Anchor plate and base isolation structure

Abstract

To suppress a height of a base isolation structure.SOLUTION: An anchor plate 24 has a flat plate shape with a hole 41 in the center, and a plurality of bolt fixing parts (through holes 42) to which tips of a plurality of anchor bolts are respectively fixed are disposed in an annular shape around the hole 41.The anchor plate 24 may be a circular annular plate having a predetermined width. The plurality of bolt fixing parts (through-holes 42) may be arranged at substantially equal intervals in a circumferential direction. The bolt fixing portion may be a through hole 42 through which the anchor bolt is inserted.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a seismic isolation structure for ensuring the seismic safety of a building, and to an anchoring plate used therein. [Background technology]

[0002] Patent Document 1 discloses a seismic isolation structure having a lower foundation structure, a seismic isolation device fixed thereon, and an upper foundation structure further fixed thereon. When a seismic isolation device is fixed to the lower or upper foundation structure via anchor bolts, the concrete of the foundation structure may collapse in a cone shape due to the tensile force generated in the anchor bolts. There are several methods to prevent this, but the most basic method is to lengthen the anchor bolts and increase the area of ​​the collapse surface when the cone collapses. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-155928 Summary of the Invention [Problem to be solved by the invention]

[0004] However, making the anchor bolts longer requires making the foundation structure thicker, which increases the overall height of the seismic isolation layer. If the seismic isolation layer is taller, more soil must be excavated to bury it underground, which increases costs. The present invention aims to solve these problems by reducing the height of the seismic isolation layer. [Means for solving the problem]

[0005] The fixing plate is flat with a hole in the center, and a plurality of bolt fixing portions to which the tips of a plurality of anchor bolts are respectively fixed are arranged in a ring shape around the hole. The seismic isolation structure includes a lower foundation structure, a seismic isolation device fixed on the lower foundation structure, and an upper foundation structure fixed on the seismic isolation device. The lower foundation structure or the upper foundation structure includes a concrete body and the anchor plate embedded in the concrete body. The seismic isolation device is fixed to the concrete body via a plurality of anchor bolts fixed to the anchor plate. Effect of the Invention

[0006] According to the above-mentioned fixing plate and seismic isolation structure, the area of ​​the fracture surface when the tensile force generated in the anchor bolt causes a cone-shaped fracture can be increased, so that the anchor bolt can be shortened accordingly and the height of the seismic isolation layer can be reduced. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a side view showing an example of a seismic isolation structure. [Diagram 2] FIG. 4 is a side cross-sectional view showing an example of a lower foundation structure. [Diagram 3] FIG. [Figure 4] FIG. 13 is a plan view showing an example of cone-shaped destruction. [Diagram 5] FIG. 4 is a side cross-sectional view showing the cone-shaped breakage. [Figure 6] FIG. 11 is a plan view showing an example of cone-shaped destruction in a comparative example. [Figure 7] FIG. 4 is a side cross-sectional view showing the cone-shaped breakage in the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The seismic isolation structure 10 will be described with reference to FIG. The seismic isolation structure 10 has, for example, a lower foundation structure 12, a seismic isolation device 13, and an upper foundation structure 14. The lower foundation structure 12 is fixed onto the ground or foundation pillars (+Z direction), for example. The seismic isolation device 13 is fixed to the top (+Z direction) of the lower foundation structure 12 via a plurality of anchor bolts 15. Similarly, the upper foundation structure 14 is fixed above (in the +Z direction) the seismic isolation device 13 via a plurality of anchor bolts. The upper foundation structure 14 supports the building. When the lower foundation structure 12 vibrates due to an earthquake or the like, the seismic isolation device 13 absorbs the vibration and suppresses the vibration transmitted to the upper foundation structure 14, thereby suppressing the shaking of the building supported by the upper foundation structure 14.

[0009] The lower foundation structure 12 will be described with reference to FIG. The lower foundation structure 12 has, for example, a concrete body 21 and an anchor plate 24 . The concrete body 21 has a plurality of bolt holes 22 for inserting the anchor bolts 15. The concrete body 21 may be, for example, precast concrete or cast-in-place concrete. The bolt holes 22 may have female threads that screw together with the anchor bolts 15, or may be inserts embedded in the concrete body 21. The anchor plate 24 is embedded in the concrete body 21. In addition to the anchor plate 24, reinforcing bars or the like may be embedded in the concrete body 21 to reinforce the concrete body 21.

[0010] The fixing plate 24 will be described with reference to FIG. The anchor plate 24 is, for example, a flat steel plate with a hole 41 in the center. The anchor plate 24 is, for example, an annular plate having a predetermined width. That is, the outer periphery is circular, and the circular hole 41 is provided concentrically with the outer periphery. This allows the anchor plate 24 to exert a substantially constant strength regardless of the direction of the force acting on the seismic isolation structure 10. However, the outer periphery and inner periphery of the anchor plate 24 are not limited to being circular, and may be of another shape, such as a rectangle. The fixing plate 24 is also provided with a plurality of through holes 42 for fixing the tips of the anchor bolts 15. The through holes 42 are an example of a bolt fixing portion. The through holes 42 are, for example, through holes through which the anchor bolts 15 are inserted, and the anchor bolts 15 are fixed to the fixing plate 24 by screwing a nut onto the tips of the anchor bolts 15 inserted into the through holes 42. The through holes 42 are, for example, arranged at approximately equal intervals in the circumferential direction. That is, the through holes 42 are arranged at positions that are approximately equidistant from the center of the fixing plate 24, and at intervals that are approximately equal in angle as viewed from the center of the fixing plate 24.

[0011] 4 and 5, the cone-shaped collapse of the lower foundation structure 12 will now be described. For example, as shown by the arrows in Figure 1, if a shear force 81 (see Figure 1) in the -X direction acts on the lower foundation structure 12, a shear force 82 (see Figure 1) in the opposite direction, in the +X direction, acts on the upper foundation structure 14. As a result, a pull-out force 83 acts on the anchor bolt 15 on the -X side, and conversely, a push-in force acts on the anchor bolt 15 on the +X side. The largest pull-out force 83 acts on the anchor bolt 15 closest to the -X side, but since the tip of the anchor bolt 15 is fixed to the anchor plate 24, cone-shaped destruction occurs in the area 91 surrounded by the destruction surface 92 having a cone side extending from the outer periphery of the anchor plate 24 and the destruction surface 93 having an inverted cone side extending from the inner periphery of the hole 41.

[0012] A lower foundation structure 12Z of a comparative example will be described with reference to FIGS. In the lower foundation structure 12Z, instead of the fixing plate 24, a plurality of fixing plates 24Z to which the respective anchor bolts 15 are separately fixed are embedded in the concrete body 21. In the comparative example, the largest pull-out force 83 acts on the anchor bolt 15 furthest on the -X side, and an area 91Z surrounded by a cone-shaped fracture surface 94 extending from the outer periphery of the fixing plate 24Z undergoes cone-shaped fracture. However, if cone-shaped destruction occurs around the anchor bolt 15 on the -X side, that anchor bolt 15 will no longer function, so the force will be concentrated on the anchor bolt 15 on the -X side next, causing a chain reaction of cone-shaped destruction. For this reason, the area of ​​the fracture surface 94 must be large so as to be able to withstand the expected maximum load.

[0013] In contrast, in the seismic isolation structure 10, if the length of the anchor bolt 15 is the same as that of the comparative example, the total area of ​​the failure surfaces 92 and 93 is larger than the failure surface 94. Therefore, the length of the anchor bolt 15 required to withstand the same load is shorter than that of the comparative example. Since the anchor bolts 15 can be short, the height of the lower foundation structure 12 can be reduced accordingly, and therefore the height of the entire seismic isolation structure 10 can be reduced.

[0014] If the anchor plate 24 is an annular plate having a predetermined width, it can exert approximately the same strength regardless of the direction of the force acting on the seismic isolation structure 10. If the bolt fixing parts such as the through holes 42 are arranged at approximately equal intervals in the circumferential direction, the seismic isolation structure 10 can exhibit approximately the same strength regardless of the direction of the force acting on it. Although a description of the upper foundation structure 14 is omitted, it may have a similar configuration to the lower foundation structure 12.

[0015] The above-described embodiment is an example for facilitating understanding of the present invention. The present invention is not limited thereto, and includes various modifications, changes, additions, or deletions without departing from the scope defined by the appended claims. This can be easily understood by those skilled in the art from the above description.

[0016] Seismic isolation structures are often used to ensure the earthquake safety of buildings. Therefore, streamlining the joints of seismic isolation devices through ingenuity has a large impact on costs, etc. In general, when planning a seismic isolation layer, it is desirable to keep the height of the base under the isolation to a minimum in order to reduce the height of the seismic isolation layer and the amount of soil excavated. However, the height of the base isolation is often determined by the length of the anchor bolts, which is determined by the examination of tensile cone destruction, and so an appropriate height is required. Therefore, the amount of excavated soil is reduced by increasing the anchor bolt's resistance to tensile cone-shaped fracture, shortening the anchor bolt length, and reducing the height of the seismic isolation foundation. Generally, when considering the tension cone of an anchor bolt, the required length of the anchor bolt is determined by considering one outermost bolt, which has the greatest tensile force, assuming that the assumption of maintaining a flat surface during horizontal deformation of the seismic isolation device holds true. By making the anchor bolt tip a one-piece ring-shaped anchor plate, the bolt on the tension side is able to resist the tensile force as a whole. This prevents the anchor bolt length from being determined solely by considering the outermost bolt. The ring-shaped anchor plate can also be used as an anchor bolt guide when converting seismic isolation foundations into PCa. Compared to when the required length of the anchor bolt is determined only by considering the outermost end where the tensile force is the greatest, the tensile force can be borne by the tension side bolt as a whole, so the required length of the anchor bolt can be shortened and the height of the seismic isolation foundation can be reduced. As a result, rationalization can be achieved by reducing the height of the seismic isolation layer and the amount of excavated soil, leading to cost reduction and reduced environmental impact. [Explanation of symbols]

[0017] 10 seismic isolation structure, 12,12Z lower foundation structure, 13 seismic isolation device, 14 upper foundation structure, 15 anchor bolt, 21 concrete body, 22 bolt hole, 24,24Z anchor plate, 41 hole, 42 through hole, 81,82 shear force, 83 pull-out force, 91,91Z range, 92~94 failure surface.

Claims

1. It is a flat plate with a hole in the center. A plurality of bolt fixing portions to which the tips of the plurality of anchor bolts are respectively fixed are arranged in an annular shape around the hole. Fixing plate.

2. The fixing plate is a circular plate having a predetermined width. The fixing plate of claim 1.

3. The bolt fixing portions are arranged at substantially equal intervals in the circumferential direction. The fixing plate of claim 2.

4. The bolt fixing portion is a through hole through which the anchor bolt is inserted. The fixing plate according to any one of claims 1 to 3.

5. A lower foundation structure; A seismic isolation device fixed on the lower foundation structure; An upper foundation structure fixed on the seismic isolation device; Equipped with The lower foundation structure or the upper foundation structure is A concrete body, An anchor plate according to any one of claims 1 to 3 embedded in the concrete body; having The seismic isolation device is fixed to the concrete body via a plurality of anchor bolts fixed to the fixing plate. Earthquake-resistant structure.

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