JP2673192B2 - Seismic isolation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a seismic isolation device configured by arranging an elastic body and a steel rod side by side between a building structure and a foundation.

<< Prior Art >> As shown in FIG. 2, a conventional seismic isolation device is an elastic body that is elastically deformed by a horizontal seismic force while supporting a vertical load between a building structure 1 and a foundation 2. 3 and a steel rod 4 having a constant cross-sectional area that is plastically deformed by elastic deformation due to horizontal seismic force have been proposed (see JP-A-60-223576). In this proposal, the upper and lower ends 4a, 4b of the steel rod 4 are loosely fitted to the structure 1 and the foundation 2 to form a simple support.

<< Problems to be Solved by the Invention >> By the way, in the above-described seismic isolation device, since the cross-sectional area of the steel rod 4 is set to be the same from the foundation 2 side to the building structure 1 side along the axial direction, A high stress is generated in the rod 4 substantially in the central portion in the axial direction corresponding to the moment distribution generated at the time of the earthquake, and as a result, a large elastic strain is concentrated only in the central portion of the steel rod 4 and not in the central portion of the steel rod 4. Was to occur. For this reason, the range of seismic force that can absorb energy by elastically deforming the steel rod 4 is relatively narrow due to the rigidity and proof stress of the central part of the steel rod 4, and it is widely applicable from small to medium earthquakes to large earthquakes. There was a problem that I could not do it. That is, when the steel rod 4 is designed with a large constant cross-sectional area in consideration of the rigidity and proof stress of the central portion, the steel rod 4 exhibits a preferable energy absorbing action against a large seismic force, but a steel sheet against a small seismic force. If the steel bar 4 is designed with a small constant cross-sectional area, it will be suitable for seismic isolation because the rigidity of the bar 4 is too high to cause sufficient elastic deformation and thus plastic deformation. However, there is a problem in that it cannot easily obtain a wide energy absorption function in any case because it is easily broken or broken against a large seismic force.

Therefore, in general, the steel rod 4 is designed with a constant cross-sectional area corresponding to such an earthquake in order to exert an effective energy absorbing action against the frequent earthquake, but a large earthquake occurs. In this case, the deformation could not follow and there was a risk of breaking.

Considering that a large relative movement occurs between the foundation 2 and the building structure 1 due to the action of a large seismic force,
It is conceivable to lengthen the steel rod 4 in order to set a large allowable deformation amount corresponding to this relative movement amount in the steel rod 4.
In this case, the elastic deformation region of the steel rod 4 is widened, and only elastic deformation occurs in the range of small and medium-sized earthquakes, so that sufficient seismic energy absorption capacity cannot be obtained.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a seismic isolation device that can be applied over a wide range from small earthquakes to large earthquakes.

<< Means for Solving the Problem >> The present invention relates to an elastic body that is elastically deformed between a building structure and a foundation in order to buffer the horizontal seismic force while supporting the load of the building structure, and a horizontal earthquake. In a seismic isolation device in which a steel rod that is elastically plastically deformed to absorb force is installed side by side, the steel rod is
The intermediate part is formed with a uniform cross-sectional area, and the lower part and the upper part are formed with a uniform cross-sectional area having a larger diameter and a smaller diameter than the intermediate part, and between the lower part and the intermediate part and between the intermediate part and the upper part, respectively The cross-sectional area of is gradually reduced along its axial direction to form a tapered tapered portion,
The lower part of the steel rod is fixed to the foundation, and the upper part of the steel rod is directly penetrated into the spherical member provided in the building structure.

<Operation> To describe the operation of the present invention, a steel bar that functions as a damper is formed with a uniform cross-sectional area in the middle part, and the lower and upper parts have a uniform cross-sectional area with a larger diameter and a smaller diameter than the intermediate part. In addition, since the cross-sectional area between the lower part and the middle part and between the middle part and the upper part was gradually reduced along the axial direction to form a tapered taper part, the steel bar was Regarding the generated stress distribution, in the tapered portion connecting the intermediate portion and each of the upper portion and the lower portion, the stress generated along the axial direction of these portions can be made uniform, and the energy can be reasonably and efficiently absorbed.

And, in particular, regarding the deformation mode of the entire steel rod, since the intermediate portion of the steel rod is formed with a uniform cross-sectional area and the intermediate portion where the bending stress gradually increases is secured between the tapered portions, the cross-sectional area is gradually increased. The bending stress generated in the upper tapered portion between the smaller intermediate portion and the upper portion can be reduced with respect to the intermediate portion that follows the upper portion. Since the bending stress is gradually increased in the intermediate portion in this way to reduce the bending stress in the upper tapered portion, it is possible to suppress the amount of bending deformation of the upper portion of the steel rod that engages with the spherical member. In other words, at the same time as increasing the deformability of the steel rod itself that functions as a damper, the steel rod with improved deformability and the spherical member on the upper part of the steel rod that has a limited rotation angle range should be designed in harmony with each other. You can Although it is preferable from the viewpoint of the damper function that the steel rod can be deformed greatly, the bending deformation amount at the top of the steel rod becomes extremely large for this reason, and the spherical member must rotate in a large rotation angle range corresponding to this deformation amount. If it is not possible, the spherical member becomes an obstacle, and the steel rod cannot exert a sufficient damper function, and the seismic isolation device cannot be realized as expected. In the present invention,
Based on the technical premise that the upper part of the steel rod is rotatably attached to the building structure, the steel rod can function like a beam of equal strength by gradually reducing the uniform cross-section area and the cross-sectional area. Since the taper portion and the taper portion are alternately combined, the amount of bending deformation of the upper portion of the steel rod, which is the portion to be joined with the spherical member, is effectively suppressed while securing a considerable deformability for the steel rod. As a result, it is possible to smoothly bend and deform the steel rod and sufficiently absorb energy while preventing the spherical member from interfering with the damper function.

Regarding the connection between the upper part of the steel rod and the spherical member, since the upper part of the steel rod was directly penetrated into the spherical member provided in the building structure, when the steel rod undergoes bending deformation to rotationally displace the spherical member, the lower part The spherical member can be directly rotated by the upper part of the steel rod itself which is structurally a continuous body from the top to the upper part, and the upper part of the steel rod is engaged with the spherical member in the form of penetration. Therefore, with this configuration, it is possible to ensure the withdrawal from the spherical member at the upper part of the steel rod, which is required when the steel rod is bent and deformed, with an extremely simple configuration. As a result, the function as a damper can be expected in a wide range from small deformation to large deformation.

«Examples» Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of a seismic isolation device according to the present invention.

The present invention basically includes an elastic body that is elastically deformed between the building structure 5 and the foundation 6 to support the load of the building structure 5 and buffer the horizontal seismic force, and the horizontal seismic force. In a seismic isolation device in which a steel rod 7 that is elastically plastically deformed to absorb is installed side by side, the steel rod 7 has an intermediate portion 7c formed with a uniform cross-sectional area, and a lower portion 7a and an upper portion 7b are respectively formed from the intermediate portion 7c. Is also formed with a large cross-sectional area of large diameter and thin diameter, and the lower part 7a
From the intermediate portion 7c to the intermediate portion 7c and between the intermediate portion 7c and the upper portion 7b are formed by taper portions 7d and 7e that are tapered by gradually reducing their cross-sectional areas along the axial direction.
The lower portion 7a of the steel rod 7 is fixed to the foundation 6, and the upper portion 7b of the steel rod 7 is formed by directly penetrating the spherical member 8 provided in the building structure 5.

The seismic isolation device of the present embodiment is interposed between an upper foundation 5 on the side of a building structure and a lower foundation 6 on the ground side, supports a vertical load, and elastically deforms against a horizontal load such as seismic force. Elastic body (not shown) and elastic deformation against horizontal load,
The steel rod 7 is plastically deformed.

The lower portion 7a of the steel rod 7 is formed with a uniform cross section, and the lower portion 7a is connected to the intermediate portion 7c by a first tapered portion 7e formed so that the diameter gradually decreases upward. There is. The middle portion 7c is formed with a uniform cross section having a smaller diameter than the lower portion 7a, and the middle portion 7c is formed by a second tapered portion 7d formed so as to have a diameter gradually decreasing upward. It is linked to 7b. The upper portion 7b is formed with a uniform cross section having a smaller diameter than the middle portion 7c.

As for the steel rod 7, only the lower portion 7a is inserted and fixed to the lower foundation 6 like a cantilever, and the lower portion 7a is fixed as described above.
From the top to the upper part 7b is tapered in the axial direction,
The structure is such that the upper portion 7b is connected to the damper receiving steel frame 9 fixed to the lower portion of the upper foundation 5 via the spherical plain bearing 8. The steel rod 7 of this embodiment is a steel rod having a circular cross section,
For example, the diameter of the lower part 7a is 160 mm, the diameter of the middle part 7c is 140 mm,
The upper part 7b has a tapered shape with a diameter of 70 mm. By adopting a cantilever-like mounting structure of this steel rod 7 and adopting a tapered shape from the lower portion 7a to the upper portion 7b, the steel rod 7 has a larger cross-sectional area corresponding to the generated moment and the steel rod is reduced as the moment is reduced. The cross-sectional area of 7 is set to be gradually smaller. Therefore, the plastic strain does not concentrate locally, and is generated substantially uniformly from the lower portion 7a to the upper portion 7b of the steel rod 7. As a result, the steel rod 7 can be sufficiently deformed in a wide range from small and medium-sized earthquakes to huge earthquakes, and functions as a damper in a wide range from small deformation to large deformation.

Further, a reinforcing member 10 for increasing rigidity is arranged between the lower portions 7a of the pair of left and right steel rods 7.

On the other hand, as in the conventional structure, the elastic body is formed by alternately laminating a flat elastic sheet made of neoprene rubber or the like and a metal sheet made of metal in the same shape with an adhesive interposed. Then, flat plate-shaped end plates are attached to both ends thereof, and each end plate is fixed to the upper base 5 and the lower base 6, respectively.

Further, although the steel rod 7 is replaced after a large earthquake, the steel rod 7 cannot be attached or detached with bolts because the lower portion 7a supporting the moment is embedded in the lower foundation 6. Therefore, the installation and removal work is performed in the following procedure. First, when removing, the spherical plain bearing 8 is removed from the damper receiving steel base 9, and then the steel rod 7 is slid upward. For this purpose, the upper foundation 5 is provided with an upwardly extending hole 5a for absorbing the displacement of the steel rod 7. Further, this hole 5a is formed so as to widen outward so that the steel rod 7 can be drawn to the outside. Next, the lower portion 7a of the steel rod 7 is lifted upward, extracted from the lower foundation 6 and then pulled out in the lateral direction, and thus the steel rod 7 is taken out between the upper structure 5 and the lower foundation 6. This completes the work of removing the steel rod 7. When the steel rod 7 is attached, the above procedure may be reversed.

<< Effects of the Invention >> As described above, according to the seismic isolation device of the present invention,
The steel rod functioning as a damper is formed such that the middle portion has a uniform cross-sectional area, and the lower and upper portions have a uniform cross-sectional area having a larger diameter and a smaller diameter than the intermediate portion, respectively. Since the cross-sectional area between the middle part and the upper part was gradually reduced along the axial direction to form a tapered taper part, regarding the stress distribution generated in the steel bar during an earthquake, In the tapered portion connecting each of the lower portions, the stress generated along the axial direction of these portions can be made uniform, and the energy can be reasonably and efficiently absorbed.

And, in particular, regarding the deformation mode of the entire steel rod, since the intermediate portion of the steel rod is formed with a uniform cross-sectional area and the intermediate portion where the bending stress gradually increases is secured between the tapered portions, the cross-sectional area is gradually increased. The bending stress generated in the upper tapered portion between the smaller intermediate portion and the upper portion can be reduced to the intermediate portion that follows the lower portion, and the bending deformation amount of the upper portion of the steel rod in engagement with the spherical member can be reduced. Can be suppressed. In this way, the steel rod is constructed by alternately combining the uniform cross-sectional area portion and the tapered portion that can be made to function like a beam of equal strength by gradually reducing the cross-sectional area. While ensuring the deformability of the, it is possible to effectively suppress the amount of bending deformation of the upper portion of the steel rod that is the mating portion with the spherical member, thereby preventing the spherical member from hindering the damper function, The steel rod can be smoothly bent and deformed to sufficiently absorb energy.

Regarding the connection between the upper part of the steel rod and the spherical member, since the upper part of the steel rod was directly penetrated into the spherical member provided in the building structure, when the steel rod undergoes bending deformation to rotationally displace the spherical member, the lower part The spherical member can be directly rotated by the upper part of the steel rod itself which is structurally a continuous body from the top to the upper part, and the upper part of the steel rod is engaged with the spherical member in the form of penetration. Therefore, with this configuration, it is possible to ensure the withdrawal from the spherical member at the upper part of the steel rod, which is required when the steel rod is bent and deformed, with an extremely simple configuration. As a result, the function as a damper can be expected in a wide range from small deformation to large deformation.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of a seismic isolation device according to the present invention, and FIG. 2 is a side sectional view showing an example of a conventional seismic isolation device. 5 …… Building structure (upper foundation) 6 …… Foundation (lower foundation) 7 …… Steel rod 7a …… One end of steel rod (lower) 7b …… The other end of steel rod (upper) 8 …… Spherical member

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenji Shirahama 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office (72) Inventor Manabu Endo 2-3-3 Kandaji-cho, Chiyoda-ku, Tokyo Stocks Obayashi Corporation Tokyo Head Office (72) Inventor Susumu Kondo 2-3 Kandajimachi, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office (56) Reference JP-A-63-114784 (JP, A)

Claims (1)

(57) [Claims] 1. An elastic body that is elastically deformed between a building structure and a foundation so as to absorb the horizontal seismic force while supporting the load of the building structure, and an elastic body for absorbing the horizontal seismic force. In a seismic isolation device in which a steel rod to be plastically deformed is installed side by side, the steel rod has a uniform cross-sectional area in the middle part, and the lower part and the upper part have a uniform cross section with a larger diameter and a smaller diameter than the intermediate part. The steel bar is formed by an area, and the cross-sectional area between the lower part and the middle part and between the middle part and the upper part is gradually reduced along the axial direction to form a tapered tapered part. A seismic isolation device characterized in that a lower part is fixed to the foundation, and an upper part of the steel rod is directly penetrated into a spherical member provided in the building structure.