Precast concrete beam-column joint structure

Abstract

To facilitate the reuse of precast members in a column-beam joint structure 11.SOLUTION: A precast concrete beam-column joint structure 11 includes a precast column member 12, a precast beam member 13 arranged opposite a side surface 12a of the precast column member 12, a filler 14 filled in a gap formed between the precast column member 12 and the precast beam member 13, and an unbonded tendon 15 that introduces prestress to the precast column member 12 and the precast beam member 13 so as to press the precast beam member 13 to the precast column member 12 via the filler 14. A release agent 25 is applied to at least one of a joint region 12c, which is a portion of the side surface 12a of the precast column member 12 that defines the gap, and an end surface 13a of the precast beam member 13.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a precast concrete beam-column joint structure that constitutes a beam-column structure made of precast members. [Background technology]

[0002] Precast concrete columns (hereafter referred to as PCa columns) and beams (hereafter referred to as PCa beams) are often used in the column-beam structures of rigid-frame buildings. These precast members are generally rigidly connected to each other using mechanical reinforcing bar joints and joint grout.

[0003] Patent Document 1 discloses a joint structure between a beam and a PCa column, in which a beam support jaw is integrally formed with the PCa column, and the PCa beam is supported at its beam end by the beam support jaw and erected between the columns. In this joint structure, a filler having a strength greater than that of the PCa column and the PCa beam is provided between the beam support jaw and the beam end, and the PCa beam is prestressed by PC steel wires and tension-fixed to the PCa column. In the event of a major earthquake, the edge between the filler and the PCa column or PCa beam breaks before the filler is destroyed, forming a hinge structure, and seismic energy is absorbed by the horizontal deformation of the building.

[0004] On the other hand, as a joint structure of precast concrete columns, an invention is known in which PCa columns are joined via grout by unbonded tendons, or via grout and PCa beams (Patent Document 2). In this column joint structure, a recess is formed on one joint surface of both adjacent PCa members, and grout is filled into the gap formed between the two PCa members. Tendon insertion holes are formed in both PCa members, and both through holes are partitioned from the gap by a cover material that covers the tendons and the nuts connecting them, and communicate with each other, and the tendons are placed there in an unbonded state. As a result, both PCa members become an unbonded prestressed concrete (unbonded PC) structure, and due to the restoring force of the tendons that can deform in the material axial direction, no deformation remains after an earthquake and they return to their original state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2909451 [Patent Document 2] JP 2021-156152 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional joint structures for PCa members, the precast members can be reused by removing the tendons and the filler during demolition. However, in conventional joint structures for PCa members, dismantling can be difficult because the filler is strongly bonded to one of the PCa members. When an earthquake occurs, the filler may peel off from one of the PCa members, but in this case, the filler remains bonded to the PCa member on the opposite side to the side where it peeled off, making it difficult to remove the filler from there.

[0007] In view of the above background, an object of the present invention is to facilitate the reuse of precast members in a column-beam joint structure using precast column members and precast beam members. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one aspect of the present invention is a precast concrete beam-column joint structure comprising a precast column member (12), a precast beam member (13) arranged opposite a side surface (12a) of the precast column member, a filler material (14) that is filled into a gap formed between the precast column member and the precast beam member, and an unbonded tendon (15) that introduces prestress into the precast column member and the precast beam member so as to press the precast beam member to the precast column member via the filler, and a release agent (25) is applied to at least one of a joint area (12c), which is a portion of the side surface of the precast column member that defines the gap, and an end face (13a) of the precast beam member.

[0009] Here, the release agent means a liquid that is applied to the concrete surface to form a film on the concrete surface and reduce the adhesive strength of the filler to the concrete. For example, the release agent may be a liquid that reduces the adhesive strength of the filler to the concrete by forming a film with lower adhesive strength to the concrete than the filler to the concrete. Alternatively, the release agent may be a liquid that reduces the adhesive strength of the filler to the concrete by forming a film with lower adhesive strength to the concrete than the filler to the concrete.

[0010] According to this aspect, the adhesive strength of the filler to at least one of the joint area of ​​the precast column member and the end face of the precast beam member is reduced, so that the filler can be easily removed from at least one of the precast column member and the precast beam member when dismantling the column-beam joint structure, thereby facilitating reuse of the precast member.

[0011] In the above aspect, it is preferable that no protrusions are provided in the joint area of ​​the precast column member and on the end surface of the precast beam member.

[0012] According to this aspect, it becomes easier to remove the filler from the precast column members and the precast beam members when dismantling the column-beam joint structure.

[0013] In the above aspect, it is preferable that no recess is provided in the joint area of ​​the precast column member and on the end face of the precast beam member.

[0014] According to this aspect, it becomes easier to remove the filler from the precast column members and the precast beam members when dismantling the column-beam joint structure.

[0015] In the above aspect, one of the joint area of ​​the precast column member and the end face of the precast beam member (e.g., end face 13a) may be roughened compared to the other (e.g., joint area 12c).

[0016] According to this embodiment, the adhesive strength of the filler to one side of the precast members is greater than the adhesive strength to the other side. Therefore, during an earthquake or demolition, the filler easily peels off from the other side of the precast members, while adhering to one side of the precast members. This prevents the filler from falling off. The filler adhering to the rough surface of the precast members can be removed with a weak force that does not damage the precast members, since the release agent is also applied to the rough surface.

[0017] In the above-mentioned aspect, the precast beam member (13) has beam widening portions (31) at both longitudinal ends which are wider than the longitudinal middle portion, the beam widening portions having shoulder surfaces (31a) facing the longitudinal middle portion, and the tension member is fixed to the shoulder surfaces of each beam widening portion of a pair of the precast beam members arranged on both sides of the precast column member by fixing devices (16).

[0018] According to this aspect, the length of the tendon is shortened, so that the cost of the tendon is reduced, and the installation and removal work of the tendon is easy. Also, damage to the end of the precast beam member during an earthquake is suppressed. Effect of the Invention

[0019] According to the above aspects, it is possible to facilitate reuse of PCa members in a column-beam joint structure using PCa columns and PCa beams. [Brief description of the drawings]

[0020] [Figure 1] A side view of a portion of a beam-column joint structure according to the first embodiment. [Diagram 2] Elevational section of the beam-column joint structure shown in Figure 1 [Diagram 3] Enlarged view of the main part of the beam-column joint structure shown in Figure 2 [Figure 4] A cross-sectional view taken along line IV-IV in FIG. [Diagram 5] An explanatory diagram of the behavior of the column-beam joint structure according to the first embodiment during an earthquake [Figure 6] A side view of a portion of a beam-column joint structure according to a second embodiment [Figure 7] Cross-sectional view taken along line VII-VII in Figure 6 [Figure 8] 11 is a side view of another portion of the beam-column joint structure according to the second embodiment; [Figure 9] Illustrative diagram of behavior of the column-beam joint structure according to the second embodiment during an earthquake DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to a precast concrete frame building made of reinforced concrete or steel-reinforced concrete.

[0022] First Embodiment First, a first embodiment of the present invention will be described with reference to Figs. 1 to 5. Fig. 1 is a side view of a portion of a column-beam joint structure 1 according to the first embodiment. As shown in Fig. 1, a column-beam joint structure 1 of a building 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, and support floors (not shown). The ends of the beams 3 are joined to the columns 2 by column-beam joint structures 11.

[0023] The column 2 includes at least one precast column member 12. The precast column member 12 is erected at a predetermined position above a lower column, foundation, etc. 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, foundation, etc. below by an unbonded tendon.

[0024] In this embodiment, the beam 3 is formed of one precast beam member 13. In another embodiment, the beam 3 may be formed of a plurality of precast beam members 13 arranged in series and connected by an appropriate means. 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 is formed between the end face 13a of the precast beam member 13 and the side face 12a of the precast column member 12 facing the end face 13a. The gap is filled with a filler material 14. After filling with the filler material 14, the precast beam member 13 has both ends joined to a pair of precast column members 12 and is hung across the pair of precast column members 12.

[0025] 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.

[0026] 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 formed on 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.

[0027] 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 12b 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.

[0028] 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 used as 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, and the precast members can be reused after the building is demolished.

[0029] Fig. 2 is an elevational sectional view of the beam-column joint structure 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 inserting the tendon 15 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.

[0030] Fig. 3 is an enlarged view of a main part of the beam-column joint structure 1 shown in Fig. 2. As shown in Fig. 3, a plurality of embedded anchors 22 may be provided in a portion of the precast column member 12 below the precast beam member 13. The embedded anchors 22 open screw holes in the outer surface of the precast column member 12 below the precast beam member 13. The embedded anchors 22 cooperate with the bolts B screwed into the screw holes to detachably hold the brackets 23.

[0031] 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.

[0032] 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 it easier to construct the column-beam joint.

[0033] As described above, the gap formed between the end of the precast beam member 13 and the precast column member 12 is filled with the filler 14. FIG. 4 is a plan sectional view taken along the line IV-IV in FIG. 3. As also shown in FIG. 4, an anti-adhesion material 24 is provided between the precast beam member 13 and the precast column member 12 to prevent the filler 14 from adhering to the tendon 15. 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 and communicates them. This prevents the filler 14 filled in the gap 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 and inserted into the beam-side through-hole 18 and the column-side through-hole 19.

[0034] By providing the adhesion prevention material 24 and leaving the tendons 15 in an unbonded state, the beam-column joint structure 11 becomes an unbonded prestressed concrete structure. This improves the recovery performance of the beam-column 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 beam-column joint structure 11. Furthermore, by reusing the precast members, CO2 emissions are reduced compared to constructing new members. 2 Environmental impacts such as emissions are reduced.

[0035] A release agent 25 is applied to the side surface 12a of the precast column member 12 that defines the gap (hereinafter, referred to as the joint region 12c of the precast column member 12) and the end surface 13a of the precast beam member 13 in order to suppress adhesion of the filler 14. The release agent 25 is applied to the concrete surface of these precast members, and suppresses adhesion of the filler 14 to the concrete surface by forming a thin film. The release agent 25 may be selected from those with appropriate components according to the filler 14. As such a release agent 25, there is one (for example, Lift Coat made by Knox Co., Ltd.) that is used in the match cast method in which precast concrete members (segments) are used as formwork to manufacture precast concrete products that are adjacently placed. Alternatively, a release agent that is applied to formwork to prevent adhesion of concrete may be used as the release agent 25. By applying the release agent 25 to the concrete surface of the precast member, the adhesive force of the filler 14 to the precast member is reduced.

[0036] The release agent 25 is applied to the entire surface (100% of the area) of the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13. In another embodiment, the release agent 25 may be applied to a part of the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13. This is because even if the release agent 25 is not applied to the entire surface of these faces, the adhesive strength reduction effect according to the application area is achieved. If the ratio of the application area of ​​the release agent 25 to the respective areas of the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13 is taken as the application ratio, the application ratio of each face is preferably 50% or more, more preferably 80% or more, even more preferably 90% or more, and most preferably 100%.

[0037] In addition, in order to suppress adhesion of the filler 14, in this embodiment, the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13 are formed by a single, generally flat surface. That is, no recess or protrusion constituting a shear key is formed on these surfaces. Here, the recess or protrusion constituting a shear key means a recess or protrusion having a depth or height of 1 cm or more. As shown in the enlarged view of FIG. 3, the joint area 12c of the precast column member 12 is a smooth surface. On the other hand, the end face 13a of the precast beam member 13 is a rough surface compared to the joint area 12c of the precast column member 12. As a result, the adhesive force of the filler 14 to the precast column member 12 is smaller than that to the precast beam member 13. In addition, the joint area 12c of the precast column member 12 does not have a beam support jaw for supporting the precast beam member 13 as disclosed in the prior patent document 1.

[0038] The rough surface may be formed by attaching a roughening sheet to the inner surface of a form used in manufacturing the precast member, or by using a form material whose form surface itself is rough. Alternatively, the precast member may be manufactured using a form having a smooth form surface, and after demolding, the rough surface may be formed by chipping, blasting, or the like.

[0039] The column-beam joint structure 11 for a building is configured as described above. Next, the action and effect of the column-beam joint structure 11 will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram of the behavior of the column-beam joint structure 11 according to the first embodiment during an earthquake, where (A) shows the column-beam joint structure 11 of the present invention and (B) shows a column-beam joint structure 111 of a comparative example.

[0040] In the beam-column joint structure 111 of the comparative example, the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13 are formed by a smooth single surface. On the other hand, the release agent 25 is not applied to the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13. Therefore, the filler 14 adheres to the precast column member 12 and the precast beam member 13 more strongly than in the present invention.

[0041] During an earthquake, a large bending moment occurs at the end of the beam due to the inertial force of lateral shaking. As shown in FIG. 5(B), in the column-beam joint structure 111 of the comparative example, the filler 14 is strongly bonded to the precast column member 12 and the precast beam member 13, so the filler 14 does not easily peel off from the precast members. Therefore, there is a risk that the end of the precast beam member 13 will be damaged. Alternatively, there is a risk that the concrete portion (the covering portion outside the reinforcing bar) forming the joint region 12c of the precast column member 12 and the end face 13a of the precast beam member 13 will peel off from the main body portion (the portion reinforced by the reinforcing bar) due to being pulled by the filler 14. Any of these damages will hinder the reuse of the precast members.

[0042] In contrast, in the beam-column joint structure 11 of the present invention, as shown in FIG. 5(A), since the release agent 25 is applied to the joint area 12c of the precast column member 12, the filler 14 is easily peeled off from the precast column member 12. Therefore, damage to the end of the precast beam member 13 during an earthquake is suppressed. In addition, since the end surface 13a of the precast beam member 13 is roughened, the filler 14 remains adhered to the precast beam member 13 even after peeling off from the precast column member 12. Therefore, the filler 14 is prevented from falling from the joint. In addition, when the beam-column joint structure 1 is dismantled, since the release agent 25 is applied to the end surface 13a of the precast beam member 13, the precast beam member 13 can be removed with a weak force that does not damage the precast beam member 13, even if the end surface 13a is rough. Therefore, the precast column member 12 and the precast beam member 13 can be easily reused.

[0043] In addition, no projections or recesses constituting a shear key are provided on the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13. Therefore, it is easier to remove the filler 14 from the precast column member 12 and the precast beam member 13 when dismantling the column-beam joint structure 1.

[0044] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figs. 6 to 9. The same or similar components as those in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted. 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. Details are as follows.

[0045] Fig. 6 is a side view of a portion of a beam-column joint structure 1 according to the second embodiment. As shown in Fig. 6, the precast beam member 13 has beam widening portions 31 at both ends that are wider than the intermediate portion in the longitudinal direction. The beam widening portions 31 form shoulder surfaces 31a that engage the fasteners 16 on the side opposite to the end surface 13a of the precast beam member 13. The tensioned state of the tension member 15 is maintained by fixing both ends of the tension member 15 to the fasteners 16 engaged with the shoulder surfaces 31a of the precast beam member 13 and the fasteners 16 engaged with the outer surface 12b of the precast column member 12.

[0046] Fig. 7 is a plan cross-sectional view taken along line VII-VII in Fig. 6. As shown in Fig. 7, shoulder surfaces 31a are formed on both sides in the width direction in the cross section of the precast beam member 13. As a result, the end surface 13a of the precast beam member 13 is joined to the corresponding joining area 12c of the precast column member 12 with uniform pressure.

[0047] Fig. 8 is a side view of another part of the beam-column joint structure 1 according to the second embodiment. As shown in Fig. 8, two precast beam members 13 are arranged on both sides of a precast column member 12, and each precast beam member 13 is pressure-joined to the corresponding side surface 12a of the precast column member 12. The beam widening portion 31 of each precast beam member 13 has a shoulder surface 31a facing the longitudinal middle portion of each precast beam member 13. The tendons 15 are fixed by fixing devices 16 to the shoulder surfaces 31a of each beam widening portion 31 of a pair of precast beam members 13 arranged on both sides of the precast column member 12.

[0048] 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 those of the first embodiment can be achieved. Moreover, in this embodiment, the length of the tendons 15 is shorter than that of the first embodiment, so that the cost of the tendons 15 is reduced and the work of placing and removing them is easy.

[0049] Fig. 9 is an explanatory diagram corresponding to Fig. 5, showing the behavior of the column-beam joint structure 11 according to the second embodiment during an earthquake. Fig. 9(A) shows the column-beam joint structure 11 of the present invention, and Fig. 9(B) shows a column-beam joint structure 111 of a comparative example.

[0050] In the beam-column joint structure 111 of the comparative example, the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13 are formed by a smooth single surface. On the other hand, the release agent 25 is not applied to the joint area 12c of the precast column member 12 and the end face 13a of the precast beam member 13. Therefore, the filler 14 adheres to the precast column member 12 and the precast beam member 13 more strongly than in the present invention.

[0051] During an earthquake, a large bending moment occurs at the beam end due to the inertial force of lateral shaking. As shown in FIG. 9(B), in the column-beam joint structure 111 of the comparative example, the filler 14 is strongly bonded to the precast column member 12 and the precast beam member 13, so the filler 14 does not easily peel off from the precast members. Therefore, there is a risk that the end of the precast beam member 13, specifically the end of the middle part in the longitudinal direction of the precast beam member 13 (the part in the vicinity of the beam widening part 31) and the end of the beam widening part 31, may be damaged. Alternatively, there is a risk that the concrete part (the covering part outside the reinforcing bar) forming the joint region 12c of the precast column member 12 and the end face 13a of the precast beam member 13 may peel off from the main body part (the part reinforced by the reinforcing bar) due to being pulled by the filler 14. Any of these damages will hinder the reuse of the precast members.

[0052] In contrast, in the beam-column joint structure 11 of the present invention, as shown in FIG. 9(A), the release agent 25 is applied to the joint area 12c of the precast column member 12, so that the filler 14 is easily peeled off from the precast column member 12. Therefore, damage to the end of the precast beam member 13 during an earthquake is suppressed. In addition, since the end surface 13a of the precast beam member 13 is roughened, the filler 14 remains adhered to the precast beam member 13 even after peeling off from the precast column member 12. Therefore, the filler 14 is prevented from falling from the joint. In addition, when the beam-column joint structure 1 is dismantled, even if the end surface 13a of the precast beam member 13 is roughened, the release agent 25 is applied to the precast beam member 13, so that the precast beam member 13 can be removed with a weak force that does not damage the precast beam member 13. Therefore, the precast column member 12 and the precast beam member 13 can be easily reused.

[0053] In addition, in this embodiment, the length of the tendon 15 is shortened, which reduces the cost of the tendon 15 and makes it easier to install and remove it.

[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, in the above embodiment, the end surface 13a of the precast beam member 13 is roughened, but instead or in addition, the joint area 12c of the precast column member 12 may be roughened. In addition, both the end surface 13a and the joint area 12c may be smooth. Alternatively, a recess or protrusion constituting a shear key may be formed on the end surface 13a and the joint area 12c. In the above embodiment, the release agent 25 is applied to both the joint area 12c of the precast column member 12 and the end surface 13a of the precast beam member 13, but the release agent 25 may be applied to only one of these surfaces. Furthermore, the specific configuration, arrangement, quantity, material, procedure, etc. of each member or part can be appropriately changed as long as it does not deviate from the gist 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] 1: Column-beam joint structure 2: Pillar 3:Beam 11: Column beam joint structure 12: Precast column members 12a: Side 12c: Junction area 13: Precast beam members 13a: End face 14: Filling material 15: Tensile material 16: Fixture 25: Stripping agent 31: Beam widening section 31a: Shoulder surface

Claims

1. A precast concrete beam-column joint structure, A precast column member; A precast beam member arranged opposite a side surface of the precast column member; A filler material is filled into a gap formed between the precast column member and the precast beam member; and an unbonded tendon that applies prestress to the precast column member and the precast beam member so as to press the precast beam member to the precast column member via the filler. A column-beam joint structure, in which a release agent is applied to at least one of a joint area, which is a portion of the side surface of the precast column member that defines the gap, and an end face of the precast beam member.

2. The column-beam joint structure according to claim 1 , wherein no protrusions are provided in the joint area of ​​the precast column member and on the end surface of the precast beam member.

3. The column-beam joint structure according to claim 1 , wherein no recess is provided in the joint area of ​​the precast column member and in the end face of the precast beam member.

4. A column-beam joint structure according to any one of claims 1 to 3, wherein one of the joint area of ​​the precast column member and the end face of the precast beam member is made a rough surface compared to the other.

5. The precast beam member has a beam widening portion at both ends in the longitudinal direction, the beam widening portion being wider than a middle portion in the longitudinal direction, and the beam widening portion has a shoulder surface facing the middle portion in the longitudinal direction, A column-beam joint structure described in any one of claims 1 to 3, wherein the tension member is fixed by a fixing device to the shoulder surface of each beam widening portion of a pair of precast beam members arranged on both sides of the precast column member.

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