Shear keys and seismic reinforcement structures for earthquake resistance

Abstract

This invention provides seismic reinforcement technology that reduces stress concentration occurring in existing reinforced concrete (RC) or steel-reinforced concrete (SRC) structures. [Solution] The seismic reinforcement structure, which attaches a reinforcing steel frame F to an existing RC or SRC structure via an indirect joint 100, comprises a seismic reinforcement shear key K having a solid rod-shaped main body and a flange provided in the middle of the main body, and a ring member 4 that fits onto the flange in the radially outward direction. A horizontal hole H is formed in the existing beam B or existing column P of the existing structure, and the main body of the seismic reinforcement shear key K is inserted into the horizontal hole H from its tip side until the flange substantially abuts against the outer surface of the existing structure A. The ring member 4 and the rear end portion of the seismic reinforcement shear key K opposite the tip side from the flange are located at the indirect joint 100. Resin is injected into the space between the main body and the horizontal hole H from an injection hole formed in the flange.

Description

Technical Field

[0001] The present invention relates to a seismic reinforcement structure, particularly a seismic reinforcement structure for a frame of RC or SRC construction and a shear key for seismic reinforcement used for such a seismic reinforcement structure.

Background Art

[0002] Conventionally, in order to reinforce a frame of RC or SRC construction, a reinforcing frame is attached using deformed bar post-installed anchors. Since the diameter of a general deformed bar post-installed anchor is 19 mm, a very large number of post-installed anchors are required to improve the strength. Therefore, the amount of work for seismic reinforcement becomes enormous. In particular, when the outer wall of the frame has an outer wall coating containing asbestos or is tiled, work related to preventing the scattering of asbestos, removing and reattaching the tiles occurs, and the labor further increases.

[0003] In view of such problems, the inventors of the present invention invented a reinforcement mechanism using a shear key made of a thick steel pipe instead of a deformed bar post-installed anchor (see Patent Document 1). Since this shear key exhibits a large bending rigidity and shear strength, it has been found through experiments that one thick steel pipe shear key has an effect equivalent to about 20 deformed bar post-installed anchors. Therefore, by using such a shear key, it is possible to reduce the displacement between the existing frame and the reinforcing frame due to an external force and the reduction in the strength of the existing frame with less labor compared to the seismic reinforcement work using post-installed anchors.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, the reinforcement mechanism of Patent Document 1 uses a shear key made of thick-walled steel pipe to attach a reinforcing frame to the existing structure, thereby reducing displacement between the existing structure and the reinforcing frame due to external forces, and reducing the load-bearing capacity of the existing structure. However, if a larger external force is applied, displacement may occur. In this case, stress concentration may occur on the existing structure side, and the existing structure may collapse.

[0006] This invention has been made in view of the above-mentioned problems, and its purpose is to provide a seismic reinforcement technology that reduces stress concentration occurring in existing reinforced concrete (RC) or steel-reinforced concrete (SRC) structures. [Means for solving the problem]

[0007] To solve the above problems, the seismic reinforcement shear key used in a seismic reinforcement structure for attaching a reinforcing steel frame to an existing RC or SRC structure via an indirect joint, according to the present invention, comprises a solid rod-shaped main body whose tip and rear end are positioned across the existing beam or column of the existing structure and the indirect joint, a flange provided in the middle of the main body, and a ring member made of an elastic material that is fitted onto the flange without being fixed in the radially outward direction.

[0008] Such seismic reinforcement shear keys are positioned across the existing structure and the reinforcing steel frame. Specifically, the main body is inserted into a horizontal hole formed in the existing structure until the surface of the flange facing the existing structure substantially abuts against the outer wall of the existing structure. Meanwhile, the remaining portion of the seismic reinforcement shear key is positioned within the indirect joint. In this state, for example, if a downward force acts on the reinforcing steel frame, stress is generated in the existing structure. At this time, with the seismic reinforcement shear key according to the present invention, the flange (seismic reinforcement shear key) is less susceptible to the force acting on it because its edge is cut off by a ring member, thereby reducing stress concentration in the existing structure. This makes it possible to suppress the destruction of the existing structure.

[0009] In one preferred embodiment of the seismic reinforcement shear key according to the present invention, the main body portion includes, on the tip side of the flange, a fitting portion having an outer diameter substantially the same as the inner diameter of a horizontal hole formed in the existing beam or existing column, and, on the tip side of the fitting portion, a guide portion whose outer diameter decreases as it approaches the existing structure.

[0010] In this configuration, when inserting the main body into the horizontal hole, if the axis of the main body and the axis of the horizontal hole are slightly misaligned, the guide portion will come into contact with the opening edge of the horizontal hole. If insertion of the main body continues in this manner, the contact between the guide portion and the opening edge will bring the axis of the main body closer to the axis of the horizontal hole. When these axes align, the fitting portion will be fitted into the horizontal hole, and the state of alignment will be maintained.

[0011] In one preferred embodiment of the seismic reinforcement shear key according to the present invention, the main body comprises a first annular groove formed in the circumferential direction on the tip side of the flange and a second annular groove formed in the circumferential direction on the rear end side of the flange.

[0012] In this configuration, the leading end of the main body is inserted into a horizontal hole formed in the existing structure, and resin is filled into the space between the main body and the horizontal hole. When the rear end of the main body is positioned at the indirect joint of the reinforcing steel frame, the resin or high-strength mortar poured into the indirect joint fills the respective circular grooves. This increases the pull-out resistance of the main body of the seismic reinforcement shear key.

[0013] Furthermore, the present invention also covers seismic reinforcement structures for attaching reinforcing steel frames to existing reinforced concrete (RC) or steel-reinforced concrete (SRC) structures via indirect joints. Such seismic reinforcement structures include a seismic reinforcement shear key having a solid rod-shaped main body and a flange provided in the middle of the main body, and a ring member made of an elastic material that fits onto the flange without being fixed in the radially outward direction. A horizontal hole is formed in an existing beam or column of the existing structure, the main body of the seismic reinforcement shear key is inserted into the horizontal hole from its tip side until the flange substantially abuts against the outer surface of the existing structure, the ring member and the rear end portion of the seismic reinforcement shear key opposite the tip side from the flange are located at the indirect joint, and resin is injected into the space between the main body and the horizontal hole from an injection hole formed in the flange.

[0014] This seismic reinforcement structure provides the same effects as the seismic reinforcement shear key described above. Furthermore, the additional features of the seismic reinforcement shear key described above can be applied to the seismic reinforcement shear key used in this seismic reinforcement structure, resulting in similar effects. [Brief explanation of the drawing]

[0015] [Figure 1] (a) Plan view and (b) Front view of a reinforced concrete (RC) or steel-reinforced concrete (SRC) structure with a reinforcing steel frame attached. [Figure 2] These are (a) a front view, (b) a left side view, and (c) a right side view of a shear key for seismic reinforcement. [Figure 3] This is a cross-sectional view of the shear key for seismic reinforcement inserted into a horizontal hole formed in the existing structural frame, shown at line III-III in Figure 2(c). [Figure 4] Figure 3 is a magnified view of the area near the flange of the seismic reinforcement shear key. [Figure 5] This diagram illustrates the operation of the automatic center-aligning mechanism. [Figure 6](a) A side section view showing the state in which a reinforcing beam has been attached to an existing beam, (b) A plan section view showing the state in which a reinforcing column has been attached to an existing column with seismic reinforcement shear keys arranged in a single vertical row, and (b) A plan cross-sectional view showing the state in which a reinforcing column has been attached to an existing column with seismic reinforcement shear keys arranged in two vertical rows in a staggered pattern. [Figure 7] This diagram shows the stress distribution on the surface of the shear key at the contact surface with the concrete of the existing structure and the indirect joint, with (a) the case when using the shear key according to the present invention and (b) the case when using the shear key according to the present invention with the ring member removed. [Modes for carrying out the invention]

[0016] The following describes an embodiment of the seismic reinforcement structure for RC or SRC structures and the seismic reinforcement shear key used therein according to the present invention, with reference to the drawings. Figure 1 is a plan view and a front view showing a state in which a reinforcing steel frame F is attached to the outer surface of an existing RC or SRC structure A via an indirect joint. As shown in the figure, the existing RC or SRC structure A includes an existing beam B and an existing column P. The reinforcing beam RB and reinforcing column RP of the reinforcing steel frame F are fixed to the existing beam B and existing column P, respectively, using a seismic reinforcement shear key K (hereinafter abbreviated as shear key K). This reduces the displacement between the existing structure A and the reinforcing steel frame F, and suppresses damage to the existing structure A. In this embodiment, the existing RC or SRC structure A does not have PC panels, ALC panels, etc. attached as an exterior wall.

[0017] Figure 2 is a front view and left and right side views of the shear key K in the present embodiment. As shown in the figure, the shear key K includes a main body portion 1 and a flange 2 provided at an intermediate portion of the main body portion 1. The main body portion 1 is a solid bar made of metal, and its outer diameter is about 70 to 80 mm. Therefore, the shear key K has a larger outer diameter compared to a general post-construction anchor having an outer diameter of about 19 mm. Although the outer diameter of the main body portion 1 can be appropriately changed, the inventor has found that an outer diameter of about 70 to 80 mm is preferable from the viewpoint of suppressing an increase in weight and considering workability while achieving a significant performance improvement compared to post-construction anchors.

[0018] Also, a plate-like ring member 4 is externally fitted to the flange 2. In the present embodiment, the ring member 4 is formed of an elastic material such as foamed polyethylene or foamed urethane resin. The flange 2 and the ring member 4 are not fixed to each other, and force transmission between them is difficult to occur. That is, the ring member 4 cuts the edge of the flange 2. Although the thickness of the ring member 4 can be appropriately changed, it has been found that a thickness of about 10 mm can sufficiently exhibit its function. In the following description, the right side of FIG. 2(a) is referred to as the tip side, and the left side is referred to as the rear end side.

[0019] The main body portion 1 includes an automatic centering portion 3 on the tip side of the flange 2. This automatic centering portion 3 is for automatically centering (aligning the axis of the horizontal hole H and the axis of the main body portion 1) when the main body portion 1 is inserted into a horizontal hole H formed in an existing beam B or an existing column P. Specifically, the automatic centering portion 3 includes a fitting portion 3a and a guide portion 3b. The fitting portion 3a is a flat plate annular member provided on the tip side of the main body portion 1 with respect to the flange 2, and is externally fitted to the main body portion 1 and contacts the surface on the tip side of the flange 2. Although the fitting portion 3a does not necessarily need to contact the flange 2, it is preferable because the centering accuracy is improved when it contacts. Also, the outer diameter of the fitting portion 3a is substantially the same as the inner diameter of the horizontal hole H, but is slightly smaller to facilitate fitting of the fitting portion 3a into the horizontal hole H.

[0020] The guide portion 3b is a conical tubular member located on the tip side of the insertion portion 3a, and its outer diameter decreases towards the tip. Specifically, the outer diameter of the rear end (insertion portion 3a side) of the guide portion 3b is the same as the outer diameter of the insertion portion 3a, and the diameter of the guide portion 3b decreases towards the tip. The operation of this self-aligning portion 3 will be described later.

[0021] As shown in Figure 2(a), a first annular groove 11 and a second annular groove 12 are formed circumferentially at the front and rear ends of the main body 1, respectively. The first annular groove 11 and the second annular groove 12 can be formed using a lathe or the like. Applying such processing to the main body 1 may lead to a reduction in strength, but since the main body 1 is solid, the reduction in strength is very slight. In this embodiment, one first annular groove 11 is formed at a position slightly displaced from the front to the rear end of the main body 1, and three second annular grooves 12 are formed from approximately the rear end, but these positions and numbers can be changed as appropriate. The important point is that annular grooves are formed at the front and rear ends of the main body 1. These annular grooves have the same effect as the uneven processing of deformed reinforcing bars, but the details will be described later.

[0022] As shown in Figures 2(b) and (c), the flange 2 has an injection hole 21 and an air vent hole 22 formed through it. Through the injection hole 21, resin is injected to fill the space S (see Figure 3) between the main body 1 of the shear key K and the horizontal hole H. Meanwhile, as the resin is injected into the space S, the air inside the space S flows out to the outside through the air vent hole 22. This allows the resin to be injected into the space S smoothly.

[0023] Furthermore, the flange 2 has three screw holes 23 formed through it on the same circumference. Screws can be inserted through these screw holes 23 to fix the shear key K to the wall surface of the existing structure A.

[0024] Figure 3 is a cross-sectional view taken along line III-III in Figure 2(c) of a shear key K inserted into a horizontal hole H formed in an existing beam B or column P of an existing structural frame A. As shown in the figure, the injection hole 21 consists of a small-diameter portion 21a formed on the rear end side and a large-diameter portion 21b formed on the front end side so as to communicate with the small-diameter portion 21a. Similarly, the air vent hole 22 consists of a small-diameter portion 22a and a large-diameter portion 22b. A resin injection pipe T1 for injecting resin is connected to the small-diameter portion 21a of the injection hole 21, and an air vent pipe T2 for discharging air is connected to the small-diameter portion 22a of the air vent hole 22. A flat ring-shaped packing 5 is provided between the flange 2 and the existing structural frame A to prevent the resin injected into the space S from leaking out from between the flange 2 and the existing structural frame A.

[0025] Figure 4 is an enlarged view of the vicinity of flange 2 in Figure 3. The large diameter portion 21b of the injection hole 21 and the large diameter portion 22b of the air vent hole 22 are formed to partially overlap with space S when viewed in the axial direction. In addition, an injection groove 3c and an air vent groove 3d are formed in the self-aligning portion 3. The injection groove 3c is formed along the longitudinal direction of the shear key K so as to overlap with the overlapping portion of the large diameter portion 21b of the injection hole 21 and space S when viewed in the axial direction. That is, the large diameter portion 21b of the injection hole 21 and space S are in communication via the injection groove 3c. The air vent groove 3d is formed similarly, and the large diameter portion 22b of the air vent hole 22 and space S are in communication via the air vent groove 3d. As a result, the resin injected from the resin injection pipe T1 can flow into space S through the small diameter portion 21a, the large diameter portion 21b of the injection hole 21, and further through the injection groove 3c. On the other hand, the air inside space S is pushed out to the outside of space S as the resin is injected, and flows out into the air vent pipe T2 through the air vent groove 3d, the large diameter section 22b of the air vent hole 22, and then the small diameter section 22a. This flow of resin and air is represented by the dashed arrows in the figure.

[0026] Next, we will describe the seismic reinforcement structure using the shear key K described above. First, a horizontal hole H is drilled in the existing beam B or existing column P of the existing frame A. The inner diameter of this horizontal hole H is slightly larger than the outer diameter of the main body 1 of the shear key K and is approximately the same as the outer diameter of the fitting portion 3a. Also, the depth (axial length) of the horizontal hole H is slightly longer than the length from the tip side to the tip of the flange 2 of the shear key K.

[0027] Next, the main body 1 of the shear key K is inserted into the horizontal hole H. At this time, it is preferable to place the dimensional adjustment packing R at the tip of the main body 1 of the shear key K, as shown in Figure 3. When inserting the main body 1 into the horizontal hole H, it is necessary to align (align) the axes of the shear key K and the horizontal hole H, but since the shear key K is equipped with an automatic alignment part 3 as described above, alignment can be performed simply by inserting it. The movement of this automatic alignment will be explained using Figure 5.

[0028] First, Figure 5(a) shows the moment when the main body 1 of the shear key K is inserted into the horizontal hole H, and the tip side of the flange 2 is just before it contacts the outer surface of the existing structure A. Note that in Figure 5, the existing structure A is shown in cross-section. In this figure, the axis of the main body 1 is located slightly below the axis of the horizontal hole H. Therefore, the opening edge He of the horizontal hole H is in contact with the guide part 3b of the automatic centering part 3. If the main body 1 is further inserted into the horizontal hole H from this state, it will be in the state shown in Figure 5(b). As shown in Figure 5(b), the main body 1 moves to the right in the drawing, but the guide part 3b and the opening edge He of the horizontal hole H also move slightly upward in the drawing due to contact. As a result, the difference between the axis of the main body 1 and the axis of the horizontal hole H becomes smaller. Then, when the main body 1 is inserted, as shown in Figure 5(c), the fitting portion 3a of the automatic centering unit 3 fits into the horizontal hole H, and the axis of the main body 1 and the axis of the horizontal hole H coincide.

[0029] Then, in this state, fixing screws (not shown) are passed through the screw holes 23 to fix the flange 2 to the existing structure A. This allows the shear key K to be firmly fixed to the existing structure A. In addition, since there are three screw holes 23 on the same circumference and at equal intervals, the flange 2 can be fixed so that a uniform force is applied to its surface.

[0030] Next, resin is injected into the space S between the main body 1 of the shear key K and the horizontal hole H. For example, epoxy resin can be used as the resin. The resin flows into the space S from the resin injection pipe T1 through the injection hole 21 formed in the flange 2, and further through the injection groove 3c formed in the self-aligning part 3. The air in the space S that is pushed out by the injection of this resin flows out into the air vent pipe T2 through the air vent groove 3d formed in the self-aligning part 3, and further through the air vent hole 22 formed in the flange 2. When resin flows out of the air vent pipe T2 instead of air, it indicates that the space S has been sufficiently filled with resin, and the resin injection is terminated. Since a packing 5 is provided between the flange 2 and the outer wall of the existing structure A, it is possible to prevent the resin from leaking out from between the flange 2 and the outer wall of the existing structure A.

[0031] In this way, the tip of the shear key K is fixed to the existing structure A. On the other hand, the rear end of the shear key K is located within the indirect joint 100, surrounded by the spiral hoop 6. Figure 6 shows the reinforcing steel frame F fixed to the existing SRC structure A via the indirect joint 100. Specifically, Figure 6(a) shows the reinforcing beam RB fixed to the existing beam B, and Figures 6(b) and (c) show the reinforcing column RP fixed to the existing column P. The existing beam B includes beam steel Bf, shear reinforcement B1, and surrounding reinforcement B2. Similarly, the existing column P includes column steel Pf, shear reinforcement P1, and surrounding reinforcement P2.

[0032] In Figure 6(b), the shear keys K are arranged in a single row vertically, whereas in Figure 6(c), the shear keys K are arranged in two staggered rows vertically. The arrangement in Figure 6(b) is suitable when the surrounding reinforcement P2 of the existing column P is not located in the center in the width direction, while the arrangement in Figure 6(c) is suitable when it is located in the center in the width direction. In Figure 6(c), the shear keys are arranged in a staggered pattern, meaning that the shear keys K of the first row and the shear keys K of the second row are arranged alternately in the height direction, and both shear keys are not located at the same height. This arrangement is preferable when the distance between the first row and the second row in the adjacent direction (width direction) is small.

[0033] Since these structures are basically similar, only Figure 6(a) will be explained. First, high-strength mortar or high-strength concrete is poured into the poured portion 101 of the indirect joint 100. Shear reinforcement bars 102 and surrounding reinforcement bars 103 are inserted into this poured portion 101 to resist shear forces. Headed studs 104 are also inserted into the poured portion 101. The tips of these headed studs 104 are welded to the reinforcing beam RB. This fixes the reinforcing beam RB and the indirect joint 100.

[0034] In this way, the tip end of the shear key K is located within the existing frame A, and the rear end is located within the indirect joint 100, thereby fixing the existing frame A, the indirect joint 100, and furthermore, the reinforcing steel frame F. However, in a structure in which a rod-shaped member like the main body 1 is inserted into a horizontal hole H, there is a risk that the main body 1 may come out of the horizontal hole H if a horizontal force is applied. In contrast, the shear key K according to the present invention has a first annular groove 11 formed in the circumferential direction on the tip end. When resin is injected into the space S, this first annular groove 11 is naturally also filled with resin. That is, in the radial direction, the resin is convex and the first annular groove 11 is concave, so when a horizontal rearward force is applied to the shear key K, the convex part of the resin catches on the concave part of the first annular groove 11, preventing the shear key K from coming out. In addition, because the bonding area between the resin and the inner surface of the horizontal hole H is large, even an existing frame A with low strength has sufficient pull-out resistance. Furthermore, a second annular groove 12 is formed in the circumferential direction on the rear end side of the shear key K, and since it is covered with high-strength mortar or the like, it is possible to suppress the shear key K from coming loose from the indirect joint 100 of the main body 1.

[0035] In Figures 6(b) and 6(c), the shear key K faces the flange of the column steel Pf of the existing column P, so the embedding depth of the main body 1 (depth of the horizontal hole H) is somewhat shallow at about 115 mm. However, it has been confirmed that the shear key K according to the present invention can fully perform its function even with such a shallow embedding depth due to the action of the first annular groove 11 and the second annular groove 12. When using a post-installed anchor, the embedding depth is required to be 13 times its diameter, so if the diameter is 19 mm, the embedding depth will be 247 mm. Therefore, a post-installed anchor cannot be used for an existing SRC structure A where the distance between the flange of the column steel Pf and the column surface is about 120 mm to 130 mm.

[0036] Next, the operation of the ring member 4 of the shear key K according to the present invention will be explained using Figure 7. Figure 7(a) is a diagram showing the stress distribution when a shear force is applied to an earthquake-resistant reinforcement structure using the shear key K according to the present invention. In this experiment, the thickness of the ring member 4 is 10 mm, and the embedding depth (the length inserted into the horizontal hole H in the main body 1) is 115 mm. The strength of the concrete on the existing structure A side is generally 18 N / mm². 2 However, in the experiment, the strength was slightly weaker at 17 N / mm². 2 The material used was [unspecified]. On the other hand, the high-strength mortar for the cast portion 101 of the indirect joint 100 had a strength of 50 N / mm². 2 The following was used. The figure shows the shear key K, and strain gauges were attached to its surface at positions g1 to g7, and the strain was measured.

[0037] In this figure, a downward force Q is applied to the reinforcing steel frame F, and the strain values ​​(measured by strain gauges) when a shear force is generated between the indirect joint 100 and the existing structure A are shown as broken lines. p1 to p7 in the figure are the values ​​measured by strain gauges at positions g1 to g7, respectively. Since this strain distribution is similar to the bending moment diagram (bending moment distribution) of the main body 1, the strain distribution and bending moment distribution will be described as the same thing below.

[0038] First, we estimate the strain values ​​at the leading edge of the region where the force Q acts on the reinforcing steel frame F side, and at the trailing edge of the existing frame A side where shear force acts (hereinafter referred to as the reinforced side leading edge strain value and the existing side trailing edge strain value, respectively). Specifically, the point obtained by extending the endpoint p4 of line segment p3p4 to the surface position on the trailing edge of flange 2 is defined as the reinforced side leading edge strain value p8. On the other hand, the point obtained by extending the endpoint p5 of line segment p6p5 to the surface position on the leading edge of flange 2 is defined as the existing side trailing edge strain value p9. At this time, the bending moment distribution at the boundary between the reinforced side and the existing side is the line segment p8p9 (line segment L). Since shear stress is the slope of the bending moment distribution, the shear stress at the flange 2 portion is the slope of line segment L.

[0039] As can be seen from this figure, since the flange 2 is cut off by the ring member 4, the bending moment at both the rear end and front end surfaces of the flange 2 is reversed, and a shear force Q is generated that balances the applied force Q. The stress distribution due to the applied force Q (shear force Q) is considered to be a straight line in the elastic range. In the figure, these straight lines are represented as SD1 and SD2. Note that Q is the integral value of the region enclosed by the straight line SD2 and the dotted line, excluding the region where the sign is reversed (the cancelout region, the region colored in gray).

[0040] On the other hand, Figure 7(b) shows the stress distribution when a shear force is applied to an earthquake-resistant reinforcement structure using the shear key K according to the present invention, with the ring member 4 removed. In this case, the force Q also acts on the flange 2, so the point obtained by extending the endpoint p4 of the line segment p3p4 to the surface position on the tip side of the flange 2 is used as the reinforced side tip strain value p10. At this time, the bending moment at the boundary between the reinforced side and the existing side is the line segment p10p9. This line segment p10p9 is a vertical line and its slope is infinite. That is, it indicates that a very large stress concentration occurs in this part. However, in reality, the stress concentration is mitigated as the failure progresses from this part towards the existing structure A, which has lower strength.

[0041] Here, we assume that line segment L is translated such that one of its endpoints p8 becomes point p10, resulting in line segment L'. At this time, considering the reduction in strength due to the failure of the existing structure A, we assume that the slope of line segment L' is 85% of the slope of line segment L. Then, the other endpoint of line segment L' becomes p9'. Then, we define the existing rear end strain value p11 as the point obtained by extending the endpoint p9' of line segment p6p9' to the surface position on the tip side of flange 2. In other words, the bending moment on the existing structure A side is line segment p6p9'p11. Note that the shear force Q' at this time is approximately 85% of the applied force Q.

[0042] As shown in Figure 7(a), when the ring member 4 is provided, the stress d on the reinforcing steel frame F side and the stress e on the existing frame A side are approximately the same. On the other hand, as shown in Figure 7(b), when the ring member 4 is not provided, the stress f on the existing frame A side is approximately 1.5 times the stress d on the reinforcing steel frame F side. The strength of the existing frame A is 17 N / mm². 2 The fact that the strength of the reinforcing steel frame F side is 50 N / mm 2 Considering this, it is thought that fracture occurs early in region R. As a result, stress disappears in region R, and the stress distribution becomes a straight line represented by SD4. Note that Q' is the integral value of the region enclosed by the straight line SD4 and the dotted line, excluding the region where the sign is reversed (cancellation region, the region colored in gray). When Q' is calculated by simulation, it is found to be approximately 84% of Q, which is roughly in agreement with the assumption that the gradient of line segment L' is 85% of the gradient of line segment L.

[0043] Thus, in the seismic reinforcement shear key K and the seismic reinforcement structure using it according to the present invention, by providing the ring member 4, stress concentration in the existing frame A can be alleviated and a decrease in load-bearing capacity can be prevented. [Industrial applicability]

[0044] This invention can be used as a seismic reinforcement technique for existing reinforced concrete (RC) or steel-reinforced concrete (SRC) structures. [Explanation of Symbols]

[0045] A: Existing structure F: Reinforced steel frame H:Horizontal hole He: opening edge K: Shear key for seismic reinforcement (shear key) S: Space 1: Main body 11: First Circular Groove 12: Second Circular Groove 2: Flange 21: Injection hole 22: Air vent 3: Automatic alignment part 3a: Inset part 3b: Information department 4: Ring component 100: Indirect joint

Claims

1. A seismic reinforcement shear key used in seismic reinforcement structures that attach a reinforcing steel frame to an existing RC or SRC structure via an indirect joint, The aforementioned seismic reinforcement shear key is A solid rod-shaped main body portion, whose front and rear ends are positioned across the existing beam or column of the existing structure and the indirect joint, A flange provided in the middle portion of the main body, A ring member made of an elastic material that is fitted onto the flange without being fixed in the radially outward direction, A shear key for seismic reinforcement, characterized by having the following features.

2. The main body is, A fitting portion having an outer diameter approximately the same as the inner diameter of the horizontal hole formed in the existing beam or column is provided on the tip side of the flange, A guide portion is provided on the tip side of the aforementioned fitting portion, the outer diameter of which decreases as it approaches the existing structure. A seismic reinforcement shear key according to claim 1, characterized by having the following features.

3. The main body is, A first annular groove is formed circumferentially on the tip side of the flange, A second annular groove is formed circumferentially on the rear end side of the flange, A seismic reinforcement shear key according to claim 1 or 2, characterized by comprising the features described above.

4. A seismic reinforcement structure in which a reinforcing steel frame is attached to an existing RC or SRC structure via an indirect connection, A seismic reinforcement shear key having a solid rod-shaped main body and a flange provided in the middle of the main body, The flange comprises a ring member made of an elastic material that is fitted onto the flange without being fixed in the radially outward direction, A horizontal hole is formed in the existing beam or column of the existing structure. The main body of the seismic reinforcement shear key is inserted into the horizontal hole from its tip side until the flange substantially abuts against the outer surface of the existing structure. The ring member and the rear end portion of the seismic reinforcement shear key, opposite to the tip side from the flange, are located at the indirect joint. An earthquake-resistant reinforcement structure characterized in that resin is injected from an injection hole formed in the flange into the space between the main body and the horizontal hole.

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