JP6817918B2 - Sound insulation floor structure construction method, design method and building sound insulation floor structure - Google Patents

Description

The present invention relates to a method for constructing a sound insulation floor structure in which a floating floor layer is arranged on an upper part of a floor slab of a building via a vibration-proof bearing, a design method, and a sound insulation floor structure of a building.

Conventionally, in order to improve the sound insulation of the boundary floor of a building, the dry double floor construction method, the straight floor construction method, etc. have been used in apartment houses, but the floor impact sound insulation performance is not sufficient, and new condominiums are sold. Even in the above, complaints have been made about the sounds of living and walking by the residents on the upper floors. For example, in the "Comprehensive Survey of Condominiums" by the Ministry of Land, Infrastructure, Transport and Tourism in 2013, according to the response from the management association of the questionnaire, 34.3% of the total 2324 buildings, 797 condominiums, had problems with "living sounds". The result of is reported. This is 37.1% in the 2008 survey, so although there is some improvement, there are still high rates of complaints about living noise, and improving the sound insulation of the floor in condominiums is one of the social issues.

Patent Document 1 describes in a double ceiling structure in which a ceiling plate is attached below a ceiling slab, the thickness of the air layer between the ceiling slab and the ceiling plate is 100 mm or less, and the surface density of the ceiling plate is 1.28 to 2. We propose a sound-insulating double ceiling structure in which the ceiling plate is 4 kg / m ² and the thickness of the ceiling plate is 20 mm to 25 mm (claim 1).

Japanese Patent No. 4736437

As a countermeasure against floor impact noise in apartment houses, the "wet floating floor construction method" in which concrete floating floor boards are installed on rock wool has been practiced. However, as described in "Building Floor Impact Sound Prevention Design" (2009, Gihodo Publishing) edited by the Japan Society for Architecture, the concrete thickness of the floating floor cannot be made sufficiently thick due to the load capacity limitation in apartment buildings. It is said that the basic natural frequency of the anti-vibration system becomes high, and it may not be possible to sufficiently reduce the sound in the 63 Hz band, which is often the frequency band for determining the Lr number due to heavy impact sound. When the thickness is not sufficiently thick as described above, the sound insulation effect of the wet floating floor structure against the heavy impact sound is insufficient, and further improvement of the floating floor structure is required.

Patent Document 1 describes heavy impact sound in the bass range upstairs by optimizing the thickness of the air layer between the ceiling slab and the ceiling plate in the double ceiling structure, and the surface density and plate thickness of the ceiling plate. Although the sound insulation performance for (near the 63Hz band) has been improved, it is not a structure in which a floating floor is placed above the floor slab of the building.

In view of the above-mentioned problems of the prior art, the present invention ensures the boundary floor sound insulation performance against heavy impact sound when the sound insulation property on the boundary floor is improved by the structure in which the floating floor layer is arranged on the upper part of the floor slab of the building. It is an object of the present invention to provide a method for constructing a sound insulation floor structure, a design method, and a sound insulation floor structure for a building.

The method of constructing the sound insulation boundary floor structure to achieve the above purpose is to improve the sound insulation of the boundary floor against heavy floor impact noise by arranging a floating floor layer on the upper part of the floor slab of the building via a vibration isolation support. In the method for constructing the sound insulation boundary floor structure, the floor plates constituting the floating floor layer are formed into small split shapes and composed of a plurality of small split floor boards, and the plurality of small split floor boards are adjacent to each other as the floating floor layer. densely arranged, the natural frequency f of the following formula small split floorboard (1), the density ρ is 1500~2500kg / m ³ small split floor, the thickness h of the small split floor, vertical length a, The dimensions, density, and bending rigidity of the small split floor board are determined so that the lateral length b satisfies h ≧ 0.05 m, a ≦ 1.5 m, and b ≦ 1.5 m, respectively, and the small split floor board has the determined dimensions, density, and bending rigidity. It is characterized by installing small split floor boards.
However, the vertical length, horizontal length, and thickness of the small split floor board are set to a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2).

According to the method for constructing the sound insulation boundary floor structure, the natural frequency f of the small split floor plate constituting the floating floor layer when the sound insulation on the boundary floor is improved by the structure in which the floating floor layer is arranged on the floor slab of the building. Can be set to a higher frequency side than the 63 Hz band, and the floor sound insulation performance against heavy impact noise can be reliably ensured.

In the method for constructing the sound insulation boundary floor structure, the natural frequency f of the small split floor board is set to a higher frequency side than the 125 Hz band by determining the dimensions and materials of the small split floor board so as to satisfy the following equation (3). can do.

ただし、
ｍ：面密度(kg/m²)、Ｅ：ヤング率（N/m²）、I：断面２次モーメント（m⁴） When the small split floor board is composed of a synthetic floor board or a hollow floor board, the equivalent of the synthetic floor board or the hollow floor board is described in "Building Floor Impact Noise Prevention Design" (2009, Gihodo Publishing) edited by the Japan Society for Architecture. The thickness he is obtained from the following formula (4), the obtained he is substituted for h in the formula (2), and the Young ratio E and the density ρ are obtained by using the values of the synthetic floor board or the hollow floor board. The natural frequency f may satisfy the equation (1).

However,
m: Area density (kg / m ² ), E: Young's modulus (N / m ² ), I: Moment of inertia of area (m ⁴ )

When the small split floor board is composed of a synthetic floor board or a hollow floor board, the dimensions, surface density, Young's modulus, and moment of inertia of area of the synthetic floor board or the hollow floor board are determined so as to satisfy the following formula (3). Therefore, the natural frequency f of the small split floor board can be set to a higher frequency side than the 125 Hz band.

Further , it is preferable to construct the floating floor layer so that the adjacent small split floor plates vibrate while being separated from each other in order to secure the boundary floor sound insulation performance against heavy impact sound.

Further, by forming the dry double floor on the upper part of the floating floor layer, a sound insulation boundary floor structure can be constructed by the floating floor and the dry double floor.

Further, by forming a floor finish having a straight floor specification on the upper part of the floating floor layer, a sound insulation boundary floor structure can be constructed by the floating floor and the direct flooring.

The sound insulation boundary floor structure of the building to achieve the above purpose is to improve the sound insulation of the boundary floor against heavy floor impact noise by arranging a floating floor layer on the upper part of the floor slab of the building via a vibration isolation support. In the sound insulation boundary floor structure, the floor boards constituting the floating floor layer are formed into small splits and are composed of a plurality of small split floor boards, and the plurality of small split floor boards are closely arranged adjacent to each other as the floating floor layer. Being done
The natural frequency f of the small split floor board is the following equation (1), the density ρ of the small split floor board is 1500 to 2500 kg / m ³ , and the thickness h, the vertical length a, and the horizontal length b of the small split floor board are h. The dimensions, density, and flexural rigidity of the small split floor board are determined so as to satisfy ≧ 0.05 m, a ≦ 1.5 m, and b ≦ 1.5 m, respectively, and the small split floor board having the determined dimensions, density, and flexural rigidity is installed. It is characterized by being done .
However, the vertical length, horizontal length, and thickness of the small split floor board are set to a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2) .

According to this sound insulation boundary floor structure, the natural frequency f of the small split floor plate constituting the floating floor layer is set to the 63 Hz band when the sound insulation property on the boundary floor is improved by arranging the floating floor layer on the floor slab of the building. It can be set to a higher frequency side than that, and the boundary floor sound insulation performance against heavy impact sound can be surely secured.

Design method for sound insulation field floor structure for achieving the above object, in order to sound insulating properties improve Sakaiyuka for heavy floor impact sound by arranging floating floor layer through the anti-vibration bearing on the top of the building floor slab In the method for designing the sound insulation boundary floor structure, the floor plate constituting the floating floor layer is formed into a small split shape, and the natural frequency f of the small split floor plate is the following equation (1) , and the density ρ of the small split floor plate is The dimensions of the small split floor board so that 1500 to 2500 kg / m ³ , the thickness h, the vertical length a, and the horizontal length b of the small split floor board satisfy h ≧ 0.05 m, a ≦ 1.5 m, and b ≦ 1.5 m, respectively. It is characterized by determining the density and bending rigidity.
However, the vertical length, horizontal length, and thickness of the small split floor board are set to a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2).

According to the design method of this sound insulation boundary floor structure, the natural frequency f of the small split floor board constituting the floating floor layer when the sound insulation property on the boundary floor is improved by the structure in which the floating floor layer is arranged on the floor slab of the building. Can be set to a higher frequency side than the 63 Hz band, and the floor sound insulation performance against heavy impact noise can be reliably ensured.

According to the method for constructing the sound insulation boundary floor structure, the design method, and the sound insulation boundary floor structure of the building of the present invention, a heavy impact is achieved when sound insulation is achieved on the boundary floor by a structure in which a floating floor layer is arranged above the floor slab of the building. The boundary floor sound insulation performance against sound can be reliably ensured.

It is sectional drawing which shows the main part of the 1st sound insulation boundary floor structure by this Embodiment. It is sectional drawing which shows the main part of the 2nd sound insulation boundary floor structure by this Embodiment. The natural frequency f of the plate was calculated by the equation (5) by appropriately setting the vertical and horizontal lengths, heights a, b, h, m, and n of the plates constituting the small split floor plate of the present embodiment within a predetermined range. It is a figure which shows the calculation example in tabular form. It is a figure which shows the waveform of acceleration (acceleration / force) when a plate of 3m × 4m × 0.08m is actually vibrated in a predetermined support state. When a 3m x 4m x 0.08m board is used as a floating floor layer and when a 0.9m x 1m x 0.08m board is used as a floating floor layer, the lower chamber is subjected to a heavy impact source by a bang machine based on JIS A 1418-2: 2000. It is a table and a graph which show the experimental measurement result of a sound pressure level.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a main part of the first sound insulation floor structure according to the present embodiment. FIG. 2 is a cross-sectional view showing a main part of the second sound insulation floor structure.

As shown in FIG. 1, in the first sound insulation boundary floor structure 11, the floating floor layer 13 is arranged above the RC (reinforced concrete) floor slab 10 of the building via a plurality of anti-vibration materials 12, and further, the floating floor layer 13 A plurality of support legs 14 are arranged on the support legs 14, and a particle board 15 and a flooring 16 are arranged on the support legs 14, and the sound insulation boundary floor structure is composed of a floating floor and a dry double floor.

The vibration isolator 12 is a small piece of a rectangular body having a predetermined height for reducing vibration, and is made of, for example, a urethane foam elastomer that reduces vibration by a damping effect. As such an anti-vibration material, for example, a cell damper (registered trademark) sold by Inoac Corporation can be used.

The support leg 14 has a vibration-proof rubber 14a mounted on the surface of the floating floor layer 13, a height-adjustable support bolt 14b, and a rectangular flat plate receiving material 14c. The particle board 15 is placed on the receiving member 14c.

The floating floor layer 13 has a subdivided shape obtained by subdividing the floor plate, and is composed of a plurality of subdivided floor plates 13a, 13b, 13c, ..., Which are rectangular flat plates. The small split floor plates 13a, 13b, and 13c form the floating floor layer 13 in a state where they are arranged and completely separated.

The small split floor boards 13 to 13c are made of homogeneous single-plate concrete, but are not limited to this, and may be made of hollow floor boards or synthetic floor boards. An example of a hollow floor board is a concrete panel having several hollow holes in the vertical direction and prestressed by PC steel wire. As a specific example of such a concrete panel, it is sold by SPANCRETE CORPORATION. There is Spancrete®. Further, as an example of the synthetic floor board, there is a synthetic floor board in which a cotter is set on the upper surface of the Spancrete (registered trademark) and the upper part is cast-in-place concrete.

As shown in FIG. 2, in the second sound insulation boundary floor structure 21, the floating floor layer 13 is arranged above the RC floor slab 10 of the building via a large number of anti-vibration materials 12, and the resin foam is placed on the floating floor layer 13. A cushion layer 22 made of non-woven fabric or a non-woven fabric, and a sawn-grooved slab-covered plywood 23 are arranged, and the sound-insulating boundary floor structure is provided by a floating floor and a direct-covered flooring as in FIG. The floating floor layer 13 has the same configuration as that of FIG. 1, has a subdivided shape obtained by subdividing the floor plate, and is composed of a plurality of subdivided floor plates 13a, 13b, 13c, ..., Which are rectangular flat plates. To. The small split floor plates 13a, 13b, and 13c form the floating floor layer 13 in a state where they are arranged and completely separated.

In the present embodiment, the floating floor layer 13 in the sound insulation boundary floor structures 11 and 21 of FIGS. 1 and 2 is composed of completely separated small split floor plates, so that the bending vibration generated in the floating floor layer 13 is constant. It is controlled so that it exceeds the frequency. As a result, the boundary floor sound insulation performance against heavy impact noise can be reliably ensured.

ここで、板の縦横長さ・厚さをａ、ｂ、ｈ（ｍ）とし、板の材質の曲げ剛性をＤ（均質単板ではＤ＝ＥＩ、ヤング率をＥ（N/m²）、単位幅当たりの断面2次モーメントＩ＝ｈ³/１２（m³））、密度をρ（kg/m³）とし、ｍ、ｎはそれぞれ板の長さａ，ｂ方向での半波数を示す。 In general, the natural frequency of a rectangular plate with simple peripheral support is given by the following equation (5).

Here, the vertical and horizontal lengths and thicknesses of the plates are a, b, and h (m), the bending rigidity of the plate material is D (D = EI for a homogeneous single plate, and Young's modulus is E (N / m ² )). second moment I = h ^3/12 per unit width (m ^3)), and the density ρ (kg / m ^3), shown m, length a of the n each plate, a half wave number in the direction b ..

In FIG. 3, when the values of the vertical and horizontal lengths a and b of the plates are variously combined within the range of 1.0 to 4.0 m and h is 0.05, 0.08, 0.12 m, they are unique in the range of m, n = 1 to 4. A calculation example in which the frequency f is calculated by the equation (5) is shown. The Young's modulus E (N / m ² ) and the density ρ (kg / m ³ ) used in the calculation example of FIG. 3 are as follows.
E = 2.4 × 10 ¹⁰ N / m ²
ρ = 2400 kg / m ³

When the support conditions of the rectangular plate are various, the vibration mode is not set even in the case of simple peripheral support, but it is possible to estimate the natural frequency and use it as an index with reference to the calculated value.

For example, looking at the calculation results of a = 3, b = 2 (3m x 2m plate) in FIG. 3, the 63Hz band (44.2 to 88.4Hz) at the time of measuring the floor impact sound blocking performance in various combinations of m and n. , It can be seen that a large amount of vibration components in the 125 Hz band (88.4 to 176.8 Hz) are contained.

The target frequency band in the heavy impact sound shielding performance test (JIS A 1418-2: 2000) is divided into octaves, and the center frequency is from 63Hz to 500Hz, and the actual building floorboard has a blocking performance at the value of the 63Hz band. Often determined, then the 125Hz band. The 250 Hz and 500 Hz bands are often relaxed by the floor finish structure.

FIG. 4 is a diagram showing a waveform of acceleration (acceleration / force) when a plate of 3 m × 4 m × 0.08 m is actually vibrated in a predetermined support state. Fig. 5 shows the heavy impact source by the bang machine based on JIS A 1418-2: 2000 when the 3m x 4m x 0.08m board is used as the floating floor layer and when the 0.9m x 1m x 0.08m board is used as the floating floor layer. It is a table and a graph which show the experimental measurement result of the sound pressure level of the lower chamber. The bare surface shown in FIG. 5 is the structure of the roof slab of the experimental building.

As shown in FIG. 4, it can be confirmed that the plate of 3 m × 4 m × 0.08 m has a natural frequency in the target frequency band (31.5 Hz band, 63 Hz band, 125 Hz band) of the heavy impact sound blocking performance. It can be seen from the experimental results of FIG. 5 that this adversely affects the heavy impact sound blocking performance. That is, the sound pressure level of the lower chamber at the weight impact source when the 3 m × 4 m × 0.08 m plate is actually used as the floating floor layer is compared with the case where the 0.9 m × 1 m × 0.08 m plate is used as the floating floor layer. As shown in FIG. 5, it was confirmed in the experiment that a difference of 8 dB was generated in the 63 Hz band, the sound pressure level was high by this amount, and the weight impact blocking performance was low. As can be seen from the calculation example in Fig. 3, the natural frequency of a small split floor board such as a 0.9m x 1m x 0.08m board is in the high frequency range, so the adverse effect of the bending vibration of the board in the 63Hz band is adversely affected. This is an avoided result.

Generally, if the plate thickness is increased, the natural frequency can be set to the high frequency side, but the floating floor layer is about 0.08 m thick from the viewpoint of economic efficiency of building the floating floor layer at the construction site and reducing the load on the structure. Is desirable in terms of cost performance.

As can be seen from the calculation example of the natural frequency of the plate in FIG. 3, the smallest natural frequency is the case of m = n = 1, and the natural frequency f in this case is set to the higher frequency side than the 63 Hz band. To do so, the dimensions, density, and flexural rigidity of the small split floor plate may be determined so as to satisfy the equation (1). However, the vertical, horizontal, and thickness dimensions of the small split floor board are a, b, and h (m), the Young's modulus of the floor board material is E (N / m ² ), and the density is ρ (kg / m). Assuming ³ ), the natural frequency (minimum value) f of the small split floor plate is given by the following equation (2) from the above equation (5).

Further, in order to set the natural frequency f of the small split floor plate to a higher frequency side than the 125 Hz band, the dimensions and materials of the small split floor plate are determined so as to satisfy the following equation (3).

According to the investigation and examination by the present inventors, when a floating floor layer having an area is arranged above the vibration isolator, bending vibration of the rectangular plate is generated by the heavy impact sound, and resonance is likely to occur in the 63 Hz band and the 125 Hz band. It has been found. On the other hand, as described above, by arranging the small split floor boards of about 1 m × 1 m completely separated to form the floating floor layer, it was possible to secure the boundary floor sound insulation performance against heavy impact sound.

That is, the weight at the boundary floor should be such that the small split floor board is made of a material with a density ρ = 1500 to 2500 kg / m ³ and the vertical, horizontal, and height dimensions of the small split floor board are a, b ≤ 1.5 m, and h ≥ 0.05 m. It is preferable for ensuring the impact sound blocking performance. Examples of the material of the small split floor board whose density is within the above range include concrete, mortar, and various fiber reinforced cement boards (flexible board, etc.).

Further, the floating floor layer may be a homogeneous single plate concrete, but may be a hollow floor plate or a synthetic floor plate. In the case of a hollow floor board or a synthetic floor board, the equivalent slab thickness he is obtained from the following formula (4), this equivalent thickness he is substituted into h in the above formula (2), and Young's modulus E and density ρ are obtained from the synthetic floor board or The natural frequency f obtained by using the value of the hollow floor plate may satisfy the above equation (1).

ただし、
ｍ：面密度(kg/m²)、Ｅ：ヤング率（N/m²）、I：断面２次モーメント（m⁴）

However,
m: Area density (kg / m ² ), E: Young's modulus (N / m ² ), I: Moment of inertia of area (m ⁴ )

Further, in order to set the natural frequency f of the small split floor board made of the synthetic floor board or the hollow floor board to a higher frequency side than the 125 Hz band, the dimensions, surface density, and Young's modulus of the synthetic floor board or the hollow floor board are satisfied so as to satisfy the above equation (3). The rate and the moment of inertia of area may be determined.

As described above, according to the present embodiment, when ensuring the floor impact sound blocking performance of the upper and lower floors in the building, it is possible to reliably secure the boundary floor sound insulation performance particularly against the heavy impact sound.

Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the present invention is preferably applied to a building of an apartment house such as an apartment, but is not limited to this, and of course, it can be appropriately applied to various buildings such as a hotel, an office building, and a school.

According to the present invention, it is possible to secure the heavy impact sound blocking performance on the boundary floor of a building with high performance, and it is possible to contribute to the elimination of complaints about living sounds in condominiums and other condominiums.

10 Floor slab 11 First sound insulation floor structure 12 Anti-vibration material, anti-vibration support 13 Floating floor layers 13a, 13b, 13c Small split floor board 14 Support legs 15 Particle board 16 Flooring 21 Second sound insulation floor structure 22 Cushion layer 23 plywood

Claims (7)

It is a method of constructing a sound insulation boundary floor structure to improve the sound insulation of the boundary floor against heavy floor impact sound by arranging a floating floor layer on the upper part of the floor slab of the building via anti-vibration bearings.
The floorboards which constitute the floating floor layers with a small split shape composed of a plurality of small split floorboards, densely arranged adjacent the plurality of small split floor plate as the floating floor layer, the natural frequency of the small split floor The number f is the following formula (1), the density ρ of the small split floor board is 1500 to 2500 kg / m ³ , the thickness h, vertical length a, and horizontal length b of the small split floor board is h ≧ 0.05 m, a ≦ 1.5. Sound insulation is characterized in that the dimensions, density, and bending rigidity of the small split floor board are determined so as to satisfy m and b ≦ 1.5 m, respectively, and the small split floor board having the determined dimensions, density, and bending rigidity is installed. How to build a boundary floor structure.
However, the vertical length, horizontal length, and thickness of the small split floor board are set to a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2).

The method for constructing a sound insulation floor structure according to claim 1, wherein the dimensions and materials of the small split floor board are determined so as to satisfy the following formula (3).

The small split floor board is composed of a synthetic floor board or a hollow floor board, and the equivalent thickness he of the synthetic floor board or the hollow floor board is obtained from the following formula (4).
A claim that the natural frequency f obtained by substituting the obtained he for h in the formula (2) and using the Young's modulus E and the density ρ with the values of the synthetic floor board or the hollow floor board satisfies the formula (1). Item 4. The method for constructing a sound insulation floor structure according to Item 1.

However,
m: Area density (kg / m ² ), E: Young's modulus (N / m ² ), I: Moment of inertia of area (m ⁴ ) The method for constructing a sound insulation floor structure according to claim 3, wherein the dimensions, surface density, Young's modulus, and moment of inertia of area of the synthetic floor board or the hollow floor board are determined so as to satisfy the following formula (3).

The method for constructing a sound insulation boundary floor structure according to any one of claims 1 to 4, wherein the floating floor layer is constructed so that the adjacent small split floor plates vibrate in a state of being separated from each other. It is a sound insulation boundary floor structure for improving the sound insulation of the boundary floor against heavy floor impact sound by arranging a floating floor layer on the upper part of the floor slab of the building via anti-vibration bearings.
The floor board constituting the floating floor layer is formed into a small split shape and is composed of a plurality of small split floor boards, and the plurality of small split floor boards are closely arranged adjacent to each other as the floating floor layer.
The natural frequency f of the small split floor board is the following equation (1), the density ρ of the small split floor board is 1500 to 2500 kg / m ³ , and the thickness h, the vertical length a, and the horizontal length b of the small split floor board are h. The dimensions, density, and flexural rigidity of the small split floor board are determined so as to satisfy ≧ 0.05 m, a ≦ 1.5 m, and b ≦ 1.5 m, respectively, and the small split floor board having the determined dimensions, density, and flexural rigidity is installed. The sound insulation floor structure of the building is characterized by being done .
However, the vertical length, horizontal length, and thickness of the small split floor board are set to a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2) .

It is a method of designing a sound insulation boundary floor structure to improve the sound insulation of the boundary floor against heavy floor impact sound by arranging a floating floor layer on the upper part of the floor slab of the building via anti-vibration bearings.
The floor board constituting the floating floor layer is formed into a small split shape, the natural frequency f of the small split floor board is the following formula (1), the density ρ of the small split floor board is 1500 to 2500 kg / m ³ , and the small split floor board It is characterized in that the dimensions, density, and flexural rigidity of the small split floor board are determined so that the thickness h, the vertical length a, and the horizontal length b satisfy h ≧ 0.05 m, a ≦ 1.5 m, and b ≦ 1.5 m, respectively. How to design a sound insulation floor structure.
However, the vertical length, horizontal length, and thickness of the small split floor board are a, b, and h (m), the Young's modulus of the material of the floor board is E (N / m ² ), and the density is ρ (kg). If / m ³ ), the natural frequency (minimum value) of the small split floor plate is given by the following equation (2).

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