Column-beam joint method and column-beam joint structure

Abstract

To improve the degree of freedom of construction in a precast concrete structure and to reduce the cost.SOLUTION: A precast column member 12 with a concave column-side shear key 21 is erected at a predetermined position, and a removable temporary support member (23) is attached to the precast column member 12. The end of a precast beam member 13 with a concave beam-side shear key 20 at the end face is placed on the temporary support member (23) so as to face the column-side shear key 21 and the beam-side shear key 20 each other. The void G formed between the precast beam member 13 and the precast column member 12 is filled with a filler material 14. A tension member 15 is placed over the precast beam member 13 and the precast column member 14, and after the filler 14 is cured, prestress is introduced into the precast beam member 13 and precast column member 12 by applying tension to the tension member 15.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a column-beam joint method for a precast concrete structure and a column-beam joint structure for a precast concrete structure. [Background technology]

[0002] Conventionally, prestressed concrete structures are known as structures with higher elastic resistance than RC structures (Patent Document 1). In these prestressed concrete structures, a large number of precast concrete columns with integrally molded girder support jaws are erected on a concrete foundation, and precast concrete girders with protrusions at their ends are supported by the girder support jaws and erected between each of the columns. Filler is provided at the joint between the girder support jaws and the protrusions, and the prestressed precast concrete girders are tensioned and fixed to the precast concrete columns by tensioning the PC steel wires.

[0003] Also, a method using multiple unbonded precast prestressed concrete columns is known as a building construction method that can shorten the construction period (Patent Document 2). In this method, a predetermined story is constructed on the core of a building that includes multiple unbonded precast prestressed concrete columns, and then a predetermined story is constructed on the outer periphery of the building. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-280092 [Patent Document 2] JP 2020-56165 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prestressed concrete structure described in Patent Document 1, the girder support jaws are integrally formed with the precast concrete columns so as to protrude from the outer surface of the columns. The ends of the precast concrete beams are formed with recesses for receiving the girder support jaws, giving them a protruding shape. When the girder support jaws are formed protrudingly on the precast concrete columns in this way, the freedom of construction is limited. In addition, because the girder support jaws and protrusions are integrally formed with the columns and girder, the manufacturing costs of these precast concrete members are high. In addition, because the precast concrete columns are bulky due to the integral formation of the girder support jaws, the transportation costs are also high.

[0006] On the other hand, in the building construction method described in Patent Document 2, the columns of the core section are constructed as unbonded precast prestressed concrete columns, but the beams of the core section are reinforced concrete beams. Therefore, there is room for improvement in terms of increasing the freedom of construction and reducing costs. In addition, paragraph

[0022] of Patent Document 2 discloses that the beams of the core section may be unbonded precast prestressed concrete beams, precast prestressed concrete beams, etc., but does not disclose the specific configuration of the column-beam joints or the specific construction method of the columns and beams.

[0007] In view of the above background, an object of the present invention is to improve the freedom of construction in precast concrete structures and reduce costs. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one aspect of the present invention is a method for joining columns and beams in a precast concrete structure, comprising the steps of erecting a precast column member (12) having a concave-shaped column-side shear key (21) at a predetermined position (FIG. 5(A)), attaching a removable temporary support member (23) to the precast column member (FIG. 5(A)), placing an end of a precast beam member (13) having a concave-shaped beam-side shear key (20) on its end face on the temporary support member, and connecting the column-side shear key and the beam-side shear key to the precast concrete structure. The method includes a step of opposing the precast beam member and the precast column member (Figure 5(B)), a step of filling a gap (G) formed between the precast beam member and the precast column member with a filler (14) (Figure 5(C)), a step of arranging a tension member (15) across the precast beam member and the precast column member (Figure 5(D)), and a step of introducing prestress into the precast beam member and the precast column member by applying tension to the tension member after the filling material has hardened (Figure 5(D)).

[0009] According to this embodiment, since the column-side shear key and the beam-side shear key are concave, the precast beam member can be positioned from both above and horizontally, and the freedom of construction is not limited. In addition, since a removable temporary support member can be attached to the precast column member and the end of the precast beam member can be placed on the temporary support member, construction is easy. Furthermore, since the column-side shear key and the beam-side shear key are concave, the manufacturing costs and transportation costs of the precast members can be reduced compared to the case where protrusions are formed on the precast column member and the precast beam member.

[0010] In the above aspect, the method may further include a step of removing the temporary support member after the tension is applied to the tendon (FIG. 5(E)).

[0011] According to this embodiment, the temporary support member can be reused, so that the material cost can be reduced. In addition, by removing the temporary support member, the appearance of the column-beam joint is improved. When the column-beam joint is covered with a board or the like, by removing the temporary support member, the dead space can be reduced.

[0012] In order to solve the above-mentioned problems, another aspect of the present invention is a precast concrete beam-column joint structure (11), comprising: a precast column member (12) erected at a predetermined position and having a concave-shaped column-side shear key (21) on its outer surface; a precast beam member (13) having a concave beam-side shear key (20) on its end face and arranged so that the beam-side shear key faces the column-side shear key; a filler (14) filled in a gap (G) formed between the precast beam member and the precast column member; and a tendon (15) arranged to span the precast beam member and the precast column member and introduce prestress into the precast beam member and the precast column member.

[0013] According to this aspect, since the column side shear key and the beam side shear key are concave, the freedom of construction when constructing a column-beam joint structure is not limited. Also, since the column side shear key and the beam side shear key are concave, the manufacturing costs and transportation costs of the precast members can be reduced compared to when protrusions are formed on the precast column members and the precast beam members.

[0014] In the above-mentioned aspect, a retaining member (22) for removably holding a temporary support member (23) for temporarily supporting the precast beam member may be provided in the lower portion of the precast column member below the precast beam member.

[0015] According to this aspect, a temporary support member for temporarily supporting the precast beam member can be attached to the precast column member and the end of the precast beam member can be placed on the temporary support member, making construction easy.

[0016] In the above-mentioned aspect, the precast beam member has a beam side through hole (18) extending longitudinally to insert the tension member, and the precast column member has a column side through hole (19) extending horizontally at a position aligned with the beam side through hole, the beam side through hole and the column side through hole are partitioned by the gap and communicate with each other, and the tension member is inserted into the beam side through hole and the column side through hole, and the precast beam member and the precast column member may be in an unbonded state.

[0017] According to this embodiment, the column-beam joint is an unbonded prestressed concrete structure. Therefore, the elastic deformation performance of the column-beam joint structure can be improved compared to the case of a bonded structure. In addition, since the precast beam member and the precast column member can be separated by removing the tension members, the precast members can be reused, and the life cycle cost of the column-beam joint structure can be reduced. Furthermore, by reusing the precast members, the environmental load such as CO2 emissions can be reduced compared to the case of constructing new members.

[0018] In the above aspect, the column-side shear key and the beam-side shear key may have upper surfaces (20a, 21a) that become lower toward the back in the vertical cross section.

[0019] According to this aspect, air pockets are prevented from forming in the gaps when the filler is filled into the gaps.

[0020] In the above aspect, the column-side shear key and the beam-side shear key may have a shape in which a pair of side surfaces (20b, 21b) widen toward the back in a plan cross section.

[0021] According to this embodiment, the column side shear key and the beam side shear key become dovetails, and the bonding force of the filler to the precast beam member and the precast column member is strong. Therefore, even if the tendon breaks and the connection by the tension is released, the precast beam member is prevented from falling from the precast column member.

[0022] In the above aspect, the filler may be non-shrink mortar, fiber reinforced mortar, or low elasticity and high toughness mortar.

[0023] According to this aspect, the filler is less susceptible to damage, thereby improving the bonding strength of the precast beam member to the precast column member. Effect of the Invention

[0024] According to the above aspect, it is possible to improve the freedom of construction in precast concrete structures and reduce costs. [Brief description of the drawings]

[0025] [Figure 1] Front view of the building according to the first embodiment [Diagram 2] Elevation section of the building shown in Figure 1 [Diagram 3] Enlarged view of the main part of Figure 2 [Figure 4] A cross-sectional view taken along the line IV-IV in Figure 3. [Diagram 5] A diagram showing a procedure for constructing a building according to the first embodiment. [Figure 6] Front view of the column-beam joint structure according to the second embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is applied to a building 1 having a rigid-frame structure made of reinforced concrete or steel-reinforced concrete.

[0027] First Embodiment First, a first embodiment of the present invention will be described with reference to Figs. 1 to 5. Fig. 1 is a front view of a building 1 according to the first embodiment. As shown in Fig. 1, the building 1 includes a pair of columns 2 and a beam 3 whose both ends in the extension direction are joined to the pair of columns 2. The columns 2 are arranged at predetermined positions with a predetermined interval in the X direction and the Y direction which are perpendicular to each other in a plan view. The columns 2 may be provided in three or more rows in at least one of the X direction and the Y direction. The beams 3 are provided so as to extend in each of the X direction and the Y direction. In addition, the beams 3 are provided at predetermined positions in the vertical direction for each story of the building 1, and support floors (not shown). The ends of the beams 3 are joined to the columns 2 by a column-beam joint structure 11.

[0028] The column 2 includes at least one precast column member 12. The precast column member 12 is erected at a predetermined position, such as on a lower column or foundation constructed below. The precast column member 12 may have the same length as the floor height of one story, or may have a length longer than the floor height of one story. Alternatively, the precast column member 12 may have a length shorter than the floor height of one story. The precast column member 12 is preferably connected to the lower lower column or foundation by an unbonded tendon.

[0029] The beam 3 is composed of one precast beam member 13. The precast beam member 13 has a length slightly shorter than the distance between a pair of precast column members 12. The precast beam member 13 is disposed between a pair of precast column members 12. Therefore, a gap G (see FIG. 5(B)) is formed between the end of the precast beam member 13 and the opposing precast column member 12. This gap G is filled with a filler material 14. After filling with the filler material 14, the precast beam member 13 has both ends joined to the pair of precast column members 12 and is spanned across the pair of precast column members 12.

[0030] The precast column members 12 and the precast beam members 13 are fabricated in advance in a factory using precast concrete and are transported to the construction site. The filler 14 is a fluid material that hardens over time, and may be, for example, mortar or cement milk. It is preferable to use fiber-reinforced mortar or low-elasticity, high-toughness mortar as the filler 14 so that the filler 14 is less likely to break after hardening.

[0031] In this way, the beam-column joint structure 11 is a joint structure between one end of a precast beam member 13 and a precast column member 12, and is configured at both ends of the precast beam member 13. In this embodiment, each end of the precast beam member 13 is pressure-joined to the corresponding precast column member 12 by a tension member 15 arranged so as to span from one precast column member 12 to the other precast column member 12. As a result, the beam-column joint structure 11 is made of prestressed concrete.

[0032] Specifically, a plurality of tendons 15 are arranged on the upper and lower parts of the precast beam member 13. Both ends of each tendon 15 are fixed to the outer surface of the outside of the precast column member 12 by fasteners 16 while tension is applied. This introduces prestress to the precast column member 12 and the precast beam member 13, and each end of the precast beam member 13 is pressure-bonded to the corresponding precast column member 12.

[0033] The tendons 15 are made of PC steel bars, PC steel wires, PC steel strands, or rods or cables made of fiber-reinforced plastic such as aramid fiber, carbon fiber, or glass fiber. The tendons 15 are preferably unbonded tendons that are not bonded to the precast column members 12 and the precast beam members 13. By making the tendons 15 unbonded, residual deformation after the end of an earthquake is reduced.

[0034] Fig. 2 is an elevational cross-sectional view of the building 1 shown in Fig. 1. As shown in Fig. 2, a beam-side through hole 18 for inserting the tendon 15 is formed in the precast beam member 13. The beam-side through hole 18 extends horizontally along the longitudinal direction of the precast beam member 13. A column-side through hole 19 for insertion is formed in the precast column member 12. The column-side through hole 19 extends horizontally at a position aligned with the beam-side through hole 18 and is continuous with the beam-side through hole 18.

[0035] A concave beam-side shear key 20 is formed on both end faces of the precast beam member 13. A concave column-side shear key 21 is formed on the inner outer surface of the precast column member 12 at a position facing the beam-side shear key 20.

[0036] Fig. 3 is an enlarged view of a main part of Fig. 2. As shown in Fig. 3, a plurality of embedded anchors 22 are provided in a portion of the precast column member 12 below the precast beam member 13. The embedded anchors 22 have screw holes opened in the outer surface of the precast column member 12 below the precast beam member 13. The embedded anchors 22 are holding members that cooperate with bolts B screwed into the screw holes to detachably hold the brackets 23.

[0037] The bracket 23 is a temporary support member for temporarily supporting the precast beam member 13 when joining the precast column member 12. The bracket 23 may be made of shaped steel such as an angle iron, a channel iron, or an H-shaped steel. The bracket 23 may be attached before the precast column member 12 is erected, and removed after the precast beam member 13 is joined.

[0038] With this configuration, brackets 23 for temporarily supporting the precast beam members 13 can be attached to the precast column members 12 and the ends of the precast beam members 13 can be placed on the brackets 23, making construction easier.

[0039] As described above, the gap G (see FIG. 5(B)) formed between the end of the precast beam member 13 and the precast column member 12 is filled with the filler 14. In order to prevent the filler 14 from adhering to the tendon 15, an anti-adhesion material 24 is provided between the precast beam member 13 and the precast column member 12. The anti-adhesion material 24 has an annular shape and partitions the beam-side through-hole 18 and the column-side through-hole 19 from the gap G, thereby preventing the filler 14 filled in the gap G from flowing into the beam-side through-hole 18 and the column-side through-hole 19. The anti-adhesion material 24 may be an elastic member disposed in a compressed state between the precast beam member 13 and the precast column member 12. In another embodiment, the anti-adhesion material 24 may be a cylindrical member disposed across the gap G and inserted into the beam-side through-hole 18 and the column-side through-hole 19.

[0040] By providing the anti-adhesion material 24 and leaving the tendons 15 in an unbonded state, the column-beam joint becomes an unbonded prestressed concrete structure. This improves the elastic deformation performance of the column-beam joint structure 11 compared to a bonded structure. In addition, the precast beam members 13 and the precast column members 12 can be separated by removing the tendons 15. This makes it possible to reuse these precast members, thereby reducing the life cycle cost of the column-beam joint structure 11. Furthermore, by reusing the precast members, environmental impacts such as CO2 emissions are reduced compared to constructing new members.

[0041] In the vertical cross section of Fig. 3, the top surface 20a of the beam-side shear key 20 becomes lower from the gap G side toward the back. The top surface 21a of the column-side shear key 21 also becomes lower from the gap G side toward the back. This prevents air from being trapped in the gap G when filling the gap G with the filler 14. The bottom surfaces of the beam-side shear key 20 and the column-side shear key 21 become higher from the gap G side toward the back in the vertical cross section of Fig. 3.

[0042] Fig. 4 is a plan cross-sectional view taken along the IV-IV cross-sectional line in Fig. 3. As shown in Fig. 4, in plan cross-section, the beam-side shear key 20 has a pair of side surfaces 20b that widen toward the rear. The column-side shear key 21 also has a pair of side surfaces 21b that widen toward the rear. This allows the beam-side shear key 20 and the column-side shear key 21 to form dovetail tenons, strengthening the bonding force of the filler 14 to the precast beam member 13 and the precast column member 12. Therefore, even if the tendon 15 breaks and the connection by tension is released, the precast beam member 13 is prevented from falling from the precast column member 12.

[0043] Here, in the embodiment, fiber reinforced mortar, which is difficult to break, is used as the filler 14. Therefore, the bonding strength of the precast beam member 13 to the precast column member 12 is improved. In other embodiments, non-shrink mortar or low-elasticity, high-tough mortar may be used as the filler 14 instead of the fiber reinforced mortar. This also improves the bonding strength of the precast beam member 13 to the precast column member 12.

[0044] The beam-column joint structure 11 of the building 1 is configured as described above. Next, a method for joining beams and columns in such a precast concrete structure will be described. Figure 5 is a diagram showing the construction procedure of the building 1 according to the first embodiment. The building 1 is constructed by workers through the following steps.

[0045] Prior to the construction of the building 1, the precast column members 12 and the precast beam members 13 having the above-mentioned configuration are prepared in the required number. As described above, the precast column members 12 have the concave column side shear key 21 formed therein, but no protrusions such as beam support jaws are formed therein. Therefore, the precast column members 12 are not bulky, and transportation costs can be reduced. Also, the precast beam members 13 have the concave beam side shear key 20 formed therein, but no protrusions to be placed on the beam support jaws are formed at their ends. As no protrusions are formed in the precast column members 12 and the precast beam members 13, the manufacturing costs of these precast concrete members can be reduced.

[0046] At the construction site of the building 1, the precast column member 12 is erected at a predetermined position as shown in Fig. 5(A). It is preferable to attach the bracket 23 to the precast column member 12 before erecting the precast column member 12. Alternatively, the bracket 23 may be attached to the precast column member 12 after the precast column member 12 is erected at a predetermined position.

[0047] Next, as shown in FIG. 5(B), the precast beam member 13 is lifted by a crane (not shown) and placed between a pair of precast column members 12, and both ends of the precast beam member 13 are placed on the brackets 23. At this time, since the column side shear key 21 and the beam side shear key 20 are concave, the precast beam member 13 can be placed from both above and horizontally, and the degree of freedom of construction is not restricted. In addition, the bracket 23 for temporarily supporting the precast beam member 13 is detachably attached to the precast column member 12, which improves the degree of freedom of construction. In addition, since the bracket 23 is attached to the precast column member 12, the end of the precast beam member 13 can be placed on the bracket 23. Therefore, construction is easy.

[0048] When the precast beam member 13 is placed in a predetermined position on the bracket 23, the beam-side shear key 20 and the column-side shear key 21 face each other. Although not shown in Fig. 5, when the precast beam member 13 is placed in a predetermined position, an anti-adhesion material 24 (see Fig. 3) is placed in a predetermined position.

[0049] Thereafter, as shown in Fig. 5(C), a filler 14 is filled into the gap G formed between the precast beam member 13 and the precast column member 12. As shown in Fig. 5(D), a tendon 15 is arranged to span the precast beam member 13 and the precast column member. After the filler 14 has hardened, tension is applied to the tendon 15 to introduce prestress into the precast beam member 13 and the precast column member 12. In this way, a prestressed concrete beam-column joint structure 11 is constructed. The tendon 15 may be arranged before filling with the filler 14 in Fig. 5(C).

[0050] Thereafter, as shown in Fig. 5(E), the bracket 23 is removed. By removing the bracket 23 after joining the precast beam members 13, it can be reused for other joints. This reduces material costs. Furthermore, removing the bracket 23 improves the appearance of the column-beam joint. When covering the column-beam joint with a board or the like, removing the bracket 23 can reduce the dead space.

[0051] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 6. As shown in Fig. 6, this embodiment differs from the first embodiment in that both ends of a precast beam member 13 are joined to a pair of precast column members 12 by pressure bonding with discontinuous tendons 15. This will be described in detail below.

[0052] The precast beam member 13 has beam widening portions 31 at both ends that are wider than the middle portion in the longitudinal direction. The beam widening portions 31 form shoulder surfaces 31a that engage the fasteners 16 on the side opposite the end faces of the precast beam member 13. The shoulder surfaces 31a are formed on both sides in the width direction in the cross section of the precast beam member 13.

[0053] Even if the precast beam member 13 is configured in this manner and both ends of the precast beam member 13 are pressure-connected to the precast column member 12 by discontinuous, independent tendons 15, the same effects as in the first embodiment can be achieved.

[0054] Although the description of the specific embodiment is finished above, the present invention is not limited to the above embodiment and can be widely modified. For example, the specific configuration, arrangement, quantity, material, procedure, etc. of each member or part can be appropriately changed without departing from the spirit of the present invention. On the other hand, all of the components shown in the above embodiment are not necessarily required and can be selected appropriately. [Explanation of symbols]

[0055] 11: Column beam joint structure 12: Precast column members 13: Precast beam members 14: Filling material 15: Tensile material 18: Beam side through hole 19: Column side through hole 20: Beam side shear key 20a:Top surface 20b: Side 21: Pillar side shear key 21a:Top surface 21b: Side 22: Embedded anchor (retaining member) 23: Bracket (temporary support member) G: air gap

Claims

1. A method for joining columns and beams in a precast concrete structure, comprising the steps of: A step of erecting a precast column member having a concave column side shear key at a predetermined position; attaching a removable temporary support member to the precast column member; placing an end of a precast beam member having a concave beam side shear key on an end surface thereof on the temporary support member, and arranging the column side shear key and the beam side shear key opposite each other; filling a gap formed between the precast beam member and the precast column member with a filler material; placing tendons across the precast beam members and the precast column members; and after the filler has hardened, applying tension to the tendons to prestress the precast beam members and the precast column members; The column-beam joining method, wherein the column-side shear key and the beam-side shear key have an upper surface that is lower toward the back in a vertical cross section, and a pair of side surfaces have a shape that widens toward the back in a horizontal cross section.

2. The column-beam joining method according to claim 1 , further comprising the step of removing the temporary support member after the tension is applied to the tendon.

3. A precast concrete beam-column joint structure, A precast column member that is erected at a predetermined position and has a concave column side shear key on an outer surface; A precast beam member having a concave beam side shear key at an end surface, the beam side shear key being arranged to face the column side shear key; A filler material filled in a gap formed between the precast beam member and the precast column member; a tendon arranged across the precast beam member and the precast column member to introduce prestress into the precast beam member and the precast column member; The column-side shear key and the beam-side shear key have an upper surface that is lower toward the back in a vertical cross section, and a pair of side surfaces that widen toward the back in a horizontal cross section. This is a column-beam joint structure.

4. A column-beam joint structure as described in claim 3, wherein a retaining member is provided in a lower portion of the precast beam member in the precast column member, for removably holding a temporary support member for temporarily supporting the precast beam member.

5. a beam-side through hole extending in a longitudinal direction for inserting the tension member is formed in the precast beam member, a column-side through hole extending in a horizontal direction at a position aligned with the beam-side through hole is formed in the precast column member, the beam-side through hole and the column-side through hole are partitioned by the gap and communicate with each other, A column-beam joint structure as described in claim 3 or claim 4, wherein the tension member is inserted into the beam side through hole and the column side through hole, and is in an unbonded state with respect to the precast beam member and the precast column member.

6. The column-beam joint structure according to any one of claims 3 to 5, wherein the filler is non-shrink mortar, fiber-reinforced mortar or low-elasticity, high-toughness mortar.

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