JP7158996B2 - Joining structure and joining method of precast concrete beam members - Google Patents

Description

The present invention relates to a joint structure and joint method between beams of precast concrete members in the construction of a building using precast concrete beam members, and more particularly, to precast concrete for placing cast-in-place concrete in joints between precast concrete beam members. The present invention relates to a joining structure and joining method of beam members.

BACKGROUND ART In reinforced concrete structures, various precast concrete members (hereinafter referred to as precast members) manufactured in factories in advance are often used for rationalization of construction and shortening of construction period. At this time, when the beams are made of precast members, beam joints may be provided for joining the precast members with division positions such as the center or the end of the span of the beams. In order to join the main reinforcing bars of the beams at this dividing position, generally a 600 to 800 mm on-site concrete placement portion is provided at the beam joints for welding work or mechanical joint work. For this reason, at the beam joint, it takes a lot of time and labor for positioning and the like in welding work and mechanical joint work, and it cannot be said that work efficiency is good.

In order to deal with these problems, Patent Document 1 discloses a precast member that reduces the work effort of the beam joint by configuring the beam joint with a gap lap joint that uses a reinforcing bar provided with a diameter expansion fixing portion. beam structure is disclosed.

Japanese Patent Application Laid-Open No. 2001-11940

However, in the joining method described in Patent Document 1, due to the difference in required strength of concrete between the beam joint and the floor slab, on-site concrete of the beam joint and the floor slab that is integrally arranged with the beam joint Casting is done in a separate process. Therefore, even if the beam structure of precast members described in Patent Document 1 is adopted, it cannot be said that the shortening of the construction period and the labor saving are sufficient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a joining structure and a joining method for precast beam members that contribute to shortening the construction period and labor saving.

In order to achieve the above object, the present invention provides a first precast concrete beam member in which a first joint reinforcing bar and a first bottom bar protrude from a cross section of at least one end of the beam in the longitudinal direction of the beam; a second precast concrete beam member in which a second joint reinforcing bar and a second bottom bar protrude from the cross section of the beam, wherein the first joint reinforcing bar and the second joint reinforcing bar forms a first spaced lap joint, said first bottom bar and said second bottom bar form a second spaced lap joint, said first spaced lap joint and said second spaced lap A beam joint is constructed with joints, the beam joint and a floor slab partly integrally formed with the beam joint have the same strength, and the first and second precast concrete beams It is characterized by being made of cast-in-place concrete having a lower strength than the concrete strength of the member.

The first joint reinforcing bar and the second joint reinforcing bar are preferably oblique reinforcing bars.

Preferably, the bottom muscle has a hook-shaped tip.

Preferably, the beam joint is located near the center of the beam span.

The beam joint is also located near a beam span end , and the first precast concrete beam member is further configured such that the first joint reinforcing bar and the first bottom bar extend from the first precast concrete beam. It is preferable to project from the side surface of the columnar portion of the member .

Preferably, the first precast concrete beam member and the second precast concrete beam member are half precast concrete beam members.

As a joining method, the present invention comprises a first precast concrete beam member in which a first joint reinforcing bar and a first bottom bar protrude from at least one end of the beam cross section in the longitudinal direction of the beam, and a second precast concrete beam member in the longitudinal direction of the beam. A second precast concrete beam member in which a joint reinforcing bar and a second bottom bar protrude from the cross section of the beam, and the first joint reinforcing bar and the second joint reinforcing bar are stacked in a first gap. said first precast concrete beam member and said second precast concrete beam member forming a joint such that said first bottom reinforcement and said second bottom reinforcement form a second spaced lap joint; to construct a beam joint, and to the beam joint and a floor slab part of which is integrally formed with the beam joint, having the same strength and the first and second precast It is characterized by placing concrete having a lower strength than the concrete strength of the concrete beam member.

ADVANTAGE OF THE INVENTION According to this invention, it can contribute to shortening of a construction term, and labor saving.

(a) is a front cross-sectional view of a joint structure of precast beam members according to the first embodiment of the present invention, (b) is a side cross-sectional view taken along the Ib-Ib cross-sectional line in (a), and (c) , and a side cross-sectional view taken along the Ic-Ic cross-sectional line of (a). (a) is a front cross-sectional view of a precast beam member for an end according to the first embodiment of the present invention, and (b) is a front cross-sectional view of the precast beam member according to the first and second embodiments of the present invention. , (c) is a side cross-sectional view shown by the IIc-IIc cross-sectional line of (a), (b) and (e), and (d) is shown by the IId-IId cross-sectional line of (a) and (b) FIG. 10(e) is a front sectional view of a precast beam member according to a second embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic lay-down diagram partially showing a beam structure composed of precast beam members according to the first and second embodiments of the present invention; (a) is a front cross-sectional view when one beam member is arranged in the method for joining precast beam members according to the first embodiment of the present invention, and (b) is a front cross-sectional view when the other beam member is arranged. (c) is a front cross-sectional view at the time of arranging the stirrup bar and the upper end bar, and (d) is a front cross-sectional view of the joining method of the precast beam members according to the first embodiment of the present invention after placing concrete on site. (a) is a front cross-sectional view when arranging the beam members of the method for joining precast beam members according to the second embodiment of the present invention, (b) is a front cross-sectional view when arranging stirrups and upper end muscles, ( c) is a front cross-sectional view after placing concrete on site. FIG. 11 is a schematic lay-down diagram partially showing a beam structure composed of precast beam members according to another embodiment of the present invention. (a) to (d) are front cross-sectional views of precast beam members according to other embodiments of the present invention.

A joint structure and a joint method for precast beam members according to the present invention will be described below with reference to the accompanying drawings. In addition, the same components are given the same reference numerals, and the description thereof is omitted.

[First embodiment]
A precast concrete beam member 1 (hereinafter referred to as a beam member 1) as a first embodiment of the present invention shown in each figure in FIG. 1 and FIGS. It is a half-precast member that uses cast-in-place concrete in a portion corresponding to the thickness of the floor slab to be installed. As shown in FIG. 3, this half precast member joint structure J1 includes a beam member 1A having a beam end joint 10 at one end in the beam longitudinal direction, and a beam member 1A having beam end joints 10 at both ends in the beam longitudinal direction. 1B (or beam member 1B and beam member 1B) are joined together. The joint structure J1, as shown in each figure of FIG. Simultaneously with the casting of the floor slab concrete, cast-in-place concrete 13 having the same strength as the floor slab concrete and lower strength than the concrete strength of the beam members 1A and 1B (or the beam members 1B and 1B) is cast. formed in As shown in FIGS. 3 and 4 as an example, the shape of these beam end joints 10, 10 is such that the beam members 1A, 1B are continuously constructed between the column members P1, P2, and the beam span is increased. It is assumed that they are joined in a central position.

<Structure 1 of the joint>
Hereinafter, configurations of the beam member 1A and the beam member 1B will be described with reference to FIGS. The beam member 1A and the beam member 1B are manufactured at a precast concrete member manufacturing factory by pouring concrete 18 into a form in which a reinforcing bar assembly assembled with a required cover thickness is arranged, and then forming a beam end. A beam end joint 10 is provided at the part.

(Configuration of beam member 1A)
As shown in FIGS. 2A, 3 and 4, the beam member 1A has a beam end joint portion 10 at one end in the beam longitudinal direction, and the other end is flush with the end surface of the column member P1. be. The beam member 1A is installed on the column member P1 at the corner. Oblique reinforcements 15 and 16 and a lower end reinforcement (lower main reinforcement) 17 are arranged so as to protrude in the longitudinal direction of the beam from an end surface 14 of the beam cross section at one end of the beam end joint 10 .

As shown in FIGS. 2(a) and 2(c), in this embodiment, two oblique reinforcing bars 15 are arranged horizontally in the longitudinal direction of the beam on the upper part of the beam, and are inclined at an angle of about 45° from the end surface 14 of the cross section of the beam. It protrudes downward. The overhang length of the oblique reinforcing bar 15 is secured to be 30 times the diameter d1 of the oblique reinforcing bar 15. - 特許庁

Two oblique reinforcing bars 16 are arranged horizontally in the longitudinal direction of the beam at the lower part of the beam near the lower end bar 17, and protrude obliquely upward at about 45° from the end face 14 of the cross section of the beam. The overhang length of the oblique reinforcing bars 16 is ensured to be 30 times the diameter d2 of the oblique reinforcing bars 16. - 特許庁

Five bottom reinforcements 17 are arranged along the lower side of the beam, project horizontally from the end surface 14 of the cross section of the beam in the longitudinal direction of the beam, and the tip is bent upward in a substantially vertical direction to form a hook shape. ing. The projecting length of the bottom muscle 17 is ensured to be 40 times the diameter d3 of the bottom muscle 17 over the entire projecting portion of the bottom muscle 17. - 特許庁

A columnar portion 25 having the same cross section as that of the column member P1 is formed on the other end side of the beam member 1A in the beam longitudinal direction. A column main-reinforcement through-hole 22 for inserting the column main-reinforcement 23 of the column member P1 is formed in the column-shaped portion 25 .

(Configuration of beam member 1B)
As shown in FIGS. 2B, 3 and 4, the beam member 1B has beam end joints 10 at both ends in the beam longitudinal direction. The beam member 1B is installed on the pillar member P2 which is an intermediate pillar. Oblique reinforcements 15 and 16 and bottom reinforcements (lower main reinforcements) 17 are arranged so as to protrude in the longitudinal direction of the beam from end faces 14 of the beam cross section at both ends of the beam end joint 10 .

A columnar portion 25 having the same cross section as that of the columnar member P2 is formed in the middle of the beam member 1B. The column portion 25 is formed with a column main-reinforcement through-hole 22 for inserting the column main-reinforcement 23 of the column member P2.

(Other configurations)
As shown in FIGS. 1( a ) and 1 ( b ), the stirrup reinforcement 11 is arranged so as to surround the oblique reinforcements 15 and 16 and the bottom reinforcement 17 . The top reinforcement 12 is processed to a predetermined length on site and arranged inside the upper ends of the stirrup reinforcements 11 and 21 .

<Composition 1 of joining structure>
A joint structure J1 of precast concrete beam members (half precast beam members) will be described with reference to FIGS. The joint structure J1 of the half-precast beam member is configured by facing the beam end joint portion 10 of the beam member 1A and the beam end joint portion 10 of the beam member 1B with a predetermined gap D1 therebetween. Between the beam members 1A and 1B, the oblique reinforcing bars 15 of the beam member 1A and the oblique reinforcing bars 16 of the beam member 1B form an open lap joint and function as members that transmit shear force. In addition, the oblique reinforcing bars 16 of the beam member 1A and the oblique reinforcing bars 15 of the beam member 1B form a lapped joint and function as members that transmit shear force. Further, the bottom reinforcement 17 of the beam member 1A and the bottom reinforcement 17 of the beam member 1B form a lapped joint and function as the bottom reinforcement of the beam between the column members P, P. In addition, the opening dimension S is 0.2 LE and 150 mm or less at each opening lap joint portion, and opening lap joint length LE=30×reinforcement diameter. Between the end faces 14, 14 of the beam cross-section of the beam members 1A, 1B, there is a site that is integral with the floor slab 40, has the same strength as the floor slab concrete, and has a lower strength than the concrete strength of the beam members 1A, 1B. Placed concrete 13 is placed. The reinforcing bars forming the lapped joints are arranged at different positions so as not to interfere with each other when the beam member is suspended, as indicated by the symbols ◯ and X in FIG. 1(b).

Normally, in half precast concrete construction, since the cast-in-place concrete for beam joints has a higher required strength than the floor slab concrete, it cannot be cast in one piece at the same time. However, in the present embodiment, the joint reinforcing bar including the diagonal reinforcing bar 15 of the beam member 1A and the diagonal reinforcing bar 16 of the beam member 1B and the diagonal reinforcing bar 16 of the beam member 1A and the diagonal reinforcing bar 15 of the beam member 1B are used. Since the joint reinforcing bars of the beam members 1A and 1B transmit part of the shear force at the beam joint, the required strength of the cast-in-place concrete 13 between the end faces 14 and 14 of the design beam cross section of the beam members 1A and 1B is determined by the beam members 1A and 1B It has the same strength as the floor slab concrete of the floor slab 40 directly above, and can be made lower in strength than the concrete strength of the beam members 1A and 1B. Therefore, the cast-in-place concrete 13 can be cast simultaneously and integrally between the end faces 14, 14 of the design cross section of the beam members 1A, 1B and part of the floor slab 40 directly above the beam members 1A, 1B. , it can contribute to shortening the construction period and labor saving. Further, since the tip portion of the bottom reinforcement 17 is bent upward to form a hook shape, the predetermined distance D1 between the end faces 14, 14 of the design beam cross-section of the beam members 1A, 1B can be shortened, and the cast-in-place concrete can be 13 can be reduced.

<Method 1 for joining precast beam members>
Next, a method of joining the beam member 1A and the beam member 1B will be described with reference to FIGS. 4 to 5 and the like. As shown in FIG. 4(a), the beam member 1A is placed on and joined to a column member P1 erected at a predetermined position on the slab plane of a predetermined floor. The beam member 1A is lowered almost vertically toward the joint position, the column main reinforcement 23 of the column member P1 is passed through the column main reinforcement through-hole 22 of the beam member 1A, and placed on the frame top 24 of the column member P1 to be joined. do. At this time, the beam member 1A is supported by the pipe support 50 as shown in FIG. 4(b).

Subsequently, the beam member 1B is placed on the column member P2 and joined. At this time, the oblique reinforcing bars 15 of the beam member 1A and the oblique reinforcing bars 16 of the beam member 1B, and the oblique reinforcing bars 16 of the beam member 1A and the oblique reinforcing bars 15 of the beam member 1B form lapped joints. The beam end joints 10, 10 are opposed to each other so that the bottom reinforcement 17 of the beam member 1A and the bottom reinforcement 17 of the beam member 1B form an open lap joint, and the column main reinforcement of the column member P2 is suspended at the beam joint position. 23 is passed through the column main reinforcement through hole 22 of the beam member 1B, and the beam member 1B is placed on and joined to the building frame top end 24 of the column member P2.

Prior to placing the cast-in-place concrete 13, as shown in FIG. 5(c), the top reinforcement 12 is arranged and the stirrup reinforcement 11 is arranged between the beam members 1A and 1B at the site. At the same time, the reinforcement of the floor slab will be arranged. After that, in order to complete the design concrete cross section, as shown in FIG. In addition, cast-in-place concrete 13 having a lower strength than the concrete strength of the beam members 1A and 1B is placed to form a joint structure J1 of half precast members.

[Second embodiment]
In the first embodiment, the joint structure J1 that forms a joint in the longitudinal direction of the beam has been described, but in the second embodiment, as shown in FIG. 2 is arranged, and the junction structure J2 is formed in a direction intersecting with the junction structure J2 in plan view. In addition, the same code|symbol is attached|subjected to the component same as 1st embodiment, and description is abbreviate|omitted.

As shown in FIG. 6C, the joint structure J2 of half precast members has a beam end joint between column members P1 and P3 in which beam members 1A and 1A each having a beam end joint 30 on the beam side surface are arranged. It consists of a structure formed by arranging beam members 2 having 10 . In the joint structure J2, the cover thickness of the stirrup reinforcement 11 and the upper end reinforcement 12 arranged at the beam joint between the beam end joints 30 and 10 is secured, and the beam joint is performed simultaneously with the pouring of the floor slab concrete. It is integrally formed by pouring the cast-in-place concrete 13 of the part. As shown in FIGS. 3 and 6 as an example, these beam end joints 30 and 10 are shaped so that the beam members 1A and 1A are installed in parallel on the column members P1 and P3, and the beam members 2 are assumed to be joined near the end of the beam span.

<Structure 2 of the joint>
Hereinafter, configurations of the beam member 1A and the beam member 2 will be described with reference to FIGS. 2 and 3. FIG. The beam member 2 is manufactured at a precast concrete member manufacturing factory by pouring concrete 18 into a form in which a reinforcing bar assembly assembled with a required cover thickness is placed. The beam end joints 10 are provided on both end surfaces of the beam member 2 in the beam longitudinal direction.

(Configuration of beam member 1A)
In addition to the configuration described in the first embodiment, the beam member 1A includes side surfaces (end surfaces) 31 of the columnar portions 25 of the beam member 1A, as shown in FIGS. 2(a) and 2(d). From the side surface 31, the lateral oblique reinforcements 32, 33 and the lateral bottom reinforcement (lateral bottom main reinforcement) 17 are arranged so as to protrude in the beam width direction to form the beam end joint 30. ing.

In this embodiment, two diagonal lateral reinforcing bars 32 are arranged horizontally in the beam width direction on the upper part of the beam, and protrude obliquely downward from the side surface 31 at an angle of about 45°. The overhang length of the lateral diagonal reinforcing bar 32 is secured to be 30 times the diameter d4 of the lateral diagonal reinforcing bar 32. - 特許庁

Two lateral oblique reinforcements 33 are arranged horizontally in the beam width direction at the lower part of the beam near the lateral bottom end reinforcement 17 and protrude obliquely upward from the side surface 31 by about 45°. The overhang length of the side diagonal reinforcing bar 33 is secured to be 30 times the diameter d5 of the side diagonal reinforcing bar 33 .

Five lateral bottom reinforcements 17 are arranged along the lower side of the beam, extend horizontally from the side surface 31 in the beam width direction, and have their tips bent upward in a substantially vertical direction to form a hook shape. there is The overhanging length of the lateral bottom reinforcement 17 is ensured to be 40 times the diameter d6 of the lateral bottom reinforcement 17 in the entire overhanging portion.

(Configuration of beam member 2)
As shown in FIGS. 2(c) and 2(e), the beam member 2 has diagonal reinforcing bars 15 and 16 and a bottom bar 17 extending along the length of the beam from an end face 14 of a beam cross section (rectangular beam cross section) consisting of a rectangular cross section. direction, forming a beam end joint 10 . The beam member 2 has the same configuration as the beam member 1B except that the column main reinforcement through-hole 22 and the column-shaped portion 25 are not provided.

<Composition 2 of joining structure>
A joint structure J2 of precast concrete beam members (half precast beam members) will be described with reference to FIGS. The joint structure J2 of half precast beam members is configured such that the beam end joint portion 30 of the beam member 1A and the beam end joint portion 10 of the beam member 2 are opposed to each other with a predetermined gap D2 therebetween. Between the beam members 1A and 2, the side oblique reinforcing bars 33 of the beam member 1A and the oblique reinforcing bars 16 of the beam member 2 form a lap joint and function as a member that transmits shear force. In addition, the side oblique reinforcing bars 32 of the beam member 1A and the oblique reinforcing bars 15 of the beam member 2 form a lapped joint to function as a member that transmits shear force. Further, the lateral bottom reinforcement 17 of the beam member 1A and the bottom reinforcement 17 of the beam member 2 form a lapped joint and function as one bottom reinforcement of the beam between the column members P1 and P3. Between the end faces 30 and 10 of the design beam cross section of the beam members 1A and 2 and at the upper end of the beam, it is integrated with the floor slab, has the same strength as the floor slab, and has a lower strength than the concrete strength of the beam members 1A and 2. Place-in-place concrete 13 is placed.

In the present embodiment, since the joint reinforcing bars, which are composed of the side oblique reinforcing bars 32 and the oblique reinforcing bars 16, and the side oblique reinforcing bars 33 and the oblique reinforcing bars 15, transmit the shear force, the beam members 1A and 2 The required strength of the cast-in-place concrete 13 between the beam end joints 30 and 10 is the same as that of the floor slab concrete directly above the beam members 1A and 2, and is lower than the concrete strength of the beam members 1A and 2. can. Therefore, the beam joints between the beam end joints 30 and 10 of the beam members 1A and 2, the beam joints, and a part of the floor slab can be simultaneously and integrally poured, so that the construction period can be shortened. It can contribute to labor saving. In addition, since the tip portions of the bottom reinforcement 17 and the side bottom reinforcement 17 are bent upward to form a hook shape, the predetermined distance D2 between the beam joints of the beam members 1A and 2 can be shortened. The amount of placing concrete 13 can be reduced.

<Joining method 2 of precast beam members>
Next, a method of joining the beam member 1A and the beam member 2 will be described with reference to FIGS. As shown in FIG. 6(a), beam members 1A are attached to column members P1 and P3 erected at predetermined positions on a slab plane of a predetermined floor so that the longitudinal directions of the beams are parallel to each other in a plan view. The column main reinforcements 23 of the members P1 and P3 are passed through the column main reinforcement through-holes 22 of the beam members 1A and 1A, and placed and joined to the building frame top ends 24 of the column members P1 and P3. At this time, the beam member 2 is supported by the pipe support 50, as shown in FIG.6(b).

Prior to placing the cast-in-place concrete 13, the top reinforcement 12, the stirrup reinforcement 11, and the floor slab (not shown) are arranged. After that, as shown in FIG. 6(c), between the beam end joints 30 and 10 of the beam members 1A and 2 (predetermined interval D2, beam joint) and at the upper and floor slab portions of the beam members 1A and 2 simultaneously. A cast-in-place concrete 13 having the same strength as the floor slab concrete and lower strength than the concrete strength of the beam members 1A and 2 is placed to form a joint structure J2 of half precast members.

[Modification]
In the above-described embodiment, the beam member has a straight precast concrete main body in plan view, but as shown in FIG. A substantially T-shaped beam member 4 may be used, and a substantially L-shaped beam member 5 or a substantially K-shaped beam member 6 may be used. Alternatively, it may be linear in a plan view, or may be one beam member 7 extending over a plurality (two) of column spans. The planar shape of the beam member can be changed according to the situation of the site, the carrying-in route, the position where the beam member is arranged, and the like. As a result, the number of beam members can be reduced, so that the number of operations for hanging the beam members can be reduced, and the number of beam joints can be reduced. Therefore, the construction period can be shortened and labor can be saved.

In addition, in the above-described embodiment, the beam member has one oblique reinforcing bar facing obliquely upward and one oblique reinforcing bar facing obliquely downward toward the end when viewed from the side. In a side view, the oblique reinforcing bars 15A and 15B facing diagonally downward toward the ends and the diagonal reinforcing bars 15A and 15B facing diagonally upward are arranged according to the strength, arrangement of reinforcing bars, and the length of predetermined intervals. It may be a beam member A (FIG. 8A) with an overhang, or a beam member having one diagonally upper part (diagonal reinforcing bar 15) and two diagonally lower parts (diagonal reinforcing bars 16A and 16B). B (FIG. 8(b)), or a beam member C (FIG. 8(c)) having only one diagonal reinforcing bar or only one diagonal reinforcing bar (FIG. 8(c)). is free. Also, the number of reinforcing bars in the beam width direction is not limited to the number shown in the above embodiment. The angle at which the reinforcing bars are bent is not limited to the angles shown in the above embodiments. For example, as shown in FIG. can be

The opening dimension S and the opening lap joint length LE are not limited to the numerical values in the above embodiment. It can be changed as appropriate according to the strength of reinforcing bars, the strength of concrete, and the like. In addition, the number and strength of rebars such as bottom rebars, oblique rebars, and lateral oblique rebars, beam width, beam length, etc., are appropriately determined according to the column span, design floor load, and the like.

In the above-described embodiments, the beam joints were provided near the center of the beam span or near the ends of the beam span in plan view, but the positions of the beam joints are not limited to these. The position of the beam joint in plan view can be changed according to plan restrictions, stress distribution, and the like.

Moreover, the shear strength may be improved by attaching a dowel, nut, or the like to the tip of the overhanging reinforcing bar.

Although half precast concrete beam members are used in the above-described embodiments, full precast concrete beam members may be used. Concrete that has the same strength as the floor slab concrete and is lower in strength than the concrete strength of the precast concrete beam members is simultaneously applied to the beam joint and part of the floor slab that is integrally arranged with the beam joint. It is good if it can be set.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of each claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

1, 1A, 1B, 2, 3, 4, 5, 6, 7, 8, A, B, C, D (Precast concrete) Beam member 10, 30 Beam end joint 11 Stirrup bar 12 Top bar 13 Cast-in-place Concrete 14 End faces 15, 16 Diagonal reinforcement 17 Bottom reinforcement, Lateral bottom reinforcement 18 Concrete 21 Stirrup reinforcement 22 Column main reinforcement through-hole 23 Column main reinforcement 24 Top end of frame 25 Column-shaped portion 31 Sides 32, 33 Side diagonal reinforcement J1 , J2 Joint structure P1, P2, P3, P4 Column member

Claims (7)

a first precast concrete beam member in which the first joint reinforcing bar and the first bottom bar extend from the cross section of the beam at at least one end in the longitudinal direction of the beam ;
a second precast concrete beam member in which the second joint reinforcing bar and the second lower end bar protrude from the cross section of the beam in the longitudinal direction of the beam;
with
The first joint reinforcement and the second joint reinforcement form a first opening lap joint, and the first bottom reinforcement and the second bottom reinforcement form a second opening lap joint. wherein a beam joint is constructed by the first lap joint and the second lap joint, and the beam joint and a floor slab part of which is integrally formed with the beam joint have the same strength and are made of cast-in-place concrete having a strength lower than that of the first and second precast concrete beam members. The joint structure of precast concrete beam members according to claim 1, wherein the first joint reinforcing bar and the second joint reinforcing bar are oblique reinforcing bars. The joint structure of precast concrete beam members according to claim 1 or 2, wherein the bottom reinforcement has a hook-shaped tip. The joint structure of precast concrete beam members according to any one of claims 1 to 3, wherein the beam joint portion is arranged near the center of the span of the beam. the beam joint is also located near a beam span end ,
Said first precast concrete beam member is further characterized in that said first joint reinforcing bar and said first bottom bar protrude from the side surface of said column portion of said first precast concrete beam member. Item 5. A joint structure of precast concrete beam members according to item 4 . The joint structure of precast concrete beam members according to any one of claims 1 to 5, wherein the first precast concrete beam member and the second precast concrete beam member are half precast concrete members. . A first precast concrete beam member in which a first joint reinforcing bar and a first bottom bar protrude from a beam cross section at at least one end in the beam longitudinal direction, and a second joint reinforcing bar and a second joint reinforcing bar in the beam longitudinal direction. A second precast concrete beam member whose bottom reinforcement extends from the cross section of the beam, the first joint reinforcing bar and the second joint reinforcing bar forming a first gap lap joint, The first precast concrete beam member and the second precast concrete beam member are arranged to form a beam joint such that the bottom reinforcement and the second bottom reinforcement form a second spaced lap joint. build and
Concrete having the same strength and lower strength than the concrete strength of the first and second precast concrete beam members for the beam joint and the floor slab part of which is integrally formed with the beam joint. A method for joining precast concrete beam members, characterized by placing a

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