JP2006009361A - Concrete member and reinforcement method for concrete member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete member and a reinforcement method for the concrete member capable of reducing the effect of constraint on the self-shrinkage and dry shrinkage of a concrete member formed of a fiber-reinforced cement based mixed material, suppressing the occurrence of crazing, and effectively increasing tensile strength characteristics and bending strength characteristics. <P>SOLUTION: This concrete member 1 formed of the fiber-reinforced cement based mixed material comprises fixed plates 3 and 3 and hollow members 5 and 5 near both ends of a tensile reinforced material formed of a tendon such as a round steel, a PC steel bar, or a PC steel strand. Elastic members 4 and 6 are fitted to one side faces 31 and the end faces 51 of the fixed plate 3 and the hollow member 5 on the concrete member end side. The fixed plate 3 and the hollow member 5 are manufactured in the buried state in the concrete member 1. When the tendon is used as the tension reinforced material 2, the concrete member 1 can be reinforced by a pretension system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a concrete member made of a fiber-reinforced cementitious mixed material and a method for reinforcing the concrete member, and in particular, can suppress the occurrence of cracks during self-shrinkage and drying shrinkage of the cementitious matrix, thereby improving bending strength. The present invention relates to a concrete member and a method for reinforcing a concrete member.

Cement-based mixed materials, which are construction materials such as beams, floor slabs, and columns that make up a concrete structure, are adapted to the increase in required levels of seismic resistance, durability, workability, etc. required for structures. Material properties are developing dramatically. Among them, fiber-reinforced cement-based mixed materials have a low water / cement ratio, ultra-high strength with a high compressive strength of 200 N / mm ² or more, and improved tensile strength by using fiber reinforcement without using reinforcing bars. The frequency of use is increasing due to its excellent material properties. Concrete members using such fiber-reinforced cement-based mixed materials can have a thin-walled cross section. For example, they can be used for girders such as bridges and floor slabs to reduce dead loads and narrow the occupied area by concrete members. Can be realized. Furthermore, since no shear reinforcing bars such as deformed bars are required, the construction period can be shortened by eliminating the need for reinforcing bars in addition to the thin wall cross section as described above, and poor wraparound of cement-based mixed materials It is possible to eliminate problems such as quality degradation due to Furthermore, by introducing prestress when such a fiber reinforced cementitious mixed material is used, it is possible to effectively exhibit the high compressive strength characteristics of the material, and therefore, it has high bending strength and shear strength. It becomes possible to obtain a concrete member economically.

  By the way, in the concrete member made of the above-mentioned fiber-reinforced cement-based mixed material, a tensile reinforcing material such as a reinforcing bar is usually not embedded, and it is generally used as a compression member having particularly excellent compressive force as a cross-sectional force. there were. An example of a concrete member with excellent compressive force is a tunnel support. The reason why a concrete member made of a fiber reinforced cementitious mixed material is used as the above-mentioned compression member is partly because of the positive reason for effectively utilizing its high compressive strength characteristics. Another reason is that it is suitable for compressive strength characteristics by adopting a structure that does not place the reinforcement inside the concrete in order to prevent the deformed reinforcing bars from obstructing the orientation of the metal fibers contained in the inside. This is due to the negative reason that it does not have only bending strength characteristics. In addition, the inventor has disclosed an invention relating to a typical segment as a tunnel support among the concrete members manufactured from the fiber reinforced cementitious mixed material in Patent Document 1.

  An attempt has been made to improve not only the compressive strength property but also the tensile strength property by arranging the inside of the concrete member made of the above-mentioned fiber reinforced cementitious mixed material. As means for improving the bending strength of beams and floor slabs using fiber reinforced cementitious mixed materials, there can be considered means for disposing deformed reinforcing bars as tensile main reinforcing bars as in the case of conventional reinforced concrete members. By using deformed reinforcing bars, sufficient adhesion strength can be expected between the deformed reinforcing bars and the cementitious matrix, so that it is possible to exert sufficient tensile stress on the deformed reinforcing bars.

  In addition, a tension material such as a PC steel rod or a strand of PC steel is used as a tensile reinforcement, and is embedded in a fiber-reinforced cement-based mixed material in a state in which a tensile force is previously introduced. A pre-tension method in which pre-stress is introduced by releasing tension after waiting for curing, or a post-tension method in which pre-stress is introduced by a tension material after the fiber-reinforced cement-based mixed material is cured may be employed. By introducing prestress with a tension material, a compressive force can be applied to the concrete member in advance, and a concrete member having high bending strength and shear strength can be produced.

JP 2003-293698 A

  When manufacturing concrete members using cement-based mixed materials, especially fiber-reinforced cement-based mixed materials, a structure in which deformed rebars are arranged inside them provides sufficient adhesion between the deformed rebars and the cement-based matrix. Since strength can be expected, cracks can be dispersed and the crack width can be controlled to be small, and the deformed reinforcing bar can serve as a tensile reinforcement. Accordingly, it is possible to improve the tensile strength characteristics of the concrete member made of the fiber reinforced cementitious mixed material. However, the ultra high strength fiber reinforced cementitious mixed material has the disadvantage that self-shrinkage increases when the cementitious matrix congeals due to the small amount of aggregate particles in addition to the large amount of cement. Therefore, when deformed reinforcing bars are arranged to increase the bond strength, the deformed reinforcing bars restrain the self-shrinkage of the cement-based mixed material, and tensile stress remains in the cement-based matrix. There is a problem that cracks are easily induced during curing of the system mixed material.

  Therefore, it is conceivable to use a tensile reinforcement made of a round steel having a circular cross section or a PC steel wire having a stranded wire section instead of disposing a deformed reinforcing bar having a high adhesion strength. However, when such a tensile reinforcing material is used, the restraining effect of the self-shrinkage of the cement-based mixed material can be eased, but this time the adhesion strength between the tensile reinforcing material and the cement-based mixed material is reduced, and the tensile reinforcing material There is a problem in that the bending strength of the concrete member cannot be improved by causing the adhesion breakage to occur before sufficient tensile stress is applied to the material and causing slippage between the tensile reinforcement and the cementitious matrix. Can occur.

  It is possible to produce a concrete member having high bending strength by using a tension material such as PC steel wire or PC steel wire as a tensile reinforcement and introducing tension force by a pretension method. However, in this case, sufficient adhesion cannot be obtained in the vicinity of the end of the concrete member, and therefore slip is easily induced between the tensile reinforcement and the cementitious matrix. There may be a problem that sufficient prestress is difficult to be introduced into the cement-based matrix. In the general design stage, from the end of the concrete member to the distance of about 60 times the diameter of the tensile reinforcement, a design method such as adopting a prestress introduction distribution as a triangular distribution in consideration of the above prestress introduction failure Has been taken. Furthermore, when pre-tension is introduced into the tensile reinforcement and the pre-stress is released after hardening of the cementitious mixed material, splitting fracture occurs between the tension material and the cementitious matrix near the end of the concrete member, causing cracks. There is also a possibility that.

  When using a post-tension method instead of the pre-tension method when manufacturing a concrete member using a fiber-reinforced cement-based mixed material, the tensile reinforcement as described above, which was a problem in the pre-tension method, is used. Problems such as induction of slip between the material and the cementitious matrix and reduction of prestress at the end of the concrete member are less likely to occur. However, in the post-tension method, the fixing bracket at the end of the concrete member is expensive, it takes time to grout into the sheath tube after the pre-stress is introduced, and the rust prevention treatment of the fixing bracket is required. There may be a problem that the cost is increased as compared with the pretension method.

  As described above, when manufacturing concrete members using cement-based mixed materials, especially fiber-reinforced cement-based mixed materials, the conventional method of disposing deformed reinforcing bars and the tension material are pre-tensioned. Also, the methods such as adopting the post-tension method have their own problems, and all of them are effective as measures for improving the tensile strength properties and bending strength properties of concrete members made of fiber reinforced cementitious mixed materials. The current situation is not right.

  The concrete member and the concrete member reinforcing method of the present invention have been made in view of the above-mentioned problems, and can reduce the restraining effect on the self-shrinkage and drying shrinkage of the fiber-reinforced cementitious mixed material, and thus suppress the occurrence of cracks. An object of the present invention is to provide a concrete member and a method for reinforcing the concrete member. Moreover, it aims at providing the reinforcement method of the concrete member which can improve the tensile strength characteristic of a concrete member, and a concrete member. Furthermore, even when the pre-tension method is adopted, the prestress introduced at the end of the concrete member can effectively act as a compressive stress, and therefore the prestress introduced stress should be effectively considered in the design up to the end of the member. It aims at providing the reinforcement method of the concrete member which can be performed.

  In order to achieve the above object, a concrete member according to the present invention is a concrete member constituting a concrete beam or floor slab in which a tensile reinforcing material such as a reinforcing bar is embedded, and the concrete member is fiber reinforced. The fixing plate is provided with a fixing plate in the vicinity of both ends of the tensile reinforcing material, and an elastic material is provided on one side surface of the fixing member end side of the fixing plate. The elastic material is embedded in the concrete member.

  Here, the fiber-reinforced cement-based mixed material refers to a cement-based mixed material whose performance such as tensile strength, bending strength, and toughness is improved by mixing metal or synthetic resin fibers into the cement-based mixed material. . The fiber-reinforced cement-based mixed material used in the present invention preferably has a high fluidity and a slow setting time. Examples of the fiber-reinforced cement-based mixed material include (1) cement, (2) aggregate particles having a maximum particle size of 5 mm or less, preferably 2 mm or less, and (3) a particle size of 1 μm or less, preferably 0.8. A cementitious matrix obtained by mixing pozzolanic reactive particles of 5 μm or less and (4) a composition containing at least one dispersant with water, has a diameter of 0.05 to 0.3 mm, and a length. It is possible to use an ultrahigh strength cement-based mixed material reinforced with fibers obtained by mixing fibers of 8 to 16 mm (chemical fibers such as metal fibers or vinylon fibers) with a volume of about 1 to 4%. .

  In conventional beams or floor slabs made of reinforced concrete or prestressed concrete, reinforcing bars or tension materials are arranged at least in the longitudinal direction of the members in order to increase the tensile strength or bending strength of the members. The concrete member of the present invention is made of a fiber-reinforced cement-based mixed material, and the concrete member is connected to, for example, a steel fixing plate in the vicinity of both ends (including both ends) of a tensile reinforcing material made of a rod-shaped reinforcing bar or a tension material. It is manufactured by embedding a tensile reinforcing material and a fixing plate inside the member. Here, for the connection between the tensile reinforcing material and the fixing plate, an appropriate connection method such as welding or pressure bonding can be selected, and a through hole is formed in the fixing plate, and the tensile reinforcing material is passed through the through hole. It is also possible to perform welding or pressure bonding in a heated state. In addition, an elastic material made of a soft resin such as rubber such as synthetic rubber or foamed urethane or styrene or foamed polystyrene is bonded to one side surface of the fixing member on the side of the concrete member.

  When using a tension member such as a PC steel rod or a strand of PC steel as a tensile reinforcement, the tension may be introduced in advance to the tension member, or the tension may not be introduced. May be. The concrete member may be a spot-cast concrete member that is directly constructed on site, but is preferably a precast product that is pre-manufactured in a factory or on-site production yard.

  By adopting a configuration in which an elastic material is provided on one side surface of the fixing plate, it is possible to relieve the fixing plate from excessively restraining the shrinkage when the cementitious matrix is self-shrinking. That is, when the concrete member self-shrinks, the cement-based matrix shrinks and moves toward the center of the member, so that the entire member shrinks. In a state where only the fixing plate is embedded in the concrete member, the fixing plate protruding from the tensile reinforcement material restrains the shrinkage movement of the cement matrix on the surface of the fixing plate, and accordingly, accompanying the self-contraction. The possibility of cracking becomes extremely high. By providing an elastic material on one side surface (concrete member end side) of the fixing plate as in the present invention, the shrinkage movement of the cementitious matrix can be absorbed by the deformation absorbing action of the elastic material. Since there is no excessive restraint, the possibility of cracking during self-shrinkage of the cementitious matrix can be made extremely low.

  As another embodiment of the concrete member according to the present invention, the fixing plate is provided with a through-hole through which the tensile reinforcing material can pass, and one side surface of the fixing plate on the end side of the concrete member. Each includes a hollow member that can be fixed to the tensile reinforcement member, and an elastic member is provided on each of the end surfaces of the concrete member on the end side of the concrete member, and the tensile reinforcement member is a through hole of the fixing plate. Further, the hollow member is connected to the hollow member through the hollow member, and the hollow member is embedded in the concrete member.

  A through-hole through which the tensile reinforcing material can be penetrated is formed in the fixing plate, and the through-hole and the hole of the hollow member are aligned, and both are welded or pressure bonded. The tensile reinforcing material and the fixing plate can be integrated by connecting the tensile reinforcing material to the hollow member in a state of passing through the through hole and the hollow member. For example, when a PC steel wire is used as the tensile reinforcing material, the tensile reinforcing material and the fixing plate can be integrated by pressing the PC steel wire to the hollow member.

  Moreover, it is set as the structure which adhered or apply | coated the elastic material to the end surface of the concrete member end side among hollow members similarly to a fixing plate. As such an elastic material, a fixed rubber elastic material or a soft resin elastic material can be used in the same manner as the elastic material adhered to the fixing plate. The reason for adhering the elastic material to the end face of the hollow member is to prevent the self-shrinkage of the cementitious matrix from being excessively restricted as in the case of the fixing plate.

  In the case where the hollow member having a predetermined extension in the longitudinal direction of the tensile reinforcement member and the tensile reinforcement member are connected as in the present invention, the end portion of the tensile reinforcement member is directly bonded to one side surface of the fixing plate. In comparison, the connection strength between the hollow member and the tensile reinforcing material can be increased, and therefore the connection strength between the tensile reinforcing material and the fixing plate can be increased via the hollow member.

  As another embodiment of the concrete member according to the present invention, a thread groove is formed on the inner surface of the hollow member, and can be screwed into the thread groove in the vicinity of the end of the tensile reinforcing material. A thread groove is engraved.

  The present invention is particularly suitable when a reinforcing bar is used as the tensile reinforcement. In this case, a nut can be used as the hollow member.

  In a preferred embodiment of the concrete member according to the present invention, the tensile reinforcing material is round steel.

  When a reinforcing bar is used as a tensile reinforcement, if it is a deformed reinforcing bar, high bond strength can be expected between the reinforcing bar and the cement matrix, but the self-shrinkage of the cement matrix is excessively restricted. This increases the possibility of inducing cracks. Therefore, when using reinforcing bars, it is possible to reduce the possibility of cracking as described above, preferably by using round steel. Moreover, with respect to the problem that the adhesion strength between the round steel and the cement matrix cannot be sufficiently secured by using the round steel, the fixing plate (and the hollow member) is provided in the vicinity of both ends of the round steel. Therefore, it is possible to expect a bearing resistance at the fixing plate. Therefore, even when a bending stress is applied to the concrete member, no slip occurs between the round steel and the cement matrix, and both can integrally exhibit the bending resistance.

  In a preferred embodiment of the concrete member according to the present invention, the tensile reinforcing material is a tension material such as a PC steel bar or a PC steel strand.

  In the case of using a PC steel rod or a PC steel strand, it is not always necessary to introduce prestress into the tensile reinforcement material in advance. When pre-stress is not introduced, the same effect as when using round steel as described above, that is, when bending stress acts on a concrete member, the PC steel rod or PC steel wire can serve as a tensile reinforcement. .

  Furthermore, the method for reinforcing a concrete member according to the present invention is a method for reinforcing a concrete member for reinforcing the concrete member, and is filled with a fiber-reinforced cement-based mixed material in a state in which the tension member previously given a tension force is embedded. And the said tension | tensile_strength is released after predetermined intensity | strength expression is characterized by the above-mentioned.

  The present invention relates to a method in the case where a tension member such as a PC steel rod or a PC steel strand is used as a tensile reinforcement, and a compressive force is applied to a concrete member in advance by adopting a pretension method. Fill the mold with the fiber reinforced cementitious mixed material with the tensioning material in the mold, and release the tension jack when the fiber reinforced cementitious mixed material reaches the specified strength. release.

  By using a PC steel rod or PC steel wire as a tensile reinforcement and adopting a pre-tension method, when the fiber-reinforced cement-based mixed material hardens and reaches a predetermined strength, the tension is released. It is possible to effectively apply a compressive force to the concrete member including the end portion of the concrete member by the support pressure action of the fixing plate provided at the end portion of the tensile reinforcement member. Therefore, it is considered that there is no need to reduce the prestress at the end of the concrete member, which has been performed at the design stage in the conventional pretension system. In addition, since the structure with the fixing plate makes it difficult for local tensile stress to occur at the end of the tensile reinforcement, cracks are generated due to bond splitting that occurred at the end of the tensile reinforcement. Need not be considered. Further, since the fixing plate or the like is not arranged outside the end portion of the concrete member as in the post-tension method, the fixing plate or the like is not required to be rust-proofed, and therefore the manufacturing cost of the concrete member is low. It can be.

  As can be understood from the above description, according to the concrete member of the present invention, the restraining effect on the self-shrinkage and drying shrinkage of the cement-based matrix made of the fiber-reinforced cement-based mixed material can be reduced, and therefore, the occurrence of cracks can be reduced. Can be suppressed. Moreover, according to the concrete member of this invention, the tensile strength characteristic and bending strength characteristic of the concrete member which consists of a fiber reinforced cementitious mixed material can be improved effectively. Furthermore, according to the method for reinforcing a concrete member of the present invention, even when the pretension method is adopted, the prestress introduced at the end of the concrete member can be effectively applied to the member as a compressive force. Accordingly, it is considered that it is not necessary to reduce the introduction prestress at the end of the concrete member at the design stage.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a concrete member of the present invention. FIG. 2A is an embodiment in which a fixing plate and a hollow member are provided in the vicinity of the end portion of the tensile reinforcement member, and FIG. 2B is a perspective view illustrating an embodiment in which a fixing plate is provided at the end portion of the tensile reinforcement member. . FIG. 3 is a side view showing an embodiment in which a fixing plate and a hollow member are provided in the vicinity 21 of the end portion of the tensile reinforcement member 2, but FIG. 3a shows a case where a PC steel strand is used as the tensile reinforcement member. 3b has shown the embodiment at the time of using a round steel. FIG. 4 is an explanatory diagram for explaining the shrinkage of the concrete member during self-shrinkage, and FIG. 5 shows the tensile stress acting on the tensile reinforcement when the bending moment acts on the concrete member and the reaction force against the tensile stress. It is explanatory drawing explaining the bearing stress which acts on a fixing board. In the following description, an I-shaped cross-section girder will be described as a concrete member based on the drawings. However, embodiments of the concrete member are not restricted to such a shape girder, but a rectangular cross-section (solid or hollow) or a U-shape. Of course, in addition to girders (beams) such as cross sections and H-shaped cross sections, appropriate concrete members such as solid floor slabs and hollow floor slabs (hollow slabs) can be selected.

  FIG. 1 shows a precast I-shaped cross girder as a concrete member 1 made of a fiber-reinforced cementitious mixed material. The fiber-reinforced cement-based mixed material to be used is a material in which about 1-4% by volume of metal fibers having a diameter of 0.05 to 0.3 mm and a length of 8 to 16 mm are mixed in the cement-based matrix as described above. Is used. A single tensile reinforcement member 2 is embedded in the upper flange portion constituting the I-shaped cross-section girder and extends to the vicinity of both ends of the I-shaped cross-section girder. Two tensile reinforcement members 2 are embedded in the lower flange portion. Since this I-shaped cross-section girder is manufactured from the above-mentioned fiber-reinforced cement-based mixed material, it has a high compressive strength and has a high cracking prevention effect because it contains metal fibers.

  The structure of the end portion of the tensile reinforcement member 2 will be described in detail with reference to FIG. 2a is an enlarged view of the vicinity of the end of the tensile reinforcement member 2 in the embodiment of FIG. A fixed elastic material 4 is bonded to one side surface 31 on the concrete member end 11 side of the fixing plate 3 in which a through hole 32 of the tensile reinforcing material 2 is formed in the center. The elastic member 4 can be manufactured from, for example, rubber or soft resin material. Further, the hollow member 5 is connected to the one side surface 31 in a state where the tube hole and the through hole 32 are aligned. Note that both the fixing plate 3 and the hollow member 5 can be manufactured from, for example, a steel material, or can be integrally formed at a factory. A fixed elastic material 6 is bonded to an end surface 51 of the hollow member 5 on the concrete member end 11 side. The tensile reinforcing material 2 is connected to the hollow member 5 by being welded or pressure-bonded in a state of passing through the through hole 32 and the hollow member 5.

  FIG. 2 b shows another embodiment of the connection structure between the tensile reinforcement member 2 and the fixing plate 3. In this case, the end of the tensile reinforcement member 2 is attached to the fixing plate 3 in which no through hole is formed. The parts are directly connected (joined by friction welding). In the embodiment of FIGS. 2a and 2b, as the tensile reinforcement member 2 to be used, a reinforcing bar such as a round steel, a tension member such as a PC steel rod or a PC steel strand can be used. In addition, when using a tendon, it can be selected suitably whether prestress is introduce | transduced into this tendon.

  FIG. 3 a is a side view of an embodiment in which a PC steel strand 2 a is used as the tensile reinforcement 2, but the PC steel strand 2 a is connected to the fixing plate 3 and the hollow member 5 in the vicinity 21 of its end. It has become the composition. On the other hand, FIG. 3b shows an embodiment in which a round steel or a PC steel rod 2b is used as the tensile reinforcement member 2, and a nut 5a having a thread groove formed on its inner surface can be used as a hollow member. it can. One end surface of the nut 5 a is welded to one side surface 31 of the fixing plate 3, and the other end surface 51 has an elastic material 6 bonded to the surface thereof. Similarly, a thread groove 2b1 is also engraved at the end of the tensile reinforcing material 2b to be used (21 near the end), and the nut 5a and the fixing plate 3 are tension-reinforced by screwing the nut 5a into the thread groove 2b1. The material 2b is integrated.

Returning to FIG. 1, the concrete member 1 is manufactured in a state in which a predetermined number of the tensile reinforcing members 2 provided with the fixing plate 3 (and the hollow member 5) in the vicinity of the end thereof are embedded in a predetermined position.
Next, an outline of a reinforcing method for reinforcing the concrete member 1 by using a tension member such as a PC steel rod or a PC steel strand as the tensile reinforcement member 2 and introducing a tension force by a pretension method will be described. The method of introducing the prestressing force to the tension material can be performed with a known tension device, and the fiber reinforced cementitious mixed material is, for example, unidirectional after the tension material into which the tension force has been introduced is set in a form not shown. To complete the filling of the cementitious mixed material. After the curing period, after the fiber reinforced cementitious mixed material reaches a predetermined strength, the tension jack is loosened to release the tension.

  FIG. 4 schematically shows a situation in which self-shrinking gradually occurs after filling with a fresh fiber-reinforced cementitious mixed material. In concrete member 1 (reinforced concrete member or prestressed concrete member) using high-strength concrete such as fiber reinforced cementitious mixed material, restraint stress due to self-contraction and coupled strain due to hydration thermal expansion / contraction occurs, There is a risk of cracking early. As shown in the drawing, the fiber-reinforced cementitious mixed material self-shrinks toward the center of the member (in the directions of arrows X and Y in the figure). In the present invention, cracks caused by such self-shrinkage can be effectively prevented by using a tension material such as a round steel, a PC steel bar, or a PC steel strand having a low restraining effect as the tensile reinforcing material 2. Further, the elastic material 4 is bonded to one side surface 31 of the fixing plate 3 and the elastic material 6 is bonded to the end surface 51 of the hollow member 5, and the protrusions from the tensile reinforcing material 2 are mixed with the fiber-reinforced cement system. It is intended to mitigate over-constraining the self-shrinkage of the material.

  FIG. 5 schematically shows stresses acting on the tensile reinforcement member 2 and the fixing plate 3 when the bending moment M acts on the concrete member 1. The illustrated concrete member 1 is a view showing the lower flange of the I-shaped cross-section girder shown in FIG. 1 and the middle of the web. When a bending moment M (positive bending moment) in the direction shown in the figure acts on the lower flange, tensile stress in the X direction in the figure acts on the tensile reinforcement member 2, and the reaction proceeds toward the center of the tensile reinforcement member 2 ( The restoring force acts in the direction of arrow Y. With this restoring force, the fixing plate 3 also receives a tensile force in the direction toward the center of the concrete member 1, and the fixing plate 3 receives a supporting stress from the concrete with respect to the tensile force (in the direction of arrow Z). Even when a tension material such as a round steel, a PC steel bar, or a PC steel strand having a low adhesion strength to the cement is used as the tensile reinforcing material 2, the fixing plate 3 has the above-mentioned bearing resistance action. Slip that may occur between the fiber-reinforced cementitious mixed material and the tensile reinforcing material 2 can be prevented, and therefore both can integrally resist the bending moment.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

The perspective view which showed one Embodiment of the concrete member of this invention. (A) is the perspective view which showed embodiment which provided the fixing board and the hollow member in the edge part vicinity of the tensile reinforcement material, (b) shows embodiment which provided the fixing board at the edge part of the tension reinforcement material. Perspective view. It is the side view which showed embodiment which provided the fixing board and the hollow member in the edge part vicinity of the tensile reinforcement, (a) is the figure which showed embodiment using round steel as a tensile reinforcement, (b ) Is a diagram showing an embodiment in which a PC steel strand is used as a tensile reinforcement. Explanatory drawing explaining the contraction condition of the concrete member at the time of self contraction. Explanatory drawing explaining the tensile stress which acts on the tensile reinforcement material at the time of a bending moment acting on a concrete member, the reaction force with respect to it, and the bearing stress which acts on a fixing board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Concrete member, 2 ... Tensile reinforcement, 2a ... PC steel strand, 2b ... Round steel or PC steel bar, 3 ... Fixing plate, 4 ... Elastic material, 5 ... Hollow member, 6 ... Elastic material, 11 ... Concrete Member end, 21 ... Near end, 31 ... One side, 32 ... Through hole, 51 ... End face

Claims (6)

In a concrete member that constitutes a concrete beam or floor slab, in which a tensile reinforcement such as a reinforcing bar is embedded,
The concrete member is made of a fiber-reinforced cement-based mixed material, and fixing plates are provided in the vicinity of both ends of the tensile reinforcing material, and an elastic material is provided on one side surface of the fixing member on the side of the concrete member. A concrete member, wherein the fixing plate and the elastic material are embedded in the concrete member.   The fixing plate is provided with a through-hole through which the tensile reinforcing material can penetrate, and a hollow member that can be fixed to the tensile reinforcing material is provided on one side surface of the fixing plate on the end side of the concrete member. An elastic material is provided on each of the end surfaces of the hollow end of the concrete member, and the tensile reinforcement member is connected to the hollow member through the through hole of the fixing plate and the hollow member. The concrete member according to claim 1, wherein the hollow member is embedded in the concrete member.   A screw groove is engraved on the inner hollow surface of the hollow member, and a screw groove that can be screwed into the screw groove is engraved near the end of the tensile reinforcement member, The concrete member according to claim 2.   The concrete member according to claim 1, wherein the tensile reinforcing material is a round steel.   The concrete member according to any one of claims 1 to 3, wherein the tensile reinforcing material is a tension material such as a PC steel rod or a PC steel strand. A concrete member reinforcing method for reinforcing a concrete member according to claim 5,
A method for reinforcing a concrete member, wherein a fiber-reinforced cement-based mixed material is filled in a state in which the tension material to which tension is given in advance is embedded, and the tension is released after a predetermined strength is exhibited.

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