JP5204732B2 - Column / beam joint structure - Google Patents

Description

  The present invention relates to a column / beam joint structure when joining columns and beams constructed of reinforced concrete.

  Conventionally, in reinforced concrete structures in which columns and beams are constructed of reinforced concrete, the arrangement of reinforcing bars is overcrowded at the joint where the columns and beams intersect, so various structures have been developed to avoid it (patents) (Refer to Literatures 1 and 2).

  In other words, in the conventional joint structure, the end of the beam main bar, which is the main reinforcing bar of the beam, is bent and fixed inside the column main bar, which is the main reinforcing bar of the column, so the reinforcing bars are concentrated at the column / beam joint. It was.

  In addition, since the tip of the column main bar is bent in a U shape to form a hook portion, the bar arrangement becomes complicated, and rebar processing and assembly with extremely high accuracy are required.

  On the other hand, Patent Document 3 discloses an invention in which an overcrowded arrangement state inside a column main bar is eliminated by embedding a fixing part of the beam main bar in a protruding beam part that protrudes on the opposite side of the beam.

Japanese Patent Laid-Open No. 10-30273 JP 2001-214512 A JP 2008-88636 A

  Here, the conventional joint structure in which the ends of all beam main bars are fixed to the inside of the column main bars, the joints are in an overcrowded state, and if a large external force acts from the side due to an earthquake, etc. It has been clarified by experiments by the inventors that the concrete at the upper end of the column on the side peels off and the fixing power of the column main bars arranged on the outermost side decreases.

  When the peeling portion is generated in this manner and the fixing strength of the column main bar or the beam main bar on the opposite side of the beam is reduced, the joint portion may be broken, and the proof stress of the concrete structure may be rapidly reduced and collapsed.

  For example, in the case of a railway ramen structure, when an excessive lateral force is applied, the column first yields, and then the beam is yielded by the force transmitted from the joint. However, if the joint is destroyed first, the premise is broken, and there is a risk of unexpected destruction.

  Therefore, an object of the present invention is to provide a column / beam joint structure in which the fixing force of the main reinforcing bar at the joint is unlikely to decrease even when an external force more than designed is applied due to a large earthquake or the like.

  In order to achieve the above object, the column / beam junction structure of the present invention is a column / beam junction structure in which a column and a beam mainly formed of reinforcing steel and concrete are joined to each other. Among the beam main bars that serve as reinforcing bars, the upper beam main bars arranged on the upper edge side of the beam are extended through the column main bars that serve as the main reinforcing bars of the columns, and the upper beam main bars are bent and more bent than the column main bars. A fixing portion for fixing on the opposite side of the beam is formed, and the fixing portion is embedded in a protruding beam portion that protrudes on the opposite side of the beam, and the main reinforcing bar of the beam is below the beam. The lower beam main bar to be arranged is bent and the fixing portion is embedded inside the column main bar.

  Here, an enlarged portion having an outer shape larger than that of the shaft portion can be provided at the tip of the column main reinforcement to form a fixing portion.

  In addition, a reinforcing material having leg portions formed on both sides of the trunk portion in a substantially U shape in plan view, the leg portions on both sides are outside the column main bars, and the trunk section is outside the fixing portion of the upper beam main bars. Can be arranged.

  The column / beam connection structure of the present invention thus configured is provided with a protruding beam portion protruding on the opposite side of the beam, and the fixing portion of the upper beam main bar of the beam main bars is embedded in the protruding beam portion. The On the other hand, the anchoring portion of the lower beam main bar among the beam main bars is embedded inside the column main bar.

  That is, the region of the joint portion is widened by the protruding beam portion, and the fixing portion of the upper beam main bar does not need to be provided inside the column main bar, so that an overcrowded state of the bar arrangement of the joint portion is reduced.

  And the anchoring part of the lower beam main reinforcement is buried inside the main part of the column main reinforcement with a large restraining force, so that a high fixing force is secured and the joint with the beam is not destroyed first. It is possible to prevent a decrease in the fixing force of the main reinforcing bar at the joint when an external force greater than the design force is applied. Further, since the column main reinforcement can sufficiently secure the covering of the concrete by the protruding beam portion, the restraining effect is improved and the fixing force of the column main reinforcement can be prevented from being lowered.

  In addition, by making the tip of the column main bar an enlarged part having a larger outer shape than the shaft part, the structure of the fixing part of the column main bar can be simplified as compared with the case where it is fixed by the hook part, and the bar arrangement is easy. As a result, the over-density of the reinforcing bars in the joint can be reduced.

  Further, by surrounding the fixing portion of the upper beam main bar and the outside of the column main bar with a substantially U-shaped reinforcing material in plan view, the binding force of the fixing unit and the column main bar increases, and as a result, the upper beam main bar and the column main bar are fixed. It can prevent power loss.

It is the elevation sectional view showing the composition of the connection structure of the pillar and beam of an embodiment of the invention. It is a cross-sectional view explaining the schematic structure of a ramen viaduct. It is sectional drawing of the AA line direction of FIG. It is sectional drawing of the BB line direction of FIG. It is a figure which shows the experimental result performed in order to confirm the performance of the junction structure of a pillar and a beam, Comprising: (a) is a displacement-load relationship figure of the junction structure of the pillar and beam of embodiment of this invention, (b) ) Is a displacement-load relationship diagram when all anchor portions of beam main bars are embedded inside the column main bars without providing protruding beam portions, and (c) is all anchor portions of beam main bars embedded in protruding beam portions. It is a displacement-load relationship figure in the case.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram showing a schematic configuration of the rigid frame viaduct 1 as a reinforced concrete structure provided with the column / beam joint structure of the present embodiment.

  First, in terms of configuration, this ramen viaduct 1 is constructed such that columns 2 and 2 are erected on a base portion 6 buried in the ground at intervals in the width direction, and between the upper ends of the columns 2 and 2. Are connected by a beam 3.

  This foundation part 6 is mainly comprised by the pile parts 61 and 61 constructed | assembled, for example by the cast-in-place concrete, and the rectangular parallelepiped footing part 62 which connects between the pile heads.

  Also, a plurality of columns 2 and 2 are arranged at intervals also in the direction orthogonal to the paper surface of FIG. 2, and the columns 2 and 2 are connected by vertical beams 4 and 4 and are vertically connected to the beams 3. A slab portion 5 is constructed on the upper surface of the beams 4. In this slab portion 5, a track is laid or a road for an automobile is constructed, and wall portions 51, 51 such as soundproof walls are constructed at both edges in the width direction.

  The column / beam joint structure of the present embodiment refers to a corner where the column 2 and the beam 3 are substantially orthogonal, and an enlarged cross-sectional view thereof is shown in FIG.

  The column 2 and the beam 3 are mainly formed of reinforced concrete, and the column 2 is provided with column main bars 21,. Reinforcing bars are arranged.

  Here, the main reinforcing bar refers to a reinforcing bar whose cross-sectional area is calculated in order to resist bending moment, shearing force, axial force and the like generated in the member by a design load in a reinforced concrete member.

  Further, the column 2 includes a plurality of column main bars so as to surround the inner periphery of the column 2 as shown in FIG. 3 which is a section taken along line AA in FIG. 1 and FIG. 4 which is a section taken along line BB in FIG. Are disposed, and band bars 22 bent in a square in plan view so as to surround the outer periphery of the columnar main bars 21 are disposed.

  Further, an enlarged portion 21 a having an outer shape larger than that of the shaft portion 21 b is formed as a fixing portion of the column main reinforcement 21 at the tip of the column main reinforcement 21.

  The enlarged portion 21a is a diameter-enlarged portion provided with a disk having a diameter larger than the diameter of the shaft portion 21b having a substantially circular cross-sectional view. The enlarged portion 21a is not limited to a circular shape in plan view, and may be a plate material having a polygonal shape in plan view such as a rectangle, a square, or a hexagon.

  Further, on the upper edge side and the lower edge side of the beam 3, a plurality of upper beam main bars 32 and lower beam main bars 30 as main bars are arranged, and abdominal reinforcing bars 34 and stirrups 35 are arranged. As shown in FIG. 3, the longitudinal beam 4 is also provided with a longitudinal beam main bar 41 and a stirrup 42 which are main reinforcing bars.

  As shown in FIG. 1, the upper beam main bar 32 extends not only through the column main bar 21 on the beam side but also through the column main bar 21 on the opposite side of the beam. The upper beam main bar 32 is bent in the middle to form a fixing portion 32a facing in a direction substantially orthogonal to the beam extending direction. That is, the upper beam main bar 32 is formed with a fixing portion 32a having a tip suspended.

  As shown in FIGS. 1 and 4, the fixing portion 32 a of the upper beam main bar 32 formed in this way is embedded in the protruding beam portion 31 protruding from the corner portion where the column 2 and the beam 3 are substantially orthogonal to each other to the opposite side of the beam. Is done.

  The protruding beam portion 31 protrudes outward from the side surface opposite to the beam of the column 2 and has a height substantially the same as that of the beam 3 as shown in FIG. 1 and its width as shown in FIG. Are formed to have substantially the same width as the pillar 2.

  On the other hand, as shown in FIG. 1, the lower beam main bar 30 is extended through the beam side column main bar 21, and then bent in the middle to face the direction substantially orthogonal to the beam extension direction. 30a is formed. That is, the lower beam main reinforcing bar 30 is formed with a fixing portion 30 a having a standing end.

  The fixing portion 30a of the lower beam main bar 30 formed in this way is embedded inside the joint surrounded by the column main bars 21, as shown in FIGS.

  Further, in the present embodiment, as shown in FIGS. 1, 3, and 4, the column main bars 21 on the vertical beam 4 side, and the fixing portions 32a of the upper beam main bars 32,. A plurality of reinforcing members 33 having a U-shape in a plan view are arranged at intervals in the vertical direction so as to surround from the outside.

  As shown in FIGS. 3 and 4, the reinforcing member 33 has leg portions 33a and 33a formed substantially orthogonal to both sides of the body portion 33b so that the body portion 33b contacts the fixing portions 32a,. It arrange | positions so that the leg parts 33a and 33a may contact | abut to the column main reinforcements 21 and ... by the side of the vertical beams 4 and 4, respectively.

  Further, as shown in FIG. 1, a slab reinforcing bar 5 a is arranged on the beam 3 and the column / beam junction, and the slab part 5 and the wall part 51 are constructed.

  Next, the operation of the column / beam joint structure of the present embodiment will be described.

  The column / beam joint structure of the present embodiment configured as described above is provided with a protruding beam portion 31 that protrudes outward from the side surface of the column 2 opposite to the beam 3, and the upper beam main bar is provided on the protruding beam portion 31. Thirty-two fixing portions 32a are embedded. On the other hand, the fixing portion 30a of the lower beam main reinforcing bar 30 is embedded inside the column main reinforcing bars 21,.

  For this reason, the area | region of a junction part becomes wide by the part which provided the protrusion beam part 31, and the overcrowding state of a bar arrangement is reduced. That is, in the conventional column / beam joint structure without the protruding beam portion 31, the fixing portion of the upper beam main bar and the lower beam main bar is embedded inside the column main bar, as in the present embodiment. By providing the protruding beam portion 31 on the upper side, the fixing portion 32 a of the upper beam main bar 32 can be embedded outside the column main bar 21.

  As a result, the overcrowding state of the reinforcing bars inside the column main bars 21,... Is eased, and the arrangement of the bars becomes easy. In addition, the concrete is sufficiently filled around the column main bars 21,. To increase.

  On the other hand, since the fixing portion 30a of the lower beam main reinforcing bar 30 is embedded inside the column main reinforcing bars 21,..., The restraining force on the fixing portion 30a is increased and a high fixing force is secured.

  Here, FIG. 5 shows the results of an experiment conducted to confirm the performance of the column / beam joint structure of the present embodiment. In the experiment, in addition to the column / beam joint structure of the present embodiment (FIG. 5A), for the purpose of comparison, all anchor portions of the beam main bars are embedded inside the column main bars without providing protruding beam portions. This was also the case (FIG. 5 (b)) and the case where all anchor portions of the beam main reinforcement were embedded in the protruding beam portion (FIG. 5 (c)).

  In the experiment, horizontal positive / negative alternating loading was repeated at the lower part of the column 2, the horizontal displacement of the loading point (column horizontal displacement) and the horizontal load at that time were measured, and the damage process and the final fracture state of the joint were observed. Here, the experimental values in FIG. 5 are measured values of this experiment, and the calculated values are “Railway Structure Design Standards / Explanation Seismic Design, October 1999” published by the Railway Technical Research Institute. It shows the proof stress required for the pillars calculated according to.

  First, the experimental results of the conventional joint structure without the protruding beam portion 31 in FIG. 5B will be described. In this conventional joint structure, the calculated maximum proof stress could not be reached in negative direction loading. This is thought to be due to the fact that the concrete on the opposite side of the beam at the top of the column peeled off during loading, and the fixing strength of the column main reinforcement was reduced.

  Further, in the experimental result of the joint structure in which the fixed portion of the upper beam main bar and the lower beam main bar is embedded in the protruding beam part 31 of FIG. 5C, the calculated maximum proof stress is exceeded in the forward loading. During the negative loading, destruction occurred, and it was not possible to load until the end.

  On the other hand, in the experimental results of the column / beam joint structure of the present embodiment in FIG. 5A, the calculated maximum proof stress without causing damage such that the protruding beam 31 is peeled off from the joint. We were able to perform loading that satisfied

  In this way, the fixing portion 32a of the upper beam main bar 32 is embedded in the protruding beam portion 31, and the fixing portion 30a of the lower beam main bar 30 is embedded inside the column main bars 21,. The column / beam joint structure can achieve the expected failure pattern in which the column first yields, and then the beam yields due to the force transmitted from the joint. It is possible to prevent a decrease in the fixing force of the column main reinforcing bars 21 at the time of acting. Note that the column / beam joint structure of the present embodiment is characterized in that the joint does not break first, so the beam first yields, and then the column is created by the force transmitted from the joint. The effect can be obtained even in the reverse destruction pattern of yielding.

  Further, since the protruding beam portion 31 is formed so as to protrude from the column main reinforcement 21 toward the beam opposite side, the concrete cover of the column main reinforcement 21 at the joint portion is thick. For this reason, the adhesion between the reinforcing bar and the concrete can be sufficiently secured, and the side surface opposite to the beam of the column main bar 21 is protected by the fixing portion 32a of the upper beam main bar 32. Therefore, the restraining effect is improved, and the reinforcing bar The fixing power of is difficult to decrease.

  In addition, by making the tip of the column main reinforcement 21 an enlarged portion 21a having an outer shape larger than that of the shaft portion 21b, the configuration of the fixing portion can be simplified as compared with the case of fixing by the hook portion, and the arrangement of the bars is easy. As a result, the overdensity of the reinforcing bars can be further reduced.

  Further, by surrounding the fixing portions 32a,... Of the upper beam main bars 32,... And the column main bars 21,. -And the deformation | transformation of the column main reinforcement 21, ... will be restrained by the reinforcing material 33.

  When the deformation of the column main bar 21 and the fixing portion 32a is suppressed in this way, the progress of destruction of the concrete is suppressed, and as a result, the fixing force of the upper beam main bar 32, the lower beam main bar 30, and the column main bar 21 is reduced. Can be prevented.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the above-described embodiment, the case where the tip of the columnar reinforcement 21 is the enlarged portion 21a has been described. However, the present invention is not limited to this, and the tip of the reinforcing bar may be processed into a hook shape.

  In the above embodiment, the upper beam main bar 32 and the lower beam main bar 30 are bent at substantially right angles to form the fixing portions 32a and 30a. It can be formed into a hook shape as a fixing portion, or an enlarged portion having an outer diameter larger than that of the shaft portion can be provided as a fixing portion.

  Furthermore, in the said embodiment, although the ramen structure was demonstrated to the example, it is not limited to this, As long as it is a structure which joins the column and beam which used the reinforcing bar and concrete, what kind of form The present invention can also be applied to those. Further, the present invention can be applied to a structure using other structural materials in addition to the reinforcing bars and concrete, such as a steel reinforced concrete structure.

2 pillar 21 pillar main reinforcement (main reinforcement)
21a Enlarged part 21b Shaft part 3 Beam 30 Lower beam main bar (beam main bar, main reinforcing bar)
30a Fixing part 31 Projecting beam part 32 Upper beam main bar (beam main bar, main reinforcing bar)
32a Fixing part 33 Reinforcing material 33a Leg part 33b Body part

Claims (3)

It is a column / beam joint structure that joins a column and a beam mainly formed by reinforcing bars and concrete,
Among the beam reinforcements that serve as the main reinforcement of the beam, the upper beam reinforcement that is arranged on the upper edge side of the beam extends through the column reinforcement that serves as the main reinforcement of the column, and the upper beam reinforcement is bent to Form a fixing part for fixing to the opposite side of the beam from the column main reinforcement, and embed the fixing part in the protruding beam part protruding to the opposite side of the beam,
Of the beam main reinforcing bars that serve as the main reinforcing bars of the beam, the lower beam main reinforcing bar arranged on the lower side of the beam is bent and the fixing portion is embedded inside the column main reinforcing bar. Junction structure.   The column / beam joint structure according to claim 1, wherein an enlarged portion having an outer shape larger than a shaft portion is provided at a tip of the column main reinforcement.   A reinforcing material having leg portions formed on both sides of the trunk portion in a substantially U shape in plan view, the leg portions on both sides are arranged outside the column main bars, and the trunk section is arranged outside the fixing portion of the upper beam main bars. 3. The column / beam joint structure according to claim 1 or 2, wherein the column / beam junction structure is configured as described above.

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