JP2014136887A - Structure of junction of rc frame and brace, and rc frame attached with brace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of the junction of RC frames and braces as well as an RC frame attached with a brace, which ensure the sufficient secureness and the easy fitting of gusset plates of braces.SOLUTION: An RC frame 4 consisting of a column 1 and a beam 2 is attached with a brace 3 connected to a brace gusset plate 5 fitted at a beam-column junction of the RC frame 4. The brace gusset plate 5 consists of a gusset plate body 6 projected at the internal angle part of the beam-column junction, a plurality of implantation plates 7 embedded in the end parts of both the column 1 and the beam 2 near the beam-column junction, and a plurality of protrusion 8. The plurality of implantation plates 7 are embedded in parallel to the structure plane of the RC frame 4. The plurality of protrusions 8, being projected from the plurality of implantation plates 7, are buried pointing outwards from the structure plane of the RC frame 4. Orthogonal plates 9 are fitted to the inner faces of the column 1 and the beam 2 roughly perpendicularly to the structure plane of the RC frame 4.

Description

  The present invention relates to a joint structure between an RC frame composed of columns and beams made of reinforced concrete (hereinafter abbreviated as “RC”) and a brace incorporated in the RC frame, and an RC frame with a brace provided with the joint structure. In particular, it is applied to an RC frame with a brace consisting mainly of an RC frame and a metal brace such as a steel frame. I will provide a.

  Conventionally, in an RC structure having an RC frame composed of RC columns and beams, an RC wall is integrally installed inside the RC frame composed of columns and beams in order to improve seismic performance. Was common.

  However, this method is not easily restricted in terms of function as a building from the viewpoint of securing entrance / exit, lighting, or ventilation, and if an opening is provided in the wall, the performance as an original earthquake-resistant wall is degraded. There was a problem.

  As a countermeasure against this problem, it is conceivable to incorporate a steel member as a brace instead of the RC wall. In fact, as a seismic reinforcement method for existing RC structures, a brace with a steel frame is installed inside an RC frame composed of RC columns and beams, and the steel frame is attached to the surrounding RC frame with a headed stud or spiral. A method of fixing with a reinforcing bar or the like is widely used (Patent Document 1).

  However, this method has a problem that it takes time to join the steel frame and the RC frame, and it is premised on seismic reinforcement of the existing RC structure.

  By the way, as a conventional technique for installing a brace without using a steel frame, as shown in FIG. 11, the head is formed on the inner surface of the end portion of the column 20 and the beam 21 of the RC frame easily conceived by Non-Patent Document 1. There is a method of fixing the bracing gusset plate 23 using the stud 22 with a hook.

  Further, in Non-Patent Document 2, as shown in FIG. 12, as shown in FIG. 12, an experiment result on a method of extending a bracing gusset plate 23 to the inside of a column beam joint and fixing it with a cross steel plate 24 or a stud (not shown). Has been reported.

  Further, Patent Document 2 discloses that a column steel member is embedded in the concrete of the column beam joint.

JP-A-9-279695 JP 2005-36598 A Patent No. 4665232

Architectural Institute of Japan “Synthetic structural design guidelines and explanation” 2010.11 Sumitomo Mitsui Construction Engineering Laboratory Report No. 2, 2004, p.129-134

  However, in the method shown in FIG. 11, the headed stud 22 is embedded in the surface of the column 20 and the beam 21 in parallel with the surface of the RC frame composed of the column 20 and the beam 21. If the bending crack 25 is generated in the concrete at the end of the column 20 or the beam 21 in the vicinity of the beam joint, the fixing performance of the fixing unit may be deteriorated because it substantially coincides with the axial direction of the headed stud 22. If the fixing performance is lowered, the bracing ability cannot be fully exhibited.

  On the other hand, in the method as shown in FIG. 12, the fixing performance of the bracing gusset plate 23 can be ensured, but in the column beam joint portion where the main bars, the hoop bars, and the ribs of the columns 20 and 21 cross each other. Since the bracing gusset plate 23 is inserted, it is difficult to place the gusset plate 23, and it is difficult to actually construct the gusset plate 23, and the filling property of the concrete is also adversely affected.

  The same can be said for Patent Document 2.

  The present invention has been made in order to solve the above-described problems. Even if the RC frame is deformed to some extent and cracks occur in the concrete, the columns and the ends of the beams in the vicinity of the beam-to-column joints are reinforced. RC with high energy absorption performance by applying a brace joint that can secure the fixing performance of the gusset plate for use and is easy to fix, and such a brace joint to a damper such as a buckling restraint brace. An object of the present invention is to provide a joint structure between a frame and a brace and an RC frame with brace.

  The present invention relates to an RC frame composed of columns and beams, and a gusset plate for bracing at a joint between the RC frame and the brace that is joined to the column beam joint of the RC frame via a brace gusset plate. Is a gusset plate body projecting at the corner of the beam-column joint, a plurality of embedded plates embedded in the column and beam ends in the vicinity of the beam-column joint, and projecting from the embedded plate. A plurality of protrusions, the plurality of embedded plates being embedded substantially parallel to the surface of the RC frame, and the plurality of protrusions protruding from the embedded plate in an out-of-plane direction of the surface of the RC frame. It is possible to remarkably improve the fixing performance of the RC frame bracing joint.

  Thereby, as a means for realizing a braced RC frame with high energy absorption performance, a damper with high energy absorption performance such as a buckling restrained brace can be incorporated as a brace.

  In addition, by using a buckling-restrained brace (Patent Document 3) that can set the initial stiffness suitable for the RC frame as a brace, it is possible to achieve a vibration-damping structure that has higher performance than an RC frame that cracks from a small deformation. It becomes possible.

  Note that studs, bolts, reinforcing bars, and the like can be used for the plurality of protrusions, but rib-like protrusions may be used instead.

  Since the present invention is based on the above-described means, it has the following effects.

 (1) Since it is easy to install a braid rather than a seismic wall on the RC frame, it is possible to reduce restrictions on the functional aspects of the building, such as securing an effective opening for entrances, lighting, and ventilation.

 (2) Since it is possible to attach a brace to the RC frame without using a frame material, it is advantageous in terms of ease of construction on site and economical aspects.

 (3) Since the fixing stability performance of the fixing part of the gusset plate for the brace is high, the stress transmission to the brace can be ensured even if the deformation of the RC frame becomes large, and the brace performance can be fully exhibited. It becomes possible.

 (4) Since the proof strength of RC frame with bracing is a simple addition of RC framing strength and bracing strength, it is easy to evaluate the proof strength.

 (5) Due to the presence of the present invention, the ends of the columns and beams are in a state close to a rigid region, so that the deterioration in yield strength during large deformation of the RC frame is alleviated.

 (6) Due to the effects (3) to (5) above, using a damper such as a buckling-restrained brace suitable for the RC frame for the brace, higher-performance vibration control of the RC frame causing cracks from small deformations Structure becomes easy.

 (7) In the above (6), by using a buckling-restrained brace suitable for the RC frame shown in Patent Document 3, it is possible to achieve a higher-performance vibration damping structure of the RC frame that cracks from a small deformation. It becomes possible.

It is a perspective view of RC frame at the time of applying the present invention. It is a perspective view which shows the junction part with the brace of RC frame by this invention. It is a side view which shows the junction part with the brace of RC frame by this invention. It is a side view which shows the junction part with the brace of RC frame by this invention. It is a general view of the test body of the experiment which confirmed the performance of the junction part by this invention. It is explanatory drawing of a buckling restraint brace. It is a figure which shows the force application apparatus of the state which set the test body. (a), (b) is a horizontal load-interlayer displacement relationship figure of a test body. It is the figure which displayed the horizontal load-interlayer displacement relationship of the test body to interlayer displacement +/- 20mm with the skeleton (skeleton curve). (a), (b) is a figure which shows the crack state of a test body when an interlayer deformation angle is about ± 1/100. It is a figure which shows the prior art example of the junction part of RC frame and a brace. It is a figure which shows the prior art example of the junction part of RC frame and a brace.

  1 to 4 show an embodiment of the present invention, and FIG. 1 shows an RC frame 4 constituted by RC pillars 1 and beams 2 and incorporating a metal brace 3. It is a perspective view.

  2, 3, and 4 show the joint portion of the RC frame 4 with the brace 3, and FIGS. 2 and 3 show the brace joint portion that joins the upper end side of the brace 3 (hereinafter referred to as “the brace joint portion A”). 2) is a perspective view thereof, and FIG. 3 is a side view thereof. 4 is a side view showing a brace joint portion (hereinafter referred to as a brace joint portion B) that joins the lower end side of the brace 3. FIG.

  In the figure, a brace gusset plate 5 is attached to the brace joint A and brace joint B, respectively.

  The bracing gusset plate 5 includes a gusset plate body 6 projecting at the corner (inner side) of the joint between the column 1 and the beam 2, and the ends of the columns 1 and 2 in the vicinity of the column beam joint. A plurality of embedding plates 7 and 7 and a plurality of protrusions 8 embedded in the concrete and a plurality of orthogonal plates 9 and 9 respectively installed on the inner surfaces of the pillar 1 and the beam 2 are integrally formed.

  The embedding plate 7 avoids the column beam joint where the main bars and strips arranged in the column 1 and the beam 2 or many stirrups are complicated, and extends to the ends of the column 1 and the beam 2 in the vicinity thereof. Embedded and extended.

  The embedded plate 7 is formed with a plurality of through holes 7 a close to the orthogonal plate 9. Then, the hoop bars (not shown) of the pillar 1 are passed through the through holes 7a of the embedded plate 7 embedded in the pillar 1, and the beams 2 are inserted into the through holes 7a of the embedded plate 7 embedded in the beam 2. The streaks (not shown) are penetrated.

  Further, the gusset plate body 6 and the embedded plates 7 and 7 are formed substantially parallel to the construction surface of the RC frame 4, and the orthogonal plates 9 and 9 are substantially perpendicular to the construction surface of the RC frame 4, that is, the gusset plate body. 6 and the embedding plates 7, 7. Further, the plurality of protrusions 8 and 8 are also provided so as to protrude substantially perpendicular to the construction surface of the RC frame 4, that is, on both sides of the gusset plate body 6 and the embedding plate 7, similarly to the orthogonal plates 9 and 9. .

  In addition, a reinforcing bar, a stud bolt, etc. are used for the some protrusion 8, and the optimal quantity protrudes according to the strength of the brace 3. Further, the orthogonal plates 9 and 9 are formed so as to serve also as a formwork for discarding the concrete of the pillar 1 and the beam 2. Furthermore, a plurality of reinforcing ribs 10 are integrally attached to the joint portion (entering corner portion) between the gusset plate main body 6 and each orthogonal plate 9, 9.

  In such a configuration, when the seismic horizontal force acts on the RC frame 4 and the column 1 is inclined, the seismic horizontal force is passed through the embedded plate 7 from the protrusions 8 such as studs embedded at the ends of the column 1 and the beam 2. Then, it is transmitted to the gusset plate body 6 and further to the brace 3.

  At this time, a shearing force acts on the protrusions 8 such as studs embedded in the ends of the pillar 1 and the beam 2, but the band and the stirrup that penetrate the embedded plate 7 also bear a certain amount of shearing force. This improves the fixability.

  Further, since the axis of the protrusion 8 such as a stud is orthogonal to the direction of the bending crack generated in the column 1 and the beam 2, the fixing stability is higher than the fixing method using only the headed stud of the conventional example (see FIG. 11). I can say that.

  Further, the orthogonal plates 9, 9 are attached to the inner side surfaces (inner slopes) of the columns 1 and 2 at the corners of the column beam joints, and the joints between the gusset plate body 6 and each orthogonal plate 9. Since the plurality of reinforcing ribs 10 are attached to the (entering corners), it is possible to suppress the concrete of the pillar 1 and the beam 2 to which the orthogonal plate 9 is attached from being squeezed out even when subjected to compressive force.

  That is, since the state close to the rigid zone is formed at the ends of the column 1 and the beam 2 due to the constraint effect on the end concrete of the column 1 and the beam 2, the effect of reducing the stress level acting on the column-beam joint is also achieved. is there.

  FIG. 5 is an overall view showing a test body of an experiment in which the performance of the joint portion between the RC frame 4 and the brace 3 according to the present invention is confirmed, and in the RC frame 4A composed of the pillar 1A and the beam 2A. It is configured by incorporating a buckling restrained brace 11 as a brace.

  As shown in FIG. 6, the buckling-restraining brace 11 wraps a steel plate 11a as a core material with a mortar-filled steel pipe 11b and attaches an unbonded material (not shown) to the contact surface between the steel plate 11a and the mortar 11c. It is configured by eliminating, and does not buckle against the compression axial force, and is configured as a brace having the same proof stress and deformation ability as when a tensile axial force is applied. In addition, it is often used as a vibration damping member because of its excellent performance.

  The outline of the experiment and the results are described below. FIG. 7 shows a force applying device in a state in which a test body is set. The horizontal actuator 12 repeatedly loaded with positive and negative alternating loads from ± 1/1600 to ± 1/25 at an interlayer deformation angle.

  Table 1 shows the material properties of the specimen, and Table 2 shows a cross-sectional list of the RC portion of the specimen. The test body is an integral part of “test body 1” having only the RC frame 4A and “test body 2” having a buckling restraint booth (BRB) 11.

  FIG. 8 shows a relationship between horizontal load and interlayer displacement of both specimens. FIG. 9 is a skeleton (skeletal curve) showing the relationship between the horizontal load and the inter-layer displacement of both specimens up to ± 20 mm between layers. The figure shows a single horizontal load of the buckling-restrained brace (BRB) 11. ~ Interlayer displacement relationship (broken line a) is also shown. FIGS. 10A and 10B are diagrams showing cracks in both specimens when the interlayer deformation angle is about ± 1/100.

  From FIG. 8, the RC frame 4A alone (test body I) shows a tendency to decrease in yield strength before the interlayer displacement ± 20 mm, but with the buckling restrained brace (BRB) 11 (test body 2), there is no such tendency. It can be seen that a stable loop is drawn even for a large deformation.

  From FIG. 9, a horizontal load curve (dotted line) simply adding the horizontal load-interlayer displacement relationship of RC frame 4 only (test body 1) (dashed line b) and buckling restrained brace (BRB) 11 alone (broken line a). It can be seen that (d) almost coincides with the solid line with the buckling restrained brace (BRB) 11 (test body 2).

  From these facts, when the buckling-restrained brace (BRB) 11 is incorporated into the RC frame 4A, the proof stress becomes a simple accumulation of both proof strengths, and the deterioration of the proof strength of the RC frame during large deformation can be improved. I understand. That is, it was confirmed that the brace joint portion according to the present invention sufficiently transmits the stress between the RC frame 4A and the buckling restrained brace (BRB) 11.

  In the crack situation of the RC frame 4A shown in FIGS. 10 (a) and 10 (b), focusing on the end of the beam 2A, a large number of bending cracks are generated only in the RC frame 4A (test body 1). It can be seen that in the case with the bending restraint brace 11 (test body 2), the crack is generated slightly from the end of the beam 2A and near the edge of the orthogonal steel plate.

  That is, it is considered that the bending deformation at the end of the beam 2A is restrained by the presence of the brace joint A of the present invention, and a state close to a rigid region is formed.

  It is preferable that the bending crack position (plastic hinge) be closer to the center of the beam because the cross-sectional stress of the beam 2A is reduced. Although this tendency is not as high as that of the beam 2A, the same can be said for the column 1A.

  The embodiment of the present invention is as described above. However, as long as the protrusion 8 can resist the shearing force, a rib-like protrusion or the like may be used instead of the stud, the bolt, or the reinforcing bar. Moreover, although the buckling restraint brace 11 was illustrated as the brace 3, if the brace joints A and B of the present invention are designed with a proof strength greater than the proof strength of the brace, various ordinary braces (including non-metallic braces). Needless to say, it can also be applied to oil dampers and the like.

  INDUSTRIAL APPLICABILITY The present invention can remarkably improve the fixing performance of a brace joint, and can provide an RC frame with a brace having high energy absorption capability.

DESCRIPTION OF SYMBOLS 1 Column 2 Beam 3 Bracing 4 RC frame 5 Bracing gusset plate 6 Gusset plate main body 7 Embedded plate 7a Through hole 8 Protrusion 9 Orthogonal plate 10 Reinforcement rib 11 Buckling restraint brace 11a Steel plate 11b used as a core material Mortar filling steel pipe 11c Mortar 12 Horizontal Actuator

Claims (5)

  In a joint structure of an RC frame composed of columns and beams and a brace that is joined to a column beam joint of the RC frame via a brace gusset plate, the brace gusset plate includes the column The gusset plate main body projecting at the corner of the beam joint, a column near the column beam joint, and a plurality of embedded plates and a plurality of projections embedded at the ends of the beam, respectively. The plate is embedded substantially parallel to the construction surface of the RC frame, and the plurality of protrusions are protruded from the plurality of embedded plates and embedded in the out-of-plane direction of the surface of the RC frame. Joint structure of RC frame and brace.   2. The RC frame / bar joint structure according to claim 1, wherein an orthogonal plate is attached to an inner surface of the column and the beam at a corner of the column beam joint at a substantially right angle to the RC frame surface. A joint structure of RC frame and brace characterized by this.   The joint structure between the RC frame and the brace according to claim 1 or 2, wherein a plurality of through holes are formed in the embedded plate so as to penetrate the reinforcing bars.   In an RC frame composed of an RC frame composed of columns and beams and a brace incorporated in the RC frame, the end of the brace is placed inside the adjacent column beam joint of the RC frame. The brace gusset plates are joined to each other via a bracing gusset plate, and the bracing gusset plate includes a gusset plate body projecting at a corner of the column beam joint and a column and beam in the vicinity of the column beam joint. The plurality of embedding plates and the plurality of protrusions embedded in the end portions are embedded, and the plurality of embedding plates are embedded substantially parallel to the construction surface of the RC frame, and the plurality of protrusions are embedded in the plurality of embedding plates. A bracing RC frame characterized by being protruded and embedded in an out-of-plane direction of the RC frame.   The RC frame with braiding according to claim 4, wherein the buckling comprises a steel plate as a core as a brace, a mortar-filled steel pipe that wraps the steel plate, and an unbonded material affixed to a contact surface between the steel plate and the mortar. A braced RC frame characterized by a restrained brace.

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