JPH11280295A - Base isolating structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base isolating structure which enables restoring forces to effect in two directions by means of one coil spring, leaves no residual deformation behind in the rubber pad of a sliding bearing, and is advantageous in terms of cost. SOLUTION: A sliding bearing 10 and a coil spring 20 are arranged horizontally in parallel between subsoil 1 and an upper building 2, the sliding bearing 10 bearing the entire weight of the upper building 2, and the coil spring 20 being placed in the vertical direction to provide the force of the sliding bearing 10 to restore horizontally in an earthquake. The sliding bearing 10 comprises a sliding base isolator comprising a sliding material 11 and a sliding mating material 12, with a rubber pad 13 added thereto in series, the rubber part 13 comprising a rubber plate and a steel plate laid one on the other. Mounting of the coil spring 20 can be achieved by pinning and therefore simple methods such as those using hooks or eyebolts, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation structure, and more particularly to a seismic isolation structure in which a vertical load such as a building load or a loading load is applied only to a sliding bearing or a rolling bearing.

[0002]

2. Description of the Related Art As seismic isolation using a sliding bearing (or rolling bearing), building load (axial force) is shared by a sliding bearing provided in parallel in a horizontal direction and a laminated rubber, and the laminated rubber is subjected to an earthquake caused by the sliding bearing. There are two types: a structure that uses horizontal restoring force at the time and a structure that bears the building load only by sliding bearings and separately provides a horizontal restoring force. The former structure has large vertical deformation (long-term creep) of laminated rubber. Because the ratio of the axial force distribution between the sliding bearing and the laminated rubber changes due to the deflection of the beam directly above the seismic isolation floor, the horizontal friction force of the sliding bearing changes, and the expected seismic isolation performance may not be exhibited. There is a defect that there is.

On the other hand, in the latter structure, it is uneconomical if the horizontal restoring force is a laminated rubber that does not bear the building load.
Conventionally, a coil spring arranged in the horizontal direction is generally adopted as a horizontal restoring force.

[0004]

However, in the case of a coil spring arranged in a horizontal plane, the restoring force of one spring works only in one direction, and it is necessary to increase the number of springs accordingly. The deformation at the time is generally ± 30-40
cm, but there is a problem that a spring satisfying this condition has a long natural length and is expensive.

[0005] Further, in the sliding bearing, rubber pads are generally added in series in a vertical direction so as to exert a seismic isolation effect even in a small earthquake, but there is a problem that residual deformation tends to remain on the rubber pads after the earthquake.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to enable a restoring force to be exerted in two directions by a single coil spring, and to cause residual deformation on a rubber pad of a sliding bearing. Another object is to provide a seismic isolation structure that is advantageous in terms of cost.

[0007]

According to the seismic isolation structure of the present invention, in a seismic isolation structure in which a vertical load is received only by a sliding bearing or a rolling bearing, the horizontal restoring force of the sliding bearing or the rolling bearing during an earthquake is reduced. It is characterized by being a coil spring arranged at an angle to the direction.

[0008] By arranging the coil spring at an angle to the horizontal direction, the restoring force of one spring can be made effective in two directions.
The extension of the spring can be reduced, and a large horizontal force is exerted at the time of large deformation, but the effect of the spring is small at the time of small deformation, so that no residual deformation remains on the rubber pad of the sliding bearing after the earthquake.

The angle of the coil spring with respect to the horizontal direction is not particularly limited, but may be, for example, 90 degrees.

As the sliding bearing, it is possible to preferably use a sliding seismic isolation device comprising a sliding material and a sliding partner material and a rubber pad formed by alternately superimposing a rubber sheet and a metal plate in series.

[0011] Rolling bearings include ball bearings
A unit in which a rubber pad is overlaid on a unit or the like can be preferably used.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory view schematically showing a seismic isolation structure according to the present invention. A sliding bearing 10 is interposed between a footing 1 'on the ground side and a footing 2' on the upper building. A coil spring 20 is vertically disposed at a position deviating from the footing between the upper building 2 and the sliding bearing 10 to bear the entire weight of the upper building 2, and the coil spring 20 restores the sliding bearing 10 in the horizontal direction in the event of an earthquake. Help.

The sliding bearing 10 is made of a sliding material (such as Teflon) 1
A rubber pad 13 formed by alternately superimposing a rubber sheet and a steel plate is added in series to a sliding seismic isolation device comprising a sliding member 1 and a sliding partner material (stainless steel or the like) 12. The sliding material 11 is fixed on the rubber pad 13 and the sliding partner material 12 is fixed on the upper building footing 2 '.

The coil spring 20 may be attached by using a pin, so that a simple method such as a hook or an eyebolt can be used. Further, as the coil spring 20, for example, a suspension spring for a large vehicle (bus, heavy equipment) can be used.

FIG. 2 schematically shows a state in which the above seismic isolation structure is horizontally deformed from the state shown in FIG. 1 at the time of the earthquake. The sliding member 10 of the sliding bearing 10 slides between the sliding member 12 and the coil spring 20 is inclined. And a horizontal restoring force for returning the mating member 12 to the initial position.

By arranging the coil spring 20 vertically, the elongation of the spring is smaller than the horizontal deformation of the seismic isolation layer,
The restoring force of one spring 20 works in two directions. Further, the vertical force of the spring 20 is effective in preventing the floating.

[0018]

As described above, in the seismic isolation structure according to the present invention, since the coil spring disposed at an angle to the horizontal direction is used as the horizontal restoring force of the sliding bearing, the restoring force is controlled by one spring. Can be applied in two directions, the number of springs can be reduced accordingly, and the extension of the spring can be made smaller than the horizontal deformation of seismic isolation. Can be used.

Further, the coil spring exerts a large horizontal force at the time of large deformation, while the effect of the spring at the time of small deformation is small, so that there is no residual deformation in the rubber pad added to the sliding bearing after the earthquake.

Furthermore, it resonates with the ground motion due to the geometric nonlinear effect (the effect that nonlinearity is caused not by the property of the material but by the geometric relationship), and hates,
Also, the hardening effect (the effect of increasing the horizontal restoring force (rigidity) as the horizontal deformation increases)
Accordingly, even in the event of an earthquake exceeding expectations, the spring suppresses the displacement as a stopper (the coil spring also plays a role in absorbing energy if it is plasticized), and has various effects such as prevention of lifting due to vertical movement.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a seismic isolation structure according to the present invention.

FIG. 2 is an explanatory view schematically showing a state deformed by the earthquake from the state of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground side 1 'Ground side footing 2 Upper building footing 2' Upper building 10 Sliding bearing 11 Sliding material 12 Sliding partner material 13 Rubber pad 20 Coil spring

Claims (1)

[Claims] In a seismic isolation structure in which a vertical load is received only by a sliding bearing or a rolling bearing, a coil spring is provided in which the horizontal restoring force of the sliding bearing or the rolling bearing during an earthquake is angled with respect to the horizontal direction. A seismic isolation structure characterized by the following.