JPH0615892B2 - Elastic-plastic damper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bending yield type elasto-plastic damper which is interposed in a joint portion of a structure and absorbs vibration energy generated in the structure due to an earthquake or the like. .

[Prior art and problems] Expansion joints should be installed between structures separated into structures for the purpose of countermeasures against thermal deformation and to prevent the occurrence of partial excessive stress during an earthquake. Is normal. Since the vibration characteristics of the structures separated by the expansion joint are different, the difference in the motion of each structure during the earthquake becomes large.

Therefore, conventionally, an oil damper or the like is interposed in a joint member that connects the structures, and the vibration energy is absorbed by utilizing the difference in movement during the vibration of the structures.

However, since the oil damper acts only on the force in one direction, it is necessary to sufficiently consider the movement of the structure before disposing it, and it is extremely difficult to determine the mounting direction. In addition, there is a drawback that the damping effect is low when vibrations occur simultaneously in multiple directions.

In recent years, for the purpose of seismic isolation of a structure, a seismic isolation structure has been developed in which a laminated rubber bearing or the like is installed between the lower end of the structure and the foundation. As an example of the damper used in the seismic isolation structure, as shown in FIG. 12, a steel rod 21 is attached to a reinforced concrete block 22 in a cantilever manner, and the periphery thereof is formed into a morning glory, and when a large horizontal force is applied. Has developed a bending yield type elasto-plastic damper in which a steel rod 21 is supported by a surrounding reinforced concrete block 22 (see JP-A-61-179972).

However, this type of elasto-plastic damper has a problem that since the damper main body is a steel rod, the yield load is small and the resistance moment cannot be large.

The present invention was developed in order to solve the problems of the conventional damper as described above, and when installing between structures, it is not necessary to determine the mounting direction and it functions in all directions in the horizontal plane. The purpose of the present invention is to provide an elasto-plastic damper in which the size of the yield load can be freely set and which has a large energy absorption capacity in the plastic region.

[Means for solving problems]

The elasto-plastic damper of the present invention is a bending yield type elasto-plastic damper interposed between structures to absorb seismic energy. The small diameter part in the center has a solid structure, and the remaining part has a hollow structure. It is composed of a drum-shaped damper body whose outer and inner diameters increase from the small diameter portion upward and downward in order to absorb energy due to bending yield, and base plates integrally provided at both ends of the damper body. .

The elasto-plastic damper is installed between the lower end of the structure and the foundation, an expansion joint, or the like, and the base plates at both ends are fixed to the separated structure.

A plurality of bolt insertion holes are bored in each base plate, and anchor bolts are passed through the insertion holes and fastened with a nut to fix the structure to the structure.

[Action]

Since the base plates at both ends are fixed to the structure in the elasto-plastic damper of the present invention, the bending moment when a horizontal force due to an earthquake acts changes linearly in the height direction of the elasto-plastic damper and at the ends. It becomes maximum and becomes 0 at the center.

On the other hand, in the elasto-plastic damper of the present invention, the small diameter part at the center of the damper main body has a solid structure and the remaining part has a hollow structure, and the smaller diameter part is sequentially moved upward and downward in accordance with the bending moment gradient. Due to the hourglass shape with a large outer diameter and inner diameter, when a large horizontal force is applied,
Sequentially, almost the entire damper body is yielded, and a large energy absorption force due to plastic deformation is exerted.

That is, energy absorption due to bending yield of the member is performed in the entire damper body, and by appropriately setting the cross-sectional rigidity of the hollow structure portion, elastic deformation up to a predetermined amount of force, and With respect to the above force, the entire damper body sequentially yields and plastically deforms, so that maximum energy absorption can be achieved.

The yielding of the damper body and the plastic deformation after yielding will be described later in examples, but due to an increase in horizontal force due to an earthquake, first, yielding occurs at the outer edge of the hollow structure portion of the damper body, except for the solid structure portion. , Sequentially (almost at the same time) longitudinal yield zones occur. Further, this yield region spreads inward in the horizontal section in the direction of action of the horizontal force, and the entire hollow structure yields from the outermost edge of the damper body toward the neutral axis.

For example, considering a cylindrical damper with a constant cross section,
Even if the horizontal section has the same cross-sectional area, the larger the outer diameter, the larger the section modulus, and the yield load can be set to some extent. However, in the case of a cylindrical damper, only the end with a large bending moment yields, the plastic deformation progresses only at the end, and the part between them does not yield (since the sectional rigidity is large against the bending moment, Remains within the elastic range), it will be destroyed at the end, and only energy will be absorbed accordingly.

On the other hand, in the elasto-plastic damper of the present invention, the entire damper main body yields and plastically deforms as described above, so that the damper main body has a large plastic deformation ability and accordingly a large amount of energy can be absorbed.

In the bending yield type elasto-plastic damper, the stress generated in the damper is dominated by the bending moment as a whole, but the shearing force (horizontal force itself) is generated in the actual cross section. Even in the central cross section, which may be zero at the bending moment, it must have a cross section capable of sufficiently resisting this shearing force. Therefore, although the central portion has a small diameter and is constricted, it is necessary to secure a certain size of the cross section, which is a solid structure. As a result, yielding due to bending moment does not occur, so the central part is not considered to be the yielding region (bumper part). However, having a solid structure in the central part also means stiffening to prevent buckling in the hollow structure part, and in reality part of the solid part also constitutes the damper part.

〔Example〕

 Hereinafter, the present invention will be described based on embodiments shown in the drawings.

FIG. 1 is a view in which the elasto-plastic damper A of the present invention is applied to an expansion joint 3 between adjacent structures 1 and 2, and a plurality of elasto-plastic dampers A are arranged along side surfaces of the structures 1 and 2. I am doing it.

FIG. 2 shows the elasto-plastic damper A of the present invention in the expansion joint 3 of FIG. 1 between the receiving portion 4 provided on one structure and the lower end surface of the sliding portion 5 of the expansion joint. The figure shows a state where the damper A is provided and is used as a direct coupling damper.

FIG. 3 shows a structure in which a plurality of elasto-plastic dampers A are arranged between the lower end surface of the upper beam 7 and the upper end surface of the wall 8 and between the upper end surface of the lower beam 9 and the lower end surface of the wall 8. 9 and the elasto-plastic damper A are fixed by the anchor bolt 10, and the wall 8 and the elasto-plastic damper A are fixed by the anchor bolt 10 or the PC steel material 11 passed through the wall 8. By connecting the beams 7 and 9 and the wall 8 via the elasto-plastic damper A, the elasto-plastic damper A absorbs the interlayer deformation due to the horizontal force so that the wall 8 is not deformed. Since the horizontal force applied to the wall 8 during an earthquake is determined by the energy absorption capacity of the damper A, if the wall has more strength than that, it will not be destroyed. That is, the wall does not need to be deformable, and only needs to have the required strength.

FIG. 4 shows an example in which the elasto-plastic damper A is provided only on the upper end surface of the wall 8, but the damper A is provided only on the lower end surface of the wall 8.
May be provided.

After the big earthquake, only damper A will be replaced and the wall will be used as it is. This also applies to the application examples shown in FIGS. 1 to 3 described above.

5 and 6 show a first embodiment of the elasto-plastic damper A.

The elasto-plastic damper A is a drum-shaped damper body 12 in which the outer diameter and the inner diameter gradually increase from the middle to the upper and lower sides.
And a base plate 13 that is integrally provided at both ends of the damper body 12, and has a small diameter portion 16 at the center.
Only the solid structure and the other parts are hollow.

A plurality of bolt insertion holes 14 are formed in the base plate 13 in accordance with the mounting positions of the anchor bolts 10,
The elasto-plastic damper A is attached by inserting the anchor bolt 10 into each of the bolt insertion holes 14 and screwing and fastening the nut 15 from the tip to the anchor bolt 10.

Here, consider a case where a horizontal force P acts on the tip of the damper main body 12 of the elasto-plastic damper A to which the base plate 13 is fixed as shown in FIG. At this time, the damper body 1
The bending moment diagram of No. 2 is as shown in FIG. (The horizontal line portion indicates the yield region.) Next, the resistance moment M _r of the damper body 12 is expressed by the following equation.

M _r = σ _b · Z (σ _b : bending stress degree, Z: sectional modulus) Since the damper body 12 has a hollow drum shape,
Since the section modulus Z gradually decreases from both ends toward the center, the bending stress σ _b is excluded except for the small-diameter portion of the central solid structure.
Always becomes almost constant and becomes a beam of so-called equal strength.

As the horizontal force P acting on the tip of the damper main body 12 increases, one point of the hollow portion of the damper main body 12 yields first, and then the yield area (vertical line portion in FIG. ) Occurs, and the yield region spreads further to the inside of the horizontal cross section, and the entire hollow portion of the damper body 12 yields from the outermost edge of the damper body 12 toward the neutral axis in the direction of the horizontal force P. The relationship between the horizontal force P and the deflection generated at the tip of the damper body 12 is obtained as shown in the graph of FIG. 8 (P _y is the load when one point of the hollow portion yields, and δ _y is the load Deflection at this time, P _max is the load when the whole yields, and δ _max is the deflection at that time).
It should be _{noted that, with} the load of P _max being maintained, the entire body is further plastically deformed to further increase beyond the deflection δ _max .

FIG. 9 shows a second embodiment of the elasto-plastic damper A.

In this embodiment, the taper portion 1 below the damper body 12
7 is formed to be longer than the upper tapered portion 18, and the small-diameter portion 16 having a solid structure is located slightly above the center.
The bending moment diagram in this embodiment is as shown in FIG.

FIG. 11 shows a third embodiment of the damper body 1
By filling the hollow part of 2 with concrete 20 (or lead 23), the buckling strength of the damper body 12 is enhanced,
The heat generated by the plasticization of the damper body 12 is absorbed, and the energy absorption capacity is improved by the cracking of the concrete and the friction after the cracking (or by the plastic deformation accompanying the shear yield of lead).

[Advantages of the Invention] Since the damper body has a small-diameter portion in the center and has a drum shape, it is not necessary to determine the mounting direction.

The small diameter part in the center is solid and has a structure that can withstand the shearing force generated by horizontal force, and the remaining part is a hollow structure that forms an hourglass shape in which the outside diameter and the inside diameter gradually increase from the middle to the upper and lower parts. Since almost all of the plastic is plastically deformed and the energy is absorbed by the entire damper body, the plastic deformation capacity is large and the energy absorption capacity is high.

The yield load can be freely set by changing the cross section of the damper body.

The central solid structure part has a stiffening effect which prevents buckling of the solid structure part.

Since the damper body and the base plate are integrated, they are compact and easy to install or replace in a building.

Since it can be integrally manufactured by casting or forging, the manufacturing is easy and the cost is low.

[Brief description of drawings]

FIG. 1 is a plan view showing an application example of the present invention, and FIG.
Side view showing the installation state of the elasto-plastic damper corresponding to the figure,
FIGS. 3 and 4 are side views showing other application examples, FIG. 5 is a perspective view showing a first embodiment of the present invention, and FIG. 6 is a sectional view showing an attached state of the elastoplastic damper of FIG. FIG. 7 is a bending moment diagram of the damper main body shown in FIG. 6, FIG. 8 is a graph showing the relationship between horizontal force P and deflection δ, and FIG. 9 is a sectional view showing a second embodiment of the present invention. FIG. 10 is a bending moment diagram of the damper body shown in FIG. 9, FIG. 11 is a sectional view showing a third embodiment of the present invention, and FIG. 12 is a sectional view showing a conventional example. A: Elasto-plastic damper 1, 2 ... Structure, 3 ... Expansion joint, 4 ... Receiving part, 5 ... Sliding part, 6 ... Foundation,
7, 9 ... Beam, 8 ... Wall, 10 ... Anchor bolt, 1
1 ... PC steel material, 12 ... damper body, 13 ... base plate, 14 ... bolt insertion hole, 15 ... nut,
16 ... Small diameter part, 17,18 ... Tapered part, 20 ...
Concrete, 21 …… Steel bar, 22 …… Reinforced concrete block, 23 …… Lead

Front Page Continuation (72) Inventor Kuniaki Sato Moto Akasaka 1-2-7, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Ban Shigeru Akasaka 1-2-7, Minato-ku Tokyo Incorporated Co., Ltd. (72) Inventor Isao Nishimura 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (56) Reference JP-A-51-66633 (JP, A) JP-A-62- 45836 (JP, A) Actually open 52-62790 (JP, U) Actually open 62-141844 (JP, U) Actually open 59-136377 (JP, U) Special public Sho 61-17984 (JP, B1) Actual public Sho 57-50420 (JP, Y1) Actual public Sho 61-46120 (JP, Y1)

Claims (1)

[Claims] 1. A bending-yield elasto-plastic damper that absorbs seismic energy between structures and has a solid structure in the central small-diameter portion and a hollow structure in the remaining portion, which results from bending yielding of members. A drum-shaped damper body having an outer diameter and an inner diameter that sequentially increase from the small diameter portion upward and downward so as to absorb energy as a whole, and base plates integrally provided at both ends of the damper body. An elasto-plastic damper characterized by.