JPH06229143A - Damping mechanism using friction force - Google Patents

Abstract

PURPOSE:To cope effectively with an earthquake in every direction by seating an upper part friction board on a lower part friction board in a sliding manner and forming a semispheric projection on one side friction board and forming a larger-sized semispheric hole than the semispheric projection on the other side friction board. CONSTITUTION:An upper part friction board 4 is loaded on a lower part friction board 3 where the vertical weight of an upper structure is transmitted to a lower structure 1. Both the friction boards 3 and 4 are formed in the horizontal direction in a sliding manner so as to provide a specified clearance DELTA1 between a semispheric projection 5 installed in the central part of the both friction boards 3 and 4 and a larger-sized semispheric hole 6. In the case when they are subjected to repeated horizontal force which exceeds friction force by an earthquake, there is produced a slip between the bottom of the upper structure 2 and the top of the lower part structure 1 so that the seismic wave energy may be absorbed from he relation between shearing force and horizontal displacement. As a result, both the upper part structure 2 and the lower part structure 1 are not subjected to the action of a large horizontal force generated during an earthquake.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic control mechanism for an earthquake such as a structure in which an upper structure is seated on a lower structure, such as an artificial ground.

[0002]

2. Description of the Related Art There are various types of building vibration control mechanisms,
One example is a laminated rubber. As shown in FIG. 6, a rubber 22 and a steel plate 23 are stacked and bonded in a multi-stage manner between the upper and lower flanges 20 and 21, and are interposed between the foundation and the upper building to form the upper and lower flanges. Each of them is fixed, and the vertical load of the upper building is supported by the compression resistance of laminated rubber while damping the horizontal force during an earthquake. That is, when the horizontal force acting on the foundation due to the seismic wave is transmitted to the upper building through the vibration control device, the laminated rubber undergoes shear deformation, and the horizontal force and the horizontal displacement draw hysteresis with time as shown in FIG. As a result, seismic energy is absorbed, and the acceleration transmitted to the upper building is reduced.

[0003]

However, in the case of the conventional vibration control mechanism using laminated rubber, it is necessary to directly support the vertical weight of the building, so that the superstructure becomes large-scale like an artificial ground. As the weight increases, it is necessary to increase the strength of the laminated rubber and increase the number of vibration control mechanisms in order to increase the pressure receiving area. Further, when it is used for a long period of time exceeding 20 years, there is a problem that the shear strength of the laminated rubber is deteriorated due to deterioration, the stability of the rubber is lost, and the vibration control performance is deteriorated. An object of the present invention is to solve the above-mentioned drawbacks and to provide a vibration control mechanism having a very simple mechanism without using a complicated mechanical device and having a large vertical supporting force and excellent durability. To do.

[0004]

Means for achieving this object are summarized below. In the support mechanism for the upper structure 2 seated on the top of the lower structure 1, the upper friction plate 4 provided on the bottom of the upper structure is slidably seated on the lower friction plate 3 provided on the top of the lower structure. Supporting the vertical load of the upper structure 2, both friction plates are made of steel material, and one hemispherical protrusion 5 is formed on one friction plate at the central portion, and the other friction plate is opposed to the hemispherical protrusion 5 and horizontally. A horizontal displacement regulating means is provided in which a hemispherical hole 6 having a diameter larger than the hemispherical projection diameter is formed so as to have a predetermined gap in the direction. Further, a more preferable vibration control mechanism can be obtained by applying a material having a non-linear characteristic with respect to load and strain relationship to one or both surfaces of the hemispherical projection 5 and the hemispherical hole 6.

According to the present invention, when the seismic wave is transmitted from the lower structure 1 to the upper structure 2, both frictions 3,
When the horizontal force (shearing force) acting on the four parts reaches the static friction force, a slip is generated between the upper and lower friction plates to absorb the vibration energy. Further, since the horizontal displacement regulating means is formed by the combination of the hemispherical projections 5 and the hemispherical holes 6 with respect to an unspecified seismic wave input direction, the seismic wave input direction can be dealt with from any direction.

FIG. 1 shows a vibration control mechanism of the present invention, in which an upper friction plate 4 is placed on a lower friction plate 3 to transmit a vertical load of the upper structure 2 to the lower structure 1. The friction plates 3 and 4 are relatively slidable in the horizontal direction. This slidable amount is determined by the displacement regulating means that makes a predetermined gap (Δ ₁ ) by the hemispherical projection 5 provided in the central portion of both friction plates and the hemispherical hole 6 having a larger diameter than this. This gap (△ ₁ ) is more than the required length to absorb the vibration energy at the time of earthquake, and is kept within the allowable horizontal displacement range of the upper structure, and when the upper structure 2 is displaced by wind load etc. In order to prevent adverse effects, the amount of expansion and contraction such as temperature difference of the structure should be taken into consideration when making the determination.

FIG. 2 illustrates the damping action with reference to the relationship between the shearing force P generated between the upper structure 2 and the lower structure 1 and the horizontal displacement Δ. Transmitted to shear forces upper structure 2 of the lower structure 1 by seismic, the upper structure 2 to P ₁ the shear force generated by the vibrating integrally corresponds to the static friction force, the lower structure 1 and the upper The structure 2 is integrally displaced within a displacement range of 0 to A ₁ (a). Then, when a shearing force equal to or greater than the static frictional force P ₁ acts, the upper structure 2 slips with respect to the lower friction plate 3, and the displacement amount A ₁ ... due to the resistance of only the shearing force P ₂ corresponding to the dynamic frictional force. A
_A displacement corresponding to ₂ (b) occurs and the hemispherical projection 5 approaches the wall of the hemispherical hole 6. The shearing force P and the displacement Δ are generated in the lateral direction due to the amplitude of the seismic wave, and 0 to A _{1 to} A _{2 to} A _{1 to} 0 to B when the seismic wave acceleration is not so large.
Slip occurs at _{1 to} B ₂ , and the shearing force between the lower structure and the upper structure is suppressed within the range of static frictional force P ₁ or dynamic frictional force P ₂ . On the other hand, when there is no vibration control mechanism, the shear force increases proportionally due to the seismic wave as shown in FIG. The seismic acceleration becomes larger, and superstructure 2
When the displacement between the lower structure 1 and the lower structure 1 exceeds A ₂ and B ₂ and the hemispherical projections 5 and the hemispherical holes 6 of the horizontal displacement regulation means come into contact with each other, if they are steel materials, the contact surface as shown by the broken line (d) The shearing force acting between them increases and the damping effect disappears. Therefore, the slidable amount (gap between the hemispherical projection and the hemispherical hole) Δ ₁ must be greater than or equal to this displacement A ₂ . On the other hand, when a material such as a rubber material whose load / strain is non-linear is provided on the contact surface of the hemispherical protrusion 5, the shearing force acting between the contact surfaces increases in a curved line (e) and draws hysteresis. The larger the area of this hysteresis loop, the larger the damping motion amount. From this point as well, it is preferable that one or both of the hemispherical projections 5 and the hemispherical holes 6 have a material exhibiting a non-linear behavior because not only the generation of impact force is suppressed but also the damping performance is increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the vibration control support mechanism 10 of the present invention is applied to an artificial ground which sits on a lower structure composed of a jacket supported by piles on the sea floor will be described below with reference to the drawings. As shown in FIG. 3, the artificial ground 2, which is an upper structure, has a deck 2b mounted on a lower friction plate 3 fixed to the top of the lower structure 1 consisting of a jacket fixed to the seabed 7 by piles 1b.
And an artificial ground (upper structure) 2 consisting of a truss structure 2a
The bottom surface of the upper friction plate 4 fixed to the bottom surface of the artificial ground 2 is seated in contact with the bottom surface of the upper friction plate 4, and the vertical load of the artificial ground 2 is supported by the friction plate surface.

FIG. 4 is a three-dimensional view showing the details of the seating portion. The normal horizontal load that acts on the artificial ground 2 is
The frictional force between the lower friction plate 3 on the jacket (lower structure) 1 and the upper friction plate 4 on the bottom surface of the artificial ground is transmitted to the ground. When a large horizontal repeated force exceeding the frictional force due to an earthquake is applied, slippage occurs between the bottom of the artificial ground 2 and the top of the lower structure 1 due to the damping action of the mechanism consisting of this friction plate. Thus, the energy of seismic waves is absorbed due to the relationship between the shear force and horizontal displacement. As a result, a large horizontal force at the time of an earthquake does not act on the artificial ground 2 which is the upper structure and the jacket 1 which is the lower structure.

The hemispherical hole 6 and the hemispherical projection 5 shown in FIG. 4 are examples of the horizontal displacement regulation means, and they act as stoppers in the event of an earthquake more than the design or in the case of external force in one direction. Is responsible for. The hemispherical protrusion 5 is the lower structure 1
On the other hand, when the artificial ground 2 slips over a certain limit, it functions as a horizontal displacement regulating means. This horizontal displacement regulation means has a hemispherical hole 6 and a hemispherical projection 5 so that the seismic wave input direction cannot be specified, so that the hemispherical hole 6 and the hemispherical projection 5 can face each other in all plane directions. Further, the contact surfaces of the hemispherical projections 5 and the hemispherical holes 6 are made of a steel material having high wear resistance and high impact resistance, such as molybdenum steel or stainless steel.

FIG. 5 shows that the present invention is applied to an artificial ground,
It is the acceleration response result of the artificial ground when the El Centro seismic wave is input. The solid line in the figure shows the case where the vibration control mechanism is not used, and the broken line shows the acceleration response result when the vibration control mechanism of the present invention is used, and only about half the acceleration occurs. As shown in FIG. 1, the center O in the hemispherical hole is
It has also been confirmed as a result of simulation analysis that the seismic control effect is the same even when the seismic wave is received in any initial position state in which the axis and the central axis O ′ of the hemispherical protrusion do not coincide.

[0012]

According to the present invention, the friction plate fixed between the lower structure and the upper structure supports a vertical load while causing a slip and absorbing a vibration energy. Therefore, it is possible to obtain a large vertical supporting force and a seismic control action at the same time, and it is economical. Also,
Since the friction plate is made of steel, it has high durability, and since the horizontal displacement regulating means is a combination of hemispherical projections and hemispherical holes, it can cope with earthquakes in all directions.

[Brief description of drawings]

FIG. 1 is a diagram of a vibration control mechanism of the present invention.

FIG. 2 is a diagram showing the relationship between shear force and displacement during an earthquake.

FIG. 3 is a front view of an embodiment in which the vibration control mechanism according to the present invention is applied to artificial ground.

FIG. 4 is a detailed three-dimensional view of the vibration control mechanism unit in FIG.

FIG. 5 is a diagram of a response analysis result during an earthquake when the vibration control mechanism of the present invention is applied to a certain artificial ground.

[Fig. 6] Example of conventional vibration control mechanism (laminated rubber type)

FIG. 7 is a diagram showing a relationship between horizontal force and horizontal displacement.

[Explanation of symbols]

 1 Lower structure (jacket) 1b Pile 2 Upper structure (artificial ground) 2a Truss structure 2b Deck 3 Lower friction plate 4 Upper friction plate 5 Hemispherical projection 6 Hemisphere hole 10 Seismic support mechanism

Claims (2)

[Claims] 1. In a support mechanism for an upper structure 2 seated on the top of a lower structure 1, a lower friction plate 3 provided on the lower part of the lower structure is slidably mounted on an upper friction plate 4 provided on the lower part of the upper structure. It is movably seated to support the vertical load of the upper structure 2, both friction plates 3 and 4 are made of steel material, and one friction plate is formed with a hemispherical projection 5 at the central portion, and the other friction plate is formed. A frictional force is utilized, which is characterized in that a horizontal displacement regulating means is provided which is opposed to the hemispherical projection 5 and has a hemispherical hole 6 having a diameter larger than the diameter of the hemispherical projection so as to have a predetermined gap in the horizontal direction. Vibration control mechanism. 2. The frictional force according to claim 1, wherein a material having a non-linear characteristic with respect to load and strain is attached to the surface of one or both of the hemispherical projection 5 and the hemispherical hole 6. The vibration control mechanism used.