JP6633426B2 - Method for joining precast concrete structural members - Google Patents

Description

  The present invention relates to a method for joining structural members made of precast concrete, in which structural members such as columns and beams made of precast concrete are joined using a plate made of carbon fiber reinforced plastic.

  When structural members made of precast concrete, such as columns or beams, are joined at the site where the structural members are erected, generally, main bars projecting from the joint surface of the structural members joined to each other are connected using a joint. After that, a filler such as mortar or concrete is filled between the joint surfaces facing each other at a distance.

  Since the joint can be buried in one of the structural members in advance, it is possible to reduce the distance between the joining surfaces of the opposing structural members. Since it is necessary to secure a gap (distance) for position adjustment and the like at the time of abutting, filling work of the filler is indispensable, and in order to complete the joint, it is necessary to wait for curing of the filler by natural drying. Therefore, there is a limit to shortening the construction period.

  On the other hand, carbon fiber reinforced plastic (hereinafter referred to as CFRP) has a tensile strength higher than that of steel, and is a material that is rich in weather resistance without the possibility of rusting or deterioration even in the presence of water, ozone, etc. It is considered that if CFRP can be used as a material instead of a main reinforcement for joining between structural members, it can contribute to overcoming the above-mentioned problem in the construction period.

  Although there is an example of applying CFRP to a structural member, it is limited to a method of using an adhesive to adhere to the surface of the structural member exclusively for the purpose of reinforcing the structural member against tensile force (see Patent Documents 1 to 4). However, there is no example used for the joint surface of the structural member.

JP-A-2000-64505 (Claim 1, paragraphs 0013 to 0020, FIGS. 1 and 2) JP-A-2000-320070 (Claim 1, paragraphs 0010 to 0013, FIG. 1) JP 2008-174989 A (Claim 1, paragraphs 0016 to 0022, FIGS. 1 and 2) JP 2010-31612 A (Claim 4, paragraphs 0033 to 0045, FIGS. 1 and 2)

  The present invention proposes a method for joining structural members made of precast concrete, which enables joining of structural members using CFRP as a joining surface of the structural members.

The method for joining precast concrete structural members according to the invention according to claim 1 is a method for joining by joining the joining surfaces of precast concrete structural members to be joined to each other,
The fixed to the structural member in a state of exposing the carbon fiber reinforced plastic plate on the joining surfaces of the structural members, the plates are opposed to each other adhesive is interposed between the opposite faces of the plate,
When heating the adhesive by irradiating microwaves, and curing the adhesive to join the two structural members ,
Prior to the microwave irradiation, a sealing material that closes a gap between the opposing bonding surfaces is disposed at a portion near the periphery of each of the bonding surfaces except for the microwave irradiation side .

  As shown in FIGS. 3 and 4, the structural members 1, 1 to be joined to each other are mainly beams, columns, columns and beams, and the beams include foundation beams. The structural member 1 includes a pile. The joining surface 1a of the structural member 1 may be a surface perpendicular to the material axis of the structural member 1, or may be a surface inclined with respect to a surface perpendicular to the material axis.

  A plate 2 made of carbon fiber reinforced plastic (hereinafter, referred to as CFRP in this item) faces the structural member 1 facing the surface, and is exposed to the structural member 1 facing the opposite side. It is fixed by being buried or the like. The term “fixed” means that, for example, at least a portion of the plate 2 near the rear surface in the thickness direction or an anchor 21 protruding from the rear surface of the plate 2 is embedded in the structural member 1 on the side thereof. To be fixed to.

  When at least a part of the plate 2 in the thickness direction is embedded in the structural member 1, the anchor 21 may be projected from the back surface of the plate 2, and the entire thickness of the plate 2 may be embedded in the structural member 1. In this case, the surface of the plate 2 and the joining surface 1a of the structural member 1 are flush with each other. When the anchor 21 on the back of the plate 2 is embedded in the structural member 1, the plate 2 itself may not be embedded in the structural member 1. The form of the anchor 21 projecting from the back surface of the plate 2 is not limited, and a reinforcing bar, a steel bar, a perforated steel plate, or the like is used, but the anchor 21 does not need to be a steel material.

  The plates 2 made of CFRP fixed to the joint surface 1a of each structural member 1 to be joined are abutted against each other with a gap secured between the opposing surfaces, and an adhesive 3 is filled (applied) between the surfaces. ), Etc., and the two structural members 1, 1 are joined together by curing. The two plates 2 and 2 are integrated so that the adhesive 3 can resist a tensile force and a shearing force acting between the surfaces of the two plates 2 and 2 due to the hardening of the adhesive 3. And acts to transmit tensile and shear forces between them. “Curing of the adhesive 3” means that the adhesive 3 exhibits a certain strength, and the bonding of the structural members 1, 1 is completed by the curing of the adhesive 3. The target constant tensile strength is about several tens to 50 MPa.

  The phrase “with the adhesive 3 interposed therebetween” means that the liquid adhesive 3 is filled or applied between the opposing surfaces of the plates 2 and 2, or is solidified into a sheet or a film. 3 means to dispose (install) them on the opposing surfaces of the plates 2, 2. The adhesive 3 in the form of a sheet is disposed so as to be inserted between the opposing surfaces of the plates 2 and 2.

  By bonding the plates 2 and 2 in a state where the tensile force and the shear force can be transmitted between the structural members 1 and 1 by the curing of the adhesive 3, the plates 2 and 2 are connected to the conventional main reinforcing bars (rebars). Although it functions as a corresponding tensile force transmitting member, the opposing plates 2 and 2 also transmit a compressive force by being in contact with each other on the surface, and thus are also a compressive force transmitting member.

The adhesive 3 to be filled between the surfaces of the plates 2 and 2 only needs to have a property that is compatible with CFRP, and specifically, an epoxy resin-based or urethane resin-based adhesive is suitable. Not limited. When the adhesive 3 is heated pressurized to hasten the cure, since heat resistance is required as performance of the adhesive 3, the thermosetting resin system is used for the adhesive 3. As a method of heating, a method of using a heater that can be attached so as to surround the joining surfaces 1a, 1a of the opposed structural members 1, 1 is also conceivable. However, in order to speed up heating of the adhesive 3 itself, micro heating is required. The heating method by wave irradiation (claim 1 ) is efficient.

  In claim 1, a plate 2 made of CFRP is fixed to the joint surface 1a of each structural member 1, and the tensile force and the shear force can be transmitted by the development of the strength of the adhesive 3 interposed between the two plates 2, 2. Since the bonding work can be completed at the work site only by the work of filling the gap between the two plates 2 and 2 with the adhesive 3, the tensile force between the structural members 1 and 1 can be reduced. There is no need to connect the main rebars using a joint for enabling transmission. As a result, in contrast to the conventional method of filling and joining a filler such as concrete between the joining surfaces, the work of connecting the main reinforcing bars is omitted, and the construction period on site can be shortened. .

  In addition, since the adhesive 3 is used for joining the plates 2 and 2 as a tensile force / shear force transmitting material to each other, the curing of the adhesive 3 can be forcibly accelerated by heating by microwave irradiation or the like. The time required to wait for the filler to be hardened by natural drying as in the case where the filler such as the conventional concrete is filled between the joint surfaces does not need to be waited, which also shortens the construction period.

The adhesive 3 by irradiating microwaves (claim 1), the adhesive 3 is heated by the friction between the molecules, the curing is accelerated by heating, strength development from the filling, etc. to between plates 2,2 Time is reduced. As a result, the construction period for joining structural members can be significantly reduced as compared with the conventional joining method using the connection between main bars and filling with a filler.

Since a gap is provided between the CFRP plates 2 fixed to the joint surface 1a of each of the structural members 1 to be joined for the interposition of the adhesive 3, the microwave At the time of irradiation, microwaves may leak to the outside of the opposing joint surfaces 1a, 1a of the structural members 1, 1, and members or parts other than the structural members 1, 1 to be joined, or friction between molecules to workers. May have the effect of heating. Therefore, a sealing material 4 that closes a gap between the opposing bonding surfaces 1a and 1a is disposed in a portion near the periphery of each bonding surface 1a except for the microwave irradiation side (Claim 1 ). It is possible to avoid leakage to the outside of 1a. The sealing material 4 is interposed between the bonding surfaces 1a, 1a before microwave irradiation.

  The “microwave irradiation side” refers to the installation side of the microwave generation (irradiation) device, and as shown in FIG. 1A, the sealing material 4 is attached to the edge of the joining surface 1a other than the installation side of the microwave generation device. Is arranged. "Disposing the sealing material 4" means filling the liquid sealing material 4 having fluidity between the joining surfaces 1a, 1a of the facing structural members 1, 1, and sealing the solidified molded product. Including installation of the material 4 means that the sealing material 4 is interposed between the joint surfaces 1a, 1a. The sealing material 4 is made of, for example, a synthetic resin that does not transmit microwaves.

  Except for the microwave irradiation side, the sealing material 4 orbits a portion near the periphery of the joint surface 1a and is continuously arranged, so that the seal member 4 is disposed around the joint surface 1a, that is, from the surface (side surface) side of the structural member 1. It also has a function as a waterproof seal in order to exhibit the effect of preventing rainwater or the like from entering the joint surface 1a.

In addition, when the microwave is applied to the adhesive 3, the microwave is also applied to the bonding surface 1 a outside the intervening area of the adhesive 3, so that the microwave is transmitted to the bonding surface 1 a other than the intervening surface of the adhesive 3. In order to avoid the influence of heating due to friction between molecules in the structural member 1, the microwave applied to the joint surface 1 a is applied to the region of each joint surface 1 a except for the surfaces facing the plates 2 and 2. It is appropriate to stick the covering sheet 5 to be reflected (claim 2 ). The covering sheet 5 is also adhered to the joint surface 1a before microwave irradiation.

  The “opposite surface of the plates 2 and 2” is a surface (front surface) on which the adhesive 3 is interposed, and the “region other than the opposing surfaces of the plates 2 and 2 of the bonding surface 1a” is Of these, the region other than the intervening portion of the adhesive 3 heated by the irradiation of the microwave. This is because the adhesive 3 needs to be exposed so that microwaves for heating are irradiated. In other words, when the joining surface 1 a is viewed in the axial direction of the structural member 1, the facing surfaces of the plates 2 and 2 (the adhesive 3 Area other than the intervening surface).

  The adhesive 3 basically intervenes uniformly between the opposing surfaces of the plates 2 and 2, and the microwave is applied to the adhesive 3, but the microwave is applied to the surface of the plate 2. However, since it is considered that there is no influence on the structural member 1 or it is considered to be small, it is only necessary that the covering sheet 5 be adhered to the joining surface 1a except for the region where the plate 2 is fixed.

  The covering sheet 5 blocks microwaves irradiated from the surface side thereof, and prevents the microwaves from entering and leaking into the concrete of the structural member 1. When microwaves enter concrete, the water contained in the concrete is heated, which may affect the material properties such as the strength of the concrete. Leakage of microwaves into concrete may reduce the efficiency of intensive irradiation on the adhesive 3, but the covering sheet 5 for preventing microwaves from entering and leaking to the joint surface 1 a other than the adhesive 3. Is adhered to the area other than the adhesive 3 (plate 2), it is possible to realize efficient irradiation of the adhesive 3 while preventing the effect on the material of the concrete.

  Since the microwave is an electromagnetic wave, a material having a high electromagnetic shielding property (reflectivity) is used as a material of the covering sheet 5, and a conductor (electric conductor) such as a metal is suitable. Among them, aluminum (aluminum foil) has a high dielectric constant (electrical conductivity) and is lightweight, so that it is effective as a material of the covering sheet 5.

  A CFRP plate is fixed to the joint surface of the structural member, and the two plates are bonded together so that the tensile force and shear force can be transmitted by expressing the strength of the adhesive interposed between the two plates. The work for joining can be completed only by intervening between the spaces, and the work of connecting the main reinforcements using the joint is not required, and the work of connecting the main reinforcements is omitted. The construction period can be shortened.

  Also, by using an adhesive to join the plates as a tensile force transmitting material, the curing of the adhesive can be forcibly accelerated by microwave irradiation or the like. There is no need to wait for hardening, which is added to the shortened work period.

(A) is a cross-sectional view perpendicular to the material axis of the structural member, showing a state where the joining surfaces of the column members as structural members are joined together, and (b) is a sectional view of the joint (joint part) of (a). It is a longitudinal section parallel to the material axis of the shown structural member. (A) is a vertical sectional view perpendicular to the material axis of the structural member, showing a state in which the joining surfaces of the beam members as structural members are joined to each other, and (b) shows a joint (joint part) of (a). It is a longitudinal section parallel to the material axis of the shown structural member. FIG. 2 is an elevational view showing a frame of a column / beam composed of a column member and a beam member as structural members, and positions of joints (joints) between structural members in the frame. It is the elevation which showed the joint part (connection part) when the joint surface of structural members is the axial end surface of a beam member, and the side surface of a column member.

  FIGS. 1 (a) and 1 (b) show a frame (frame) composed of a column member and a beam member made of precast concrete. In FIG. 3, a joining surface 1a of a column member as a structural member 1, 1 indicated by a chain line circle A in FIG. 1a shows a state of joining together. In the case of the example shown in FIG. 3, the joints A and B between the joint surfaces 1a and 1a of the structural members 1 and 1 are portions where the structural member 1 is discontinuous in the axial direction. An axial middle portion other than the end portion where the bending moment generated in the axial direction of the member 1 does not increase is reasonable, but need not be so.

  The joining surface 1a of the structural member 1 may be inclined with respect to a plane orthogonal to the material axis of the structural member 1, but FIG. 1 shows a plane where the joining surface 1a is orthogonal to the material axis of the structural member 1. An example of the case is shown. The joining surface 1a does not necessarily have to be flat. In the example of FIG. 1, the joining surface 1a forms a horizontal plane as shown in FIG. 1- (b).

  In FIG. 3, the axially central portion of the structural member 1 is the joints A and B because the unit of precast concrete is formed in a cross-shaped elevation shape in which the column member and the beam member are integrated. The joint may be disposed near the axial end of the structural member 1, and as shown by a chain line circle C in FIG. , 1 joining surface 1a, 1a. The elevational shape of the unit of precast concrete is determined according to the position of the joining surfaces 1a, 1a of the structural members 1, 1, and is not limited to the cross shape.

  As shown in FIG. 1- (b), a plate 2 made of carbon fiber reinforced plastic is fixed to the joint surface 1a of each structural member 1 with the surface facing the joint surface 1a. The plate 2 is formed into a plate shape by laminating carbon fibers with a thermosetting resin such as an epoxy resin as a binder. When viewed in the thickness direction, the plate 2 is mainly formed in a rectangular shape according to the shape of the joint surface 1a of the structural member 1, but may be formed in a circular shape, a polygonal shape, or the like.

  As shown in FIG. 1- (a), the plate 2 is arranged at one position at the center of the joint surface 1a, or at a plurality of positions distributed near the center or distributed over the entire surface of the joint surface 1a. The central part of the joint surface 1a indicates the central part when the joint surface 1a is viewed in the axial direction of the structural member 1. Since the joining surfaces 1a, 1a to be joined are opposed to each other, the plates 2, 2 fixed to the both joining surfaces 1a, 1a also face each other.

  The plate 2 is in a state where only the surface on the side of the plate 2 (joining surface 1a) facing the plate 2 is exposed on the side facing the plate 2 or the space between the surface of the plate 2 and the side perpendicular to the surface faces the joint. Is fixed in the structural member 1 (concrete) by being buried or the like in a state of being exposed. In the former case, the entire thickness of the plate 2 is embedded in the structural member 1, and in the latter case, the section on the back side in the thickness direction of the plate 2 is embedded in the structural member 1 as shown in FIG. Is done.

  FIG. 1 shows that a plate-like anchor 21 buried in the concrete of the structural member 1 protrudes from the back side (the structural member 1 side) of the plate 2 and the anchor 2 is buried in the concrete, thereby connecting the plate 2 to the structural member. 1 shows an example in the case of fixing to the bonding surface 1a. As shown in FIG. 2B, a perforated plate is suitable for the plate-like anchor 21 in order to increase the adhesion area with concrete and to secure in-plane shear resistance.

  The anchor 21 is not limited to the plate shape, but may be a rod shape. Regardless of the form, it does not matter whether the material of the anchor 21 is the same as the plate 2 or not. It doesn't matter. Since the plate 2 is made of carbon fiber reinforced plastic, the anchor 21 is integrated with the plate 2 mainly by welding or bonding.

  The joint surfaces 1a, 1a of the structural members 1, 1 to be joined to each other are surfaces which are opposite surfaces of the plates 2, 2 fixed to the joint surfaces 1a, 1a as shown in FIG. The two plates 2, 2 are butted against each other with a distance such that a gap for interposition of the adhesive 3 is secured therebetween, and the two plates 2, 2 can transmit a tensile force between the surfaces of the opposed two plates 2, 2. The adhesive 3 to be joined in the state is interposed by filling (injection) or the like. 1 (a) and 1 (b) show a situation where the adhesive 3 spreads all over the surface of the plate 2, but the adhesive 3 is interposed so as to substantially cover the surface of the plate 2. It should just be.

  As the adhesive 3, an epoxy resin-based or urethane resin-based adhesive compatible with the carbon fiber reinforced plastic as a material of the plate 2 is mainly used, but a liquid (fluid) is used at the site (joining place). It may be filled in a state or applied or installed (adhered) before carrying the structural member 1 to the site. The adhesive 3 to be applied is a liquid, but the adhesive 3 to be installed is a product processed in advance into a sheet or a film.

  In the case of a sheet or the like, the adhesive 3 is installed (adhered) to at least one of the plates 2 and 2 fixed to the opposing joint surfaces 1a and 1a, but is installed later when the structural members 1 and 1 are joined. One of the structural members 1 is axially butted toward the other structural member 1, and the plates 2, 2 are brought into contact (close contact) with each other so that the adhesive 3 installed on one of the plates 2 becomes the other. The plate 2 is also in close contact. The adhesive 3 is pressed in the thickness direction of the plate 2 by the contact between the plates 2 and 2.

  When the adhesive 3 is filled (injected) in a liquid state at the site, the adhesive 3 may be cured by leaving it for a certain period of time after filling and develop strength. However, when the adhesive 3 is thermosetting, Needs to be heated after filling or after contact of the joining surfaces 1a, 1a. The method of heating is arbitrary, but in the drawings, microwave irradiation is used for the purpose of shortening the time until curing by heating.

  When irradiating the adhesive 3 with microwaves, a plate when the bonding surface 1a is viewed in the axial direction of the structural member 1 is used to prevent the microwave from leaking outside between the opposing bonding surfaces 1a and 1a. The sealing material 4 that fills the gap between the opposing joint surfaces 1a, 1a is mainly filled in three directions around the surroundings other than the microwave irradiation side among the surroundings surrounding the 2 (adhesive 3) by filling or installation. It is interposed. As the seal member 4, a seal member made of a synthetic resin through which microwaves are hardly transmitted is used.

  Microwave leakage to the outside between the joint surfaces 1a, 1a is also possible by interposing the sealing material 4 at the boundary (edge of the joint surface 1a) between the joint surface 1a and the side surface (peripheral surface) of the structural member 1. However, in the drawing, the sealing material 4 is arranged closer to the inner periphery than the edge of the joint surface 1a in order to increase the safety of leakage prevention.

  FIGS. 1 (a) and 2 (a) show a column member and a beam member in which a wall 7 is arranged in the surface of a frame (frame) of columns and beams, and the wall 7 is a structural member 1 made of precast concrete. An example in the case of being joined to is shown. Here, both sides sandwiching the wall 7 from the side surface (surface) of the structural member 1 in contact with the wall 7 to the sealing material 4 interposed between the joining surfaces 1a and 1a of the structural members 1 and 1 opposed in the axial direction. This shows a situation where waterproof seals 71, 71 for waterproofing between them are installed. FIG. 1A shows a case where the structural member 1 is a column member, and FIG. 2A shows a case where the structural member 1 is a beam member.

  When irradiating the adhesive 3 with microwaves, in order to prevent the microwaves from transmitting to the bonding surface 1a, irradiate the bonding surface 1a to the region of each bonding surface 1a except for the surface facing the plate 2. A covering sheet 5 such as an aluminum foil for reflecting microwaves to be applied is attached.

  As shown in FIG. 1A, the microwave is generated with the horn antenna 6 having a pyramid shape connected to the irradiation side of the microwave generator facing the gap between the joint surfaces 1a, 1a. FIG. 1 shows an example in which the joining surfaces 1a and 1a form a horizontal plane. The height of the opening at the tip of the horn antenna 6 is set to prevent the microwave from leaking between the joining surfaces 1a and 1a. , Is set so as to fit within the height of the gap between 1a.

  FIGS. 2- (a) and (b) show a state in which the joining surfaces 1a and 1a of the beam members as the structural members 1 and 1 indicated by a chain line circle B in FIG. Also in this example, the joining surface 1a does not need to form a plane orthogonal to the material axis of the structural member 1, but FIG. 2 shows an example in which the joining surface 1a is a plane orthogonal to the material axis of the structural member 1. I have. In this case, the joining surface 1a has a vertical surface as shown in FIG.

  In the example of FIG. 2 as well, the height (width) of the opening at the tip of the horn antenna 6 is set to the height (width) of the gap between the bonding surfaces 1a and 1a in order to prevent microwave leakage from between the bonding surfaces 1a and 1a. ) Is set to fit. In FIG. 2A, reference numeral 8 denotes a slab.

  FIG. 4 shows both joint surfaces 1a when the joint surface 1a of one structural member 1 is the axial end surface of the beam member and the joint surface 1a of the other structural member 1 is the side surface of the column member as described above. 1A shows a joint C between the two.

1 ... structural member, 1a ... joining surface,
2 ... Carbon fiber reinforced plastic plate, 21 ... Anchor,
3 ... adhesive,
4 ... sealing material, 5 ... covering sheet,
6 ... horn antenna,
7 ... wall, 71 ... waterproof seal,
8 ... Slab.

Claims (2)

A method in which the joining surfaces of precast concrete structural members to be joined to each other are joined to face each other,
The fixed to the structural member in a state of exposing the carbon fiber reinforced plastic plate on the joining surfaces of the structural members, the plates are opposed to each other adhesive is interposed between the opposite faces of the plate,
When heating the adhesive by irradiating microwaves, and curing the adhesive to join the two structural members ,
Before the microwave irradiation , a precast concrete material characterized by disposing a sealing material that closes a gap between the opposing joint surfaces in a portion near the periphery of each of the joint surfaces except for the microwave irradiation side . How to join structural members. Before the irradiation of the microwave, a coating sheet that reflects the microwave irradiated on the bonding surface is attached to a region of each of the bonding surfaces other than a surface facing the plate. The method for joining precast concrete structural members according to claim 1 .

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