JP2009138455A - Shear-reinforcing structure for existing reinforced concrete construction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shear-resistant structure for an existing reinforced concrete construction, which is high in anchoring efficiency, and excellent in durability. <P>SOLUTION: In implementation of the shear-resistant structure, reinforcing steel bars 12 for shear reinforcement are inserted into the existing reinforced concrete construction. Firstly, reinforcing steel bar insertion holes 11 each having a diameter equal to the external diameter of the reinforcing steel bar 12 and an allowance, are bored in a wall 1 portion from an inside to an outside, and the reinforcing steel bars 12 each having coupled thereto a rear end anchoring body 14 made of an anticorrosive material such as ceramic or UFC, are inserted into the reinforcing steel bar insertion holes 11, respectively, followed by filling a hardening filler 13 such as cement grout in each gap between the reinforcing steel bar insertion hole 11 and the reinforcing steel bar 12. Since the rear end anchoring body 14 has corrosion resistance, a rear end of the reinforcing steel bar 12 can be arranged in cover concrete and an anchorage length can be set to a longer value, which brings about large anchoring efficiency and high shear reinforcing effect of the reinforcing steel bar. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shear reinforcement structure by an incision method for improving seismic resistance of a reinforced concrete structure, for example, a wall of a box culvert, a bottom plate, a top plate, a footing, etc. For reinforced concrete structures, it is suitable for shear reinforcement when reinforcing from one direction.

  As a means of seismic reinforcement by post-construction, there is a widely known method for shear reinforcement of existing underground structures such as box culverts and tunnels by inserting reinforcing bars from the inside into reinforced concrete walls. It has been.

  For example, in Non-Patent Document 1, as a method of seismic reinforcement that can be performed without reducing the internal cross section, there is a method of inserting a reinforcing bar (reinforcing bar) from the inside of a land tunnel or a U-shaped retaining wall and reinforcing the shear. Shown with a cross-sectional view.

  Similarly, in Patent Document 1 and Patent Document 2, as a shear reinforcement by post-construction of a reinforced concrete structure, a hole is drilled in the structure to be reinforced, a reinforcing steel material is inserted as a reinforcing bar, and mortar is filled Filling the material is described. Moreover, the form which made it shorter than the hole which drilled the rod-shaped reinforcement steel material so that it might not be exposed inside is shown.

  Patent Document 3 and Patent Document 4 are also related to post-construction shear reinforcement using a reinforcing bar. In Patent Document 3, only the rear end part of the shear reinforcing bar as the reinforcing bar or both the rear end part and the front end part are used. A fixing member having a cross section larger than that of the shear reinforcing reinforcing bar is integrated, and the fixing member has a cover concrete thickness equivalent to that of the existing main reinforcing bar.

JP 2002-275927 A JP 2003-113673 A JP 2005-105808 A JP 2004-293294 A “Case 3: Shear reinforcement by improving the submerged tunnel (Tokyo Port 2nd seafloor tunnel) joint”, Nikkei Construction January 12, 2001, Nikkei BP, P72-73

(1) Improving the fixing efficiency In the shear reinforcement of the wall-like member into which the shear reinforcing steel material is inserted later, if the cover is secured and fixed at the position of the main reinforcing bar as in Patent Document 3, the fixing efficiency is improved even if the fixing portion is provided. Insufficient, it will be necessary to increase the diameter of the shear-reinforced steel material more than necessary or increase the number of insertions.

  In addition, when a member having a fixing member at the front end portion is inserted, it is necessary to drill with a hole diameter that allows a margin with respect to the diameter of the fixing member. Therefore, even if a shear reinforcement steel material having the same thickness as that of the fixing member is inserted, it is the same after all.

  In addition, when a resin is injected as a filler, it is not a problem that the gap is narrow. Rather, the injection amount is small, and a decrease in strength due to heat generation during the resin curing process is small.

  There is no significant difference in the shear force that can be borne by the shear reinforced steel, whether it is a shear reinforced steel with a fixing member at the tip and high fixing efficiency or a large diameter shear reinforced steel with no fixing member and low fixing efficiency. However, since the fixing member is processed, there is no great difference between the two.

  Since the cost of drilling is the highest, the cost of drilling is the highest, so it is reasonable to insert a large-diameter shear-reinforced steel material that fits the drilling interval after the drilling interval is large as far as the design allows. .

(2) Problems related to the durability of the fixing portion In the conventional construction method in which the fixing member is arranged at a position where it is embedded in the concrete, the drilled portion of the fixing member portion has to be backfilled with mortar or the like. Such mortars are more permeable than concrete.

  In addition, the drying shrinkage of the mortar is larger than that of the concrete, and there is a difference in age with the existing concrete, so the mortar shrinkage often leaves the skin with the existing concrete. If moisture and salt penetrate from there, there is a problem that a sufficient effect cannot be obtained for rust prevention of the fixing body.

  In addition, the conventional method of arranging the fixing member at the position of the main reinforcing bar may not actually satisfy the cover thickness necessary for the steel material. This is because the cover thickness required by the design criteria is larger than that at the time of designing and constructing an existing structure, and the current design can be achieved even if the shear reinforcement steel material by post-construction is placed at the main reinforcing bar position. This is because the required cover thickness may not be satisfied when compared with the standards.

  In the conventional shear reinforcement method, which can drill concrete and generate fine cracks in the concrete, considering the possibility of rust prevention defects due to the above-mentioned backfill mortar, it is very effective for rust prevention of steel materials. There's a problem.

  The present invention has been made to solve the above-described problems in the prior art, and aims to provide a shear reinforcement structure for an existing reinforced concrete structure having high fixing efficiency and excellent durability of a fixing portion. Yes.

  The invention according to claim 1 of the present application includes a reinforcing steel material insertion hole drilled in an existing wall-shaped or plate-shaped reinforced concrete structure from one surface side to the opposite surface side, and the reinforcing steel material insertion. In a shear reinforcement structure of an existing reinforced concrete structure comprising a rod-shaped reinforcing steel material inserted into a hole and a curable filler filled in a gap between the reinforcing steel material insertion hole and the reinforcing steel material, the reinforcing steel material A rear end side fixing body made of a corrosion-resistant material covering the end portion of the reinforcing steel material is integrated on the rear end side in the insertion direction, and a rear end side fixing portion having a diameter larger than the outer diameter of the reinforcing steel material is formed. It is characterized by being.

  The concept of improving the shear strength and toughness of existing wall-shaped or plate-shaped reinforced concrete structures by means of bar reinforcement-type shear reinforcement with rod-shaped reinforcing steel is the same as the various conventional technologies described in the background section. The present invention differs from the conventional one in that a rear end side fixing body made of a corrosion-resistant material covering the rear end portion is integrated with the rear end of the reinforcing steel material in the insertion direction.

  In the inventions described in Patent Document 1 and Patent Document 2, the rear end of the reinforcing steel material in the insertion direction is embedded in the reinforced concrete structure so as not to be exposed on the surface. There is a risk of being affected by cracks and peeling of concrete from the surface, and even if the surface is repaired with mortar or the like, there are problems of rust prevention and fixing strength.

  For this reason, in the invention described in Patent Document 3, a fixing member having a large cross section is provided at the position of the main bar. However, the shear reinforcement efficiency is lowered as the shear reinforcing steel material is shortened, and a fixing member having a large outer diameter is provided for shearing. Although the reinforcement efficiency is improved, as described above, the relationship between the diameter of the perforation and the diameter of the shear reinforced steel material is not efficient.

  In the present invention, the end portion of the reinforcing steel material is covered with a rear end side fixing body made of a corrosion-resistant material, so that it is not necessary to repair with rust prevention cover concrete or mortar, at least about the rear end side fixing body portion. However, there is no problem of cracking itself, and conversely, the stress is dispersed by the fixing member having a large cross section, and cracking of the concrete in the vicinity can also be suppressed.

  In other words, the conventional reinforcing bar type shear reinforcement structure has the purpose of shortening the reinforcing steel material in relation to the cover concrete and the main reinforcement, and also fixing the fixing member integrated with the reinforcing steel material into the concrete. If the rear-end side fixing body made of a corrosion-resistant material is integrated, it is not necessary to embed it deeper than the cover concrete, and the length of the reinforced steel is as long as possible without causing a problem of protrusion to the inner surface. The fixing efficiency can be increased by increasing the length.

  In addition, if the fixing efficiency is large, sufficient shear strength can be easily obtained without providing a fixing portion on the front end side or reducing the diameter of the fixing portion. Therefore, the diameter of the reinforcing steel material insertion hole should be made as small as possible. Therefore, it is possible to reduce the cost of drilling, which has a large proportion of costs, and to save the filling amount of the curable filler.

  The curable filler may be filled before or after the reinforcement steel material is inserted, depending on the type of curable filler, the relationship between the diameter of the reinforcing steel material insertion hole and the diameter of the reinforcing steel material, the type, etc. It can select suitably.

  As for the joining of the reinforcing steel material and the rear end side fixing body, it is usual to use a threaded reinforcing bar and to screw a kind of nut formed with a female screw as the rear end side fixing body, like a conventional ceramic insert or ceramic anchor. Various methods are conceivable, such as a method using an anchor body that can be screwed with an M screw and using a reinforced steel material in which all screw rods or screw rods are joined.

  Further, in order to increase the adhesion with the curable filler, and in order to lengthen the moisture permeation path, the side surface of the rear end side fixing body may be formed into an uneven shape or a wave shape.

  Claim 2 is the shear reinforcement structure for an existing reinforced concrete structure according to claim 1, wherein the rear end of the rear end side fixing body is flush with the surface of the existing reinforced concrete structure or the existing reinforced concrete structure It protrudes from the surface of the body, and the rear end of the reinforcing steel material is located near the surface of the existing reinforced concrete structure.

  As described above, since the rear end side fixing body made of a corrosion-resistant material covering the end of the reinforcing steel material is integrated, in the present invention, the reinforcing steel material and the rear end side fixing body are purposely placed deeper than the cover concrete. There is no need to embed, and the fixing efficiency can be increased by making the length of the reinforcing steel material as long as possible within a range in which the amount of protrusion to the inner surface does not matter.

  In addition, installing the rear end portion at a shallow position from the surface of the existing reinforced concrete wall such as in the cover concrete is also effective in reducing the amount of drilling of the rear end side fixing body portion.

  Therefore, in claim 2, the rear end of the rear end side fixing body is flush with the surface of the existing reinforced concrete structure or protrudes from the surface of the existing reinforced concrete structure, and the rear end of the reinforcing steel material is It is designed to be located near the surface of an existing reinforced concrete structure.

  In the case where the rear end of the rear end side fixing body is flush with the surface of the existing reinforced concrete structure, for example, in shear reinforcement such as a box culvert or a tunnel wall, there is no protrusion inside the existing reinforced concrete structure, Shear reinforcement can be performed without narrowing the internal space.

  Also, under the condition that it may be protruded inward partially or entirely, the rear end of the fixing member on the rear end side protrudes from the surface of the existing reinforced concrete structure. The fixing length can be increased, and the fixing efficiency can be further increased.

  According to a third aspect of the present invention, in the shear reinforcement structure of the existing reinforced concrete structure according to the first or second aspect, the material of the rear end side fixing body is any one of ceramic, hard plastic, ultra high strength fiber reinforced concrete, or stainless steel. It is characterized by this.

  Claim 3 specifically defines the material of the rear end side fixing body, and if it is ceramic, hard plastic, ultra high strength fiber reinforced concrete or stainless steel, it can satisfy the necessary corrosion resistance and strength. .

Ultra high strength fiber reinforced concrete (hereinafter referred to as “UFC”) is a material in which steel fiber, carbon fiber, glass fiber, or the like is mixed in concrete or mortar with high compressive strength, and has a compressive strength of 100. An ultrahigh strength fiber reinforced concrete or mortar having a tensile strength of ˜250 N / mm ² , a bending tensile strength of 10 to 40 N / mm ² , and a tensile strength when cracking of 5 to 15 N / mm ² is preferable.

  According to the UFC guidelines, if the length from the surface of the UFC to the embedded steel material is 20 mm or more, it can prevent the penetration of chloride ions that cause corrosion in the service life (assuming about 300 years). It is clear. That is, it is possible to reduce the fog required for durability compared to ordinary concrete.

  In addition, in the invention according to claim 1, other materials may be used as long as they are provided with necessary corrosion resistance and strength and are not excessive in cost, such as metal plated or other anticorrosion treatment. Is possible.

  According to a fourth aspect of the present invention, in the shear reinforcement structure for an existing reinforced concrete structure according to any one of the first to third aspects, the rear end side fixing body is screwed to the rear end portion of the reinforcing steel material. Is.

  If a male screw and a female screw are formed respectively on the rear end portion and the rear end side fixing body of the reinforcing steel material, both can be simply joined in a screw manner.

  In addition, if a threaded bar that is a deformed steel bar is used for the reinforcing steel and a screw groove is formed on the fixing member on the rear end side to be screwed with the threaded bar of the screwed reinforcing bar, no additional threading is required for the reinforcing steel. All you need to do is cut off commercially available threaded bars.

  According to a fifth aspect of the present invention, in the shear reinforcement structure for an existing reinforced concrete structure according to any one of the first to fourth aspects, a front end side fixing portion having a diameter larger than the outer diameter of the reinforcing steel material is provided on the front end side in the insertion direction of the reinforcing steel material. It is characterized by being.

  By providing a tip side fixing portion having a diameter larger than that of the reinforcing steel material on the tip side of the reinforcing steel material, fixing efficiency is increased by the support pressure of the tip side fixing portion, and a shear reinforcement effect can be further improved.

  The tip side fixing portion may be formed in advance at the tip of the reinforcing steel material before being inserted into the reinforcing steel material insertion hole, or may be formed at the time of insertion or after insertion.

  When the former is inserted in a state where the tip side fixing portion has been formed in advance, it is necessary to increase the diameter of the reinforcing steel material insertion hole, which increases the cost, and there is a limit to the possible diameter. However, since the reinforcing steel material and the tip fixing portion can be inserted and installed at the same time by forming the fixing portion at the tip of the reinforcing steel material in advance, the construction efficiency can be improved.

  As a method of avoiding an increase in the diameter of the latter reinforcing steel material insertion hole, a method in which a nut-like fixing body is first installed at the bottom of the reinforcing steel material insertion hole and the tip of the reinforcing steel material is screwed thereto, the reinforcing steel material A method of unifying the ring by elastically expanding the ring from the cut part by installing a fixing body having a shape obtained by cutting a part of the ring at the bottom of the insertion hole and pushing the tip of the reinforcing steel material into it. A capsule filled with a resin-based hardener is installed at the bottom of the reinforcing steel material insertion hole, and the tip of the reinforcing steel is pushed into the capsule to break through the capsule. For example, a cross is cut at the tip of the steel material, and a wedge member is inserted into the notched portion.When the tip of the reinforcing steel material reaches the bottom of the reinforcing steel material insertion hole, the wedge member pushes the notched portion at the tip of the reinforcing steel material. Spread tip The method of forming the fixing portion and the like.

  In the method in which a nut-shaped fixing body is first installed at the bottom of the reinforcing steel material insertion hole and the tip of the reinforcing steel material is screwed to the reinforcing steel material, the entire reinforcing steel material integrated with the fixing body is long and uneven. Rather than inserting the nut-shaped fixing member into the hole wall, there is a degree of freedom in inserting the nut-shaped fixing member, so that the fixing member can be easily inserted. In addition, in the method in which the tip side fixing portion is formed by a wedge member by cutting a cross at the tip of the reinforcing steel material, the fixing portion expands at the tip of the hole after inserting the reinforcing steel material. It is possible to provide a fixing portion whose tip is larger than the diameter of the reinforcing steel material while minimizing the diameter.

  According to a sixth aspect of the present invention, in the shear reinforcement structure for an existing reinforced concrete structure according to the fifth aspect, the front end side fixing portion is formed of a front end side fixing body made of a corrosion-resistant material that covers the front end portion of the reinforcing steel material. It is characterized by.

  As for the front end side fixing body, similarly to the rear end side fixing body, by using a material having corrosion resistance, the limitation due to the thickness of the cover concrete is relaxed, and the fixing length can be made larger.

  In particular, when the construction must be unidirectional from the inner space side, such as a box culvert or a tunnel wall, there is a great merit that the processing on the front side of the reinforcing steel material can be simplified.

  In addition, if a male screw and a female screw are formed on the front end portion and the front end side fixing body of the reinforcing steel material, respectively, as in the case of claim 4 relating to the rear end side, it is possible to easily join the screw type.

  As the material having corrosion resistance, ceramic, hard plastic, ultra-high-strength fiber reinforced concrete, resin, stainless steel, or the like can be used as in the case of the fixing member on the rear end side described above.

  According to a seventh aspect of the present invention, in the shear reinforcement structure for an existing reinforced concrete structure according to the sixth aspect, the front-end-side fixing body is positioned in a cover concrete portion of the existing reinforced concrete structure. .

  The cover concrete portion referred to in claim 7 is a cover concrete opposite to the insertion side of the reinforcing steel material, and there is no problem in the state of the cover concrete portion of the portion, and the tip portion of the reinforcing steel material is positioned with a certain degree of accuracy. In such a situation, it is possible to increase the fixing length by positioning the front-end side fixing body in the cover concrete portion.

  The present invention provides a shear reinforcement structure for an existing reinforced concrete structure according to claim 6 or 7, wherein a tip end portion of the rear end side fixing body and / or a rear end portion of the front end side fixing body is the existing reinforced concrete structure. It is characterized by extending from the cover concrete part to the inner concrete part.

  In general, the current design standards are stricter than the cover at the time of designing existing structures, and the required cover thickness is generally larger, so even if a corrosion-resistant fixing body is placed inside the existing cover, In design, there is a possibility that the rust prevention of the shear reinforced steel material is not sufficient.

  As one solution thereof, in claim 8, one or both of the front end portion of the rear end side fixing body having corrosion resistance and the rear end portion of the front end side fixing body is located inside the cover concrete portion of the existing reinforced concrete structure (reinforced concrete). By extending to the concrete part (deep position of the structure), the rust prevention of the shear reinforced steel material is ensured.

  In the present invention, by covering the end portion of the reinforcing steel material with a rear end side fixing body made of a corrosion-resistant material, there is no need for repairing with rust-proof cover concrete or mortar, at least for the rear end side fixing body portion, There is no problem of cracks in itself, and conversely, stress is dispersed by the fixing member having a large cross section, and cracks in the nearby concrete can also be suppressed.

  In other words, the conventional reinforcing bar type shear reinforcement structure has the purpose of shortening the reinforcing steel material in relation to the cover concrete and the main reinforcement, and also fixing the fixing member integrated with the reinforcing steel material into the concrete. If the rear-end side fixing body made of a corrosion-resistant material is integrated, it is not necessary to embed it deeper than the cover concrete, and the length of the reinforced steel is as long as possible without causing a problem of protrusion to the inner surface. By increasing the length, the length from the shear crack point to the end of the reinforcing bar, that is, the fixing length is increased, and the fixing efficiency can be increased.

  Further, in a reinforced concrete structure that undergoes shear failure, the reinforcing steel material crosses the fracture surface, that is, the shear crack generated in the reinforced concrete structure, and the resistance of the reinforcing steel material that has crossed greatly contributes to the shear strength. That is, the greater the number of reinforcing steel materials that cross one shear crack, the higher the shear reinforcement effect.

  Therefore, regardless of the rear end and the front end, making the fixing portion as close as possible to the surface of the member and increasing the probability that the shear crack crosses the reinforcing steel material installation position contributes to the improvement of the shear reinforcement effect. In other words, providing the anchoring part at a shallow position from the surface of the reinforced concrete structure has two meanings: the anchoring length from the shear cracking part becomes longer, and the reinforcing steel material crossing one shearing crack increases. Contributes to the improvement of the shear reinforcement effect.

  If the fixing efficiency and the reinforcing effect are increased, sufficient shear strength can be easily obtained without providing a fixing portion on the tip side or by reducing the diameter of the fixing portion. Therefore, the diameter of the reinforcing steel material insertion hole is made as small as possible. Thus, it is possible to reduce the cost of drilling, which has a large proportion of costs, and to save the filling amount of the curable filler.

  In the case where the rear end of the rear end side fixing body is flush with the surface of the existing reinforced concrete structure, for example, in shear reinforcement such as a box culvert or a tunnel wall, there is no protrusion inside the existing reinforced concrete structure, Shear reinforcement can be performed without narrowing the internal space.

  Also, under the condition that it may be protruded inward partially or entirely, the rear end of the fixing member on the rear end side protrudes from the surface of the existing reinforced concrete structure. The fixing length can be increased, and the fixing efficiency can be further increased.

  By using a threaded bar that is a deformed steel bar for the reinforcing steel, and forming a screw groove to be screwed into the screw joint of the screwed bar on the rear end side fixing body, no additional screw processing is required for the reinforcing steel, which is commercially available. All that is required is to cut the threaded bar.

  If a tip side fixing portion having a diameter larger than that of the reinforcing steel material is provided also on the tip side of the reinforcing steel material, fixing efficiency is increased by the support pressure of the tip side fixing portion, and a shear reinforcement effect can be further improved.

  As for the front end side fixing body, similarly to the rear end side fixing body, by using a material having corrosion resistance, the limitation due to the thickness of the cover concrete is relaxed, and the fixing length can be made larger.

  In particular, when the construction must be unidirectional from the inner space side, such as a box culvert or a tunnel wall, there is a great merit that the processing on the front side of the reinforcing steel material can be simplified.

  FIG. 1 shows one embodiment of the shear reinforcement structure of the present invention, and FIG. 2 shows details of the front and rear ends of the shear reinforcement steel material.

  In this embodiment, a reinforcing steel material 12 is inserted into a wall portion of a reinforced concrete box culvert from the inner side of the box culvert (hereinafter referred to as the inner surface side) to the natural ground side (hereinafter referred to as the outer surface side), and shear reinforcement is performed. This is an example of the case. In the present embodiment, the front end side fixing body is not provided.

In the figure, 2 indicates an existing main reinforcing bar, 3 indicates an existing distribution reinforcing bar, and 4 indicates an existing concrete portion. In addition, P ₁ and P ₂ in the dimension line indicate the necessary cover thickness of the steel material, t ₁ indicates the length necessary for fixing the reinforcing steel material 12, and t ₂ indicates the length of the portion that further requires rust prevention. .

  In such an existing reinforced concrete wall 1, the direction in which the shear stress is generated is an oblique direction in the figure, and the reinforcing steel material insertion hole 11 crossing the direction in which the shear stress is generated is substantially perpendicular from the inner surface side of the wall 1. Drilled in the thickness direction of the wall 1, a reinforcing steel material 12 is inserted into the reinforcing steel material insertion hole 11, and fixed with a curable filler 13 filled in the gaps.

  A rear end side fixing body 14 made of a corrosion-resistant material is integrated on the rear end side in the insertion direction of the reinforcing steel material 12, that is, the inner surface side of the wall 1, and the rear end side fixing larger in diameter than the outer diameter of the reinforcing steel material 12. Forming part. In this embodiment, a threaded bar of a deformed steel bar is used as the reinforcing steel material 12, and the rear end side fixing body 14 is joined to the screw type using a screw node at the rear end.

  As the rear-end-side fixing body 14, a ceramic countersunk nut 14 a in which a screw groove that is screwed with a screw node of the reinforcing steel material 12 is formed is used. In the illustrated dish-shaped nut 14a, the straight portion extends from the frustoconical dish-shaped portion, and covers the entire portion of the rear end portion of the reinforcing steel member 12 located in the cover concrete. Further, when the cover thickness at the time of design is small, it is also possible to use a long straight portion that extends beyond the position of the main rebar 2 and reaches the deep position of the concrete 4.

  In addition to this, the material of the rear end side fixing body 14 may be hard plastic (including FRP), non-ferrous metal such as stainless steel, ultra high strength fiber reinforced concrete (UFC), steel material subjected to heavy anticorrosion, etc. In addition to the strength and rigidity of the fixing body, it is desirable that it is excellent in corrosion resistance and that the gland expansion coefficient is substantially equal to that of concrete, and considering these points, ceramic is preferable.

  For example, in the case of ceramic, the thickness required to ensure sufficient corrosion resistance for the reinforcing steel material 12 may be about 5 mm. Therefore, according to the present invention, the rear end side fixing body 14 of the reinforcing steel material can be installed at a position as shallow as possible from the surface of the reinforced concrete structure.

  Further, by forming the fixing portion in the shape of a truncated cone or having a bulge on its side surface, the ceramic fixing portion is restrained by the surrounding existing concrete, and a stable fixing force can be expected. Also, since the reaction force of the restraining force acts on the ceramic itself as a compressive force, it is necessary to make the fixing part a frustoconical shape or a shape having a bulge on its side surface. This has the effect of canceling the split tensile force generated in the ceramic.

  For example, an existing insert or the like has a curved upper surface of the fixing portion for the purpose of enhancing the restraining effect of the surrounding concrete against the tensile force and increasing the resistance force by the arch effect. On the other hand, for the purpose of increasing the resistance force with respect to the compression force with the same mechanism, the lower part of the fixing body is also curved, and an oval shape is adopted as a whole. On the other hand, in the present invention, since the reinforcing steel material provided with the fixing body is inserted from one surface of the reinforced concrete wall and expected to resist only the tension, there is no need to have the resistance against the compressive force in the above-mentioned insert.

  Therefore, in the present invention, a shape similar to the upper part of the egg-shaped insert, that is, a truncated cone shape, or a fixing body having a bulge on its side surface is suitable. Further, since the largest diameter portion of the rear end side fixing body 14 becomes the surface of the existing concrete wall, there is almost no portion where the curable filler 13 is exposed on the surface, and the penetration of moisture and salt can be minimized. .

  It should be noted that the outer diameter of the frustum-shaped fixing portion may be set to a size that does not cause the bearing to break the bearing. For example, when SD345 D22 is used as the reinforcing steel material, if the outer diameter is about 60 mm or more, the bearing failure of the concrete can be prevented against the standard yield strength of the reinforcing steel material, and the fixing of the reinforcing steel material 12 is ensured. Is done.

  It is also conceivable to use a fixing body made of ultra high strength fiber reinforced concrete in which a metal nut for joining to the reinforcing steel material 12 is embedded as will be described later.

  As the curable filler 13, an organic grout material such as an epoxy resin or an acrylic resin, an inorganic grout material such as a cement grout, or the like can be used. .

  If it is an ultra-high-strength cement-based hardener with the same composition as the UFC and does not mix fibers, it has excellent adhesion strength with the reinforcing steel material 12 and has high resistance to moisture and salt penetration from the concrete surface. Therefore, it is excellent in durability and is the most preferable filler. In addition, these curable fillers 13 may be filled before the reinforcement steel material 12 is inserted or after the reinforcement steel material 12 is inserted, depending on design conditions and the like.

  Further, in this embodiment, since there is no front-end fixing body, the diameter of the reinforcing steel material insertion hole 11 may be a size that does not hinder the insertion of the reinforcing steel material 12, and the fixing efficiency is impaired by suppressing the diameter as much as possible. Therefore, the cost of drilling and the amount of the curable filler 13 can be saved.

  When a typical dimension example is given, when a threaded joint of D22 (outer diameter D = 22 mm) is used as the reinforcing steel material 12, the diameter of the reinforcing steel material insertion hole 11 is set to about 30 to 35 mm.

  An example of the construction procedure in this embodiment will be described as follows.

  Drilling with the outer diameter of the reinforcing steel material 12 plus a marginal diameter (drill drilling, core drilling, etc.).

  On the reinforcing steel material insertion side where the rear end side fixing body 14 is installed, the diameter of the portion where the straight portion of the countersunk nut 14a is positioned is drilled (the drill diameter is changed by replacement).

  For the frustoconical dish-shaped part, change the drilling jig (such as a taper reamer for concrete) and drill it in an umbrella shape.

  Next, the rear end side fixing body 14 is bonded in advance, and the reinforcing steel material 12 to which a masking tape or the like is stuck so that the curable filler 13 does not adhere to the surface (rear end surface) is inserted into the reinforcing steel material insertion hole 11.

  After filling with a curable filler 13 such as resin or cement grout, the surface is cleaned and the masking tape is removed.

  The order of drilling may be the reverse of the above, but when it hits an existing reinforcing bar, it is necessary to shift the position and start drilling again. .

  Further, with respect to the rear end side fixing body 14, by making the shape of the fixing body having a circular cross section with respect to the drilling hole having a circular cross section, the drilled space can be used without waste and less material for backfilling is required. .

  In the illustrated example, the bottom of the reinforcing steel material insertion hole 11 and the tip of the reinforcing steel material 12 are substantially located at the position of the main rebar 2 so as not to enter the cover concrete portion. It is also possible to increase the fixing length by applying a rust prevention treatment to the front end portion by, for example, epoxy resin coating, so that the front end of the reinforcing steel material 12 enters the cover concrete portion.

  FIG. 3 shows details of the front and rear end portions of the shear reinforcing steel material when the front side fixing body 15 is provided on the front side of the reinforcing steel material 12 as another embodiment.

  Specifically, in the present embodiment, a ceramic bag-like nut in which a thread groove that is screwed with a screw node of the reinforcing steel material 12 is attached to the distal end side of the reinforcing steel material 12 as the distal-side fixing body 15. .

  If the tip side fixing portion is formed by the ceramic tip side fixing body 15 having corrosion resistance, it is not necessary to stop the tip side at the position of the main rebar 2 and the fixing length can be increased.

  When the head portion (tip portion) of the tip side fixing body 15 is disc-shaped or cylindrical, the outer surface side can also be fixed in the cover concrete part, so that the fixing length as a shear reinforcement steel material becomes long and the main reinforcing bar 2 is positioned. Even if the head diameter is smaller than the case of fixing, the same fixing efficiency can be obtained. Accordingly, the diameter of the hole is small, and the construction time and cost related to the hole can be shortened and reduced.

  An example of the construction procedure in this embodiment will be described as follows.

  Drilling with the outer diameter of the fixing member 15 at the front end (substantially equal to the outer diameter of the straight portion of the countersunk nut 14a) + the diameter of the margin (drill drilling, core drilling, etc.).

  For the frustoconical dish-shaped part, change the drilling jig (such as a taper reamer for concrete) and drill it in an umbrella shape.

  Next, the front-end side fixing body 15 and the rear-end side fixing body 14 are joined in advance, and a masking tape or the like is applied so that the curable filler 13 does not adhere to the surface (rear end face) of the rear-end side fixing body 14. The steel material 12 is inserted into the reinforcing steel material insertion hole 11.

  After filling with a curable filler 13 such as resin or cement grout, the surface is cleaned and the masking tape is removed.

  The order of drilling may be the reverse of the above, but as described above, when hitting an existing reinforcing bar, it is necessary to shift the position and redo the drilling. It is good.

FIG. 4 shows four types of examples relating to rust prevention of the rear end portion of the shear-reinforced steel material in the present invention. In the figure, P ₁ in the dimension line indicates the necessary cover thickness of the steel material, t ₁ indicates the length necessary for fixing the reinforcing steel material 12, and t ₂ indicates the length of the portion where further rust prevention is required.

  FIG. 4 shows a case where the rear ends of the rear end side fixing bodies 14a to 14d are flush with the inner surface side of the existing reinforced concrete wall 1, and the rear end of the reinforcing steel material 12 is located near the inner surface.

(a) shows that the overall shape of the rear end side fixing body 14b made of ceramic or the like is a truncated cone shape having a height substantially equal to the required cover thickness P _{1 of the} steel material, and is screwed with the screw node of the reinforcing steel material 12 inside. A screw groove is formed, and the entire area where rust prevention of the reinforcing steel material 12 is required is covered by the corrosion-resistant rear end side fixing body 14b.

  (b) is a case where the rear end side fixing body 14a having a dish-like portion and a small-diameter straight portion described with reference to FIGS. 1 to 3 is used. The entire range is covered with the corrosion-resistant rear end side fixing body 14a.

  (c) is covered with a corrosion-resistant plate-shaped nut-shaped rear end side fixing body 14c made of ceramic or the like as long as necessary for fixing the reinforcing steel material 12, and the remaining portion of the cover concrete is coated with epoxy resin 16; It is rust-proof by etc.

  (d) shows a case in which the rear end portion of the reinforcing steel material 12 is replaced with a corrosion-resistant steel material such as a stainless steel screw rod 17 and joined to the rear end side fixing body 14d having a dish-like nut shape. In the example of (d), the joining to the rear end side fixing body 14d is not joining by a screw node but joining by a normal screw.

  FIG. 5 shows a modification relating to the position of the rear end portion of the shear reinforced steel material.

  (a) is a reinforced concrete wall in which the rear end side fixing body 14a having a dish-like portion and a narrow straight portion protrudes from the inner surface side of the wall 1 and the rear end of the reinforcing steel material 12 is an existing reinforced concrete wall described in FIGS. In the case where it is substantially flush with the inner surface of 1, (b) is a case where the rear end of the reinforcing steel material 12 is also located on the inner space side from the inner surface of the existing reinforced concrete wall 1.

  These have a problem of aesthetics and a problem of narrowing the inner space in that the rear end side fixing member 14a protrudes to the inner surface side of the wall 1, but is more advantageous in terms of fixing efficiency.

  FIG. 6 shows a modified example of the joint portion between the rear end portion of the shear-reinforced steel material 12 and the rear end side fixing body. Similar to the case of FIG. It is joined with screws.

  However, in FIG. 4 (d), a stainless steel screw rod 17 is used, whereas in the example of FIG. 6 an ordinary screw is provided at the end of the deformed steel bar, so that the rear end side fixing body 14e is provided. The entire part is covered and anticorrosive.

  FIG. 7 shows a modification regarding the shape of the rear end side fixing member.

  The rear end side fixing member is not limited to a plate nut shape, but is a cylindrical rear end fixing member 14f as shown in (a), a hemispherical rear end fixing member 14g as shown in (b), (a). Various forms such as a multi-stage disk-shaped rear end side fixing body 14h can be used.

  FIG. 8 (a) shows another modification regarding the shape of the rear end side fixing member. The rear end surface of the truncated conical rear end side fixing member 14i is formed into a smooth lens shape, and the reinforcing steel material 12 The rear end is substantially flush with the inner surface of the existing reinforced concrete wall 1 to improve the fixing efficiency, and the protrusion of the rear end side fixing body 14i from the inner surface is not noticeable and obstructive. Is.

  In other words, the rear end surface of the rear end side fixing body 14i made of ceramic or the like is swelled by a thickness necessary for rust prevention, but the swell amount may be about several millimeters. An increase in the degree coefficient is negligible.

  Further, FIG. 8B shows a shape in which the rear end side fixing body 14j has a bulge on the side surface of the cone for the purpose of increasing the restraining pressure from the surrounding concrete and increasing the fixing force. In addition, when manufacturing a nut-shaped ceramic, the shape is molded using a mold. In that case, the side of the truncated cone has a moderate bulge than the straight shape. However, manufacture becomes easy.

  FIG. 9 shows another modification of the fixing portion of the rear end side fixing body.

  In this example, in the case of using the rear end side fixing body 14a having the dish-like portion and the narrow straight portion described with reference to FIGS. 1 to 3, the rear end side fixing body 14a portion is not an umbrella-shaped drilling hole. Also, a cylindrical hole is made, and a spiral reinforcing bar 18 is embedded and reinforced in the widened hole portion.

  FIG. 10 shows a modification of the rear end portion of the shear-reinforced steel material when UFC is used for the rear end side fixing body.

  In the case of the above-mentioned ceramic nut, the size of the diameter that can be manufactured is limited, and in the case of stainless steel rebar, there may be cases where sufficient corrosion resistance cannot be expected in an environment where corrosion factors such as seawater are directly touched, With respect to these points, the rear end side fixing member made of UFC is advantageous.

  In FIG. 10, a commercially available nut 25 with a plate embedded in a disk-shaped UFC 27 is used as the rear end side fixing body 24. Other configurations are the same as those in FIG. 1, and the tip of the shear-reinforced steel material (not shown) can be the same as in FIG.

  When the fixing portion by the rear end side fixing body 24 is provided in the cover as shown in FIG. 10, the shear crack can cross the shear reinforcing steel member 12 even in the cover, and the shear reinforcing steel member crossing one shear crack. The number of 12 increases compared to the case where the fixing portion is provided at the position of the main muscle 12, and the reinforcing effect is increased accordingly. Conversely, the number of shear reinforced steel materials 12 can be reduced.

  As the plate-equipped nut 25, a commercially available product corresponding to a threaded reinforcing bar or the like as the shear reinforcing steel material 12 can be used. Generally, nuts with a plate of a threaded bar are commercially available for D16 to D41, and these materials are relatively easily available. That is, even when the large-diameter reinforcing bar is used as the shear reinforcing steel material 12, reliable fixing can be realized, and the durability of the fixing portion can be ensured.

  The shear-reinforced steel material 12 is basically based on the use of screw joints. This is because fixing with a nut with a plate is possible for many diameters from D16 to D41 as described above. However, you may use what installed the screw part by the friction bonding in the edge part of a reinforcing bar, or what was manufactured by machining. In this case, a nut with a plate corresponding to the installed and manufactured screw portion may be used for fixing.

  The shape of the UFC rear end side fixing body 24 and the dimensions of the nut 25 with a plate are the following: bearing failure of the plate 26, bearing failure of the UFC27 portion, shear failure of the plate 26 portion of the nut 25, failure of the nut 25 itself And to ensure sufficient durability during the service life period.

  As a construction procedure, a reinforcing steel material insertion hole 11 having a size with a margin added to the diameter of the shear reinforcing steel material 12 is drilled from the inside of the reinforced concrete wall, and the insertion port portion is formed with the diameter of the UFC rear end side fixing body 24. Widen to a size and depth according to the height.

  Next, the shear reinforcing steel material 12 having the rear end side fixing body 24 made of UFC attached to the rear end is inserted into the reinforcing steel material insertion hole 11 and filled with the curable filler 13. Instead of filling the curable filler 13 later, a capsule filled with a curable filler 13 such as an epoxy resin is placed in the reinforcing steel material insertion hole 11 and the shear reinforced steel material 12 is inserted. At this time, the capsule may be broken and fixed with the curable filler 13.

  FIG. 11 shows another modified example of the rear end portion of the shear-reinforced steel material when UFC is used for the rear end side fixing body. The UFC rear end side fixing body 24 is a part of the existing reinforced concrete wall surface. It is a case where it protrudes from.

  In this case, since the shear reinforcing steel material 12 can be lengthened accordingly, the probability that the above-mentioned shear crack crosses the reinforcing bar is increased, which is significant in improving the reinforcing effect. Moreover, the excavation depth of the widening hole of a reinforced concrete wall inner surface can be made small in the construction method mentioned later.

  FIG. 12 shows an example of the shape of the UFC rear end side fixing member 24 in which the nut 25 with a plate is embedded. In this example, a simple disk shape centering on the nut 25 with a plate is used.

  The diameter of the circle is assumed to show a cone-like fracture at an angle of 45 degrees when the nut 25 receives a tensile force, and is assumed to be the diameter of the plate 26 + the threaded portion height x 2. Thereby, the bearing stress transmitted from the UFC rear end side fixing body 24 to the existing concrete side can be relaxed, and the bearing failure of the existing concrete portion can be prevented.

  On the other hand, the bearing failure of the plate portion of the plate-equipped nut 25 can be prevented by the high compressive strength of the UFC. As described above, the thickness of the nut 25 is set to the total height of the nut 25 + the cover (20 mm or more) so that the cover can secure a minimum cover thickness of 20 mm or more from the plate 26 of the nut 25 with a plate.

To give a specific example, the design condition is that a shear-reinforced steel member 12 uses SD345 D22 threaded joints, and commercially available nuts with plates are used. UFC is an ultra-high-strength fiber reinforced concrete with a design standard strength of 180 N / mm ^2. When the concrete design standard strength of the reinforced concrete structure to be reinforced is 21 N / mm ² , the diameter R ₁ of the plate 26 = 55 mm, the total height L _{1 of the} nut 25 L 53 = 53 mm Nut cover d = 20 mm, UFC disk height H = 73 mm, UFC disk diameter R = 139 mm are conceivable.

  FIG. 13 shows another example of the shape of the UFC rear end side fixing body 24 in which a nut 25 with a plate is embedded.

  While the example of FIG. 12 is a disk type, in FIG. 13, the diameter of the rear end side of the fixing portion in the insertion direction is set to a size that takes into account durability and bearing load failure of the concrete. Appropriate taper is provided to expect the restraining effect from the reinforced concrete structure.

  Also, if the shape on the rear end side in the insertion direction is a columnar shape that secures the diameter to the position of the cover of the plate 26 of the nut 25 with a plate, even if the cone is broken at an angle of 45 degrees, the concrete support It is possible to secure the bearing area (determined by the diameter on the rear end side in the insertion direction) necessary for preventing pressure breakage.

  That is, in FIG. 13, although the fixing force and durability are the same as in FIG. 12, the shape is complicated, but the size of the UFC rear end side fixing body 24 can be reduced, which is advantageous in cost and manufacturability. It becomes.

In the same design conditions as those in FIG. 12, a specific example is shown in FIG. 13. In FIG. 13, the diameter R ₁ of the plate 26 is 55 mm, the total height L _{1 of the} nut 25 is 53 mm, the fogging of the nut in the UFC is d = 20 mm, UFC The dimensions such as the height H = 73 mm, the UFC diameter R _L = 99 mm, and the diameter R _S = 599 mm can be considered.

  In this case, the shape is more complex than that of FIG. 12, but the amount of UFC used can be reduced by about 65%, and sufficient fixing power and durability can be expected with respect to the yield strength of SD345 D22. it can.

It is sectional drawing which shows one Embodiment of the shear reinforcement structure of this invention. It is sectional drawing which shows the detail of the shear reinforcement steel material front-end | tip part and rear-end part in embodiment of FIG. It is sectional drawing which shows the detail of the shear reinforcement steel material front-end | tip part and rear-end part in other embodiment. It is explanatory drawing regarding the rust prevention of the shear reinforcement steel material rear end part in this invention. It is sectional drawing which shows the modification regarding the position of a shear reinforcement steel material rear-end part. It is sectional drawing which shows the modification regarding the junction part of a shear reinforcement steel rear end part and a rear end side fixing body. FIG. 10 is a cross-sectional view illustrating a modification example regarding the shape of the rear end side fixing body. (a), (b) is sectional drawing which shows the other modification regarding the shape of a rear-end side fixing body, respectively. FIG. 10 is a cross-sectional view showing another modification example regarding the fixing portion of the rear end side fixing body. It is sectional drawing which shows the modification of the shear reinforcement steel material rear end part at the time of using UFC for a rear end side fixing body. It is sectional drawing which shows the other modification of the shear reinforcement steel material rear end part at the time of using UFC for a rear end side fixing body. An example of the shape of a UFC rear end side fixing body in which a nut with a plate is embedded is shown, (a) is a bottom view and (b) is a longitudinal sectional view. It is a longitudinal cross-sectional view which shows the other example of a shape of the rear end side fixing body made from UFC which embedded the nut with a plate.

Explanation of symbols

1 ... wall, 2 ... main rebar, 3 ... distribution rebar, 4 ... concrete
DESCRIPTION OF SYMBOLS 11 ... Reinforcement steel material insertion hole, 12 ... Reinforcement steel material, 13 ... Hardening filler, 14 ... Rear end side fixing body, 15 ... Front end side fixing body, 16 ... Anticorrosion coating, 17 ... Stainless steel screw rod, 18 ... Spiral Rebar,
24: UFC rear end side fixing body, 25 ... Nut, 26 ... Plate, 27 ... UFC

Claims (8)

  A reinforcing steel material insertion hole drilled in an existing wall-shaped or plate-shaped reinforced concrete structure from one side of the structure to the opposite surface side, and a rod-shaped reinforcing steel material inserted in the reinforcing steel material insertion hole; In the shear reinforcement structure of an existing reinforced concrete structure including a curable filler filled in a gap between the reinforcing steel material insertion hole and the reinforcing steel material, the reinforcing steel material is disposed on the rear end side in the insertion direction of the reinforcing steel material. An existing reinforced concrete structure in which a rear end side fixing body made of a corrosion-resistant material covering the end portion of the reinforcing steel material is integrated to form a rear end side fixing portion having a diameter larger than the outer diameter of the reinforcing steel material. Shear reinforcement structure.   A rear end of the rear end side fixing body is flush with a surface of the existing reinforced concrete structure or protrudes from a surface of the existing reinforced concrete structure, and a rear end of the reinforcing steel material is the existing reinforced concrete structure. The shear reinforcement structure for an existing reinforced concrete structure according to claim 1, wherein the structure is located near the surface of the body.   3. The shear reinforcement structure for an existing reinforced concrete structure according to claim 1, wherein the material of the rear end side fixing body is ceramic, hard plastic, ultra-high strength fiber reinforced concrete, or stainless steel.   The shear reinforcement structure for an existing reinforced concrete structure according to any one of claims 1 to 3, wherein the rear end side fixing body is screwed to a rear end portion of the reinforcing steel material.   The existing reinforced concrete structure according to any one of claims 1 to 4, wherein a front-side fixing portion having a diameter larger than an outer diameter of the reinforcing steel material is provided on a front end side in the insertion direction of the reinforcing steel material. Body shear reinforcement structure.   6. The shear reinforcement structure for an existing reinforced concrete structure according to claim 5, wherein the front end side fixing portion is formed of a front end side fixing body made of a corrosion-resistant material covering the front end portion of the reinforcing steel material.   The shear reinforcement structure for an existing reinforced concrete structure according to claim 6, wherein the front end side fixing body is positioned in a cover concrete portion of the existing reinforced concrete structure.   7. A front end portion of the rear end side fixing body and / or a rear end portion of the front end side fixing body is extended to a concrete portion inside the cover concrete portion of the existing reinforced concrete structure. Or the shear reinforcement structure of the existing reinforced concrete structure of 7.

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