JP2006016893A - Shear reinforcement method for existing structures - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shear reinforcement method for an existing structure capable of performing the shear reinforcement of the constituent member by a simple method without increasing the thickness of the constituent member of the existing structure.
SOLUTION: A drilling step of forming a drilling portion 2 having a predetermined length in a member thickness direction or a substantially member thickness direction of a constituent member 1 of an existing structure, and a filling material 31 to the drilling portion 2 A tension member installation step for filling and inserting a tension member 4 such as a PC steel wire or a PC steel rod, and a tension force is introduced into the tension member 4 after the filler 31 is cured. This is a shear reinforcement method for an existing structure, which includes a tension introducing step for installing at least the fixing plate 5 in the vicinity of the rear end. Here, an enlarged drilling portion 8 is provided at the drilling tip portion of the drilling portion 2, and the protruding member 7 provided at the tip of the tension member 4 is embedded in the enlarged drilling portion 4.
[Selection] Figure 1

Description

  TECHNICAL FIELD The present invention relates to a method for shear reinforcement of an existing structure made of reinforced concrete, and in particular, a member of a constituent member that can easily shear-reinforce an underground structure built in the ground and constitutes an existing structure. The present invention relates to a method for shear reinforcement of an existing structure which can be shear reinforced without increasing the thickness.

  It is no exaggeration to say that the earthquake resistance standards based on the Building Standards Act of Japan, an earthquake-prone country, have been revised each time triggered by the occurrence of a major earthquake. Recently, after the Great Hanshin-Awaji Earthquake that occurred in 1995, the earthquake resistance standards in various standards and guidelines have been revised, so that recent structures (structures of a certain size or larger) satisfy the earthquake resistance standards. It is constructed as a rigid or flexible structure.

  On the other hand, there are many existing structures (reinforced concrete structures) that were constructed based on the old earthquake resistance standards (among them, divided into several stages with the transition of earthquake resistance standards). is there. Such existing structures have not been sufficiently shear-reinforced for large-scale earthquakes such as the Great Hanshin-Awaji Earthquake and the Great Kanto Earthquake due to the absence of a requirement for earthquake resistance according to the earthquake resistance standards at the time of construction. Therefore, there is a great potential for shear failure during such an earthquake. Therefore, seismic reinforcement work for structures made of reinforced concrete constructed based on such old earthquake resistance standards is being actively carried out in various places. For example, there are a wide variety of structures to be reinforced such as tunnels for various underground infrastructures, including ground structures such as expressways and Shinkansen ramen piers. Seismic reinforcement of existing structures is not necessarily required to be reinforced to the extent that there is no damage to the structure at the time of a large earthquake, although there is a difference in the degree of reinforcement depending on the importance of the structure, etc., and at least brittle shear It is thought that it should be reinforced to such an extent that it will not cause human injury by causing destruction.

  By the way, when reinforcing the shear characteristics of an existing structure, it is necessary to pay attention to the following points. That is, (1) Reinforcing work costs are relatively low and sufficient reinforcing effect can be expected. (2) In principle, the in-service suspension period associated with shear reinforcement work should be shortened as much as possible because the structure in service will be reinforced. (3) The shape of an existing structure is increased by shear reinforcement, and such a shape change does not hinder the use of the structure (for example, by adding concrete inside a tunnel for a subway, the building limit is violated. Such).

  Reinforcing existing structures (existing reinforced concrete structures) in addition to preventing brittle shear failure in the event of a major earthquake as described above, as described above. In addition, it is extremely important to minimize the impact on social life due to the increase in construction costs due to reinforcement or new rebuilding and the suspension of operation during the construction period.

  There are various methods for shear reinforcement of existing reinforced concrete structures, and one common method is to increase the thickness of the structural members of the structure. For example, as shown in FIGS. 3a and 3b, when reinforcing and reinforcing a pillar that is a component 1 of an existing structure, a plurality of pillar main bars 91, 91,... Are arranged around the pillar existing portion 1a. , Concrete 93 or the like is placed in a state where a plurality of band bars 92, 92,... Are disposed so as to surround the main bars 91, 91,. As another method, as shown in FIGS. 4a and 4b, the reinforcing steel plate 94 is wound with a predetermined gap between the pillars so as to surround the pillar (existing portion 1a) which is the component member 1 as shown in FIGS. This is a method in which the existing portion 1a and the reinforcing steel plate 94 are integrated with each other by filling and hardening a filler 95 such as non-shrink mortar in the gap.

  The above-described method of reinforcing the constituent members of the existing structure is not a problem as long as the thickness of the constituent members can be increased, but the existing structure has already been built to the building limit or the site limit. It is difficult to adopt when there is a reservoir (reservoir, subway tunnel, etc.), or when an existing structure is embedded in the ground, and therefore the ground exists on the back of the component to be reinforced.

  Patent Document 1 discloses a shear reinforcement method (earthquake-proof reinforcement method) for an existing structure when a method of increasing the member thickness cannot be employed as in the case of shear reinforcement of an existing structure in the ground. Such a reinforcing method is to cut a vertical depth from the roof of a building to a predetermined depth in an existing reinforced concrete column, and then insert a shear reinforcement material such as a steel pipe or a steel rod into the drilled portion. This is a method of filling the hole with a grout material.

  As another reinforcement method, after forming a hole in the thickness direction of the component of the existing structure, insert a deformed steel rod for shear reinforcement into the hole and fill it with a filler such as grout. There is also a method of hardening and reinforcing. Specifically, as shown in FIG. 5, a drilling portion 96 is formed from one side of the component 1 of the existing structure to the vicinity of the main bar 11 on the other side, and a deformed steel rod 97 for shear reinforcement is formed in the drilling portion. It inserts in 96 and fills the grout 98 and aims at the integration of the deformed steel rod 97 and the structural member 1.

Japanese Patent Laid-Open No. 10-18608

  According to the seismic reinforcement method disclosed in Patent Document 1, it is possible to perform shear reinforcement (seismic reinforcement) without increasing the thickness of the constituent members of the existing structure. However, in order to drill holes vertically from above the components and insert the shear reinforcement, the target structure must be on the ground, and even if it is applied to a pillar of an underground structure, etc. Construction such as drilling or pushing in of shear reinforcements is forced, and in some cases, it is necessary to carry out renovation work with mountain retaining. Therefore, problems such as a rise in construction costs, the necessity of securing a construction occupation zone on the ground, and an increase in the total construction period can be considered. Further, when the underground structure is a tunnel or the like, it requires drilling of existing structures or insertion of shear reinforcement according to the curvature shape, and the construction becomes extremely difficult.

  In addition, according to the method of forming a drilled portion in the thickness direction of the constituent member, inserting and installing a deformed steel rod for shear reinforcement in the drilled portion, and filling and hardening a filler such as grout to reinforce. The problem as in the reinforcing method disclosed in the above-mentioned patent document cannot occur. However, this reinforcing method has the following problems. That is, (1) when the insertion tip of the shear reinforcement bar is not sufficiently fixed, the shear reinforcement effect cannot be expected. (2) In order to obtain a shear reinforcement effect that can cope with a large earthquake, it is necessary to form a large number of drilled holes, which increases the possibility that the construction period will be prolonged and requires a lot of construction work. Become. (3) By forming a large number of holes in the existing structure, the sound structure may be damaged as a result.

  The present invention has been made in view of the above-described problems, and is a simple method for an existing structure capable of performing shear reinforcement of the constituent member without increasing the thickness of the constituent member of the existing structure. It aims to provide a shear reinforcement method. In particular, it is applied to shear reinforcement of existing structures that are to be reinforced and embedded in the ground or when existing structures have already been built to the construction limit or site limit. Is effective. Another object of the present invention is to provide a method for shear reinforcement of an existing structure that has a very low possibility of damaging the existing structure at the time of shear reinforcement construction.

  In order to achieve the above object, a shear reinforcement method for an existing structure according to the present invention is a shear reinforcement method for an existing structure made of reinforced concrete, and is a member thickness direction or a substantially member of a constituent member constituting the existing structure. A drilling step of forming a drilling portion of a predetermined length in the thickness direction, a tension member installing step of filling the drilling portion with a filler and inserting a tension member such as a PC steel wire or a PC steel rod, And a tension force introducing step of introducing a tension force to the tension member after the filler is cured and installing at least a fixing plate in the vicinity of the rear end of the tension member in the insertion direction.

  The existing structure made of reinforced concrete has a broad meaning including a reinforced concrete structure and a reinforced concrete structure in which a reinforced concrete and a steel frame are used together. The existing structures include public facilities such as buildings standing on the ground and water and sewage treatment facilities, and various underground structures such as subway tunnels and underground common trench tunnels.

  Here, the member thickness direction means, for example, the wall thickness direction when the constituent member is a wall, and the column thickness direction when the constituent member is a column. Moreover, the substantially member thickness direction is a direction having a slight inclination from the member thickness direction due to workability, construction errors, and the like.

  Furthermore, the predetermined length of the drilling portion is, for example, when the component is a wall, the vicinity of the tip of the drilling hole started from one side of the wall entering the inside of the wall about the cover on the other side This means the part that has been drilled. Usually, since the main bars are arranged at predetermined intervals in the constituent members of the existing structure, the tip of the hole drilling part is located between the main bars and the main bars on the other side such as walls and columns. Is good. In addition, an appropriate size can be selected as the hole diameter from the dimension of the tension member to be used. In forming the drilled portion, a known core boring or the like that is drilled into concrete using a cylindrical core bit can be used.

  It is possible to shift to the tension member installation process after completing the formation of the drilling hole by carrying out the above drilling process all at once in the construction extension, or the drilling process and the tension member while preceding the drilling process. The installation process can be paralleled. In other words, the time-series relationship between the drilling process and the tension member installation process depends on the construction period (in order to shorten the construction period, each process is performed in parallel) and construction cost (by increasing the number of workers by making each process in parallel). It may be determined as appropriate in consideration of the fact that construction costs will rise.

  A resin material such as grout or polyester resin can be used as a filler for the drilling hole. After filling the filler with the filler, a tension member such as a PC steel wire or PC steel rod is inserted. After the filler has cured to a strength suitable for introducing tension, tension is introduced into the tension member. After the tension is introduced, a fixing plate is installed at the end of the tension member and the nut is tightened to keep the tension. Here, when the width of the fixing plate to be used is wider than the width between the main bars of the components of the existing structure, the fixing plate is brought into contact with the main bars and the main bars from the outside, and the main bars are used as a stopper. Therefore, tension can be more effectively introduced into the component. However, even when the width of the fixing plate to be used is narrower than the width between the main bars, the tension force is directly introduced into the concrete of the component member, and the effect of introducing the tension force can be sufficiently expected. . After tightening the nut of the tension member, as a countermeasure against the appearance of the existing structure and the leakage treatment, post-processing of the end portion of the drilled portion can be performed with a mortar for filling in some cases.

  As described above, by adopting the post-tension method and introducing a tension force, it is possible to obtain an effective shear reinforcement effect with a minimum number of shear reinforcement bars in the constituent members of the existing structure. If tension is not introduced, it will be necessary to create a relatively large number of holes for deformed steel bars compared to the present invention, so problems such as damage to existing structures and construction work are likely to occur. It is considered to be. Furthermore, since the drilling portion is created in the member thickness direction (or substantially the member thickness direction) of the constituent members of the existing structure, the construction is simplified, and particularly suitable for shear reinforcement construction of underground structures. it is conceivable that.

  Further, as a preferred embodiment of the shear reinforcement method for an existing structure according to the present invention, among the drilling portions, an enlarged portion in which the tip portion in the drilling direction is drilled larger than other portions of the drilling portion. A drilling hole is formed, and among the tension members, a projecting member projecting radially from the axial center of the tension member is provided near the distal end in the insertion direction, and the projecting member is disposed in the enlarged hole drilling section. It is embedded in.

  An enlarged drilling portion is provided at the tip of the drilling portion (tip in the drilling direction), and a projecting member (for example, a nut) protruding radially from the axial center of the tensioning member is provided near the tip of the tensioning member. When the tension member is inserted and installed so that the protruding member is disposed in the enlarged hole portion, the filler is cured in the hole portion (and the enlarged hole portion), thereby introducing a tension force to the tension member. The tightening effect of the component members at the time can be improved. When a nut is used as the projecting member, a thread groove is formed in the tension member, and the nut is inserted into the drilling portion in a state where the nut is screwed to the tip of the tension member. Moreover, as a protrusion member, it can also be set as the structure welded to the front-end | tip of tension | tensile_strength members, such as PC steel bar, using a fixing plate made from steel besides a nut.

  By creating the enlarged hole portion, it is possible to effectively transmit the tension force introduced into the tension member to the constituent members (periphery of the hole portion) of the existing structure via the protruding member. Further, in the case of an embodiment in which such an enlarged hole portion is formed, it is not always necessary to fill the entire hole portion with a filler as long as at least the enlarged hole portion is sufficiently filled with the filler. This is because it is considered that a sufficient shear reinforcement effect can be exhibited because the tension force is sufficiently transmitted to the constituent members of the existing structure through the enlarged hole portion. Moreover, it is good also as a structure provided with the protrusion member near the front-end | tip of a tension member in the state which does not create this enlarged hole part. It should be noted that the drilling of the enlarged hole part can be performed by using a known core boring or the like whose tip part can be enlarged or reduced.

  If there is a margin in the cover, the enlarged hole portion is formed to the outside of the main bar, and the tension member is inserted and installed until the protruding member provided near the tip of the tension member is arranged outside the main bar. preferable. In this case, since the projecting member provided on the tension member is arranged so as to press the main bar from the outside, the effect similar to that of the shear reinforcing bar hook-fixed to the main bar in a normal new structure should be expected. Because you can.

  Further, as a preferred embodiment of the shear reinforcement method of the existing structure according to the present invention, in the drilling step when the constituent members of the existing structure to be shear reinforced stand in the vertical direction, the drilling portion is It is formed so as to extend obliquely downward from the rear end to the front end in the drilling direction.

  When the structural member to be sheared is erected in the vertical direction, such as a wall or column, for example, by forming the drilling portion obliquely downward toward the drilling tip, the filler such as grout is drilled. Therefore, the tip of the tension member and the constituent member can be reliably integrated. In this case, the inclination angle of the drilled hole is appropriately determined in consideration of the viscosity of the filler used, the curing rate, and the like.

  Furthermore, as another embodiment of the shear reinforcement method for an existing structure according to the present invention, the constituent member of the existing structure is a wall or a pillar embedded in the ground.

  In the case where the existing structure is embedded in the ground, the back side of the wall or column, which is a constituent member of the existing structure to be reinforced, is in contact with the ground. Under such conditions, increasing the thickness of the wall will cause the increased thickness part to enter the existing structure as it is, reducing the size of the inner space of the structure. become unable. Therefore, by applying the present invention to an existing structure, in particular, an existing structure embedded in the ground, the structural member can be shear-reinforced without violating the internal dimensions of the structure (without violating the building limit). It becomes possible to carry out.

  As can be understood from the above description, according to the shear reinforcement method for an existing structure of the present invention, even if the existing structure is an underground structure, an effective shear reinforcement can be easily realized. Can do. In addition, since the construction of the constituent members is not increased, it is not necessary to consider the problem of interference with the construction limit or the site limit that the reinforcement construction of the existing structure has. Moreover, by introducing tension, the number of drilling portions for inserting tension members can be reduced as much as possible, and therefore the possibility of damaging existing structures during shear reinforcement can be extremely reduced. . In addition, the required shear reinforcement effect can be exerted by filling at least the enlarged hole portion with the filler, and therefore it is not necessary to fill the filler over the entire length of the hole portion. Can be reduced. Furthermore, since construction can be performed in a relatively short construction period, sufficient shear reinforcement construction can be performed without hindering the use of existing structures to be reinforced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a longitudinal sectional view of an existing structure reinforced by the shear reinforcement method of the present invention, and FIG. 2 schematically shows the bearing stress acting on the components of the existing structure from the enlarged hole portion. It is explanatory drawing shown in. Hereinafter, a wall will be described as a component 1 of an existing structure buried underground based on the drawings. However, the existing structure to be subjected to shear reinforcement may be a ground structure, and further, a component. It goes without saying that 1 may be a pillar or floor slab that can constitute a structure. Moreover, although the case where the hole-drilling part is formed by being inclined slightly obliquely downward from the member thickness direction is shown, it goes without saying that the hole-drilling part may be formed in the horizontal direction (member thickness direction). That is.

  The method for shear reinforcement of an existing structure of the present invention will be described in time series based on FIG. First, in the wall which is the structural member 1 of the existing structure embedded in the ground G to be reinforced, the hole portion 2 is cut at predetermined intervals from the inside of the existing structure in the vertical and horizontal directions of the wall. Make a hole. Core boring (tip expansion / contraction type core boring) is used for the formation of the drilling portion 2, and the drilling is performed obliquely downward from the inside of the existing structure to the outside (from the rear end to the front end in the drilling direction). Drilling is performed so that the hole 2 is formed (drilling step). By forming the hole drilling portion 2 so as to be obliquely downward, a filler 31 described later can be surely poured into the tip of the hole drilling portion 2. Here, the hole-cutting portion 2 is formed between the inner main bars 11a and 11a of the wall of the existing structure, and the tip of the hole-cutting portion 2 is similarly arranged between the outer main bars 11b and 11b of the wall. To build. Further, the enlarged hole part 8 can be formed by drilling the tip part of the hole part 2 with the tip diameter of the core boring enlarged. The formation extension of the drilled hole portion 2 is adjusted so that the vicinity of the tip of the enlarged drilled hole portion 8 is approximately the position of the outer main reinforcing bar 11b. Further, the hole diameter of the hole portion 2 depends on the bar arrangement interval of the wall main bars 11a, 11a,..., 11b, 11b,. Therefore, an appropriate hole diameter can be selected.

  Moreover, in the range from the wall surface on the inner side of the existing structure to the main bar 11a in the hole drilling part 2, it is preferable to form the hole diameter to gradually decrease from the wall surface toward the main bar 11a (the minimum diameter is smaller). It has the same diameter as the general portion 21 of the drilling portion 2). This is for securing an installation space for installing the fixing plate 5 to be described later and a work space for tightening the nut.

  In the drilling step described above, all the drilling portions 2 can be formed at once, or the tension member installation step and the drilling step described later can be performed in parallel while the drilling step is slightly advanced.

  Next, a filler 31 is filled into the formed hole portion 2. As the filler 31, it is preferable to use a material that can secure sufficient adhesion strength with the concrete wall and the tension member 4 constituting the existing structure, for example, grout or polyester resin material may be used. it can. Here, the filling range of the filler 31 may be up to the extent of entering the enlarged hole portion 8 and the general portion 21 of the hole portion 2 as shown in FIG. The reason will be described later. Of course, the filling material 31 may be filled over the entire length of the hole-cutting portion 2.

  After the filling material 31 is filled, the tension member 4 is inserted into the drilling portion 2. Here, the tension member 4 is made of a PC steel rod or a PC steel strand. For example, when a PC steel rod is used, screw grooves are formed on both ends thereof. The PC steel rod is inserted into the drilled hole 2 in a state where a protruding member 7 (for example, a nut or the like) that is screwed into the screw groove is screwed into the screw groove at one end of the PC steel rod. The insertion installation of the PC steel rod is completed in a state where the protruding member 7 is disposed in the enlarged hole portion 8 (tension member installation step). The projecting member 7 may be a steel plate having a rectangular shape in plan view instead of a nut, and the steel plate may be pressure-bonded to the tip of a PC steel rod.

  After the filler 31 is cured to an extent suitable for introducing tension to the tension member 4, the tension is introduced to the tension member 4. After the introduction of the tension, the fixing plate 5 is installed at the end of the tension member 4 and the introduced tension can be maintained by screwing the nut 6 into the thread groove at the end of the tension member 4. As shown in the figure, when the hole-drilling portion 2 is inclined from the horizontal direction, it is preferable to use the fixing plate 5 manufactured so that one side surface is inclined at least. For example, after the tension introduction work of all the tension members 4 is completed, the tension introduction process is performed by performing the filling work of the filling material 32 (for example, mortar) on the end part (inner wall surface side) of the drilling part 2. Ends.

  FIG. 2 is an enlarged view of a portion II in FIG. By introducing the tension force T <b> 1 to the tension member 4, the supporting stress T <b> 2 acts from the protruding member 7 to the filler 31 in the enlarged hole portion 8. That is, the bearing stress T2 is a stress in which the tension force T1 is dispersed, and the bearing stress T2 is transmitted from the hole surface of the enlarged hole portion 8 to the wall concrete on the outer periphery of the enlarged hole portion 8. Therefore, if at least the filler 31 is sufficiently filled in the enlarged hole portion 8, the tension force T1 introduced into the tension member 4 causes the enlarged hole portion 8 (the filler 31 cured inside) to expand. Therefore, the effect of tightening the concrete of the existing structure by the tension force T1 can be sufficiently expected. In addition to the case where the position where the protruding member 7 is arranged is approximately the same position in the longitudinal section as the position of the main muscle 11 as shown in FIG. 2, the position where the protruding member 7 is further on the ground G side (outside) from the main muscle 11. May be present (not shown). In this case, since the enlarged hole portion 8 is arranged so as to press down the main reinforcing bar 11 from the outside, it is possible to expect the same effect as the shear reinforcing bar hook-fixed to the main reinforcing bar in a normal new structure.

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

The longitudinal cross-sectional view of the existing structure reinforced with the shear reinforcement method of this invention. It is an enlarged view of the II part of Drawing 1, and is explanatory drawing which showed bearing stress from an enlarged hole part. The pillar reinforced with the shear reinforcement method of the conventional existing structure is shown, (a) is a cross-sectional view of a pillar, (b) is a longitudinal cross-sectional view of a pillar. The pillar reinforced with the shear reinforcement method of the conventional existing structure is shown, (a) is a cross-sectional view of a pillar, (b) is a longitudinal cross-sectional view of a pillar. The longitudinal cross-sectional view which showed the wall reinforced by the shear reinforcement method of the conventional existing structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Constituent member, 2 ... Drilling part, 4 ... Tension member, 5 ... Fixing plate, 6 ... Nut, 7 ... Projection member, 8 ... Enlarged drilling part, 11, 11a, 11b ... Main reinforcement, 21 ... General part, 31 ... Filler, 32 ... Filling material

Claims (4)

A method for shear reinforcement of an existing structure made of reinforced concrete,
A drilling step of forming a drilling portion having a predetermined length in the member thickness direction or substantially the member thickness direction of the constituent members constituting the existing structure, filling the drilling portion with a filler, and PC steel wire A tension member installation step for inserting a tension member such as a steel rod or a PC steel rod, and a tension force is introduced into the tension member after the filler is cured, and at least a fixing plate is provided near the rear end of the tension member in the insertion direction. A method for shear reinforcement of an existing structure, characterized by comprising a tension force introducing step to be installed.   In the drilling portion, an enlarged drilling portion that is drilled larger than the other portions of the drilling portion is formed at a tip portion in the drilling direction. The existing member according to claim 1, wherein a projecting member projecting radially from the axial center of the tension member is provided near the tip, and the projecting member is embedded in the enlarged hole portion. A method for shear reinforcement of structures. A method for shear reinforcement of an existing structure according to claim 1 or 2,
In the drilling step when the structural members of the existing structure to be sheared are erected in the vertical direction, the drilling portion is formed to extend obliquely downward from the rear end to the front end in the drilling direction. A method for shear reinforcement of an existing structure.   The method for reinforcing a shear of an existing structure according to any one of claims 1 to 3, wherein the constituent member of the existing structure is a wall or a pillar embedded in the ground.

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