JPH03229027A - Metal damper - Google Patents

Abstract

PURPOSE:To improve earthquake resisting performance of a metal damper provided on a horizontally displacing position of a structure by shaping the metal damper such that the whole region subjected to bending moment by the horizontal displacement of the structure reaches the plastic region. CONSTITUTION:A metal damper 10 is an apparently rod-like member having the radius r1 in a position spaced l1 from the predetermined section and the radius r2 in a position spaced l2 from the neutral shaft. When the metal rod having the length 2l0 and both ends restrained from rotation is assumed to displace horizontally, the central point C of the metal damper 10 becomes a point of inflection to generate opposite symmetrical bending stress. When the metal rod is selected to have l1/l2=(r1/r2)<3>, it yields by the bending moment simultaneously over the range l1-l2. Thus, since a plasticizable region can be enlarged, large energy can be absorbed to improve the earthquake resisting performance of the metal damper, thereby that of the structure.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a metal damper suitable for use as a damper in a seismic isolation structure.

"Prior Art" Metal dampers using lead or steel have been conventionally provided as dampers used in seismic isolation structures.

An example of such a metal damper is the one shown in FIG. A mounting member 4 having a rectangular appearance is provided, and this mounting member 4 is fixed at a predetermined position on the structure by a plurality of bolts 5,.

The metal damper 3 damps vibration energy using the energy of plastic strain when the structure 1 is subjected to earthquake motion.

Furthermore, this type of metal damper generally uses a material with a high yield ratio to increase the plastic region and increase energy absorption.

``Problem to be Solved by the Invention'' However, the yield ratio has a limit due to the nature of the material, and only areas with high stress become plastic, resulting in poor energy absorption efficiency.

Further, as shown in FIGS. 3 and 4, when the upper and lower ends of the conventional metal damper 3 are rotationally restrained, the following problem occurs when the metal damper 3 is horizontally displaced. arise. Here, FIG. 3 is a state diagram showing the state when horizontal displacement occurs in the metal damper 3, and FIG. 4 is a diagram showing the relationship between the height position of the metal damper 3 and the bending moment applied thereto. , the vertical axis is the distance Q from the midpoint C of the metal tamper 3
, and the horizontal axis indicates the magnitude of the bending moment M generated therein.

Assuming that the recursion point is at the center of the metal damper 3, the metal tamper 3
If the length of is 2Q and the yield ratio of the metal is YR, then the range of the yield region is (+-YR)Xi! becomes. Therefore, the other intermediate portion remains elastic.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a metal damper that reaches its yield point almost simultaneously over the entire area when the metal damper is subjected to bending stress.

The metal damper of the present invention is provided at a horizontally displaced position of a structure, and when a bending moment is applied due to the horizontal displacement of the structure, the metal damper undergoes plastic deformation almost simultaneously over the entire area. It is characterized by being formed in a shape that reaches the area. Specifically, for example, if the radius at the position Ql from the cross-sectional shape of the metal damper or a predetermined cross-section of the metal damper is 1, and the radius dividing the position Q2 from the neutral axis is r2, then r2-(ρ2/ ρ) l/3Xr+, 7) It is formed so that the relationship holds true.

"Operation" The metal tamper of the present invention has a radius r2 at a position Ql from a predetermined cross section, and a radius r at a position Q from the neutral axis.
2, when the metal damper is horizontally displaced, the midpoint of the metal damper becomes a recursion point, and an antisymmetrical bending stress is generated. At this time, the metal damper simultaneously breaks down over a range of ~12t.

"Embodiment" Hereinafter, an embodiment of the metal damper of the present invention will be described with reference to FIG.

The metal damper 10 of this embodiment is a member with a rod-like appearance, and its cross-sectional shape is Q from a predetermined cross section of the metal damper 10.
When the radius at the position l is r9 and the radius at the position Q2 from the neutral axis is r2, r 2-(Q 2 /
Q + ) ” 3X r 1 is formed so that the relationship holds true.

Both ends of the length 2Qo or the rotationally restrained metal ring are horizontally displaced to be f2.

The midpoint C of the metal damper lO becomes the recursion point, and an antisymmetrical bending stress is generated.

If the shape of this metal is chosen as ρ,/Q=−(r,/r−)3, it will simultaneously yield due to the bending moment over the range of Q, to g.

Hereinafter, such an effect will be discussed based on a calculation formula.

Take the midpoint C as the origin and take the length Q downward.

When the upper end 10a and lower end 10b of the metal damper 10 are horizontally displaced due to forced deformation of the metal damper 10, a bending moment M is generated in the metal damper. If the shearing force generated in the metal damper at this time is Q (t), then M = Q
Q (t-Cl1+) If the cross section of the metal damper lO is circular and the section modulus is Z, then Z-πr3/32 (cz) If the bending stress degrees σ1 and σ at points e1 and 37 are found and equalized, then , R, point is σI−(32Q/rr)X (C,
/ r, 3) At 37 points, c 2-(32Q , / π
)X (+22/r2'), and from these Cl and σ2, the following relationship holds:

When using the metal damper 10 of this embodiment, a plurality of metal dampers 10 are generally provided on the same base plate and used.

The metal damper 10 is made of a metal with a high yield ratio (ratio of YR yield strength to breaking strength), whether steel or lead, and is elongated so that bending stress is greater than shear stress.

When formula (1) is solved for r, r,=(ρ2/ρ+)"Xr+" (2) Here, for example, from the 0 point (midpoint) to 1. When the cross-sectional radius r1 of the metal damper at the Oc shoulder is set to Ocx, and the total length 2Q of the metal damper 10 is set to 20cx, the relationship between the position Q2 from the 0 point and the cross-sectional radius r2 is as follows. become that way.

According to the metal damper IO of this embodiment, when a bending moment is applied, the yield point is reached almost simultaneously over the entire area of the metal damper IO, so the plasticity region can be enlarged, and the energy can be reduced. Absorption can be increased. This has an excellent effect of improving the seismic isolation performance of the metal damper and, by extension, the seismic isolation performance of the structure.

"Effects of the Invention" The metal gnova of the present invention has a metal damper installed at a horizontally displaced position of a structure, and has a shape that reaches a plastic region almost simultaneously over the entire area when subjected to a bending moment due to horizontal displacement of the structure. Since the plasticity region is formed to be large, the plasticization region can be enlarged, and the absorption of mechanical stress can be further increased. This has an excellent effect of improving the seismic isolation performance of the metal damper and, by extension, the seismic isolation performance of the structure.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the metal damper of the present invention;
Figures 2 to 4 are diagrams showing a conventional example of a metal damper, in which Figure 2 is a side view, Figure 3 is a state diagram showing a displacement state, and Figure 4 is a height position of the metal damper. It is a figure which shows the relationship with the bending moment applied there. l Structure, 3, IO... Metal damper.

Claims (1)

[Claims] A metal damper provided at a horizontal displacement position of a structure, characterized in that the metal damper is formed in a shape that reaches a plastic region almost simultaneously over the entire area when receiving a bending moment due to horizontal displacement of the structure. damper.