGS AND BUILDINGS CONSTRUCTED THEREFROM This is a continuation-in-part application of our pending parent application Ser. No. 298,64l 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.
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 r'einforced 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 specialtype 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 US. 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 prestressed 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 fireproof 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 fourstory 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 abovementioned 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 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 coarselaid 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, 1-- 6 and (I e 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 col umn. 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 pa tent 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 for insertion of end portions of the extra coarselaid 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 coarselaid 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 US. 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 builtup lay so as to cross one another at a phase angle of about 180; 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 coarselaid 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 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 after the lapse of 28 days after mixing. Each mortar piece 21 assumed a cylindrical shape having a diameter of 68mm, 21 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 coarselaid wire rope mortar, and (B) that of the deformed bar mortar. Here, symbol o'C represents applied compressive pressure, 6 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 1*: 3C, to obtain a test piece 24 (simple beam) as shown in FIG. 10 which had a mixing strength of 180kg/cm a sectional area of 10cm X 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 X meter), and e 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 l8Okg/cm 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 X 7 18, while the deformed bar to be used as a stirrup had a size of SD 194), and a stirrup size of 2 9 (15 at 200. The sleeve beam 26, which is shown in FIG. 13, had a sectional area of 280mm X 150mm, with a central through bore of a diameter of mm. 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, 1' represents shearing unit stress, and 0 joint translation angle (kg/cm In FIG. 15, a means stress (kg/cm and 6 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 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:
Issue date: August. 1971 Writer: Hajime Umemura et al Title: Methods of Designing Deformed Bar Concrete Structures Publisher: The Kozaikurabu (a corporation) Issue date: August. 1971 Writer: Yuji Morohashi et :11
Title: Wire Rope Concrete Structures (a treatise) Publisher R.I.L.E.M. Israel International Symposium Issue date: January. I972 Writer: Yuji Morohashi et 31 Title: Methods of Designing Extra Coarse-laid Rope Concrete Structures Publisher: Universal Consulting Engineering. Inc.
Issue date: December, 1973 Writer: Yuji Morohashi Takashi Morohashi S. Saeed Mirza Title: Extra Coarse-laid Wire Rope Concrete Structures (a treatise) Publisher: Canada Institution of McDill University 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 0. Beam Adhesive Strength Test Here in this specification is described only the test of the item (0). 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 Tension bar or wire rope 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 Fe 22Okg/cm The extra coarse-laid wire rope had a strength corresponding to class WD 120 having a diameter of 22.4mm whose yield point was or I2.2ton/cm and whose tensile strength was max l6.5ton/cm and the deformed bar had a strength corresponding to Class SD 35 having a diameter of 22mm whose yield point was 0-2 3.8ton/cm and tensile strength was max 5.7ton/cm The test results are shown in FIG. 17, and in which the adhesive stress was determined by the following formula:
Q: shearing force (ton),
j: distance between centers of tension and compression,
qb: 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),
1: 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) and an extra coarse-laid wire rope concrete beam (25), each having a size of 25.4cm 10 inches) Width X 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:
Concrete Dia. SA! WA I) m! Y (WO'I Y) so'mux can can (mm) (cm (tlcm (t/cm) (kg/cm) (X I0 kg/cm Test piece of deformed 25 5.07 3.25 4.90 242 I 2.58
bar concrete -continued Tension bar or wire rope Concrete (mm) (cm (t/cm (tlcm (kglcm (7c) (XIO-kg/cm") Test piece of extra coarsc- 25 5.07 12.20 l6.5() 242 I80 258 laid Note: Mark* represents second modulus at point 1/4 cos. where,
KAI. sectional area of tension reinforcing bar wAl: sectional area of tension wire rope .m-(Y: yield point of tension main reinforcement 11-01 Y: yield point of tension main wire rope can: concrete strength ceu: strain of concrete at the ultimate load 15*: 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 0' 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 I-Iayato Umemura): Mc (4.2 3.7 Pt) bD where At: sectional area of tension bar or wire rope (cm 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 8 (mm). This is ofcourse, 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 X D 20 X 20 Main Reinforcement: SD40 (13mm in dia.)so"r 4.20 t/cm WD120 (12.5mm in dia.)-s 12.20t/cm I-loop--SR30 (6mm in dia.) sar 3.85t/cm Concretecou l53kg/cm The configuration of the test piece is shown in FIG. 21.
The following test pieces were used:
Main reinforcement 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 (so-r X sA 0.85 co-B X cA)a, where,
so'r, 3A are yielding point stress or sectional area of the deformed bar or the wire rope respectively 008, cA are maximum stress or sectional area of the concrete respectively and a is function of the hoop ratio Pw (approx. 0.9 1.2).
In the above formula, if a is let to be I, it will conform to the ultimate strength formula of the US. AC1 standards. In FIG. 22, the dotted lines show the values obtained with 01 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 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-comer 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
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|U.S. Classification||52/252, 52/649.4, 52/857, 52/414, 52/263|
|International Classification||E04H9/04, E04C5/01, E04B1/21, E04B1/20, E04H9/02, E04C5/16, E04C5/06|
|Cooperative Classification||E04H9/02, E04C5/0618, E04C5/162, E04B1/21, E04H9/04|
|European Classification||E04H9/02, E04C5/16B, E04H9/04, E04B1/21, E04C5/06A3|