JP2002332750A - Aseismic reinforcing structure for reinforced concrete support column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide aseismic reinforcing structure for a reinforced concrete support column allowing the aseismic reinforcing work of a bridge pier to be easily performed without causing the extension of a construction period and the increase of a construction cost. SOLUTION: An aseismic reinforcing part 12 formed of reinforced concrete installed around an existing wall type concrete bridge pier skeleton 11, for instance, as the reinforced concrete support column, is wound up, and a plurality of anchors 14 are anchored in a surface layer part of the wall type concrete bridge pier skeleton 11. The heads of anchor bolts 13 provided at the anchors 14 are fixed to the aseismatic reinforcing part 12 to restrain at least a structural element of the aseismatic reinforcing part 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic retrofit structure for a reinforced concrete support column, and more particularly to a technique for improving the seismic performance of an existing reinforced concrete support column such as a wall-type concrete pier.

[0002]

2. Description of the Related Art In recent years, reinforced concrete piers for supporting railway bridges, road bridges, and the like have been subjected to seismic reinforcement work to improve their seismic performance. Heretofore, as this kind of seismic reinforcement method, a method of arranging a seismic reinforcement part around a reinforced concrete pier using a steel plate, reinforced concrete, or both together has been generally used.

In such a seismic retrofitting method for a reinforced concrete pier, for example, a wall-type concrete pier, in other words, the ratio of the length of the short side to the long side of the cross section of the pier is approximately 1: 3.
In the case of reinforced concrete bridge piers, etc., which exceed the above, a hole is drilled from one surface of the existing reinforced concrete pier body to the other surface that penetrates the body (drilled), and an intermediate penetrating PC steel rod is passed through this hole The method of fixing both ends to the seismic reinforcement part which was rolled up was common.

Here, an example of the conventional seismic retrofitting method of a wall-type concrete pier by reinforced concrete wrapping reinforcement will be specifically described. First, as shown in FIG. 8 and FIG. The seismic reinforcement part 2 is formed by winding up a predetermined thickness around the periphery. A large number of bending reinforcing bars (axial reinforcing bars) 3 extending along the longitudinal direction of the existing reinforced concrete bridge pier frame 1 and a large number of band reinforcing bars 4 are arranged to bundle these axial reinforcing bars. Has been arranged.

Before arranging the bending reinforcing bars 3 and the band reinforcing bars 4, a plurality of reinforced concrete bridge piers 1 extending from one surface of the existing reinforced concrete bridge pier 1 to the other surface on the opposite side through the bridge pier 1 are arranged. Holes are drilled at intervals in the axial direction, then a PC steel rod 5 is passed through each hole, and then bending reinforcement bars 3 and band reinforcing bars 4 are arranged, and finally, both ends of the PC steel bar 5 The nut was screwed in and fixed so as to restrain the bending reinforcing bar 3 and the band reinforcing bar 4.

At this time, as a method of restraining the bending reinforcing bar 3 and the band reinforcing bar 4, for example, three PC steel bars 5 arranged in the longitudinal direction are used.
In contrast, one steel groove steel 6 is used as a restraining member, and the PC steel bar is disposed adjacent to the outside of the steel bar 4 so that the restraining effect extends to the entire belt reinforcing bar 4. Specifically, the grooved steel 6 has three Ps.
A hole into which the end of the C steel rod 5 is inserted is formed, and the end of the PC steel rod 5 is disposed after the end of the PC steel rod 5 is inserted and protruded relative to each hole of the grooved steel 6. Tighten with the nut screwed to the part and fix.

As a result, the grooved steel 6 prevents the strip reinforcing bar 4 from sticking out, and as a result, the buckling of the axial reinforcing bar 3 is also prevented, thereby improving the seismic performance of the existing reinforced concrete bridge pier frame 1. The grooved steel 6 is finally embedded in the reinforced concrete forming the seismic retrofitting part 2.

[0008] In the case of the conventional seismic retrofitting method for a wall-type concrete pier using a steel plate wrapping reinforcement, a reinforcing steel plate is wrapped around the existing reinforced concrete pier frame at intervals, and mortar is filled into the gap. And integrated with the pier frame. At this time, as in the case of the seismic retrofitting method of the wall-type concrete pier by reinforcing the reinforced concrete, a plurality of through holes are drilled in advance in the existing reinforced concrete pier frame 1 and a PC steel rod is passed through each hole, and the reinforcing steel plate is rolled up. After that, the end of each PC steel rod is passed through an insertion hole formed in the reinforcing steel plate, and a nut is screwed and tightened to exert a restraining effect.

Further, in the case of the seismic retrofitting method of a wall-type concrete pier by jointly using reinforced concrete and steel plate, the cross section of the pier finally reinforced by seismic resistance is first described above, as shown in FIG. Wall-type concrete piers with reinforced concrete roll-up reinforcement
Then reinforced steel plate 7 around the reinforced concrete rolled up
Is arranged, and the gap between the rolled-up reinforced concrete and the reinforcing steel plate is filled with mortar and integrated to form an earthquake-resistant reinforcing portion 8 used in combination.

The end of each PC steel rod 5 attached to the existing reinforced concrete bridge pier frame 1 penetrates the reinforced concrete wrapped portion and the reinforcing steel plate 7 wrapped around the reinforced concrete pier and protrudes. The nuts and the like are screwed together and tightened to exert a restraining effect.

[0011]

However, the drilling of through holes in the cross section of a wall-type pier, which is performed by the conventional wall-type concrete pier seismic retrofitting method as described above, is generally a large-scale construction, and the construction period and the construction cost increase. There was a problem of doing. Moreover, as the cross section of the pier becomes larger, the drilling length also increases, and this problem becomes remarkable.

Further, there is also a problem that such a drilling of a through hole in a section of a wall-type concrete pier has a high possibility of damaging existing reinforcing bars inside a reinforced concrete pier skeleton. That is, this type of through hole is usually drilled until it penetrates from one side in one direction. In such a case, it is possible to pre-examine the reinforcing bar inside the reinforced concrete bridge pier body on the drilling start side and drill while avoiding the existing reinforcing bar position, but still avoid damage to the reinforcing bar on the drilling end side It is difficult.

[0013] Further, the state of the reinforcement in the pier skeleton is investigated from both sides of the wall type concrete pier skeleton, and holes are drilled from both sides so as to avoid the reinforcing bars located on both sides of the pier skeleton. It is conceivable that the holes are united and communicated with each other, but it is not easy to match two holes drilled from both sides at the center, and extremely high precision is required for drilling, which is not practical.

Furthermore, when the wall type concrete pier is installed underwater, such drilling and subsequent reinforcement work are more difficult than on the ground, and the construction period and construction cost are increased. there were.

An object of the present invention is to solve such a conventional problem, and a reinforced concrete support capable of easily performing seismic reinforcement of a pier without increasing the construction period and construction cost. An object of the present invention is to provide a seismic reinforcement structure for columns.

[0016]

SUMMARY OF THE INVENTION The present invention relates to a seismic reinforcement structure for a reinforced concrete support column, and has the following structure to solve the above-mentioned technical problems. That is, the seismic retrofit structure of the reinforced concrete support column of the present invention includes an antiseismic reinforcement portion wound around an existing reinforced concrete support column frame and a plurality of anchors fixed in the surface layer of the existing reinforced concrete support column frame. The head of the anchor rod included in the anchor is fixed to the seismic reinforced part, and at least the structural elements of the seismic reinforced part are restrained.

<Specific Structure in the Present Invention> The seismic retrofit structure of the reinforced concrete support column of the present invention includes the essential components described above, and is established even when the components are specifically as follows. I do. The specific component is characterized in that the anchor is an expanded anchor. Expandable anchors are particularly effective for this type of seismic reinforcement because of their very high anchoring power in concrete.

Further, in the seismic retrofitting structure of the reinforced concrete support column of the present invention, the seismic retrofitting portion is constituted by one or both of the reinforcing steel plate and the reinforced concrete installed around the existing reinforced concrete support column frame. Are also used in combination.

Further, in the seismic reinforcement structure of the reinforced concrete support column of the present invention, when the seismic reinforcement part is formed of reinforced concrete, the reinforced concrete used as the seismic reinforcement part can be formed of a precast concrete formwork.

When a precast concrete formwork is used as the seismic reinforcement part, mortar or concrete is interposed between the precast concrete formwork and the existing reinforced concrete bridge pier body to be integrated. Furthermore, it is preferable to apply the seismic strengthening structure for reinforced concrete support columns according to the present invention having the above-mentioned features, particularly to a wall-type concrete pier.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a reinforced concrete supporting column according to an embodiment of the present invention. FIG. 1 schematically shows an earthquake-resistant reinforcement structure 10 in which a wall-type concrete pier is reinforced with seismic resistance by rolling it up with reinforced concrete as one embodiment of an earthquake-resistant reinforcement structure of a reinforced concrete support column according to the present invention.

That is, in the seismic reinforcement structure 10 for a wall-type concrete pier according to this embodiment, as shown in FIG. 1, an earthquake-resistant reinforcement 12 made of reinforced concrete is wound around an existing wall-type concrete pier frame 11. ing. A large number of bending reinforcing bars 3 and band reinforcing bars 4 are arranged in the seismic reinforcement unit 12 made of reinforced concrete, similarly to the seismic reinforcement unit of the conventional reinforced concrete.

In the seismic reinforcement structure 10 of the wall-type concrete pier in which the reinforced concrete reinforced portion 12 is wound around the outer periphery, a large number of anchors 14 are disposed on the surface layer of the wall-type concrete pier frame 11. 14
An anchor bolt 13 which is a component of the present invention is disposed so as to penetrate the reinforced concrete earthquake-resistant reinforcement 12. Here, the anchor 14 to be used is particularly preferably an expanded anchor, but may be another anchor.

The expanded bottom anchor 14 is a post-installed anchor that exerts a mechanical anchoring mechanism by undercutting concrete and forming an anchoring section (bottom expansion).
It has higher anchoring power than general adhesive anchors and mechanical expansion anchors, and exhibits high anchoring power even when cracks occur in the anchor installation position due to mechanical engagement of the expanded bottom part. Such bottom-up anchors per se are already well known.

That is, such an expanded bottom anchor 14
Is press-fitted when a hole is made in the surface layer of the wall-type concrete bridge pier body 11 in advance and the inner part is enlarged and drilled,
The metal extension of the anchor is expanded and mechanically anchored. Thereafter, around the wall-type concrete bridge pier body 11, the bending reinforcing reinforcing bar 3 and the band reinforcing bar 4 are arranged as in the related art, and the formwork is arranged so as to surround it.

The anchor bolt 13 of the expanded bottom anchor 14 is arranged so that its head projects from an insertion hole formed in the formwork, and concrete is then poured into the formwork. The nut 15 is screwed into the projecting screw portion of the anchor bolt 13 projecting from the surface of the reinforced concrete earthquake-resistant reinforcement 12 formed in this way, and is fixed to the surface of the earthquake-resistant reinforcement 12.

At this time, a strip-shaped steel plate having holes through which the heads of several anchor bolts 13 arranged in the longitudinal direction are respectively inserted is applied to form a base plate (not shown). If the heads of the anchor bolts 13 are taken out of the base plate, and the nuts 15 are screwed onto the protruding heads of the anchor bolts 13 to caulk the base plate, the restraining effect can be exerted widely.

The reason why such an expanded bottom anchor 14 is used is that bending cracks and shear cracks easily occur easily, particularly at the base of the wall type concrete pier frame 11 due to the action of seismic force. In general adhesive anchors and metal expansion anchors, the anchoring force of the anchor is almost lost when the crack passes through the anchoring portion, and the anchor does not function. Therefore, in places where cracks are expected to occur, the restraining effect of the lateral restraint bars made of band rebars or steel plates cannot be improved unless the anchors are expanded or steel bars are penetrated.

Further, since anchoring of the expanded anchor 14 is merely to make a hole in the surface layer of the existing wall-type concrete pier, it is sufficient to drill a hole so as to avoid the existing reinforcing bars based on the arrangement of reinforcing bars in the surface layer. Damage to the existing rebar due to anchor construction can be reliably prevented.

By the way, as shown in FIG. 2, a precast formwork 16 formed in advance in a factory or the like can be used for such a reinforced concrete seismic reinforcement section 12. However, when the precast formwork 16 is used as the reinforced concrete seismic reinforcement section 12, the bending reinforcement bar 3 is arranged around the existing wall-type concrete bridge pier frame 11, and then the precast formwork 16 is installed outside thereof. ,
Wall-type concrete pier frame 11 and precast formwork 16
Is filled with mortar or concrete 17.

If the existing reinforced concrete wall pier is underwater, the precast formwork 16 must be used as the reinforced concrete seismic reinforcement 12 and the existing pier frame 11 and precast formwork 16 must be used.
Is filled with mortar that is inseparable in water instead of ordinary mortar or concrete 17.

The tools required for the construction of the expanded anchor are:
The workability is excellent in that the operator can easily operate it by holding it in his hand, and the time required for drilling is short. Considering that a heavy-duty hydraulic boring machine must be used when drilling through holes in the wall-type concrete pier body, it is easy to construct the seismic reinforcement structure of the wall-type concrete pier according to this embodiment. I know if it is possible. In particular, an air tool that can be held by an operator may be used even when an expanded bottom anchor is constructed underwater, and the workability is excellent.

As described above, in the seismic retrofit structure 10 of the wall-type concrete pier according to the present embodiment, the floor-type anchor is disposed on the surface layer of the wall-type concrete pier, and the seismic reinforcement of the reinforced concrete around the wall-type concrete pier frame. The part is rolled up, and the expanded anchor is fixed to the structural element of the seismic reinforcement part to improve the restraint effect of the lateral restraint, so that seismic reinforcement work can be easily performed without damaging the internal reinforcement. As a result, the construction period can be shortened and the construction cost can be reduced.

Incidentally, a model of a conventional seismic reinforcement structure of a wall-type concrete pier and a model of a seismic reinforcement structure of a wall-type concrete pier according to one embodiment of the present invention (FIG. 3).
Fig. 4 shows a model test piece 1 with a conventional seismic retrofit structure.
The model specimen 2 with the seismic retrofit structure according to the present invention
Are shown), and the difference in strength of each model was confirmed by positive and negative alternating loading tests on the model piers.
Table 1 shows the results.

[0035]

[Table 1]

In Table 1, calculated values (railroad / road)
Is calculated based on the existing design guidelines for railway structures and road structures. Generally, the seismic performance of a member is evaluated by the area surrounding a hysteresis curve of a load-displacement relationship. FIG. 5 is a characteristic diagram showing a load-displacement relationship in the test body 1, and FIG. 6 is a characteristic diagram showing a load-displacement relationship in the test body 2. As is clear from the envelope comparison diagram of FIG. 7, it can be seen that the envelopes of the two almost coincide.

As is apparent from the experimental results, there is almost no difference in seismic performance between the seismic reinforcement structure of the wall type concrete pier according to the embodiment of the present invention and the conventional seismic reinforcement structure of the wall type concrete pier. I understand.

The above-described embodiment of the present invention relates to a case where the seismic retrofitting part wound around the existing wall-type concrete pier body is made of reinforced concrete (including precast concrete). But,
The present invention can be similarly applied to a case where a reinforcing steel plate is used as the earthquake-resistant reinforcing portion or a case where a reinforced concrete and a reinforcing steel plate are used together.

For example, in the case of seismic retrofitting of a wall-type concrete pier by steel plate rolling reinforcement, as described above, an expanded-bottom type anchor is previously installed at a predetermined position on the surface layer of an existing wall-type concrete pier frame. Reinforcing steel plates are arranged at intervals around the reinforced concrete bridge pier and the reinforcing steel plates are filled with mortar or concrete to integrate them. At this time, the anchor bolt head of each expanded anchor is projected outward through each insertion hole formed in the reinforcing steel plate, and finally the nut etc. is screwed and tightened to exert the restraining effect. To

In the present specification, the present invention has been described by taking an example of an embodiment relating to an earthquake-resistant reinforcement structure for a wall-type concrete pier, but the present invention is not limited to such a specific embodiment. It goes without saying that the present invention can be widely applied to reinforced concrete pillars under load, that is, reinforced concrete support columns.

[0041]

As described above, according to the seismic reinforcement structure of the reinforced concrete support column of the present invention, the seismic reinforcement portion is rolled up around the reinforced concrete support column, and at this time, the anchor is attached only to the surface layer of the support column. By arranging and fixing the anchor rods to the seismic reinforcement part, the structural elements of the seismic reinforcement part are restrained, so that seismic reinforcement work can be easily performed without damaging the internal rebar. As a result, the construction period can be shortened and the construction cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a seismic retrofitting structure of a wall-type concrete pier by reinforced concrete roll-up reinforcement, which is one embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a seismic reinforcement structure of a wall-type concrete pier having a seismic reinforcement part using a precast concrete formwork as another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a test sample 1 of a model using a conventional earthquake-resistant reinforcement structure.

FIG. 4 is a sectional view showing a test specimen 2 of a model having an earthquake-resistant reinforcement structure according to the present invention.

FIG. 5 is a characteristic diagram showing a load-displacement relationship in the test body 1.

FIG. 6 is a characteristic diagram showing a load-displacement relationship in a test body 2.

FIG. 7 is an envelope comparison diagram of the characteristic curves shown in FIGS. 5 and 6;

FIG. 8 is a perspective view partially showing an earthquake-resistant reinforcement structure in a conventional wall-type concrete pier by reinforced concrete reinforced reinforcement.

FIG. 9 is a cross-sectional view of the conventional wall-type concrete pier seismic retrofit structure shown in FIG.

FIG. 10 is a cross-sectional view of a conventional seismic retrofitting structure in a wall-type concrete pier with a steel plate wrapping reinforcement.

[Explanation of symbols]

 3 Bending reinforcement 4 Band reinforcement 10 Seismic reinforcement structure of wall-type concrete pier 11 Existing wall-type concrete pier body 12 Seismic reinforcement 13 Anchor bolt 14 Expandable anchor 15 Nut 16 Precast concrete form 17 Mortar or concrete

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Akira Suzuki 2- 10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. (72) Inventor Tetsuya Mishima 2- 10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. (72) Inventor Minoru Tabata 2-10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. F-term (reference) 2D059 AA03 GG40 2E176 AA04 BB29

Claims (6)

[Claims] 1. An anchor bar comprising: an earthquake-resistant reinforcing portion rolled up around an existing reinforced concrete support column; and a plurality of anchors fixed in a surface layer of the existing reinforced concrete support column. A seismic reinforcement structure for a reinforced concrete support column, wherein a head is fixed to the seismic reinforcement part to restrain at least structural elements of the seismic reinforcement part. 2. The seismic reinforcement structure of a reinforced concrete support column according to claim 1, wherein the anchor is an expanded anchor. 3. The seismic retrofitting part is configured by either one of a reinforcing steel plate and a reinforced concrete installed around the existing reinforced concrete supporting column body, or is configured by using both of them. The seismic strengthening structure of the reinforced concrete support column according to claim 2, characterized in that: 4. The seismic reinforcement structure of a reinforced concrete support column according to claim 3, wherein the seismic reinforcement part formed of the reinforced concrete is formed of a precast concrete formwork. 5. When the precast concrete formwork is used as the seismic reinforcement part, the precast concrete formwork and the existing reinforced concrete bridge pier body are integrated with a mortar or concrete interposed therebetween. The seismic reinforcement structure of the reinforced concrete support column according to claim 4, characterized in that: 6. The existing reinforced concrete support column is a wall-type concrete pier.
5. The seismic reinforcement structure of the reinforced concrete support column according to any one of 5.