JP2023009741A - Column-beam joint method and column-beam joint structure - Google Patents

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 The present invention relates to a beam-to-column joining method for a precast concrete structure and a beam-to-column joining structure for a precast concrete structure.

Conventionally, a prestressed concrete structure is known as a structure having higher elastic strength than RC structures (Patent Document 1). In this prestressed concrete structure, a large number of precast concrete columns with girders supporting jaws integrally formed stand on a concrete foundation, and precast concrete girders having projections at their ends are supported by the girders supporting jaws. Installed between pillars. A filler is provided on the joint surface between the girder receiving jaw and the projection, and the prestressed precast concrete girders are fixed to the precast concrete pillars by tensioning the PC steel wires.

As a building construction method capable of shortening the construction period, a method using a plurality of unbonded precast prestressed concrete columns is known (Patent Document 2). In this method, a given story is constructed about the perimeter of the building after a given story is constructed about the core of the building, which includes a plurality of unbonded precast prestressed concrete columns.

JP-A-5-280092 JP 2020-56165 A

However, in the prestressed concrete structure described in Patent Document 1, the girders are integrally formed with the precast concrete column so as to protrude from the outer surface of the column. The precast concrete beams are lobed at the ends by forming recesses for receiving the girder receiving jaws. When the girders are protruded from the precast concrete columns, the freedom of construction is limited. In addition, since the beam receiving jaws and projections are formed integrally with the columns and beams, the manufacturing cost of these precast concrete members increases. In addition, since the precast concrete column is bulky due to the integrally formed girders, the transportation cost is also high.

On the other hand, in the building construction method described in Patent Document 2, the core columns are constructed as unbonded precast prestressed concrete columns, but the core beams are reinforced concrete beams. Therefore, there is room for improvement in increasing the degree of freedom in construction and in reducing costs. In paragraph [0022] of Patent Document 2, it is disclosed that the beam of the core portion may be an unbonded precast prestressed concrete beam, a precast prestressed concrete beam, or the like. The concrete construction method of the beam is not indicated.

In view of the above background, an object of the present invention is to improve the degree of freedom of construction in precast concrete structures and to reduce costs.

In order to solve the above problems, one aspect of the present invention is a beam-to-column joining method for a precast concrete structure, in which a precast column member (12) having a concave column side shear key (21) is erected at a predetermined position. (Fig. 5(A)), attaching a detachable temporary support member (23) to the precast column member (Fig. 5(A)), and having a concave beam side shear key (20) on the end face a step of placing the end of the precast beam member (13) on the temporary support member and opposing the column side shear key and the beam side shear key (FIG. 5(B)); A step of filling a gap (G) formed between the precast column member with a filler (14) (Fig. 5(C)); 15) (FIG. 5(D)), and introducing prestress to the precast beam member and the precast column member by applying tension to the prestressing tendon after the filler has set. (FIG. 5(D)).

According to this aspect, since the column-side shear key and the beam-side shear key are concave, the precast beam member can be arranged from both above and horizontally, and the degree of freedom in construction is not limited. In addition, since the detachable 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 cost and transportation cost of the precast members can be reduced compared to the case where the precast column member and the precast beam member are formed with protrusions.

The above aspect may further include a step of removing the temporary support member after the tension force is applied to the tendon (FIG. 5(E)).

According to this aspect, since the temporary support member can be diverted, the material cost can be reduced. Also, by removing the temporary support member, the appearance of the beam-to-column joint is improved. When the column-to-beam joint is covered with a board or the like, the dead space can be reduced by removing the temporary support member.

In order to solve the above problems, another aspect of the present invention is a precast concrete column-to-beam joint structure (11), which is erected at a predetermined position and has a concave column side shear key (21) on the outer surface. a precast beam member (13) having a concave beam-side shear key (20) on an end face and arranged so that the beam-side shear key faces the column-side shear key; a filling material (14) filled in a gap (G) formed between the precast beam member and the precast column member; A prestressing tendon (15) for introducing prestress to the member and said precast column member.

According to this aspect, since the column-side shear key and the beam-side shear key are concave, the degree of freedom of construction when constructing the column-to-beam joint structure is not restricted. In addition, since the column-side shear key and the beam-side shear key are concave, the manufacturing cost and transportation cost of the precast members can be reduced compared to the case where the projections are formed on the precast column member and the precast beam member.

In the above aspect, a holding member (22) detachably holding a temporary support member (23) for temporarily supporting the precast beam member is provided in the portion of the precast column member below the precast beam member. may be

According to this aspect, since the temporary support member for temporarily supporting the precast beam member can be attached to the precast column member and the end portion of the precast beam member can be placed on the temporary support member, construction is easy.

In the above aspect, the precast beam member is formed with a beam-side through hole (18) extending in the longitudinal direction through which the tendon is inserted, and the precast column member is provided at a position aligned with the beam-side through hole. A column-side through-hole (19) extending in the horizontal direction is formed in the beam-side through-hole (19), the beam-side through-hole and the column-side through-hole are separated from the gap and communicate with each other, and the tendon passes through the beam-side through-hole It may be inserted through the hole and the column-side through-hole, and may be in an unbonded state with respect to the precast beam member and the precast column member.

According to this aspect, the column-to-beam joint becomes an unbonded prestressed concrete structure. Therefore, compared with the bond structure, the elastic deformation performance of the beam-to-column joint structure can be enhanced. In addition, since the precast beam member and the precast column member can be separated by removing the tendon, the precast member can be reused, and the life cycle cost of the column-to-beam joint structure can be reduced. Furthermore, by reusing precast members, it is possible to reduce environmental loads such as CO ₂ emissions compared to constructing new members.

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.

According to this aspect, when filling the gap with the filler, the occurrence of air pockets in the gap is suppressed.

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

According to this aspect, the column-side shear key and the beam-side shear key are dovetail tenons, and the binding force of the filler to the precast beam member and the precast column member is strengthened. Therefore, even if the tendon is broken and the joint due to the tension force is released, the precast beam member is prevented from falling from the precast column member.

In the above aspect, the filler may be non-shrinkage mortar, fiber-reinforced mortar, or low-elasticity, high-tenacity mortar.

According to this aspect, since the filler is less likely to be damaged, the bonding strength of the precast beam member to the precast column member is improved.

According to the above aspect, it is possible to improve the degree of freedom of construction in the precast concrete structure and reduce the cost.

Front view of building according to the first embodiment Elevation section of the building shown in Figure 1 Enlarged view of main part of Fig. 2 Plane cross-sectional view along the IV-IV cross-sectional line in Fig. 3 A diagram showing a building construction procedure according to the first embodiment. Front view of beam-to-column joint structure according to the second embodiment

Embodiments of the present invention will be described below with reference to the drawings. The present invention is applied to a rigid-frame structure building 1 made of reinforced concrete or steel-reinforced concrete.

<<First embodiment>>
First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. FIG. 1 is a front view of a building 1 according to the first embodiment. As shown in FIG. 1, a building 1 includes a pair of pillars 2 and a beam 3 joined to the pair of pillars 2 at both ends in the extending direction. The pillars 2 are arranged at predetermined positions at predetermined intervals in the X direction and the Y direction which are orthogonal to each other in plan view. The pillars 2 may be provided in three or more rows in at least one of the X direction and the Y direction. The beam 3 is provided so as to extend in each of the X direction and the Y direction. Moreover, the beams 3 are provided at predetermined positions in the vertical direction for each floor of the building 1 to support the floor (not shown). The ends of the beams 3 are joined to the columns 2 by column-to-beam joining structures 11 .

Column 2 includes at least one precast column member 12 . The precast column member 12 is erected on a predetermined position such as a lower column constructed below or on a foundation. The precast column member 12 may have the same length as the floor height of the first floor, or may have a length longer than the floor height of the first floor. Alternatively, the precast column member 12 may have a length that is less than the height of one story. The precast column members 12 are preferably joined to the lower lower column, foundation or the like by unbonded tendons.

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 the pair of precast column members 12 . A precast beam member 13 is arranged 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 precast column member 12 facing it. This gap G is filled with a filler 14 . After filling with the filler 14 , the precast beam member 13 is joined at both ends to a pair of precast column members 12 and stretched over the pair of precast column members 12 .

The precast column member 12 and the precast beam member 13 are prefabricated in a factory using precast concrete and carried to the construction site. Filler 14 is a flowable material that hardens over time, and may be, for example, mortar or cement milk. It is preferable to employ fiber-reinforced mortar or low-elasticity, high-toughness mortar as the filler 14 so that the filler 14 is less likely to break after curing.

Thus, the beam-column joint structure 11 is a joint structure between one end of the precast beam member 13 and the 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 crimped and joined to the corresponding precast column member 12 by tendons 15 arranged so as to extend from one precast column member 12 to the other precast column member 12. . As a result, the column-to-beam joint structure 11 is made of prestressed concrete.

Specifically, a plurality of tendons 15 are arranged above and below the precast beam member 13 . Each tendon 15 is anchored at both ends to the outer surface of the precast column member 12 by anchors 16 under tension. As a result, prestress is introduced to the precast column member 12 and the precast beam member 13 and each end of the precast beam member 13 is crimped to the corresponding precast column member 12 .

The tendon 15 is made of a PC steel bar, a PC steel wire, a PC steel stranded wire, or a bar or cable made of fiber-reinforced plastic such as aramid fiber, carbon fiber, glass fiber, or the like. The tendon 15 is preferably an unbonded tendon that is not adhered to the precast column member 12 and the precast beam member 13 . By making the tendons 15 unbonded, the residual deformation after the end of the earthquake becomes small.

FIG. 2 is a cross-sectional elevational view of the building 1 shown in FIG. As shown in FIG. 2, the precast beam member 13 is formed with a beam-side through-hole 18 through which the tendon 15 is inserted. The beam-side through-hole 18 extends horizontally along the longitudinal direction of the precast beam member 13 . A column-side through-hole 19 is formed in the precast column member 12 for insertion. 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 .

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

3 is an enlarged view of a main portion of FIG. 2. FIG. As shown in FIG. 3 , a plurality of embedded anchors 22 are provided in the portion of the precast column member 12 below the precast beam member 13 . The embedded anchor 22 has a screw hole opened in the outer surface of the precast column member 12 below the precast beam member 13 . The embedded anchor 22 is a holding member that detachably holds the bracket 23 in cooperation with the bolt B screwed into the screw hole.

The bracket 23 is a temporary support member for temporarily supporting when joining the precast beam member 13 to the precast column member 12 . The bracket 23 may be made of section steel such as angle steel, channel steel, H-section steel, or the like. The bracket 23 is preferably attached before erecting the precast column member 12 and removed after joining the precast beam member 13 .

With this configuration, the bracket 23 for temporarily supporting the precast beam member 13 can be attached to the precast column member 12, and the end of the precast beam member 13 can be placed on the bracket 23, which facilitates construction.

The gap G (see FIG. 5B) formed between the end of the precast beam member 13 and the precast column member 12 as described above is filled with the filler 14 . An anti-adhesion material 24 is provided between the precast beam member 13 and the precast column member 12 to prevent the filler material 14 from adhering to the tendon 15 . The anti-adhesion member 24 has an annular shape, and separates the beam-side through-hole 18 and the column-side through-hole 19 from the gap G so as to communicate with each other. This prevents the filler 14 filling 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 arranged in a compressed state between the precast beam member 13 and the precast column member 12 . In another embodiment, the anti-adhesion member 24 may be a cylindrical member arranged across the gap G and inserted into the beam-side through-hole 18 and the column-side through-hole 19 .

By providing the anti-adhesion material 24 and unbonding the tendon 15, the beam-to-column joint becomes an unbonded prestressed concrete structure. As a result, the elastic deformation performance of the beam-to-column joint structure 11 becomes higher than in the case of the bond structure. Moreover, the precast beam member 13 and the precast column member 12 can be separated by removing the tendon 15 . Therefore, these precast members can be reused, and the life cycle cost of the beam-to-column joint structure 11 can be reduced. Furthermore, by reusing precast members, environmental loads such as CO ₂ emissions are reduced compared to constructing new members.

In the vertical section of FIG. 3, the upper surface 20a of the beam-side shear key 20 is lowered from the gap G side toward the back. The upper surface 21a of the column-side shear key 21 is also lowered from the gap G side toward the back. Therefore, when the filling material 14 is filled into the gap G, the occurrence of air pockets in the gap G is suppressed. The bottom surface of the beam-side shear key 20 and the bottom surface of the column-side shear key 21 increase in depth from the gap G side in the vertical cross section of FIG.

FIG. 4 is a plan cross-sectional view along the IV--IV cross-sectional line in FIG. As shown in FIG. 4, in a plane section, the beam-side shear key 20 has a shape in which a pair of side surfaces 20b widen toward the back. The pillar-side shear key 21 also has a shape in which a pair of side surfaces 21b widen toward the back. As a result, the beam-side shear key 20 and the column-side shear key 21 form a dovetail tenon, and the binding force of the filler 14 to the precast beam member 13 and the precast column member 12 is strengthened. Therefore, even if the tendon 15 is broken and the joint due to tension is released, the precast beam member 13 is prevented from falling from the precast column member 12 .

Here, in the embodiment, fiber-reinforced mortar, which is hard to break, is adopted 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-shrinkage mortar or low-elasticity high-tenacity mortar may be employed as filler 14 instead of fiber-reinforced mortar. This also improves the bonding strength of the precast beam member 13 to the precast column member 12 .

The beam-to-column connection structure 11 of the building 1 is configured as described above. Next, a beam-to-column joining method for such a precast concrete structure will be described. FIG. 5 is a diagram showing the construction procedure of the building 1 according to the first embodiment. The building 1 is constructed by workers according to the following procedures (steps).

Prior to construction of the building 1, the necessary number of precast column members 12 and precast beam members 13 having the above configuration are prepared. As described above, the precast column member 12 is formed with the concave column-side shear key 21, but is not formed with a projection such as a beam-receiving jaw. Therefore, since the precast column member 12 is not bulky, transportation costs can be reduced. Further, although the precast beam member 13 is formed with the concave beam-side shear key 20, the projecting portion to be placed on the beam-receiving jaw is not formed at the end. Thus, since the precast column member 12 and the precast beam member 13 are not formed with projection-shaped portions, the manufacturing cost of these precast concrete members can be reduced.

At the construction site of the building 1, as shown in FIG. 5A, a precast column member 12 is erected at a predetermined position. The bracket 23 is preferably attached 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.

Next, as shown in FIG. 5B, 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. Place. At that time, since the column-side shear key 21 and the beam-side shear key 20 are concave, the precast beam member 13 can be arranged from both above and horizontally, and the degree of freedom of construction is not limited. In addition, the bracket 23 for temporarily supporting the precast beam member 13 is detachably attached to the precast column member 12, thereby improving the flexibility of construction. By attaching the bracket 23 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.

When the precast beam member 13 is placed at a predetermined position on the bracket 23, the beam-side shear key 20 and the column-side shear key 21 face each other. Although omitted in FIG. 5, when arranging the precast beam member 13 at a predetermined position, an anti-adhesion material 24 (see FIG. 3) is arranged at a predetermined position.

After that, as shown in FIG. 5(C), the gap G formed between the precast beam member 13 and the precast column member 12 is filled with the filler 14 . As shown in FIG. 5(D), a tendon 15 is arranged so as to extend over the precast beam member 13 and the precast column member. After the filler 14 has hardened, prestress is introduced into the precast beam member 13 and the precast column member 12 by applying tension to the tendons 15 . As a result, the beam-to-column joint structure 11 made of prestressed concrete is constructed. The tendon 15 may be placed before filling the filler 14 in FIG. 5(C).

After that, as shown in FIG. 5(E), the bracket 23 is removed. By removing the bracket 23 after the precast beam member 13 is joined, it can be diverted to another joint. Therefore, material costs are reduced. Also, by removing the bracket 23, the appearance of the column-to-beam joint is improved. When the column-to-beam joint is covered with a board or the like, the dead space can be reduced by removing the bracket 23 .

<<Second embodiment>>
A second embodiment of the present invention will now be described with reference to FIG. 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 crimping with discontinuous tendons 15 . A specific description will be given below.

The precast beam member 13 has beam widened portions 31 at both ends, which are wider than the middle portion in the longitudinal direction. The beam widened portion 31 forms a shoulder surface 31 a for locking the fixture 16 on the side opposite to the end surface of the precast beam member 13 . The shoulder surfaces 31 a are formed on both sides in the width direction in the cross section of the precast beam member 13 .

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

Although the description of the specific embodiments is finished above, the present invention is not limited to the above embodiments and can be widely modified. For example, the specific configuration, arrangement, quantity, material, procedure, etc. of each member and part can be changed as appropriate within the scope of the present invention. On the other hand, not all of the components shown in the above embodiments are essential, and can be selected as appropriate.

11: Column-beam joint structure 12: Precast column member 13: Precast beam member 14: Filler 15: Tendon 18: Beam side through hole 19: Column side through hole 20: Beam side shear key 20a: Upper surface 20b: Side surface 21: Column Side shear key 21a: upper surface 21b: side surface 22: embedded anchor (holding member)
23: Bracket (temporary support member)
G: Gap

Claims (8)

A method for joining columns and beams of a precast concrete structure,
erecting a precast column member having a concave column side shear key in place;
attaching a detachable temporary support member to the precast column member;
placing an end portion of a precast beam member having a concave beam-side shear key on its end surface on the temporary support member so that the column-side shear key and the beam-side shear key face each other;
filling a gap formed between the precast beam member and the precast column member with a filler;
placing tendons across the precast beam member and the precast column member;
and introducing prestress to the precast beam member and the precast column member by applying tension to the tendon after the filler has hardened. The beam-to-column joining method according to claim 1, further comprising a step of removing the temporary support member after the tension force is applied to the tendon. A beam-to-column joint structure made of precast concrete,
A precast column member erected at a predetermined position and having a concave column side shear key on the outer surface;
a precast beam member having a concave beam-side shear key on an end surface, the beam-side shear key being arranged to face the column-side shear key;
a filler filled in a gap formed between the precast beam member and the precast column member;
A column-to-beam connection structure comprising a tendon disposed across the precast beam member and the precast column member and introducing prestress to the precast beam member and the precast column member. 4. The column beam according to claim 3, wherein a portion of the precast column member below the precast beam member is provided with a holding member that detachably holds a temporary support member for temporarily supporting the precast beam member. junction structure. The precast beam member is formed with a longitudinally extending beam-side through hole through which the tendon is inserted, and the precast column member is provided with a horizontally extending column side at a position aligned with the beam side through hole a through-hole is formed, and the beam-side through-hole and the column-side through-hole are separated from the gap and communicate with each other;
The beam-to-column joint according to claim 3 or 4, wherein the tendon is inserted through 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. structure. The column-to-beam joint structure according to any one of claims 3 to 5, wherein the column-side shear key and the beam-side shear key have upper surfaces that become lower toward the back in a vertical section. The column-to-beam joint structure according to any one of claims 3 to 6, wherein each of the column-side shear key and the beam-side shear key has a shape in which a pair of side surfaces spreads toward the back in a plan cross section. The beam-to-column joint structure according to any one of claims 3 to 7, wherein the filler is non-shrinkage mortar, fiber-reinforced mortar or low-elasticity high-toughness mortar.

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