JP4709767B2 - Concrete block manufacturing method and reinforcement cage used in manufacturing this block - Google Patents

Abstract

The method involves casting a cement mass (2) in a casing after setting a reinforcing housing (3) in the mass, to fabricate a slab (1). The housing has lower longitudinal frameworks (31) and upper longitudinal frameworks (31) connected with each other. Each framework (31) has locking parts (43, 43) supported in the mass at respective locking zones (B, B) formed inside the slab, in direction opposite to absorbed tensile stress. An independent claim is also included for a reinforced concrete piece comprising a reinforcing housing.

Description

  The present invention relates to a method for manufacturing a concrete member, and more particularly to the use of a new type of reinforcement that can greatly increase the stress level at which many advantages, particularly harmful cracking, occur.

  The principle of reinforced concrete is the combination of two materials that have complementary properties: concrete with high compressive strength but low tensile strength, and steel that is excellent in tensile strength and embedded in concrete to protect against corrosion in the air. It is known that there is to be. Since these two materials have similar expansion coefficients, a combination of them can produce a composite member that has the durability of concrete and can resist bending moments or loads. This member, when stressed, is provided with two parts on either side of the neutral axis, ie a compressive part which is mainly subjected to compressive stress absorbed by the concrete, and at least one longitudinal reinforcement of a reinforcing cage which is mainly embedded in the concrete. And a tension portion that receives tensile stress absorbed by the material.

  The stiffener must be placed at a minimum distance called the “distance de enrobage” from the outside surface of the concrete member to block air and avoid corrosion. However, it is inevitable that the concrete member is deformed under the action of stress, the tension portion is extended, and cracks are generated in the exterior concrete. The occurrence of this crack is inevitable, but the width of the crack is quite small. For example, if it is 3/10 mm or less, it is possible to prevent air and water from penetrating into contact with the reinforcing material.

  As long as the applied load does not exceed a certain threshold value, the reinforced concrete member behaves as a composite member that deforms integrally due to stress transmission between the two components. For this purpose, in order to improve the stress transmission link between the reinforcing material and the concrete, for example, a so-called highly adhesive rod having a groove in its entire length is used. In general, both ends of the rod are bent to form an anchor crosshead to increase the length of the reinforcing material embedded in the concrete, and thus the length of internal stress transmission between the reinforcing material and the concrete.

  However, when the stress exceeds a certain threshold, the crack spreads, and the portion of the free short tension reinforcement between the opposing faces of one crack supports the elongation corresponding to the thickness of the crack and is adjacent to it. The part is locked in the concrete. Therefore, the tendency for the tension surface to easily stretch due to the applied stress is concentrated in the free part of the reinforcing material, and since the length of that part is short, the metal exceeds the elastic limit due to the applied elongation, thereby tightening the reinforcing material, The structure is destroyed.

  An object of the present invention is to provide a novel method for producing a concrete molded member that can reduce the risk of cracking with respect to the same stress by using a new type of reinforcing material that solves the above problems. .

  In the method of the present invention, the resistance to a large stress can be greatly increased, and the concrete member manufactured by the method of the present invention is highly flexible and has a safety factor from the occurrence of initial cracks to complete destruction of the structure. There is an advantage of high. This advantage is particularly important in the construction of civil engineering structures or buildings in areas prone to earthquakes.

The present invention is generally applied to a method of manufacturing a concrete member having a reinforcing cage that is embedded in the concrete during the casting of the concrete, which when subjected to load, has two parts on either side of the neutral axis: A compressive portion that is primarily subjected to compressive stress absorbed by the concrete and a tension portion that is primarily subjected to tensile stress absorbed by at least one longitudinal tension reinforcement of the reinforcement cage, wherein the longitudinal reinforcement is a longitudinal member of the concrete member. It extends along the longitudinal direction where tensile stress is applied at a short covering distance from the directional tensioned surface and has a cross section determined by a function of the applied stress.
In the present invention, at least each longitudinal tension reinforcement consists of at least one flat strip having a rectangular cross section, a wide side and a narrow side, the strip inside the concrete member, Forming at least two clamping areas and at least one sliding area between the clamping areas, wherein a part of the longitudinal tension reinforcement is in the direction opposite to the absorbed tensile stress in the concrete The corresponding part of the longitudinal tension reinforcement can be freely stretched by the action of the absorbed stress in the sliding region, and the tension is evenly distributed over the entire length of this part.

  As will be described in detail below, reinforced concrete technology generally connects the total length of each reinforcement with the concrete covering the reinforcement to create a composite member that deforms entirely under the action of a load. On the contrary, the fastening areas are spaced apart. In this clamping area, the reinforcement consisting of a flat strip is supported on the wide side in the concrete and there is no risk of exceeding the allowable compression limit of the concrete. When the stress exceeds a certain threshold, the part of the reinforcement between the two compression zones leaves the concrete and slides slightly against the concrete covering it, thereby causing the elongation of the reinforcement caused by the applied tensile stress The action is always distributed over the entire length between the two clamping regions, so that stress concentration can be avoided and the breakage of the stiffener in case of extreme stress can be avoided.

In a particularly advantageous embodiment, the orientation of the wider surface of the strip is gradually and continuously changed with respect to the longitudinal tension surface of the member to displace the corresponding portion of the tension reinforcement in the form of a strip. To make each tightening area.
In the first embodiment, each tightening region is created by gradually rotating at least 1/4 of the wide surface of the belt about the longitudinal axis of the belt and twisting the belt over a certain length. However, it is also possible to rotate the twisted part of the strip fully or more so that it is supported by the concrete over a longer length.
In another embodiment, a flat strip is bent about a transverse axis to form an anchor crosshead that is supported on the concrete by the wider surface, thereby creating each clamping area.

  However, it is also possible for at least one rigid rod portion extending in the lateral direction to be fixed to the flat strip in the desired position and supported in concrete on both sides of the flat strip, thereby creating a clamping area. This transverse rod can be formed by a transverse dispersion rod.

Similar to the conventional method, the reinforcement cage is a transverse dispersion rod composed of rods perpendicular to the longitudinal main rod, connecting a plurality of longitudinal sectors to each other and forming a reinforcement web as a whole. The transverse dispersion rod can be welded to the longitudinal rod, and if the longitudinal rod is in the form of a flat strip, a durable weld can be made.
Each weld joint can constitute a clamping region, and the dispersing rod is supported in the concrete on both sides of the longitudinal rod. In general, each sector of the reinforcing cage has at least two longitudinal rods (compression rod and longitudinal tension rod) which are connected to each other by a connecting stirrup. The compression reinforcement is also preferably formed of a flat strip.
Similarly, in another advantageous arrangement, each connecting stirrup can be formed by at least one flat strip, which is connected to the reinforcement by a weld bead or glue extending over a length equal to the width of the strip. it can. Therefore, it is particularly durable.

  Further, each band constituting the stirrup is inclined with respect to the direction of the tension rod to form a kind of wedge supported by the concrete in the entire welded portion between these flat bands having different directions. Thus, each clamping region between the tension reinforcement and the concrete can be formed by a connection joint between the tension reinforcement and the connecting stirrup in the form of a strip.

  There are other possibilities when using flat strips to make tension reinforcement. That is, to form a tightening region, a tension reinforcement in the shape of a strip can be cut open axially over a certain length, the two parts of the strip thus formed are arranged apart from each other, and at least An opening for inserting one rigid rod portion from the lateral direction can be formed, and the rigid rod portion can be brought into contact with the concrete on both sides of the longitudinal band in a direction against tensile stress applied to the longitudinal reinforcement. The rigid rod can be a dispersive rod through which the longitudinal strip passes in the plane, or a single rod through which the longitudinal strip passes perpendicular to the plane.

  There are many possibilities for the method of the invention using a flat strip. In particular, each longitudinal reinforcement can have at least two bands that are assembled together. They are substantially aligned with each other and extend in the longitudinal direction and are subjected to tensile stresses in opposite directions. The two strips combined are overlapped over a certain length, and each end becomes two crossheads on opposite sides of the overlapped portion, facing each other. Thus, under the action of opposing tensile stresses applied to both corresponding strips, they tend to approach each other, compressing the concrete core between the two crossheads over the covering length.

In the general case where the reinforcing cage is formed of parallel sectors connected via a dispersion rod, the dispersion rod element can pass through the crossheads of two adjacent sectors, The compressive stress generated in each sector due to the tendency to approach each other is transmitted to the concrete portion between the sectors.
In a special arrangement, the set of two strips forming the longitudinal reinforcement of each sector of the cage constitutes two pieces of a single strip. These pieces form a loop between two spaced apart levels, form a crosshead that is opposed at both ends, and the above-mentioned loop is made up of the longitudinal reinforcement by the action of tensile stress applied in opposite directions. Compress the concrete core by tightening with two pieces.

  In a particularly advantageous embodiment, in each sector, the longitudinal reinforcement is formed by a series of strips. Each band has two curved ends in the shape of a crosshead, and the adjacent crossheads of two consecutive bands are arranged adjacent to each other and partly overlap, and a connecting pin between the continuous bands A transverse space for inserting at least one rod part forming In this case, the longitudinal reinforcing material behaves like a tension chain formed by a plurality of links. Each link is formed of a strip and is connected by two pairs of adjacent crossheads keyed together.

In yet another advantageous embodiment, in each sector, the longitudinal tension reinforcement consists of a stack of at least two flat strips. The laminate has a first level that is closest to the longitudinal tension surface of the concrete member, the first level having a strip with ends in the shape of a crosshead facing the inside of the concrete member. At least one second level has at least two substantially parallel strips arranged side by side, each end of each flat strip in the form of a crosshead (inner and outer crossheads, respectively). The second level strips overlap for a certain length and the inner ends in the form of crossheads are facing each other. The concrete member made in this way is compressed by the tendency of the inner crossheads to approach each other by the action of tensile stress applied in opposite directions on the corresponding band, forming a core between the inner crossheads of both bands. Between at least one portion and two end portions between the outer crossheads of the first and second level strips and each outer crosshead of the first level strip is supported by the strips With two end portions that are compressed by the tendency to approach inward under the action of tensile stress, so that the entire concrete of the concrete member can be compressed.
In the following, other possible arrangements and many advantageous features of the invention will be described with reference to the accompanying drawings, but the invention is not limited to the following examples.

[FIG. 1] [FIG. 2] shows a longitudinal section and a transverse section of a concrete member manufactured according to the present invention.
The concrete member 1 is composed of a slab having two surfaces (in the illustrated embodiment, a lower side surface 20 and an upper side surface 21) as in the conventional example. The slab is formed by casting a concrete 2 after a cage de ferraillage 3 is placed in the case. The reinforcing cage 3 has two reinforcing webs (a lower reinforcing web 30 and an upper reinforcing web 30 ', respectively) substantially parallel to the two surfaces 20, 21 of the slab 1.

The reinforcement cage 3 generally comprises a plurality of sectors S1, S2,... Each centered in a plane P1, P2,... Parallel to the longitudinal axis of the concrete member 1 (and hence the plane of [FIG. 1]). Each sector comprises a lower longitudinal reinforcement 31 and an upper longitudinal reinforcement 31 ′. These reinforcing members 31, 31 'are lateral reinforcing elements called etriers in the plane P1 (P2) of the sector S1 (S2) (not shown in [FIG. 1] [FIG. 2]). Are connected to each other.
The sectors S1, S2,... Of the reinforcing cage 3 are connected to each other by lateral rods 32, 32 ′ perpendicular to the plane of FIG.

As is well known, for example, when a vertical load M is applied to the upper surface 21, the concrete member 1 is compressed into two parts on both sides of the neutral axis 10, that is, between the neutral axis and the surface 21 to which the load is applied. 11 'and a partie tendue 11 extending to the surface 20 opposite to the surface to which the load is applied.
These structures and arrangements are all general and will not be described in detail.

The reinforcement cage 3 of the present invention is different from a general cage in that at least one longitudinal reinforcement 31 extending from the lower surface 20 at a short covering distance in the tension portion 11 of the concrete member is wider. The cross section having the surface 41 and the narrow surface 42 is composed of a rectangular metal band (band) (described in the following document of the present applicant). This metal band (band) consists of a flat metal rod 4 whose width l is much larger than the thickness e.
Applicant's French Patent Application No. 2,814,480

Although it is preferable that the compression reinforcing member 31 ′ is also composed of a flat rod, a general round rod can be used from an economical point of view.
The cross section (l × e) of the metal strip 4 is added to the concrete member 1 as described in the above-mentioned Patent Document 1 of the present applicant (French Patent Application No. 2,814,480 of the present applicant). Considering the load, it can be calculated as a function of the tensile stress to be supported. That is, when the load M is applied, the concrete member 1 tends to be slightly warped, and tensile stress is applied to each longitudinal reinforcing member 31 of the lower reinforcing web 30 to elongate.

  In the conventional technology of reinforced concrete, in order to strengthen the transmission link between the reinforcement and the concrete, the composite member is generally formed by using a grooved reinforcing rod. It is required to increase the rigidity of the member. However, the deformation of the concrete member is unavoidable, and the tension reinforcing material and the concrete covering it stretch, and the tensile strength of this concrete is small, so that cracks occur when a certain load is exceeded.

  In the prior art, the reinforcing material is connected to the concrete along its entire length, but in the present invention, conversely, in the concrete 2, the transverse direction intermediate surface Q of the concrete member along each longitudinal tension reinforcing material 31. Two clamping areas (zone de blocage) B and B ′ are provided on both sides of the frame. The two tightening regions B and B ′ are separated from each other by the central region C. When a load is applied, the longitudinal reinforcement 31 can freely extend in the central region C, and the longitudinal reinforcement It can slide against the concrete covered with the material 31.

  In the present invention, a flat belt is used as the longitudinal reinforcing member, and therefore the above-described tightening regions B and B 'can be formed only by bending the corresponding portion of the tension reinforcing member 31. That is, it can be made by changing the direction of the wider surface of the longitudinal tension surface 20 little by little and continuously with respect to the longer surface of the longitudinal tension surface 20. The band 4 forming the longitudinal reinforcing member 31 is supported in the concrete so as to oppose the direction of tensile stress absorbed mainly through the wider surface 41 in the tightening regions B and B '.

In the embodiment shown in [FIG. 1] to [FIG. 4], the belt body 4 is gradually rotated about its axis 40 and its wide surface 41 is rotated to twist the belt body 4 over a certain length L1. Tightening regions B and B ′ are formed.
In the embodiment shown in FIG. 3, the band 4 is twisted and rotated completely. When a rightward tensile stress T is applied to the horizontal band 4, if there are portions 43 twisted by one full turn on both sides of the intermediate surface P, the tensile force applied to the band 4 is the same as in the case of the tension screw. The stress T is supported in the concrete by both sides 41, 41 'of the strip 4. Since the strip 4 is supported in the concrete via two flat and wide surfaces, the concrete is not sheared and the compressive stress is small. Furthermore, the width l of the strip 4 can be determined by a function of the applied stress so that the compressive stress applied to the concrete is less than or equal to the allowable limit value.

The reinforcing band 4 connected to the concrete via both twisted portions 43, 43 ′ constituting the tightening regions B, B ′ is formed in the central portion 44 between the two twisted portions 43, 43 ′. Conversely, it can grow freely.
An adhesive bond exists between the concrete and the reinforcing material over its entire length after the concrete is cast. Unlike the prior art, this adhesion need not be increased by, for example, grooving.

That is, in the present invention, each band 4 constituting the longitudinal reinforcing member 31 is connected to the concrete only by two tightening regions B and B ′ arranged at a distance from each other, and a stress is applied to extend the reinforcing member. If, the force can be uniformly dispersed in the entire length L ₂ of the central portion 44 between the two torsion portions 43, 43 ', the center portion 44 is bonded to the concrete when the stress exceeds a certain threshold Come off.
Since the concrete 2 is not deformed in the same way as the reinforcing material, the occurrence of cracks is inevitable, but the risk of cracking can be uniformly distributed over the entire length L ₂ of the central portion 44, and a large number of cracks with a small width that do not adversely affect Can be.

As a result, it is not necessary to increase the rigidity of the concrete member in order to reduce the deformation of the concrete member as in the prior art, and conversely, the concrete member can be made relatively flexible.
When the applied stress is small, the concrete member of the present invention behaves as a conventional composite member, and the concrete is deformed in the same manner as the reinforcing material.

When the stress exceeds a certain threshold value, the central portion 44 moves away from the concrete covered with the reinforcing material and slightly slides relative to the reinforcing material while maintaining the connection with the concrete only by the tightening portions 43 and 43 ′. . As a result, the tension (i.e., tendency to extend the reinforcing member) is almost uniformly distributed over the entire length L ₂ of the central portion 44, is avoided tensile stress is concentrated at the short length of the upper reinforcement, whereby cracks The risk of stiffening of the stiffener due to excessive stress is avoided.

When a bending test was performed to gradually increase the load applied to the slab made according to the present invention, the slab of the present invention surprisingly allowed large bending before breaking, and the crack was relatively narrow. Has been observed.
Furthermore, as described in Patent Document 1 (French Patent Application No. 2,814,480), the entire thickness of the slab can be reduced by using a flat strip as a reinforcing material. That is, stirrups composed of flat strips (which may be twisted if necessary) can be welded to the inner surface of each of the strips, and the outer surface of each strip is ordered from the surface 20 of the slab. It suffices to separate by a minimum covering distance determined by.

  In a reinforced concrete member manufactured by a conventional method, it is necessary to curve both ends of a longitudinal tension rod in the shape of a cross head in order to increase the transmission length of the force between the reinforcing material and the concrete. However, considering the hardness of the steel used, the degree of curvature imparted to the rod is inevitably limited, and the rule is that the curvature diameter of the crosshead be at least 10 times the rod diameter. Therefore, the concrete member must have a minimum thickness of 20 times the diameter of the tension rod, and must add a minimum thickness that is twice the minimum covering thickness.

  Even when the flat rod of the present invention is used, the crosshead 5 can be provided at both ends of the rod as shown in the projection view of FIG. 5, but the inner diameter D of the crosshead 5 is a round rod (a plurality of rods). However, it can be made smaller than in the case of (may be). This is because the thickness e of a flat rod having a rectangular cross section is smaller than the diameter of a round rod having the same cross section.

  Furthermore, when a flat rod is used, the diameter D of the curved portion can be further reduced by using steel with high elastic strength. That is, it can be easily bent around the axis 50 parallel to the wide surface of the band. Furthermore, as shown in FIG. 20, the thickness of the slab 1 can be further reduced by rotating the crosshead around the vertical axis. As a result, when the weight of the reinforcing material is the same, a member thinner than a member that can be conventionally made of reinforced concrete can be made. Furthermore, each crosshead 5 also becomes a tightening region B1 in the concrete 2.

  In the present invention, the longitudinal reinforcement is anchored to the concrete to a certain extent within the tightening regions 43 and 5 and the central portion 44 can freely extend, so that the stress applied to the concrete via the reinforcement is the conventional reinforcement. (In this case, it was required to connect over the entire length of the reinforcing material). It is clear that this means that the compressive stress in the concrete is greater in the tightening region, more precisely that the concrete exhibits excellent compressive strength.

Furthermore, since the width l of each flat rod can be determined with respect to the load applied so that the compressive stress of the concrete does not exceed a predetermined limit value, there is no danger of the shearing action of the concrete as in the case of a round rod.
If the strip 4 is subjected to a large tensile stress T (which is absorbed by the clamping area B1 inside the crosshead 5), if the adhesion between the strip 4 and the concrete is not sufficient, the crosshead 5 May return.

In order to avoid this phenomenon of winding back, an auxiliary crosshead 51 facing slightly in the opposite direction and having a slightly smaller diameter can be added to the crosshead 5.
Furthermore, in the preferred embodiment shown in FIG. 1, it is noted that the wider surface 41 of each tension rod 31 comprising a flat strip 4 is oriented substantially parallel to the tension surface 20 of the concrete member. I want to be. In this arrangement, the resistance of the flat strip 4 to bending is small, and the flexure of the concrete member appears only in the elongation of the reinforcement, thus increasing the flexibility of the slab.

  However, in order to reinforce the bending strength, it is also possible to use a band 4 having an orientation as shown in FIG. In such a case, each reinforcing band 4 is twisted by two portions 43 and 43 'spaced apart from each other, but twisted by a quarter turn, and the central portion 44' has a wide band body 4 over its entire length. The side surface 41 is arranged in a plane perpendicular to the tension surface 20 of the concrete member.

  In this case, the tightening of the band 4 in the concrete is realized substantially at the areas B1 and B1 ′ inside the cross heads 5 and 5 ′ provided at both ends of the band 4, and the tightening portion 43 , 43 ′ has a small tightening effect. On the other hand, the central portion 44 ′ of each reinforcing band 4 is oriented at right angles to the tension surface 20, so that it has a certain bending strength, increases the rigidity of the concrete member, and can reduce the bending caused by the applied load. .

As in the prior art, the longitudinal rods 31, 31 'of the lower web 30 and the upper web 30' can be connected to each other by a stirrup, which is disclosed in the above-mentioned patent document 1 (French patent application No. 2). , 814, 480), which is advantageously formed by a flat corrugated strip 13 which is welded or glued to the longitudinal reinforcement at the top of the corrugation. The
However, when carrying out the method of the present invention, the corrugated band 13 constituting the tension reinforcing member 31 as shown in FIG. 9 is provided so that the central portion 44 of each band 4 can freely extend. It is preferable that welding between the belt member 4 and the belt 4 is performed only in the vicinity of both ends of the concrete member 1.

Conversely, the stirrup can be welded or glued to the compression rod 31 'at the upper portion of each corrugation. For this purpose, it is preferable that each compression rod 31 ′ is formed of at least one flat rod, and a weld bead is formed over the entire width of the corrugated band 13.
Each welding or bonding portion 34 between each rod 4 and the corresponding portion 13 of the stirrup forming an angle with respect to this rod 4 constitutes a tightening region B by a wedge action. Therefore, in this case, it is meaningless to add a twisted portion to the band 4. In this case, it is advantageous to bend both ends into the shape of the cross head 5 and to provide tightening regions B1 and B1 ′ at both ends of the reinforcing material 31 as in the previous case.

  The present invention can be modified in addition to the above. In particular, the support load applied to the concrete by the tightening region of the longitudinal reinforcement can be fully utilized. For example, various modifications conceptually shown in FIG. 10 to FIG. 20 can be made. In these figures, the compression reinforcement 31 'is not shown for the sake of simplicity.

In the first modification shown in FIG. 10, the lower web 30 of the reinforcing cage 3 is composed of two overlapping levels. At the lowest level closest to the lower tension surface 20 of the concrete member, each sector of the reinforcement cage has a longitudinal reinforcement 31 consisting of a flat strip extending over the entire length of the concrete member 1. Both ends 5, 5 'of the longitudinal reinforcing member 31 are curved in the shape of a cross head as described above.
This longitudinal rod 31 is combined with a second level longitudinal rod displaced upward. This second level longitudinal rod cage has two rods 33, 34 in each sector, each rod 33, 34 being formed of a flat strip and arranged side by side. Each rod 33, 34 has a curved end 51, 51 ', 52, 52' in the shape of a crosshead.

  Further, the band bodies 33 and 34 combined in the same sector are shifted in the vertical direction, and the two cross heads 51 and 51 '(52 and 52') formed at both ends of each band body 33 (34) are They are arranged at different distances from the transverse intermediate surface Q of the concrete member 1 on both sides of the transverse intermediate surface Q. That is, the outer cross head 51 of the rod 33 arranged on the left side of [FIG. 10] is further away from the intermediate surface Q than the outer cross head 51 ′ of the same strip 31 arranged on the right side. In the case of two longitudinal strips 34 this arrangement is reversed. On the other hand, the lengths of the longitudinal rods 33 and 34 are such that the cross heads 5, 51, 52 arranged on the same side of the transverse intermediate surface Q are only a certain length of the concrete member 1 from the end 11 of the concrete member 1. To be distributed.

Accordingly, the concrete member 1 is divided into a plurality of adjacent areas:
(A) A central region B3 between the inner crosshead 51 ′ of the longitudinal reinforcing member 33 disposed on the right side of the transverse intermediate surface Q and the inner crosshead 52 of the reinforcing member 34 disposed on the left side of the surface Q. .
(B) Two lateral regions B2 and B2 ′ arranged on the left and right sides of the intermediate surface Q (the left region B2 is a region between the outer crosshead 51 of the band 33 and the inner crosshead of the rod 34). Yes, the right region B2 ′ is a region between the outer crosshead 52 ′ of the band 34 and the inner crosshead 51 ′ of the rod 33).
(C) Two end regions B1 and B1 ′ between the crossheads 5 and 5 ′ of the lower band 31 and the outer crossheads 51 and 52 ′ of the upper bands 33 and 34, which are arranged on the left side and the right side, respectively. .

When a load that bends the concrete member 1 downward is applied to the concrete member 1, the longitudinal reinforcement is subjected to tensile stress and is in contact with and supported by the concrete via both ends in the shape of a crosshead. Distorted.
Since the longitudinal reinforcing members 33 and 34 that overlap each other in the central portion of the concrete member extend in different directions, the central tightening region B3 is compressed by the tendency of the inner crossheads 51 'and 52 of the reinforcing members 33 and 34 to approach each other. Is done.

Similarly, the outer cross heads 51 and 52 ′ tend to approach the intermediate surface Q by the action of tensile stress applied to the rods 33 and 34, and the lateral regions B 2 and B ′ 2 are compressed by this tendency.
For the same reason, the end regions B1 and B′1 are also compressed by the crossheads 5 and 5 ′ that react to the tensile stress applied to the reinforcing material 31.

Therefore, the concrete member 1 is compressed over its entire length due to the tendency of the crossheads of the various reinforcements to approach each other inwardly, this compression phenomenon being limited by the crosshead and, further, the neutral axis 10 as usual over the full thickness of the concrete. Also works on top.
Therefore, the risk of cracking of the concrete member in the vicinity of the tension surface 20 is greatly reduced. Furthermore, it has been found from load tests performed on concrete members of the above structure that the concrete members are subjected to very large deflections that are not so common in reinforced concrete members before breaking.
In the above embodiment, the compression of the central region B3 of the concrete member between the inner cross heads 52, 51 'of the strips 33, 34 combined with each other occurs by superimposing these strips 33, 34, and the transverse intermediate plane It occurs in opposite directions on both sides of Q.

However, the tension reinforcement of the cage 3 can also be formed by simply stacking longitudinal strips of different lengths as shown in FIG. The first strip 35 extends over a length l ₁ that is slightly shorter than the length of the concrete member, the second strip 36 extends over a length l ₂ that is shorter than l ₁ , and the end of each strip is the inner side of the concrete member. It looks like a crosshead facing the

Also in this case, the concrete is compressed by the cross heads 5, 5 ′, 51, 51 ′ that absorb the bending stress of the concrete member and the tensile stress applied to the bands 35, 36.
From this point of view, it is advantageous to realize the compressive stress applied by the crosshead with a plurality of metal strips having different mechanical characteristics in order to adjust as a function of the distribution of the load applied to the concrete member.
It will be understood that the elastic modulus can be easily changed if a flat strip is used as the reinforcing rod. That is, a flat strip can be made by cutting a metal plate, and metal plates with various characteristics are commercially available, but with concrete round rods there are fewer possible choices than a flat strip .

Further, in contrast to the usual technique that attaches importance to connecting the reinforcing material and the concrete covered with the reinforcing material, the two laminated belt bodies 31 and 35 can be arranged in contact with each other. The body behaves like a leaf spring.
[FIG. 12] [FIG. 13] shows a modification of the embodiment of [FIG. 10]. In this variant, two adjacent strips 33, 34 consist of a single strip forming a closed loop and the opposing crossheads 51 ′, 52 are made of a strip portion 37 at the upper level 30 ′ of the cage 3. It has been.

Each longitudinal reinforcement is formed by a single strip 33, 37, 34 surrounding the core of concrete B3, which concrete cores 33, 34 when the member 1 is subjected to a vertical load. The loop formed in this manner is compressed by the action of tensile stress applied in opposite directions to each other.
In this case, it should be understood that the upper portion 37 of each longitudinal reinforcement forming the loop or the portion of the upper web 30 'of the reinforcement cage 3 can be constructed.

  On the other hand, in the case of [FIG. 10], as shown in [FIG. 12], the mutually facing cross heads 51 'and 52 for compressing the concrete core B3 are not necessarily symmetrically separated on both sides of the transverse intermediate surface Q of the member 1. There is no need to place them. That is, the portion of the concrete member 1 in which the tensile stress generated in the concrete by the applied load becomes maximum can be determined according to the load mode applied to the concrete member, and the reinforcing material is compensated so that at least a part of the tensile stress generated by the load is compensated. And its crosshead can be arranged and compensated by the compressive forces in opposite directions in the same region applied to the concrete core between the two crossheads by tensile stress.

In each of the above figures, the sector of the reinforcing cage generally located at the center of the vertical plane parallel to the longitudinal axis and the crosshead formed on the reinforcements of two adjacent sectors are positioned at approximately the same height. is doing. Accordingly, the transverse tie rod 32 that receives inward stress passes through the aligned clamping region of sectors S ₁ , S ₂ , S ₃ . These tie rods distribute the compressive stress applied by the crossheads 5, 51, 52 onto the concrete between two adjacent sectors. These distributed transverse rods can have a circular or rectangular cross-section as shown. However, the use of a flat rod can easily create a weld bead between the longitudinal and transverse rods.

  In another embodiment conceptually shown in FIG. 14, each longitudinal tension reinforcement 6 of the cage 3 is composed of a series of a plurality of strips 6a, 6b,. A pair of crossheads 5'a and 5b adjacent to each other of two continuous strips 6a and 6b having two curved ends in the shape of 'a, 5b and 5'b are located at substantially the same level. Are slightly overlapped so as to surround the space E. In this space E, a rod 38 constituting a lateral dispersion rod can be inserted.

Each rod 38 inserted into the space E compressed by the two opposing cross heads 5'a and 5b constitutes a connecting pin between the two continuous strips 6a and 6b. Each longitudinal reinforcement 6 composed of a series of a plurality of strips 6a, 6b, 6c... Behaves like a chain. The chain links 6a, 6b, 6c,... Are tensioned under the action of a load applied to the concrete member 1.
The present invention is not limited to the details of the above embodiments, and other modifications can be made without departing from the scope of the present invention.

  For example, it is possible to obtain each tightening region simply by using a lateral rod inserted into an opening formed in the longitudinal reinforcing rod. That is, as shown in FIG. 17, the flat rod 4 is used as a longitudinal reinforcing rod, and a central hole 45 is formed in the flat rod. This central hole 45 extends over a certain length and defines two lateral portions 46, 47. By opening the lateral portions 46 and 47 away from each other, an opening 45 ′ for passing the lateral rod 48 can be opened. For example, when tensile stress is applied to the band 4 in the direction of the arrow in FIG. 16, the band 4 is supported by the lateral rod 48, which is supported in the concrete, and the band 4 is tightened. Realize.

In the case of FIG. 16, both parts 46, 47 of the strip extend in a state supported on the plane of the strip, so that the transverse rod 48 is perpendicular to this plane.
However, as shown in FIG. 17, it is also possible to place both portions 46, 47 apart from each other at right angles to the surface S of the strip and insert a lateral rod 48 there. In this case, the transverse rod 48 is parallel to the plane of the strip. This rod constitutes a lateral dispersion rod 32 between the sectors of the reinforcing cage.

When the band is twisted to form the tightening region, a central hole can also be formed in the twisted portion 43. As shown in FIG. 18, the central hole allows the two portions of the band to be separated from each other and an opening 45 ′ for inserting the lateral dispersion rod 32 can be formed.
Furthermore, as shown in FIG. 19, the tightening action of the crosshead 5 can be enhanced by providing the orifice 45 ′ for inserting the lateral rod 52 in both portions of the crosshead 5. The transverse rod 52 further prevents the crosshead from being unwound by the action of tensile stress applied to the band 4.

  Furthermore, it will be understood that by using the flat rod 4 as a longitudinal reinforcing rod, the orientation of the crosshead provided at the end of the rod can be changed. In general, since the flat rod 4 can be easily bent around an axis parallel to the surface thereof, as shown in FIG. 20, the end of the band 4 is twisted by 1/4 turn, and the crosshead 5 is moved to the vertical axis. It can be made by bending around 50. In this case, the same tightening action can be obtained by limiting the height of the crosshead to the width e of the band 4. This arrangement is particularly advantageous when manufacturing thin members, such as narrow slabs at both ends. In particular, by using the flat strip 4, the flat strip 4 can be changed in direction as necessary, for example, as shown in FIG.

As already mentioned, it is advantageous to make a compression stiffener 31 'in the form of a flat strip, but for economic reasons ordinary rods can also be used. However, it will be appreciated that the benefits provided by the use of a flat rod more than make up for the additional cost of the reinforcement.
From this point of view, it is advantageous to make the rod from stainless steel. Stainless steel can secure corrosion strength even when the exterior thickness is reduced, and has high ductility to enhance fatigue strength and energy absorption capability. This advantage is particularly important in civil engineering structures because of the ability to withstand uneven settlement and, in some cases, resistance to earthquake shocks.

  Although slabs or flat beams are shown for simplicity of illustration, the use of flat strips as reinforcing rods has many advantages in the manufacture of curved and warped concrete members. I understand. That is, a flat strip having a wide side parallel to the facing surface of the concrete member can be easily matched to the curved cross-sectional shape of the concrete member.

In particular, it is possible to create a flat reinforcing cage that can be used for curved concrete members, and when the reinforcing cage is placed in the mold, the cross-sectional shape of the bottom of the mold can be naturally taken by its own weight.
The flat strips constituting the longitudinal and lateral reinforcements can also be curved in opposite directions to match a cross-sectional shape that is laterally warped, such as a curved surface having non-parallel transverse buses. This is the case, for example, in the case of the exterior of a bridge tilted laterally at various angles from one end to the other, and this reinforcement is difficult to manufacture by conventional methods.

In addition, since a flexible concrete member capable of allowing a considerably large deflection can be manufactured, the present invention is particularly suitable for manufacturing a submerged passage structure having a curved cross-sectional shape. This dike passage structure can be slightly deformed under a load applied so as to abut against the dike laterally at both ends thereof.
Furthermore, as mentioned above, the clamping area between the clamping areas where the concrete is compressed can be placed at a position determined by calculation, where the concrete is subjected to the maximum tensile stress and the risk of cracking is maximized. It is a place that becomes. Therefore, the present invention can be adapted from a typical model to a predictable stress distribution taking into account the load applied to the reinforcement of each concrete member.

For example, in a slab or beam that is uniformly weighted in the vertical direction, a central region where the tensile stress applied to the lower surface is maximum, two lateral regions where the slab is subjected to shear stress, and two support ends can be distinguished. However, as already mentioned, the arrangement of the compression regions does not necessarily have to be symmetrical with respect to the intermediate surface of the concrete member.
According to the present invention, the reinforcing material can be matched to the main load to be absorbed by each part of the concrete member without complicating the reinforcing material. That is, the tension is compensated by the compressing action of the concrete so that the tightening region comes to the most stretched portion by appropriately changing the direction of the flat band constituting the reinforcing material.

Further, as described above, the tension band is oriented in the vertical direction as shown in [FIG. 8] to increase the bending strength, or the band is inclined as shown in [FIG. 20] to optimize the shear stress. It is possible to resist, or to create a horizontal crosshead as shown in FIG. 20 to reduce the thickness of the member at the support point, and these various variations can be combined.
Furthermore, as already mentioned, the compression zones need not be arranged symmetrically with respect to the intermediate surface of the concrete member.
Therefore, the shape of the reinforcing cage can be changed by the arrangement of the present invention, and the action of the reinforcing material can be adjusted and changed as a function of the load applied to the concrete member during use.

The conceptual longitudinal cross-sectional view of the concrete member manufactured according to this invention. FIG. 2 is a partial cross-sectional view taken along line II-II in FIG. 1. The projection figure of the twist part of a reinforcing material. Sectional drawing by the cross direction intermediate surface of a twist part. The partial projection figure of the part in the shape of a crosshead. The partial side view of a double crosshead. The longitudinal cross-sectional view of the concrete member manufactured according to another Example of this invention. The projection figure of the twist part applied to the Example of FIG. The longitudinal cross-sectional view of the concrete member manufactured according to the further another Example of this invention. The longitudinal cross-sectional view of another Example of this invention using a some reinforcement layer. The longitudinal cross-sectional view of another Example of this invention using a some reinforcement layer. FIG. 11 is a longitudinal sectional view of a concrete member of the type shown in FIG. 10 using a closed loop reinforcing material. Projection view of closed loop reinforcement. FIG. 4 is a longitudinal sectional view of another embodiment of the present invention using a chain-shaped reinforcement. FIG. 15 is a projected view of a joint between two reinforcement elements of the type shown in FIG. The projection figure which shows another Example of a fastening area | region. The projection figure which shows another Example of a fastening area | region. The projection figure which shows another Example of a fastening area | region. FIG. 3 is a projected view of a tightening area in the shape of a crosshead. FIG. 5 is a projection view of another embodiment of one end of a crosshead shaped reinforcement.

Claims (12)

During the casting of the concrete have a concrete (2) reinforcing cage (3) which is embedded in, concrete member (1), when subjected to a load, two portions on either side of the neutral axis, i.e., primarily concrete ( a compression portion for receiving a compression stress that is absorbed by 2), and a tensioning portion which receives a tensile stress absorbed mainly at least one longitudinal tension reinforcement of the reinforcing cage (3) by (31), concrete part ( 1) deforms when subjected to a load, and cracks occur in the concrete (2) due to the extension of the stretched part. The longitudinal reinforcement (31) of the concrete member (1 ) is narrower than the wider surface (41) And at least one flat strip (4) having a lateral surface (41 '), the strip (4) having a cross section sufficient to absorb the maximum stress within the elastic range The twisted portion (43, 43 ') is made by gradually changing the direction of the wider surface (41) of the strip (4) little by little, and the strip (4) A method for producing a concrete member (1) having a straight central part (44) between two twisted parts (43, 43 ') ,
Each of the two twisted portions (43, 43 ′) forms a fastening region (B, B ′), which is the wider surface 41 of the band (4). So that the width of the wider surface (41) of the strip (4) does not exceed the predetermined limit of compressive stress. The central portion (44) between the two twisted portions (43, 43 ') is separated from the concrete covering it when it exceeds a predetermined limit value, and freely moves relative to it. A method characterized in that stress can be evenly distributed over the entire length (L2) of the central portion (44), the longitudinal reinforcement (31) can be stretched, and the concrete can be prevented from breaking . The twisted portion (43, 43 ') of the band (4) is at least 1 little by little with the wider surface (41) of the band (4) as the center in the longitudinal axis (40) of the band (4). The method according to claim 1, wherein the method is made by twisting / 4 rotation . 3. A method according to claim 2, wherein the twisted portion (43) of the strip (4) is twisted by making a complete rotation about the longitudinal axis (40) of the strip (4) . One end of the flat strip (4) is bent around the transverse axis (50) to form an anchor crosshead (5) held in the concrete by the wider face (41). each clamping region (5) (B, B ' ) the method according to claim 1 to make. 5. A reinforcement cage having two longitudinal reinforcements for tension (31) and compression (31 ') is made, and the compression longitudinal reinforcement (31') is also made from a flat strip. The method according to one item . The strip (4) forming the longitudinal tension reinforcement (31) is cut open in the axial direction over a certain length at the twisted portion (43, 43 '), and the two portions (46, 47) are separated from each other to form an opening (45 ′) for inserting at least one rigid rod portion (48), which rigid rod portion (48) forms a longitudinal reinforcement (31). The method according to claim 2 or 3 , wherein the concrete (2) is abutted against the tensile stress applied to (4). Each longitudinal tension reinforcement consists of a plurality of flat rods in the form of strips (4) superimposed on each other at least two levels, the first level of which is the longitudinal tension surface (20 of the concrete member (1)) This first level has at least one tension flat rod (35) with ends in the form of cross-heads (5, 5 ') facing inward, which is substantially the same as the concrete member (1). At least one flat rod (36), which extends over the entire length and is shorter than the lower level rod (35) in at least one second level, is arranged, both ends of the flat rod facing inward (51, 51). ') And arranged longitudinally apart from each other on both sides of the transverse intermediate plane, the compression region (B3) between the crossheads (51) and (51') and at least two lateral sides Compression region (B2, B'2) the method according to claim 4, divided by the cross-head (5,5 ') of the lower level of the rod (35). Each longitudinal tension reinforcement is formed of a laminate of at least two flat rods abutting each other along the wider side, and the overall cross section of the laminate is determined with respect to the applied stress, and the laminate 8. A method according to any one of claims 4 to 7, which has the same tensile strength as a single bar of the same size and resists deformation like a leaf spring . The method according to claim 7 or 8 stacked flat rods (35, 36) have different mechanical characteristics from each other. Each longitudinal tension reinforcement is formed of a plurality of continuous strips (6a, 6b,...), Each strip having the shape of a crosshead (5a, 5′a) (5b, 5′b). The crossheads adjacent to each other of two continuous strips (6a, 6b) are arranged to partially overlap each other, and a connecting pin is provided between the continuous strips (6a, 6b). A space E for inserting at least one rigid rod portion (58) to be formed is defined in the transverse direction, and the longitudinal reinforcing member is a tension chain comprising a plurality of links formed by strips (6a, 6b,...). The method according to claim 4, wherein each link is connected two by two by a pair of adjacent crossheads (5a, 5'a) (5b, 5'c) fixed by pins. Horizontal by directional spreading rod (32) forming a reinforcing cage that have at least two sectors being connected to one another, together crosshead reinforcements of two adjacent sectors (5,51,52,6) concrete member ( 1) is arranged at substantially the same level inside, and the transverse dispersion rod (32) is inserted into the crosshead (5, 51, 52, 6) and the whole of the concrete (2) arranged at that level. The method according to claim 4 , wherein the compression is performed.
Described in. The reinforcement cage, placed in the interior of the mold or mold having a curved bottom, concrete to produce a member that is curved by casting poured into a mold, the reinforcing cage (3) a flat using a flat strip body 12. A method according to any one of the preceding claims , wherein the reinforcing cage (3) is sufficiently flexible and is placed in the mold so that it forms a curved shape at the bottom of the mold with its own weight.

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