Vibration-proof structure

Abstract

To provide a vibration control structure which can prevent locking vibration caused by excitation force from an area above a floor with a floating floor kept in a horizontal state even if a movable load placed on the floating floor is uneven.SOLUTION: A vibration control structure includes: a floating floor 3 provided on a structure 2; multiple support springs 4 provided between the structure 2 and the floating floor 3; support spring compression means 5 which may compress the support spring 4 from the structure 2 side to the floating floor 3 side; and an inertial mass device 6 installed in parallel with the support spring 4 between the structure 2 and the floating floor 3. The multiple support springs 4 are provided spaced apart from each other in a horizontal direction. When a step floor part 7 (a loaded objected) is placed at a position offset from a centroid of the floating floor 3, the support spring compression means 5 compresses the support spring 4 located below a portion, on which the step floor part 7 is placed, of the floating floor 3. The inertial mass device 6 is installed at a position which is symmetrical to a centroid of the step floor part 7 with respect to the centroid of the floating floor 3 in a plan view viewed from a vertical direction. An inertial mass is set to the same value as a mass of the step floor part 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vibration isolation structure.

Background Art

[0002] In facilities such as music live halls and dance studios, vertical vibrations (so-called vertical vibrations) may occur due to the stretching and bending movements of a large number of guests. To address this, a vibration isolation structure is known in which the floor of the relevant part is a floating floor insulated from the structural frame (see, for example, Patent Document 1). In such a vibration isolation structure, the structural frame is partially recessed, and a floating floor supported by supporting springs is provided in the recessed part. The floating floor needs to be displaced relative to the structural frame in the vertical direction, and this is achieved by the expansion and contraction of the supporting springs.

[0003] The magnification of the reaction force with respect to the exciting force is the "reaction force reduction ratio". The larger the ratio of the exciting vibration frequency to the natural vibration frequency of the floating floor, the smaller the reaction force reduction ratio (the higher the vibration isolation effect). Therefore, the weight of the floating floor can be increased or the spring stiffness of the supporting springs can be decreased. However, increasing the weight increases the cost, and decreasing the spring stiffness of the supporting springs results in a so-called "fluffy spring" state. Therefore, in a practical vibration isolation floating floor, a huge RC floor slab with a thickness of about 1 m is used to make the floor self-weight (m×g, where g is the gravitational acceleration) more than 10 times the exciting force, and the natural vibration frequency is set to about 1 Hz. As a result, the vertical displacement during normal use is kept at about 2 cm or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, the upper surface finish of the floating floor is configured to be horizontal and uniform throughout. The upper surface of the floating floor may be used as a flat surface as a whole, or a stepped floor member (stepped floor section) may be installed on the floating floor and used as a stepped floor. When installing a stepped floor section on the floating floor, if the stepped floor section is installed at a position offset from the center of gravity of the floating floor, the load carried on the entire floating floor will not be constant, and the floating floor will always tilt. On the other hand, if the support springs are increased only at locations with a large load, such as under the stepped floor section, there is a risk of inducing rocking vibrations (rotational vibrations around the horizontal axis) in which the side opposite to the side where the stepped floor section is installed shakes significantly due to the vertical excitation force acting across the entire floating floor.

[0006] Therefore, an object of the present invention is to provide a vibration isolation structure that can prevent rocking vibrations caused by excitation force from the floor while the floating floor maintains horizontal even when the load on the floating floor is unevenly distributed.

Means for Solving the Problems

[0007] To achieve the above object, the vibration isolation structure according to the present invention includes a structure, a floating floor provided on the structure, a plurality of support springs provided between the structure and the floating floor to support the floating floor so as to be displaceable in the vertical direction with respect to the structure, support spring compression means capable of compressing the support springs, and an inertial mass device installed in parallel with the support springs between the structure and the floating floor. The plurality of support springs are provided at intervals in the horizontal direction from each other. When a load is placed at a position offset from the center of gravity of the floating floor, the support spring compression means compresses the support spring located below the portion of the floating floor where the load is placed from the structure side toward the floating floor side, and the inertial mass device is installed at a position symmetric to the center of gravity of the load with respect to the center of gravity of the floating floor in a plan view seen from the vertical direction, and the inertial mass is set to the same value as the mass of the load.

[0008] In the present invention, when a load is placed at a position deviated from the center of gravity on the floating floor, by compressing the support spring located below the portion of the floating floor where the load is placed from the structure side to the floating floor side, it is possible to prevent the portion of the floating floor where the load is placed from sinking below other portions and the floating floor from tilting, and the floating floor can be kept horizontal. The inertial mass device is installed at a position symmetric to the center of gravity of the load with respect to the center of gravity of the floating floor in a plan view seen from the vertical direction, and the inertial mass is set to the same value as the mass of the load between the structure (fixed end) and the floating floor. This is equivalent to adding the mass of the load to the position of the inertial mass device, which is the same as arranging the load (loading load) symmetrically with respect to the center of gravity of the floating floor. Therefore, it can be regarded as a structure (vibration model) without eccentricity where the center of gravity, the center of rigidity, and the center of applied force coincide, and rocking vibration during vertical excitation can be prevented even when the loading load on the floating floor is unevenly distributed.

[0009] Further, in the vibration isolation structure according to the present invention, the support spring compression means may be an electric jack provided between the structure and the support spring and capable of pushing and compressing the support spring toward the floating floor side.

[0010] With such a configuration, the support spring can be easily compressed. Also, it becomes possible for an operator to perform the telescoping operation of the electric jack remotely without directly performing it between the floating floor and the structure.

Advantages of the Invention

[0011] According to the present invention, even when the loading load on the floating floor is unevenly distributed, the floating floor can be prevented from rocking vibration caused by the excitation force from the floor while maintaining the horizontal.

Brief Description of the Drawings

[0012]

Figure 1

Modes for Carrying Out the Invention

[0013] Hereinafter, the vibration isolation structure according to an embodiment of the present invention will be described with reference to FIG. 1. As shown in FIG. 1, the vibration isolation structure 1 according to the present embodiment includes a structure 2, a floating floor 3 installed above the structure 2, a support spring 4 provided between the structure 2 and the floating floor 3, a support spring compression means 5 capable of compressing the support spring 4 upward, and an inertial mass device 6 provided between the structure 2 and the floating floor 3.

[0014] The vibration isolation structure 1 according to the present embodiment is adopted in a building such as a large hall, for example, and is assumed to have people and objects placed on the floating floor 3. When the building is used for a music live, dance, etc., when the floating floor 3 is excited by a large number of guests bending and stretching in accordance with the music on the upper part of the floating floor 3, the vibration isolation structure 1 is configured such that vertical vibration (so-called vertical vibration) occurs on the floating floor 3. Note that when the building is used for an exhibition, a sports event, etc., it may be configured such that the floating floor 3 can be used as a fixed floor that does not vibrate vertically.

[0015] The structure 2 is, for example, a building foundation or the like and is constructed of RC construction. In the present embodiment, the structure 2 has a recess 21 that opens upward. The structure 2 has a bottom plate portion 22 located below the recess 21 and a side wall portion 23 located on the side of the recess 21 and extending upward from the peripheral edge of the bottom plate portion 22.

[0016] The floating floor 3 is formed in a flat plate shape and is disposed in the recess 21 of the structure 2 with the plate surface in a horizontal plane orientation. The floating floor 3 is disposed overlapping with a space above the bottom plate portion 22. In the present embodiment, the upper surface 31 of the floating floor 3 is disposed so as to be substantially at the same height as the upper end surface 231 of the side wall portion 23 of the structure when the floating floor 3 does not vibrate vertically.

[0017] A plurality of support springs 4 are horizontally spaced between the bottom plate portion 22 and the floating floor 3. In the present embodiment, the plurality of support springs 4 are each connected to the floating floor 3 and are connected to the bottom plate portion 22 via support spring compression means 5. When the floating floor 3 is vibrated, the support springs 4 expand and contract, and the floating floor 3 is configured to vibrate vertically with respect to the structure 2. The spring stiffnesses of the plurality of support springs 4 are set to the same value.

[0018] The support spring compression means 5 is installed between the lower end portion of the support spring 4 and the bottom plate portion 22. The support spring compression means 5 is, for example, an electric jack that can push the support spring 4 upward (toward the floating floor 3) and compress it. The support spring compression means 5 is disposed in a recess 222 formed in the bottom plate portion 22. When the support spring 4 is to be compressed, the electric jack rises and protrudes above the upper surface 221 of the bottom plate portion 22, and when it is not necessary to compress the support spring 4, the electric jack descends and is configured to be accommodated in the recess 222 so as to be at the same height as the upper surface 221 of the bottom plate portion 22. Note that the support spring compression means 5 may be installed between the lower end portion of the support spring 4 and the bottom plate portion 22 when the support spring 4 is to be compressed, and may be configured to be removable when it is not necessary to compress the support spring 4. The compression of the support spring 4 by the support spring compression means 5 will be described later.

[0019] The inertial mass device 6 is installed between the bottom plate portion 22 and the floating floor 3. The inertial mass device 6 is, for example, a rotational inertial mass damper, and has a mechanism that converts a linear displacement (vertical displacement) into a rotational displacement by a ball screw mechanism or the like and rotates a rotating weight (flywheel). The inertial mass device 6 can impart an inertial mass that is several hundred to several thousand times larger than the mass of the rotating weight. The rotational inertial mass damper is a device that generates a reaction force by multiplying the inertial mass by the relative acceleration at both ends. When installed between the bottom plate portion 22 of the structure 2 without displacement and acceleration and the floating floor 3, the relative acceleration becomes the same as the acceleration of the floating floor 3, and the response of the floating floor 3 becomes the same as when a mass corresponding to the inertial mass is added to the installation position of the rotational inertial mass damper of the floating floor 3.

[0020] In this embodiment, it is possible to install a load such as a stepped floor portion 7 that forms a stepped floor on the floating floor 3 according to the event (usage) performed on the floating floor 3. Hereinafter, a case where the stepped floor portion 7 is installed on the floating floor 3 will be described. When the stepped floor portion 7 is installed at a position deviated from the center of gravity G1 of the floating floor 3 in plan view, the portion where the stepped floor portion 7 is installed sinks more than the other portions, and the floating floor 3 is in a tilted state. In order to prevent the floating floor 3 from tilting when the stepped floor portion 7 is installed at a position deviated from the center of gravity G1 of the floating floor 3, the support spring 4, the support spring compression means 5, and the inertial mass device 6 are set as follows.

[0021] When the stepped floor portion 7 is placed on the floating floor 3 in a horizontal state, the support spring 4 (hereinafter referred to as the stepped floor portion lower support spring 41) below the portion of the floating floor 3 where the stepped floor portion 7 is placed is compressed more than the other support springs 4, and this portion is in a state of moving more downward than the other portions. At this time, when the portion of the floating floor 3 where the stepped floor portion 7 is placed and the stepped floor portion lower support spring 41 are moved upward, the floating floor 3 becomes horizontal. The value for moving the portion of the floating floor 3 where the stepped floor portion 7 is placed and the stepped floor portion lower support spring 41 upward to make the floating floor 3 horizontal is denoted as v. This value v is a value that compresses the stepped floor portion lower support spring 41 more than the other support springs 4. Hereinafter, v is denoted as the compression amount v.

[0022] In this embodiment, the support spring compression means 5 compresses the stepped floor portion lower support spring 41 from below, and is set so that the compression amount becomes the same value as the above-described compression amount v. As a result, the portion that has moved downward due to the placement of the stepped floor portion 7 on the floating floor 3 moves upward, and the floating floor 3 becomes horizontal.

[0023] The value obtained by multiplying the compression amount v of the stepped floor portion lower support spring 41 by the spring constant k is the preload acting on the floating floor 3. Let the mass of the stepped floor portion 7 be m´, the spring constant of the support spring 4 be k, and the gravitational acceleration be g (g = 9.8 m / sec 2 ) Then, The unevenly distributed load m´g = Σ (spring constant k × compression amount v) It becomes.

[0024] Let a be the horizontal distance from the center of gravity G1 of the floating floor 3 in plan view to the center of gravity G2 of the stepped floor portion 7. An inertia mass device 6 is installed at a position horizontally distant a from the center of gravity G1 of the floating floor 3 on the side opposite to the stepped floor portion 7 with respect to the center of gravity G1 of the floating floor 3 so that the inertia mass ψ = m'(mass of the stepped floor portion 7). The mass m of the floating floor 3, the moment of inertia I θ , the total spring constant K = Σk of the support springs 4, the rotational stiffness K of the floating floor 3 by the support springs 4 θ be defined as. Ignoring damping, the vibration equation of the floating floor 3 is expressed by the following (1) and (2) with the vertical displacement as z. Since the floating floor 3 is vertically vibrated over its entire surface, the vibration force is assumed to act on the center of gravity G2 of the floating floor 3.

[0025] Vibration equation in the vertical direction

[0026]

Equation

[0027] Vibration equation of rocking (rotation)

[0028]

Equation

[0029] This is the same as the vibration equation of the floating floor 3 when the load is evenly distributed, that is, when there is no mass eccentricity, meaning that the floating floor 3 vibrates only in the vertical direction without accompanying rocking vibration. Since ψ = m', the floating floor 3 with unevenly distributed load and added inertia mass device 6 has the same center of gravity position as in the case without these, and the mass and moment of inertia are shown in the following (3).

[0030]

Equation

[0031] In addition, since the center of gravity G1 of the floating floor 3 without a load is the center of rotation, the structure has no eccentricity.

[0032] When removing the stepped floor portion 7, for example, when an event performed on the floating floor 3 is completed, the compression of the support spring 4 (the stepped floor portion lower support spring 41) by the support spring compression means 5 is released, and the inertial mass device 6 is removed.

[0033] Next, the operation and effects of the vibration isolation structure 1 according to the above-described embodiment will be described. In the vibration isolation structure 1 according to the above-described embodiment, when the stepped floor portion 7 is placed at a position deviated from the center of gravity G1 on the floating floor 3, the stepped floor portion lower support spring 41 is compressed from the structure 2 side to the floating floor 3 side, thereby increasing the spring reaction force by the load of the stepped floor portion. Thus, it is possible to prevent the portion of the floating floor 3 where the stepped floor portion 7 is placed from sinking lower than other portions and the floating floor 3 from tilting, and the floating floor 3 can be held horizontally. The inertial mass device 6 is installed at a position symmetric to the center of gravity G2 of the stepped floor portion 7 with respect to the center of gravity G1 of the floating floor 3 in a plan view seen from the vertical direction, and the inertial mass is set to the same value as the mass of the stepped floor portion 7. Therefore, it is possible to consider that the stepped floor portion 7 (loaded load) is symmetrically arranged with respect to the center of gravity G1 of the floating floor 3, so that it can be regarded as a structure (vibration model) without eccentricity in which the center of gravity, the center of rigidity, and the center of applied force coincide. Even when the loaded load on the floating floor 3 is unevenly distributed, it is possible to prevent the rocking vibration during vertical excitation. Note that since the inertial mass device 6 such as an inertial mass damper is lightweight, it can be installed and removed manually without using a heavy machine.

[0034] The support spring compression means 5 is an electric jack provided between the bottom plate portion 22 of the structure 2 and the support spring 4, and pushes up and compresses the support spring 4 from below. With such a configuration, the support spring 4 can be easily compressed. In addition, it is possible for an operator to perform the telescoping operation of the electric jack remotely without directly performing it between the floating floor 3 and the structure 2.

[0035] The loading load on the floating floor 3 may be installed or removed including the stepped floor portion 7. Therefore, it is preferable that the load placed on the floating floor 3, such as the stepped floor portion 7, can be changed according to the event (usage) performed on the floating floor 3. In the vibration isolation structure 1 according to the present embodiment, not only can it be applied to building facilities having a newly installed floating floor, but also by adding it to building facilities having an existing floating floor, it can easily cope with events in which the loading load on the floating floor is unevenly distributed.

[0036] As described above, the embodiment of the vibration isolation structure 1 according to the present invention has been described. However, the present invention is not limited to the above-described embodiment and can be appropriately changed without departing from the gist thereof. For example, in the above-described embodiment, the support spring compression means 5 is a jack provided below the support spring 4 to push up and compress the support spring 4 from below. However, as long as the support spring 4 can be compressed and lifted from below, it may be other than a jack. In the vibration isolation structure 1 according to the present embodiment, the jack is driven or the installation / removal work is performed manually according to the event. Since these do not need to be moved rapidly, a control device such as a motor can be a simple one.

[0037] In the above-described embodiment, the spring stiffness of the plurality of support springs 4 is set to the same value. The spring stiffness of the plurality of support springs 4 does not necessarily have to be the same value. However, by setting the spring stiffness proportional to the axial force when there is no loading load, the floating floor 3 remains horizontal even after settlement when there is no loading load, and when there is a loading load, the support spring 4 near the loading load can be lifted by a jack or the like to make the floating floor 3 horizontal.

[0038] Also, in the above-described embodiment, the inertial mass device 6 is a rotational inertial mass damper, but it may be other than a rotational inertial mass damper, such as a mechanism that generates an inertial mass with a strut and a weight. Also, in the case of a vibration isolation structure that enhances the vibration isolation effect by constantly installing an inertial mass device, instead of installing or removing the inertial mass device 6 at a position symmetric to the center of gravity of the load with respect to the center of gravity of the floating floor 3 in plan view as in the present embodiment, the rotating weights of the inertial mass devices installed at that position may be increased or decreased so that the increase or decrease in the inertial mass is set to the same value as the mass of the load. Based on the state without the load, when a load is added, an inertial mass corresponding to the mass is installed at that location with an inertial mass device, or the rotating weights of the inertial mass devices installed at that location are increased (by adding weights or replacing them with weights having a larger diameter so as to increase the moment of inertia of the rotating weights) to cope with it. When the load disappears, do the opposite.

[0039] Also, in the above embodiment, the inertial mass device 6 (inertial mass) was added only at one location, but a plurality of inertial mass devices 6 may be provided, and the sum of these inertial masses may be set to the mass m' of the stepped floor portion 7, and the center of gravity position of these inertial masses may be set to a position symmetric to the center of gravity of the load with respect to the center of gravity of the floating floor 3 in plan view.

Explanation of Reference Numerals

[0040] 1 Vibration isolation structure 2 Structure 3 Floating floor 4 Support spring 5 Support spring compression means 6 Inertial mass device 7 Stepped floor portion (load)

Claims

1. A structure, A floating floor provided on the structure, A plurality of support springs provided between the structure and the floating floor, which support the floating floor so as to be displaceable in the vertical direction with respect to the structure, Support spring compression means capable of compressing the support springs, An inertial mass device installed in parallel with the support springs between the structure and the floating floor, and having, The plurality of support springs are provided at intervals in the horizontal direction from each other, When a load is placed at a position deviated from the center of gravity of the floating floor, The support spring compression means compresses the support spring located below the portion of the floating floor where the load is placed from the structure side toward the floating floor side, The inertial mass device is installed at a position symmetric to the center of gravity of the load with reference to the center of gravity of the floating floor in a plan view seen from the vertical direction, and an anti-vibration structure in which the inertial mass is set to the same value as the mass of the load.

2. The anti-vibration structure according to claim 1, wherein the support spring compression means is an electric jack provided between the structure and the support spring and capable of pushing and compressing the support spring toward the floating floor side.

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