JP5908787B2 - Pre-tensioned prestressed concrete member - Google Patents

Description

The present invention is the main reinforcement or the like, the pre-tensioned prestressed concrete the concrete in a state of pre-tension is applied axially muscle placed me along the wood-axis direction prestress is introduced to the concrete by being pouring This relates to the member.

When utilizing axial muscle of main reinforcements or the like to be reinforcement along the timber axis as a tension member for prestressing introduction into the concrete (see Patent Document 1), transmission of the tensioning force due to adhesion between the concrete In order to ensure the effect, deformed reinforcing bars (including screw reinforcing bars) are often used as axial reinforcing bars (see Patent Document 2).

  Concrete is placed around the reinforcing bars with tension applied to the reinforcing bars (axial reinforcing bars) in advance, and pre-stress is introduced into the concrete by releasing the tension of the reinforcing bars after the concrete has hardened. However, when the tension force is released, the reinforcing bar tries to contract from the stretched state, so that the cross section is increased (expanded), and thus a radial force is applied to the concrete around the reinforcing bar.

  This radial force acts on the concrete as a tensile force in the circumferential direction around the cross section of the reinforcing bar, and it is necessary to reinforce the concrete in order to generate cracks in the concrete. With respect to the tensile force in the circumferential direction around the reinforcing bars, it is considered that the concrete can be reinforced by arranging reinforcing bars such as spiral bars around the reinforcing bars (see Patent Document 2).

  Moreover, damage to the concrete at the end face can be prevented by preventing a part of the end of the reinforcing bar from adhering to the concrete.

Japanese Patent Laid-Open No. 3-093929 (Claim 1, page 3, lower left column, line 3 to page lower right column, line 20, FIG. 1, FIG. 2) Japanese Patent Laying-Open No. 2007-120002 (Claim 1, paragraphs 0008 to 0013, FIG. 2)

  On the other hand, when the rebar in the extended state is about to contract by releasing the tension force, the tension force (tensile force) generated in the reinforcing bar is introduced into the concrete as an axial compressive force by the adhesion force.

  In Patent Document 2, the spiral bars arranged around the reinforcing bars mainly serve as a resistance element against the tensile force in the circumferential direction around the cross section of the reinforcing bars, and thus include a concrete member including a section where the reinforcing bars do not adhere to the concrete. It is arrange | positioned ranging from the end surface of this to the area where a crack is assumed. However, in the section where the reinforcing bar does not adhere to the concrete, the reinforcing bar can slide relative to the concrete when contracted. Therefore, the effect on the concrete due to the cross-section increase (expansion) of the reinforcing bar does not appear as much as the bonded section, so it is substantially spiral. There is no meaning in the section where the reinforcing bars are not attached, because the reinforcing bars act as resistance elements against the tensile force in the circumferential direction.

  The present invention is based on the above background, and when using axial muscles such as main muscles as a tension material for introducing prestress, against the tensile force in the axial direction that can be generated in the concrete together with the radial force when releasing the tension force. However, the present invention proposes a pretensioned prestressed concrete member having a reinforced structure.

Pretension type prestressed concrete member of the invention described in claim 1, the concrete is pouring in a state of pre-tension is applied axially muscle placed me along the timber axis, prestress to the concrete In the concrete member in which
A portion of the axial streak near the end surface of the concrete member does not adhere to the concrete, and at least in a section closer to the intermediate portion in the axial direction of the concrete member than a section where the adhesion with the concrete breaks, the shaft A reinforcing material is disposed to reinforce the concrete around the direction line in the radial direction,
Disperse the adhesive force from the axial streak in a state where the tension force is applied to the concrete in the axial direction at least in a section closer to the axial middle portion of the concrete member than the section where the adhesion with the concrete is cut off. The axial material to be transmitted along the circumference of the axial line, or so as to surround the axial line,
The axial member transmits the tension force transmitted from the axial line through the adhesive force generated between the axial line and the concrete existing between the axial line in the axial direction of the axial line. It is a constituent requirement to disperse and act on the concrete as a compressive force .

Deformed bars (including threaded bars and deformed PC steel bars) are mainly used for the axial bars, but they do not have to be deformed bars because they only need to generate an adhesive force with concrete. Any irregular surface may be formed on the surface. The "arrangement I along the timber axis direction", and be Haisuji parallel to timber axis of the concrete member as main reinforcement, the waveform I along the tension side of the concrete member as PC steel Haisuji It is intended that the concrete member may be disposed in parallel or close to the material axis direction over the whole or the entire length of the concrete member.

  “A part of the axial streak near the end face of the concrete member does not adhere to the concrete” means that the axial streak is not attached to the concrete (separated from the concrete) and the It means that the axial force is not transmitted to the concrete. Cutting off the adhesion of the axial streak to the concrete can be obtained, for example, by applying grease to the axial streak or covering the sleeve, but the method is not limited.

  Since the axial force is not transmitted to the concrete from a part of the end of the concrete member on the end side of the axial reinforcement, the section where the adhesion to the concrete breaks when the tension force on the axial reinforcement is released is the axis relative to the concrete. It is in a state that can move relative to the direction and can cause slipping. For this reason, as in the case where the concrete is constrained from the periphery, the cross section of the section close to the end of the axial streak (section without adhesion) can increase (expand) when the tension is released, but in the section without adhesion Since there is a clearance that absorbs this cross-sectional increase (expansion) by means of cutting adhesion, the action of radial force on the surrounding concrete and the action of the circumferential tensile force associated with that force And the cracking of the concrete on the end face is suppressed.

  In the section closer to the middle in the axial direction of the concrete member than the section where the adhesion with the concrete is cut off, the U-shaped reinforcing bar and shear reinforcement as shown in FIG. A reinforcing material such as a streak is arranged. In the section closer to the axial middle part of the concrete member than the section closer to the end of the axial streak (the section without adhesion) due to the placement of the reinforcing material, the concrete has a radial force (circumferential direction due to the expansion of the axial streak). It is reinforced against the force to generate cracks due to the tensile force. “At least from the section where the adhesion has been cut off” means that the reinforcing material is disposed on the intermediate part side of the concrete member from the portion including the section where the adhesion has been broken, and the reinforcing material is disposed in the section where the adhesion has been broken. It also has a meaning.

  The reinforcing material surrounds at least a part of the periphery of the axial streak in the circumferential direction. For example, when the axial streak is viewed in the axial direction, the reinforcing material has a ring shape, a U-shape, etc. By encircling the part in the circumferential direction, it bears the tensile force in the circumferential direction caused by the radial force and suppresses cracking of the concrete. If the reinforcing material has a shape that surrounds at least a part of the periphery of the axial streak, it can bear a tensile force in the circumferential direction, and therefore, shear reinforcement that surrounds a plurality of main bars as shown in FIG. A part of the muscle may be used as a reinforcing material. When the reinforcing material is intermittently arranged in the axial direction of the axial streak like a plurality of U-shaped reinforcing streaks, and as shown in FIGS. May take the form of

  In addition, since the axial member is arranged along the axial streak in the section closer to the axial middle portion of the concrete member than the section where the adhesion with the concrete is cut off, the axial member is released from the tension state. Because the tension (tensile force) applied to the axial streaks is distributed in the axial direction and uniformly acts as a compressive force on the concrete, the prestress introduced into the concrete is unbalanced in the axial direction. It is suppressed. “At least” means that, in the same way as the reinforcing material placement section, the axial material is placed on the intermediate portion side of the concrete member from the location including the section where the adherence is broken, and is arranged in the section where the adherence is broken. This also means that the concrete member may be disposed over the entire length including the section where the adhesion is broken.

  Axial material is arranged along the axial streak, and acts to disperse the tension force transmitted from the axial streak through the adhesive force with the concrete in the axial direction and give it to the concrete as a compressive force. At the same time, it functions as a resistance element against the tensile force when a tensile force is generated in the concrete around the axial streak due to the difference in the compressive force in the axial direction. “Along the axial streak” means that the axial streak has a clearance that allows the adhesive force to be transmitted through the concrete that exists between the axial streak and the axial material. And a case where the material is formed between the axial member.

  The axial member does not necessarily have to face the axial direction of the axial streak as the splicing bars arranged parallel to the axial streak. Even if any part (element) of the axial member is oriented in the direction intersecting the axial direction of the axial line, it is possible to bear the component of the tensile force facing the axial direction of the axial line, It can function as a resistance element against the axial tensile force of the axial streak.

  If any part (element) of the axial member is oriented in the direction intersecting the axial direction of the axial streak, that part (element) is the component of the axial direction of the axial streak and the direction perpendicular thereto. Since it can be decomposed into components, in addition to the axial force component of the axial streak, the force component in the direction orthogonal to the axial direction of the axial streak can be borne. Therefore, the axial member can function as a resistance element against tensile force acting on the concrete in the circumferential direction together with the axial force of the axial streak.

  For example, the axial member is composed of a cylindrical mesh streak as shown in FIGS. 3 and 4, or a fiber knitted in a mesh shape, and a resistance element that intersects the axial direction and the circumferential direction of the axial streak. If so, the resistance element can bear the axial force component and the circumferential force component, so in addition to the original function of bearing the axial force of the axial muscle, the radial direction around the axial muscle It becomes possible to also serve as a reinforcing material that bears a force acting on (a tensile force in the circumferential direction). That is, the cylindrical axial member in the example shown in FIGS. 3 and 4 has a shape that serves as the reinforcing member and the axial member in FIGS. 1 and 2. The reason why the axial material is a cylindrical mesh is that it is necessary to attach the axial streaks to the concrete in the sections other than the section where the adhesion of the axial streaks to the concrete is performed. This is because the concrete needs to reach the surface of the bar.

  By disposing the axial member so as to follow the surrounding of the axial streak or to surround the axial streak, the adhesive force of the axial streak is distributed over the entire length of the axial direction as described above. To the concrete. At the same time, it bears the tensile force in the axial direction that may occur in the concrete in place of the concrete, and acts to suppress cracking due to the tensile force that attempts to separate the concrete in the axial direction.

Pretension type prestressed concrete member of the invention according to claim 2, concrete is pouring in a state of pre-tension is applied axially muscle placed me along the timber axis, prestress to the concrete In the concrete member in which
A portion of the section near the end face of the concrete member that surrounds the axial streak is cut out from the end face, and at least from the notch to a section near the axial middle portion of the concrete member in the axial direction. A reinforcing material having a shape that is continuous in the axial direction of the axial streak is provided to reinforce the concrete around the streak in the radial direction, and an end of the reinforcing material on the notch side is located on the outer peripheral side of the notch. It is a constituent requirement that it is fixed in concrete.

  The “notch” is formed so as to surround the entire circumference of the axial streak when the concrete member is viewed in the axial direction. In the axial direction of the axial streak, the “reinforcing effect of concrete by the reinforcing material” described later is provided. The length of the notch is arbitrarily set within a range that does not impede “influence on concrete due to contraction of axial streak”.

  In claim 2, a portion of the partial section near the end face of the concrete member surrounding the axial streak is cut out from the end face, so that a partial section of the axial streak near the end face of the concrete member is exposed from the concrete. Therefore, the axial streak is similar to the situation in claim 1 in which “a part of the section near the end face of the concrete member does not adhere to the concrete”. However, it is different from “no adhesion” in that the axial force from the axial streak is not completely transmitted to the concrete in the section where the concrete is cut out.

  “Axial continuous shape (reinforcing material)” means that the reinforcing material itself is continuous between both ends in the axial direction, but the notch end of the reinforcing material is notched. Since it is fixed in the concrete on the outer peripheral side, at least at the end on the notch side, the cross section perpendicular to the axial direction of the axial direction stripe surrounds the notch, and basically a spiral shape In some cases, it may have a cylindrical shape.

  In the notch section of concrete, since the axial force is not transmitted to the concrete from the section of the axial reinforcement on the concrete member end side, the adhesion to the concrete breaks when the tension force on the axial reinforcement is released. The section is movable relative to the concrete in the axial direction. Since the end section of the axial streak is not surrounded (restrained) by the concrete, the axial streak can freely contract when the tension is released, but it can also affect the concrete (tensile force and compressive force) with the contraction. Absent. Therefore, since the tensile force in the circumferential direction is not generated in the concrete in the end section of the axial streak in which the notch is formed, the crack of the concrete is prevented.

  In the notch section of the concrete, the reinforcement does not cause the crack due to the tensile force in the circumferential direction due to the axial contraction of the axial streak. In the section closer to the middle of the direction, at least the circumferential tensile force accompanying expansion (expansion) of the cross section due to contraction of the axial streak may be borne, and the function of reinforcing the concrete against cracks may be achieved. “At least the tensile force in the circumferential direction” means that in addition to the tensile force in the circumferential direction, an axial tensile force may be borne.

  In the second aspect of the present invention, the reinforcing material is disposed at least from the notch portion of the concrete in the section near the axial middle portion of the concrete member, as in the first aspect. In the section closer to the axial middle part of the concrete member than the near section, the concrete is reinforced against the force that tends to generate cracks due to radial force (circumferential tensile force) accompanying expansion of the axial streak. The

  The reinforcing material surrounds the axial streak in the circumferential direction, and thus bears the tensile force in the circumferential direction caused by the radial force and functions to suppress cracks in the concrete. “At least from the notch portion” means that the reinforcing material is disposed on the intermediate portion side of the concrete member from the portion including the notch section of the concrete, similarly to the reinforcing material of claim 1, and from the end surface of the concrete member. Sometimes placed.

  The notch side end of the reinforcing material is fixed in the concrete on the outer periphery side of the notch, so that the notch side end of the reinforcing material is formed while the notch is formed in the concrete around the axial streak. In addition, the entire length of the reinforcing material does not slip with respect to the concrete. By fixing the end of the notch to the concrete, the reinforcing material is fixed in the concrete over the entire length. The “outer peripheral side of the notch” refers to a portion around the axial streak when the concrete member is viewed in the axial direction.

  As shown in FIGS. 5 and 6, the reinforcing member 7 has an outer circumference, a height, a width, etc., such as the outer diameter, the height, and the width of the reinforcing member 7 in the direction perpendicular to the axial direction of the axial stripe 2. By being larger than the inter-surface distance, it is fixed in the concrete 3 on the outer peripheral side of the notch 6. 5 and 6 show a case in which the notch 6 is formed in a truncated cone shape or the like in which the cross section gradually decreases from the end face side of the concrete member 1 toward the intermediate portion side, but the notch 6 has a circular cross section. Even in some cases, if the outer diameter of the reinforcing material 7 is larger than the distance between the inner peripheral surfaces of the notches 6, the reinforcing material 7 is fixed to the concrete 3.

  As shown in FIG. 6, the notch 6 may be filled with a filler 8 such as mortar or adhesive after or before the contraction of the axial streak 2. The filler 8 filled before shrinkage may be mixed with a reinforcing fiber as a resistance element against a tensile force due to an increase in the cross section of the axial streak 2 after shrinkage. In that case, in addition to forming the notch 6 in the shape of a truncated cone, the filler 8 can also function as a wedge for preventing axial contraction of the axial streak 2 when the axial streak 2 contracts. It is.

  By fixing the reinforcing material (full length) in the concrete, the reinforcing material has a continuous shape in the axial direction, and also for the tensile force in the circumferential direction acting on the concrete over the entire length, It is possible to effectively resist the tensile force due to the difference in compressive force that can act in the axial direction of the reinforcing bar, and has both functions of the reinforcing material and the axial material in claim 1.

  In addition to the function as a resistance element against the tensile force in the circumferential direction on which the reinforcing material acts on the concrete, it is possible to demonstrate the function as a resistance element against the tensile force due to the difference in the compressive force in the axial direction. In item 2, it is not always necessary to arrange the axial member in claim 1 along the axial line.

However, in order to increase the safety against the tensile force in the axial direction acting on the concrete, the axial direction in which tension force is applied at least in the section closer to the middle axial direction of the concrete member than the notch portion of the concrete member An axial member that transmits the adhesive force from the streaks to the concrete in an axial direction may be disposed along the axial streaks. Axial material is a compressive force applied to concrete by dispersing the tension transmitted from the axial reinforcement through the adhesive force generated between the axial reinforcement and the concrete existing between the axial reinforcement in the axial direction of the axial reinforcement. To act as.

  Since the axial member is arranged along the axial streak in the section closer to the axial middle portion of the concrete member than the notch portion, as in the case of claim 1, the axial direction is released when the axial streak is released from the tension state. The tension (tensile force) applied to the muscles is dispersed in the axial direction and tries to act equally on the concrete as a compression force.

  The effect of the axial member being arranged along the axial streak is the same as in the case of claim 1, and the axial member disperses the tension of the axial streak in the axial direction and gives the compressive force to the concrete. Both function as resistance elements against tensile forces when generated in concrete. In the case of claim 3 as well, “at least from the notch portion” means that the axial member is arranged on the intermediate part side of the concrete member from the location including the notch section, like the reinforcing material arrangement section. Arranging in the notch section also means that the concrete member may be disposed along the entire length of the concrete member including the notch section.

  As shown in FIGS. 7 and 8, a fixing member 9 for fixing the axial streak 2 to the end portion of the concrete 3 may be disposed in the concrete notch 6 portion. The fixing member 9 has, for example, an insertion hole through which the axial streak 2 can be inserted, and has a cross section larger than that of the axial streak 2 so that the fixing member 9 is fixed in the concrete 3 in the surrounding portion with the axial streak 2 inserted. (Buried).

  When the cross section of the fixing member is larger than the cross section of the axial streak, the axial force applied to the axial streak when the axial streak is inserted into the fixing member and fixed in the concrete in a connected state ( (Tensile force) is transmitted as a compressive force to the concrete by the bearing pressure from the end surface of the concrete member of the fixing member in the axial direction of the axial direction or by the bearing pressure and the adhesion force on the circumferential surface. Is done.

  The axial force of the axial streak is transmitted to the concrete also from the end face and peripheral surface of the fixing member, so that the axial force is transmitted to the concrete rather than the case where the axial force is transmitted to the concrete only by the adhesive force of the axial streak alone. Therefore, the difference in compressive force transmitted from the peripheral surface of the axial streak to the concrete is less likely to occur. As a result, it becomes difficult to generate a tensile force due to a difference in compressive force, so that it is possible to reduce reinforcement against the tensile force that can be generated in the concrete.

  According to the first aspect of the present invention, the reinforcing material is disposed in the section closer to the middle portion in the axial direction of the concrete member than the section in which the adhesion to the concrete is broken, without attaching a part of the axial streak near the end surface of the concrete member to the concrete. Therefore, it is possible to resist the tensile force in the circumferential direction on the concrete due to the cross-sectional increase (expansion) when releasing the tension of the axial streak in the reinforcing material arrangement section.

  In addition, since the axial member is arranged along the axial streak in a section closer to the axial middle part of the concrete member than at least the section where the adhesion with the concrete is cut off, the axial streak is released when the axial streak is released from the tension state. The tension force (tensile force) applied to can be dispersed in the axial direction and can be applied uniformly to the concrete as a compression force.

  According to claim 2, a portion of the partial section near the end face of the concrete member is cut out from the end face so as to expose a portion of the axial stripe near the end face of the concrete member from the concrete. For this reason, in the notch section of concrete, the axial force from the axial streak can not be completely transmitted to the concrete. As a result, in the notch section, there is no generation of circumferential tensile force on the concrete in the end section of the axial streak, so that cracking of the concrete can be completely prevented.

In addition, by fixing the notch end of the reinforcing material in the concrete on the outer periphery side of the notch, the reinforcing material acts on the concrete over its entire length, together with the shape of the reinforcing material being continuous in the axial direction. The reinforcing material can be made to resist the tensile force in the circumferential direction and the tensile force in the axial direction.

(A) A part of the axial streak near the end face of the concrete member is not attached to the concrete, a U-shaped reinforcing material is arranged around the axial streak, and a rod-shaped axial direction is provided along the axial streak. Sectional drawing seen in the width direction of the concrete member which showed the example at the time of arrange | positioning a material, (b) is an end elevation of the axial streak part of (a). It is sectional drawing which showed the example at the time of using a shear reinforcement as a reinforcing material as a modification of FIG. It is sectional drawing which showed the example at the time of arrange | positioning the cylindrical reinforcement material which serves as the axial direction material in FIG. It is sectional drawing which showed the example at the time of arrange | positioning the frustoconical reinforcement material which serves as the axial direction material in FIG. It is sectional drawing which showed the example at the time of notching some sections near the end surface of a concrete member, and arrange | positioning the cylindrical reinforcing material fixed to concrete around an axial direction stripe | line | muscle. It is sectional drawing which showed the example at the time of notching some sections near the end surface of a concrete member, arrange | positioning a cylindrical reinforcement around an axial direction stripe | line | column, and filling the notch with the filler. It is sectional drawing which showed the example at the time of arrange | positioning the nut-shaped fixing member for fixing an axial streak to concrete in a notch. It is sectional drawing which showed the other example at the time of arrange | positioning the sleeve-shaped fixing member for fixing an axial streak to concrete in a notch.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

Figures 1-8 are in a state of pre-tension is applied axially muscle 2 arranged me along the Zaijiku direction, the concrete 3 is pouring the section including the axial muscle 2, release of tension An example of manufacturing a pretension type prestressed concrete member (hereinafter, concrete member) 1 in which prestress is introduced into the concrete 3 will be described. 1 and the subsequent drawings show an example in which the concrete member 1 is a horizontal member (horizontal member) such as a beam member (girder member), and therefore the axial streak 2 is a lower end rebar (lower end main rebar). However, it does not necessarily have to be the bottom streak.

  FIGS. 1 to 4 show concrete members in which the concrete 3 is reinforced with the reinforcing material 4 and the axial material 5 without attaching the axial streak 2 to the concrete 3 in a part of the concrete member 1 near the axial end. 1 is a specific example. 5 to 8 show concrete in which a concrete 3 around the axial streak 2 is cut out in a partial section of the concrete member 1 near the end in the axial direction, and the concrete 3 is reinforced with a reinforcing material 7 having a shape continuous in the axial direction. 3 is a specific example of the member 1. In FIG. 1 to FIG. 4, a section where the adhesion of the axial streak 2 to the concrete 3 is cut (not adhered) is indicated by hatching.

  In the cross section perpendicular to the axial direction of the concrete member 1, one axial streak 2 is arranged on the side receiving the tensile force when the concrete member 1 receives a vertical load (long-term load), or in parallel in the width direction. Are arranged. The axial member 5 serves to transmit the adhesive force from the axial streak 2 in a state where a tension force is applied to the concrete 3 by dispersing it in the axial direction as an axial compressive force. For example, when the reinforcing material 4 has a cylindrical shape as shown in FIGS. 3 and 4 and has an element that can be disassembled in the axial direction of the axial stripe 2, the reinforcing material 4 also serves as the axial material 5. There is also.

  1 to 4, a portion of the axial streak 2 near the end surface of the concrete member 1 does not adhere to the concrete 3, and at least closer to the intermediate portion in the axial direction of the concrete member 1 than a section where the adhesion with the concrete 3 is broken. The reinforcing material 4 for reinforcing the concrete 3 around the axial streak 2 in the radial direction is disposed in the section.

  In some sections where the adhesion of the axial streak 2 to the concrete 3 is cut, the inside of the cylindrical sleeve fixed in the axial direction 2 by applying grease or the like to the surface of the axial streak 2 or the like in the axial direction. By being inserted so as to be relatively movable, the adhesion with the concrete 3 is cut off, and a relative movement in the axial direction with respect to the concrete 3 is possible. The axial member 5 is disposed along the axial streak 2 in a section closer to the intermediate portion in the axial direction of the concrete member 1 than at least a section where the adhesion with the concrete 3 is broken.

  FIG. 1 shows that a part of the concrete member 1 near the axial end of the concrete member 1 is cut off from adhering to the concrete 3 and includes a part of the concrete member 1 which is cut off from adhering to the concrete 3. A plurality of U-shaped reinforcing bars as the reinforcing member 4 are arranged at intervals in the axial direction of the axial direction reinforcing member 2, and a supplementary reinforcing bar as the axial member 5 is axially disposed in a section near the intermediate portion. The example at the time of arrange | positioning on the stripe | line | muscle 2 is shown. In FIG. 1, a U-shaped reinforcing bar in which the lower end side of the concrete member 1 is closed is disposed as the reinforcing member 4, so that the axial member 5 is juxtaposed in the width direction on the upper side of the axial line 2. However, they may be arranged on both sides in the width direction of the axial stripe 2 or on the lower side.

  The reinforcing member 4 is continuous in the axial direction of the axial streak 2 as shown in FIGS. 3 and 4 in addition to the form in which the reinforcing member 4 is separated in the axial direction of the axial streak 2 as shown in FIG. 1 and FIG. The continuous form includes a spiral shape.

  FIG. 2 shows an example in which a shear reinforcing bar 41 that surrounds all the axial bars 2 in the concrete member 1 including the axial bars 2 to which a tension force is applied in advance and uses the shear reinforcing bars 41 that restrain the axial bars 2 as the reinforcing material 4. Is shown. The all axial bars 2 refer to the lower and upper main bars as the axial bars 2 arranged in the concrete member 1.

  The amount of contraction of the reinforcing material 4 when the axial direction muscle 2 is shifted from the state where the tension force is applied to the state where the tension force is released and contracts is large near the end of the axial direction muscle 2 and is axially centered. Since the influence of the tensile force in the circumferential direction on the surrounding concrete 3 due to the cross-sectional increase (expansion) accompanying the contraction of the axial reinforcement 2 tends to occur in the section near the end of the axial reinforcement 2, In FIG. 1 and FIG. 2, the reinforcing material 4 is densely arranged in a section near the end of the concrete member 1 in the concrete 3.

  1 and 2, the axial streak 2 is in a state where it can slip in the axial direction with respect to the concrete 3 in the section where the adhesion with the concrete 3 in the end section is broken, but the axial member 5 itself is By being located in the concrete 3, it is in a state of being fixed to the concrete 3, so that it can bear the tensile force in the axial direction.

  3 and 4 show an example in which the reinforcing member 4 in FIGS. 1 and 2 is replaced with a cylindrical, mesh-like (mesh-like) member. The mesh-shaped cylindrical member is orthogonal to the axial tensile force of the axial streak 2 by causing the mesh components (line elements) to face in a direction inclined with respect to the axial direction of the axial streak 2. In order to retain resistance to the tensile force in the circumferential direction, the reinforcing material 4 as a resistance element against the tensile force in the circumferential direction and the function of the axial member 5 as resistance element against the tensile force in the axial direction are combined. It also serves as the direction member 5.

  3 and 4, since the concrete 3 is cast in a state in which the cylindrical reinforcing material 4 surrounds the section including the non-attached section of the axial reinforcement 2, the reinforcing material 4 is used as the axial reinforcement. The reinforcing material 4 is formed in a mesh shape so as not to inhibit the concrete 3 from adhering to the surface of the axial streak 2 in a section other than the section where the adhesion of the concrete 2 to the concrete 3 is cut.

  Although the reinforcing material 4 is cylindrical, it has a mesh shape, so that the concrete 3 placed in a state where the axial reinforcing bars 2 are arranged enters the reinforcing member 4 so that the axial reinforcing bars 2 are not attached. It adheres to the surface other than the section. The mesh-shaped reinforcing material 4 is manufactured from a reinforcing bar, and is manufactured from a reinforcing fiber (reinforced fiber) made of steel, a reinforced fiber plastic, or the like. 3 shows a case where the reinforcing material 4 is formed in a cylindrical shape, and FIG. 4 shows a case where the reinforcing material 4 is formed in a truncated cone shape.

  5 to 8 show a notch 6 of inner method (inner diameter) surrounding the axial streak 2 in a partial section from the end face of the concrete member 1 toward the axially intermediate portion side, and the outer peripheral side of the notch 6 An example in which, for example, a cylindrical reinforcing member 7 having a shape continuous in the axial direction of the axial streak is disposed in the concrete 3 is shown. The reinforcing material 7 shown in FIGS. 5 to 8 is distinguished from the reinforcing material 4 in FIGS. 1 and 2 in that it has a shape that is continuous in the axial direction of the axial stripe 2.

  The notch 6 is formed at the same time as the concrete member 3 is completed by disposing the formwork in the shape at the position where the notch 6 is formed and then releasing it after the concrete 3 is hardened. The notch 6 has the same meaning as the “no adhesion” state in FIGS. 1 to 4 in that the end section of the axial reinforcement 2 is not attached to the concrete 3, but the axial reinforcement 2 in the notch 6 section. This is different from “no adhesion” in that no tensile force is applied to the concrete 3 at the time of shrinkage.

  5 and 6, the notch 6 is formed in a truncated cone shape in which the cross-sectional area perpendicular to the axis decreases from the end face side of the concrete member 1, but the notch 6 has a cylindrical shape as shown in FIGS. 7 and 8. In some cases, the shape of the notch 6 is not limited. In order to form the notch 6 in the shape of a truncated cone, the axial direction of the axial streak 2 is applied to the filler 8 filled in the notch 6 when the tension of the axial streak 2 is released as will be described later. It is meaningful to act to prevent contraction.

  The distance (inner diameter) between the inner peripheral surfaces of the cylindrical reinforcing material 7 is larger than the inner method of the notch 6, and the reinforcing material 7 is embedded in the concrete 3 over the entire length without being exposed to the notch 6 side. It is fixed. Since the reinforcing material 7 is fixed in the concrete 3 over the entire length, it can resist the circumferential tensile force and the axial tensile force acting on the concrete 3 around the axial streak 2. As the cylindrical reinforcing member 7, a spiral line or the like is used in addition to a mesh-like member, like the above-described cylindrical reinforcing member 4.

  In the examples of FIGS. 5 to 8, the reinforcing material 7 has a continuous shape in the axial direction, so that the axial tensile force acting in the concrete 3 is the same as the reinforcing material 4 in the examples of FIGS. 3 and 4. This also means that the axial member 5 is disposed along the axial streak 2. That is, the reinforcing material 7 continuous in the axial direction also serves as the functions of the reinforcing material 4 and the axial material 5 in the examples of FIGS. However, in addition to the reinforcing material 7, the axial material 5 may be embedded in the concrete 3 in an auxiliary manner.

  FIG. 6 shows a state in which the filling material 8 such as mortar and adhesive is filled in the notch 6 of FIG. 5 before releasing the tension of the axial muscle 2. For the mortar, a fiber reinforced mortar mixed with short fibers that become a resistance element against a tensile force may be used. In this case, the tension of the axial muscle 2 is released after the filler 8 is cured (after the strength is developed). With the release of the tension, the filler 8 is compressed in the truncated cone-shaped notch 6, but the cross-sectional area of the notch 6 decreases from the end surface of the concrete member 1 to the intermediate side. The filler 8 presses the outer peripheral side of the notch 6 in the radial direction and clamps the axial stripe 2 in the notch 6 to restrain it, so that the axial contraction of the end of the axial stripe 2 is reduced. It acts to suppress and maintain the tension of the axial muscle 2.

  7 and 8, a fixing member 9 for fixing or holding the axial streak 2 on the concrete 3 is arranged in a notch 6 portion formed (to be formed) in a columnar shape, and the fixing member 9 has a shaft. The axial streak 2 in a state in which the tension force is introduced by fixing the fixing member 9 in the concrete 3 or engaging the axial streak 2 in the axial direction while connecting (connecting) the directional streak 2. The example in the case of trying to suppress shrinkage | contraction of an edge part is shown. By attempting to maintain the fixing member 9 fixed or locked to the concrete 3, the tension of the axial streak 2 is introduced into the concrete 3 without loss as prestress.

  When the fixing member 9 is completely fixed in the concrete 3 as shown in FIG. 8, the fixing member 9 adheres to the concrete 3 and the contraction of the axial streak 2 when the axial streak 2 attempts to contract in the axial direction. In the direction, it tries to maintain the state fixed to the concrete 3 by the supporting pressure by engaging with the end face of the concrete 3 which is the end face on the back side of the notch 6. When there is no adhesion to the concrete 3 as in the fixing member 9 shown in FIG. 7, the fixing member 9 tries to maintain the position in the axial direction with respect to the concrete 3 only by locking (supporting pressure) to the end surface of the concrete 3. To do.

  As shown in FIG. 8, when the fixing member 9 is embedded in the concrete 3 in advance, the fixing member 9 is embedded in the concrete 3 in the surrounding portion so that the adhesion force and the axial intermediate portion side are directed to the concrete 3. 6 is more resistant to the tension force of the axial muscle 2 due to the supporting pressure at the end face, so that the ability to maintain the state fixed to the concrete 3 is higher than the filler 8 filled in the notch 6 in FIG. The effect of trying to keep the axial muscle 2 at the position when releasing the tension is high. As shown in FIG. 7, when the entire fixing member 9 is inserted into the notch 6 after the concrete 3 is hardened and is screwed into the end of the axial streak 2 and disposed in the concrete member 1, the fixing member 9 engages with the end face of the concrete 3 on the back side of the notch 6 to resist the tension of the axial muscle 2 and stays in the notch 6.

  The fixing member 9 has an insertion hole through which the axial streak 2 is inserted, and the axial streak 2 is filled with a screw (screwing) or in a state where the axial streak 2 is inserted, such as mortar. Is integrated with the axial streak 2.

  The fixing member 9 shown in FIGS. 7 and 8 shows an example in which the fixing member 9 is integrated with the axial streak 2 by screwing with the axial streak 2 threaded in the end section. FIG. 7 shows a case where the fixing member 9 has a nut shape with a small axial length, and FIG. 8 shows a case with a sleeve shape with a large axial length.

  The fixing member 9 shown in FIG. 7 is inserted into the notch 6 while being screwed into the end of the axial thread 2 that has been threaded in advance after the concrete 3 is cured, as described above. By engaging with the end face, the tension of the axial streak 2 can be resisted and stopped in the notch 6. The fixing member 9 is further rotated around the axis, thereby enabling reintroduction of the tension force to the axial muscle 2.

  The sleeve-like fixing member 9 shown in FIG. 8 may be entirely embedded in the concrete 3 together with the axial streak 2 in advance, but the shaft portion and the nuts arranged on both sides in the axial direction like a coupler. 7, only the nut portion located on the end surface side of the concrete member 1 is inserted into the notch 6 after the concrete 3 is cured, like the fixing member 9 in the example of FIG. 7. Sometimes.

1 …… Concrete material,
2 ... Axial streak, 3 ... Concrete,
4 …… Reinforcing material, 41 …… Shear reinforcement, 5 …… Axial material,
6 ... Notch, 7 ... Reinforcing material (shape continuous in the axial direction of the axial streak),
8: Filler, 9: Fixing member.

Claims (3)

Concrete is pouring in advance a state in which tension is applied axially muscle placed me along the timber axis, in a concrete member which prestress is introduced to the concrete,
A portion of the axial streak near the end surface of the concrete member does not adhere to the concrete, and at least in a section closer to the intermediate portion in the axial direction of the concrete member than a section where the adhesion with the concrete breaks, the shaft A reinforcing material is disposed to reinforce the concrete around the direction line in the radial direction,
Disperse the adhesive force from the axial streak in a state where the tension force is applied to the concrete in the axial direction at least in a section closer to the axial middle portion of the concrete member than the section where the adhesion with the concrete is cut off. The axial material to be transmitted along the circumference of the axial line, or so as to surround the axial line,
The axial member transmits the tension force transmitted from the axial line through the adhesive force generated between the axial line and the concrete existing between the axial line in the axial direction of the axial line. A pre-tensioned prestressed concrete member characterized by being dispersed and acting on the concrete as a compressive force . Concrete is pouring in advance a state in which tension is applied axially muscle placed me along the timber axis, in a concrete member which prestress is introduced to the concrete,
A portion of the section near the end face of the concrete member that surrounds the axial streak is cut out from the end face, and at least from the notch to a section near the axial middle portion of the concrete member in the axial direction. A reinforcing material having a shape that is continuous in the axial direction of the axial streak is disposed to reinforce the concrete around the streak in the radial direction, and the end portion on the notch side of the stiffener is located on the outer peripheral side of the notch. A pretension type prestressed concrete member characterized by being fixed in concrete. Dispersing the adhesive force from the axial streak in a state where the tension is applied at least in a section closer to the axially intermediate portion of the concrete member than at least the notched portion of the concrete member in the axial direction on the concrete. The transmitting axial material is arranged so as to follow or surround the axial streak;
The axial member transmits the tension force transmitted from the axial line through the adhesive force generated between the axial line and the concrete existing between the axial line in the axial direction of the axial line. The pretension type prestressed concrete member according to claim 2, wherein the pretensioned prestressed concrete member is dispersed and acts on the concrete as a compressive force .

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