JP3723570B1 - Bearing stress distribution member, fixing tool and prestressed concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an external dimension of a supporting stress dispersion member that transmits prestress as a reaction force of a tension force applied from a tension material to a fixing tool while dispersing the prestress from a guide constituting the fixing tool to a surrounding concrete. The bearing stress distribution member is stabilized in the mounted state on the guide.
SOLUTION: A guide insertion having a shape corresponding to the shape of a guide 3 is manufactured so that a cylindrical guide 3 through which a tension material 2 is inserted is manufactured in a flat plate shape symmetrical to the thickness direction. A hole 1a is formed, and a plurality of through holes 1e are formed around the guide insertion hole 1a at intervals in the circumferential direction. The thickness of the edge portion 1b around the guide insertion hole 1a is made larger than the thickness of other portions, and the edge portion 1b having a large thickness is locked to the outer peripheral surface of the guide 3 in the axial direction of the guide 3. On the inner peripheral surface of the edge portion 1b, a convex portion 3b formed on the outer peripheral surface of the guide 3 is fitted in the axial direction of the guide 3 to form a concave portion 1c that can be engaged in the circumferential direction.
[Selection] Figure 1

Description

  The present invention is a fixing device for a tension material such as a PC steel material, which is installed at an end portion of concrete and introduces prestress into concrete, and prestress is applied as a reaction force of a tension force applied from the tension material to the fixing device. The present invention relates to a supporting stress dispersion member that is dispersed and transmitted to concrete, a fixing tool including the same, and prestressed concrete in which the fixing tool is fixed in the concrete.

  As shown in FIG. 4, the fixing tool to which the end of the tendon is fixed is disposed between the fixing block to which a plurality of tendons are fixed and the sheath to the fixing block arranged in the concrete. It is composed of a cylindrical guide for transmitting the prestress received by the concrete to the concrete.

  Since compressive stress (bearing stress) is transmitted to the concrete around the guide in a cone shape from the outer peripheral surface of the guide, excessive stress is generated in the stress transmission area, so that the stress is not concentrated in part. In order to prevent concrete crushing, it is necessary to arrange reinforcing bars for reinforcing concrete as shown in FIGS. 4 and 5 around the guide (see Patent Documents 1 and 2). FIG. 4 shows an example of a reinforcing bar (grid bar) in which two reinforcing bars formed in a waveform are assembled in a lattice shape, and FIG. 5A shows an example of a reinforcing bar assembled in a spiral shape.

  When using grid bars as shown in FIG. 4- (a), the minimum bending radius of the bent portion through which the reinforcing bars are inserted is determined according to the diameter of the reinforcing bars (main bars) placed in the concrete. If an attempt is made to satisfy the required amount of reinforcing steel in the prestressed concrete, the radius of curvature of the bent portion increases, and the external dimensions of the grid reinforcement increase.

  If the outer dimension becomes large, it becomes difficult to secure the distance from the outermost reinforcing bar of the grid reinforcement to the concrete surface, and it becomes difficult to ensure the cover. In such a case, as shown in FIG. 4- (b), if the grid lines are arranged in a double manner, the size of each grid line can be reduced, so that the necessary cover thickness can be secured. However, because the reinforcing bars are mixed around the guides, the reinforcing bar workability and the filling of the concrete in the direction intersecting the main bars are reduced, and the amount of grid bars used increases, so the cost required for reinforcement increases. With disadvantages.

JP 2002-97745 A (Claim 4, paragraphs 0013 to 0019, FIGS. 1 to 3) JP 2003-41710 A (paragraphs 0011 to 0012, FIGS. 1 and 2)

  In addition, since the grid bars shown in FIG. 4 are shaped by combining reinforcing bars in a lattice shape, there is no stability in the thickness direction. It is easy to rotate and deform. Similarly, since the spiral muscle shown in FIG. 5- (a) has poor rigidity as a whole, it itself is easily deformed in the axial direction, so that it is also shown in FIGS. 5- (b) and (c) when placing concrete. Thus, it is easy to be displaced with respect to the guide, and it is difficult to maintain the mounting state against the compressive stress received from the guide.

  Both grid and spiral bars efficiently distribute the bearing stress from the guide and transmit it to the concrete. However, if the guide is deformed or displaced at the time of mounting on the guide as described above, the effect of dispersing the bearing stress cannot be exhibited.

  From the above background, the present invention provides a bearing stress distribution member that can stably maintain the mounting state on the guide while suppressing the external dimensions, and that can effectively distribute the bearing stress from the guide and transmit it to the concrete, and The present invention proposes a fixing tool including the same and prestressed concrete.

  The bearing stress distribution member according to the first aspect of the present invention is manufactured in a plane-symmetrical plate shape in the thickness direction, and the shape of the guide for inserting a cylindrical guide through which the tension material is inserted into the center portion. A guide insertion hole having a shape corresponding to the guide insertion hole is formed, a plurality of through holes are formed around the guide insertion hole at intervals in the circumferential direction, and the thickness of the edge portion around the guide insertion hole is the other part. And a convex portion formed on the outer peripheral surface of the guide on the inner peripheral surface of the edge portion. Is configured to have a recess that fits in the axial direction of the guide and can be engaged in the circumferential direction.

  Since the bearing stress distribution member itself is plane-symmetric in the thickness direction, there is no distinction between the front and back sides, so it is possible to distribute the bearing stress without considering the direction of the thickness direction on either side of the concrete. The member can be attached to the guide, and can be attached to the guide even if any one of both surfaces in the thickness direction faces the end surface side of the concrete. In other words, since there is no room for making a mistake in the direction of the thickness direction, the support stress distribution member is easy to handle. This is because if there is a difference between the front and back sides, it cannot be said that there is no possibility of arranging the bearing stress distribution members in the wrong direction.

  In addition, by forming a plurality of through holes around the guide insertion hole at intervals in the circumferential direction, the concrete enters the through hole when the support stress distribution member is in use, and the support stress distribution member Adhesive force is generated between them. As a result, as shown by the arrow in FIG. 3- (b), the supporting stress dispersing member exerts an adhesive force against the supporting stress transmitted in a cone shape from the guide to which the tension material is fixed into the concrete, By resisting, the supporting stress is dispersed and transmitted from the plurality of through holes to the surrounding concrete.

  The support stress distribution member is attached to the guide by inserting the guide through the insertion hole. The thickness of the edge portion around the guide insertion hole is larger than the thickness of the other portion, and the edge having the large thickness is inserted. By engaging the guide with the outer peripheral surface of the guide in the axial direction of the guide, the distance from the end surface of the guide is always mounted at a fixed position. As a result, since the bearing stress distribution member is accurately positioned with respect to the end surface of the concrete fixing the end portion of the tendon, the installation depth from the end surface of the concrete is always kept constant. By mounting the guide at a fixed position, the support stress distribution member can always be arranged at the most effective position to exert the support stress distribution effect. It is surely demonstrated without being lost.

  In particular, the support stress distribution member is not only locked to the outer peripheral surface of the guide, but also the locking portion is formed thick, so that the guide is cylindrical and the guide insertion hole has a corresponding shape. In addition, the outer peripheral surface of the guide can be maintained in a state of being fitted into the guide insertion hole, and when the thick edge portion is locked to the guide, the bearing stress distribution member is moved in the out-of-plane direction. High stability against tilt and displacement. Furthermore, since the support stress distribution member is stable against inclination and displacement in the concrete by being locked to the outer peripheral surface of the guide, the work for ensuring stability is extremely simple. Compared with the case of fixing by welding or the like, the work efficiency is high.

  In addition, on the inner peripheral surface of the edge portion around the guide insertion hole, a convex portion formed on the outer peripheral surface of the guide is fitted in the axial direction of the guide, and a concave portion that can be engaged in the circumferential direction is formed. Therefore, the support stress distribution member in the mounted state is prevented from rotating in the circumferential direction with respect to the guide, so that the support stress distribution member is not only stable against inclination and displacement but also stable against rotation in the circumferential direction. As a result, the effect of dispersing the bearing stress and transmitting it to the concrete is effectively exhibited. The inner peripheral surface of the edge portion refers to the surface of the edge portion on the guide insertion hole side.

  The invention according to claim 2 is the bearing stress distribution member according to claim 1, wherein the thickness of the outer peripheral edge portion of the bearing stress distribution member is the inner peripheral edge portion around the guide insertion hole. It must be larger than the thickness of the part to be excluded. In this case, since the thickness of the outer peripheral edge portion of the supporting stress dispersion member is larger than the thickness of the portion excluding the edge portion around the guide insertion hole, the bending rigidity of the outer peripheral portion of the supporting stress distribution member is increased. Since it is difficult to bend and deform, the ability to disperse the supporting stress from the guide and transmit it to the concrete is improved.

  According to a third aspect of the present invention, in the bearing stress distribution member according to the first or second aspect, a rib is formed on the outer periphery of the edge portion around the guide insertion hole. In this case, since the bearing stress dispersion member has ribs, the surface area in contact with the concrete is increased and the adhesion force with the concrete is increased. Therefore, the effect of transmitting the bearing stress from the bearing stress dispersion member to the concrete is increased. growing.

  According to a fourth aspect of the present invention, there is provided a fixing tool comprising the supporting stress dispersing member according to the first to third aspects, a cylindrical guide through which the guide insertion hole is inserted, and a tension material is inserted therethrough. The outer peripheral surface of the guide is configured to have a convex portion that is fitted in the axial direction into the concave portion of the supporting stress dispersion member and engaged in the circumferential direction. Since the fixing tool is composed of a support stress distribution member and a guide, and inherits the benefits of the support stress distribution member according to claims 1 to 3, it is easy to handle the support stress distribution member and attach it to the guide. The effect of having a high stability and the effect that the bearing stress can be dispersed and transmitted to the concrete by the bearing stress dispersing member.

  According to a fifth aspect of the present invention, in the fixing device according to the fourth aspect, the supporting stress dispersion member is locked to the outer peripheral surface of the guide at the edge portion around the guide insertion hole to the end side of the tension material. Is a constituent requirement. The supporting stress distribution member is locked to the end of the tension material on the outer peripheral surface of the guide in a state where the convex portion of the guide is fitted in the concave portion. Concrete is placed with a support stress distribution member attached to the guide, and the pressure at the time of placement tends to act from the sheath side to the end of the tendon at the outer periphery of the guide. Since the dispersing member is locked to the end of the tendon material, the stability of the supporting stress dispersing member at the time of placing the concrete is high.

  The invention according to claim 6 is characterized in that the fixing tool according to claim 4 or 5 is attached to at least one end portion of the tendon disposed in the prestressed concrete. Since the fixing tool includes the bearing stress dispersion member according to claims 1 to 3, the bearing stress dispersion member is supported by the support stress dispersion member and the effect that the bearing stress dispersion member is easy to handle and has a high stability when mounted on the guide. Has the effect of transmitting pressure stress dispersed in concrete.

Since the support stress distribution member itself is plane-symmetric in the thickness direction, the support stress distribution member can be used on either side of both ends of the concrete, even if either side of the thickness direction faces the end surface of the concrete. Can be attached to the guide.
In addition, since a plurality of through holes are formed around the guide insertion hole at intervals in the circumferential direction, an adhesive force is generated between the support stress distribution member and the concrete. The bearing stress can be dispersed and transmitted to the surrounding concrete with respect to the bearing stress transmitted in a shape.

  The thickness of the edge part around the guide insertion hole is larger than the thickness of the other part, and the edge part of the guide is always locked in the axial direction of the guide on the outer peripheral surface of the guide at this thick edge part. Since the distance from is fixed at a fixed position, the installation depth from the end face of the concrete can always be kept constant. In addition, since the locking portion of the supporting stress distribution member to the outer peripheral surface of the guide is formed thick, the inclination of the supporting stress distribution member when the thick edge portion is locked to the guide and High stability against deviation.

  Furthermore, a convex portion formed on the outer peripheral surface of the guide is fitted in the axial direction of the guide on the inner peripheral surface of the edge portion around the guide insertion hole, and a concave portion that can be engaged in the circumferential direction is formed. Since the support stress distribution member in the mounted state is prevented from rotating in the circumferential direction with respect to the guide, the effect of dispersing the support stress and transmitting it to the concrete is effectively exhibited together with stability against inclination and displacement. be able to.

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

  The support stress distribution member 1 according to claim 1 is mounted around a cylindrical guide 3 through which the tension material 2 is inserted as shown in FIG. The pressure stress is dispersed in the concrete 4 and transmitted. The support stress distribution member 1 and the guide 3 constitute a fixing tool for fixing the tendon 2.

  For the tendon 2, a fiber reinforced material using stainless steel, aramid or carbon fibers is used in addition to PC steel. The support stress distribution member 1 and the guide 3 are manufactured mainly by casting or forging carbon steel, but may be manufactured using a fiber reinforced composite material (fiber reinforced plastic, fiber reinforced alloy, etc.).

  The guide 3 is connected to a sheath 5 arranged in the concrete 4 or to a trumpet sheath 6 arranged by dispersing a plurality of tendons 2 at the end positions of the concrete 4 as shown in FIG. 2 is exposed from the concrete 4. A space 7 for fixing the end of the tendon 2 is formed on the end side of the tendon 2 of the concrete 4. This space 7 is formed after the tendon 2 is fixed. It is buried with mortar, concrete, etc. to protect it.

  On the inner periphery of the head 3a of the guide 3 exposed to the space 7, a fixing block 8 to which the tension material 2 is fixed and having insertion holes for the number of the tension materials 2 is fitted in the axial direction of the guide 3. , Installed in a restrained form. The tendon 2 is fixed to the fixing block 8 by a wedge 9, a nut or other means.

  The outer peripheral surface of the guide 3 generally has a shape in which the diameter increases from the sheath 5 side to the fixing block 8 side, and the intermediate position between the distal end on the sheath 5 side and the head 3a, specifically, from the guide 3 to the cone. A convex portion 3b for stabilizing the bearing stress dispersion member 1 in the circumferential direction in the mounted state is formed at a position effective for dispersing the bearing stress that spreads in a shape and is transmitted to the concrete 4. Concavities and convexities are formed on portions other than the positions where the convex portions 3b are formed to ensure adhesion with the concrete 4, if necessary.

  The convex portion 3b is formed on the smaller diameter side of the portion where the outer diameter of the guide 3 relatively increases as shown in FIG. 1 (b), which is a partially enlarged view of FIG. The member 1 is formed in the axial direction so that the member 1 is fitted in the axial direction of the guide 3 and is locked in the circumferential direction. Since the supporting stress dispersion member 1 is manufactured in a plane-symmetrical plate shape in the thickness direction, the diameter of the portion where the supporting stress distribution member 1 is mounted, that is, the portion where the convex portion 3b is formed is constant. Become. The supporting stress distribution member 1 is locked to the fixing block 8 side where the outer diameter of the guide 3 increases relatively from the smaller outer diameter side.

  The supporting stress dispersion member 1 is manufactured in a plane-symmetrical plate shape in the thickness direction, and corresponds to the shape of the guide 3 through which the guide 3 is inserted in the center as shown in FIG. A shaped guide insertion hole 1a is formed. In the drawing, the guide insertion hole 1a is circular because the outer shape of the guide 3 is circular. However, since the outer diameter of the guide 3 does not necessarily have to be circular, it may have a shape other than circular. In FIG. 2- (a), the external shape of the support stress distribution member 1 is a shape in which the corners of the quadrangle are curved. However, the external shape of the support stress distribution member 1 itself may be arbitrary, such as a circular shape. is there.

  As shown in FIGS. 1 and 2, the thickness of the edge portion 1b around the guide insertion hole 1a is larger than the thickness of the other portions, and the supporting stress distribution member 1 has the guide 3 at the edge portion 1b having a large thickness. The guide 3 is locked in the axial direction.

  A convex portion 3b formed on the outer peripheral surface of the guide 3 is located on the inner peripheral surface of the edge portion 1b corresponding to the convex portion 3b of the guide 3 as shown in FIG. A recess 1c that fits in the direction and can be engaged in the circumferential direction is formed. In the drawing, the recesses 1c are formed uniformly at four locations in the circumferential direction. However, the recesses 1c only need to be formed at one location because the recesses 1c only need to be fitted and locked with the projections 3b of the guide 3. Sometimes. Moreover, since the recessed part 1c should just be the shape which the convex part 3b of the guide 3 fits, it is formed in arbitrary shapes, such as square shape and semicircle shape.

  As shown in FIG. 1- (b) and FIG. 2- (b), the wall thickness of the outer peripheral edge portion 1d of the bearing stress distribution member 1 is increased in order to increase the bending rigidity of the outer peripheral portion. It is larger than the thickness of the portion excluding the edge portion 1b around the insertion hole 1a. Between the edge portion 1b around the guide insertion hole 1a and the edge portion 1d on the outer periphery, the concrete 4 of the supporting stress distribution member 1 as a whole In order to ensure adhesion, a plurality of through-holes 1e into which the concrete 4 enters are formed at intervals in the circumferential direction as shown in FIG. Ribs 1f for gaining adhesion to the concrete 4 are also formed in portions other than the formation portion of the through-hole 1e between the peripheral edge portion 1b and the outermost peripheral edge portion 1d of the guide insertion hole 1a.

  As shown in FIG. 1- (a), the support stress distribution member 1 is placed around the guide 3 and placed in a place where the concrete 4 is to be cast or filled together with the sheath 5 and the tension material 2. As described above, the concrete 4 is placed so that the head 3 a of the guide 3 is exposed from the concrete 4 to the space 7.

  As shown in FIG. 3B, the supporting stress from the guide 3 is dispersed and transmitted to the concrete 4 around the guide 3 in an enlarged region from the guide 3 side to the sheath 5 side. In order to reinforce the concrete 4 against the bearing stress transmitted in this manner, as shown in FIG. Reinforcing bars 10 are arranged.

  After the concrete 4 is cured, a tension force is applied to the tendon 2 and the tendon 2 is fixed to the fixing block 8 by the wedge 9 or the like. After the tension material 2 is fixed, a grout cap 11 is put around the fixing block 8, and the inside is filled with grout. After filling the grout, the space 7 is filled with a filler such as concrete or mortar, and the grout cap 11 is filled.

(A) is sectional drawing which showed the arrangement | positioning state in concrete of the bearing stress distribution member and guide of this invention, (b) is the partially expanded view of (a). (A) is the elevation which showed the bearing stress dispersion | distribution member, (b) is the xx sectional view taken on the line of (a). (A) is a cross-sectional view showing the relationship between the bearing stress dispersion member disposed near the end of the concrete and the cover of the concrete, (b) is the transmission of the bearing stress acting from the outer peripheral surface of the guide to the concrete It is sectional drawing which showed the mode. (A) is sectional drawing which showed the example of arrangement | positioning of the conventional grid reinforcement for resisting the bearing stress from a guide, (b) is sectional drawing which showed the mode when the conventional grid reinforcement was arrange | positioned doubly. It is. (A)-(c) is sectional drawing which showed the mode when it replaces with a grid | stitch line and has arrange | positioned the conventional spiral streak.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Supporting stress dispersion | distribution member 1a ...... Guide insertion hole 1b ...... Edge part 1c ...... Recessed part 1d ...... Outer peripheral edge part 1e …… Through hole 1f …… Rib 2 ... …… Tension material 3 ... …… Guide 3a …… Head 3b …… Convex 4 ……… Concrete 5 ……… Sheath 6 ……… Trumpet sheath 7 ……… Space 8 ……… Fixing block 9 ……… Wedge 10 …… Reinforcement 11… ... grout cap

Claims (6)

  A guide insertion hole is formed in a shape corresponding to the shape of the guide, through which a cylindrical guide through which a tension material is inserted is formed in the center portion, and is formed into a plane-symmetric plate shape in the thickness direction. A plurality of through-holes are formed around the guide insertion hole at intervals in the circumferential direction, and the thickness of the edge portion around the guide insertion hole is larger than the thickness of the other portion, and the edge having the large thickness is formed. The protrusion can be engaged with the outer peripheral surface of the guide in the axial direction of the guide, and the convex portion formed on the outer peripheral surface of the guide fits in the axial direction of the guide on the inner peripheral surface of the edge portion. And the recessed part which can be engaged in the circumferential direction is formed, The bearing stress distribution member characterized by the above-mentioned.   The supporting stress distribution member according to claim 1, wherein a thickness of an outer peripheral edge portion is larger than a thickness of an inner peripheral portion excluding an edge portion around the guide insertion hole.   The bearing stress distribution member according to claim 1, wherein a rib is formed on an outer periphery of an edge portion around the guide insertion hole.   A bearing stress distribution member according to any one of claims 1 to 3, a cylindrical guide through which a guide insertion hole is inserted, and a tension material is inserted, and the support pressure is provided on an outer peripheral surface of the guide. A fixing device characterized in that a convex portion is formed in the concave portion of the stress dispersion member so as to be fitted in the axial direction and engaged in the circumferential direction.   The fixing tool according to claim 4, wherein the supporting stress distribution member is locked to an outer peripheral surface of the guide at an edge portion around the guide insertion hole toward an end portion side of the tension material. . A prestressed concrete in which the fixing tool according to claim 4 or 5 is attached to at least one end of the tendon.

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