Ceiling structure and method for constructing the ceiling structure

Abstract

To effectively reduce a heavy floor impact sound propagated from an upper floor to a lower floor.SOLUTION: A ceiling structure 2 for reducing a floor impact sound of a building comprises a ceiling plate 20 arranged under a floor slab 4 with a gap left and a plurality of vibration control bodies 22 mounted on the ceiling plate 20. The vibration control bodies 22 each comprise a vibration control material 24 including many granules and a box body 26 accommodating the vibration control material 24. The box body 26 includes a bottom plate 28 having a double-layer structure forming an air layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a ceiling structure for reducing floor impact noise in a building and a method for constructing the same. [Background technology]

[0002] In order to suppress the radiation of heavy floor impact noise from upper floors to lower floors in a building with multiple floors, a ceiling structure in which a vibration-damping body is placed on the ceiling board to improve sound absorption performance is known (Patent Documents 1 to 3).

[0003] The vibration-damping body described in Patent Document 1 has a bag with closed edges and vibration-damping granular material filled inside the bag, and is placed on the upper surface of a ceiling board so as to straddle adjacent joists with a gap between them.

[0004] In the sound absorbing structure described in Patent Document 2, a first sound absorbing body and a second sound absorbing body, each consisting of granular material and a container that contains the granular material, are placed on the ceiling. For the container, a bag made of craft paper or glass cloth that does not impede the vibration of the granular material inside is used. The first sound absorbing body and the second sound absorbing body are arranged so that they are placed separately on the ceiling board and the base material, respectively. This makes it difficult for the load of the granular material to act on the base material, solving the problem that the expected sound absorbing effect cannot be obtained.

[0005] The vibration damper described in Patent Document 3 includes a damping material containing a large number of granular bodies and a bag body that contains the damping material, and the bag body includes a tray part that contains the damping material and a sheet-like cover part that closes the upper surface of the tray part. The damping material is contained in the tray part with a gap between it and the cover part. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-60147 A [Patent Document 2] JP 2018-13031 A [Patent Document 3] JP 2017-36549 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the above-mentioned conventional technology, the vibration-damping material cannot vibrate freely within the bag or container, and there is a risk that the vibration energy propagating from the floor above cannot be sufficiently dampened, resulting in ineffective reduction of heavy floor impact noise.

[0008] In view of the above background, an object of the present invention is to provide a ceiling structure and a method for constructing the same that can effectively reduce heavy floor impact noise propagating from an upper floor to a lower floor. [Means for solving the problem]

[0009] In order to solve the above problems, one embodiment of the present invention is a ceiling structure (2) for reducing floor impact noise in a building, comprising a ceiling board (20) arranged below a floor slab (4) with a gap therebetween, and a plurality of vibration damping bodies (22) placed on the ceiling board, each of the vibration damping bodies comprising a vibration damping material (24) containing a number of granular bodies and a box (26) for housing the vibration damping material, and the box includes a bottom board (28) having a layer structure of at least two layers forming an air layer.

[0010] According to this embodiment, the vibration energy can be attenuated by the vibration of the floor impact sound propagating from the floor slab, as the vibration-damping material vibrates within the box. In particular, the bottom plate of the box has at least a two-layer structure forming an air layer, and the bottom plate is given rigidity and elasticity, which makes it easier for the vibration-damping material to bounce, allowing the vibration-damping material to vibrate freely on the bottom plate. Therefore, the vibration energy can be sufficiently attenuated, and the floor impact sound can be effectively reduced.

[0011] In the above aspect, the bottom plate may be an integral structure having an upper plate (36, 46), a lower plate (38, 48), and a plurality of connecting plates (40, 50) arranged parallel to each other at a predetermined interval and connecting the upper plate and the lower plate.

[0012] According to this aspect, since the bottom plate is formed of an integral structure, the box body is easy to manufacture and handle.

[0013] In the above embodiment, the bottom plate may include a base plate (52) having a predetermined rigidity, and bubble cushioning material (54) consisting of two sheets (54a, 54b) placed on the base plate and forming a plurality of sealed air bubbles.

[0014] According to this aspect, the base plate ensures the rigidity of the bottom plate of the box, and the air bubbles in the bubble cushioning material form an air layer that gives elasticity to the bottom plate.

[0015] In the above aspect, the box may further include a partition plate (34) that horizontally divides the internal space.

[0016] According to this aspect, floor impact noise can be reduced more effectively.

[0017] In the above-mentioned aspect, the ceiling board is attached to the underside of a plurality of rafters (12) arranged to extend horizontally and parallel to one another below the floor slab, and the box body may further include a pair of engagement pieces (42) arranged above the rafters so that it can engage with a pair of adjacent rafters from above.

[0018] According to this embodiment, the vibration damper can be temporarily supported by the pair of engaging pieces engaged with the pair of rafters, so that the vibration damper can be easily placed on the ceiling board.

[0019] In order to solve the above-mentioned problems, another aspect of the present invention is a method for constructing a ceiling structure for reducing floor impact noise in a building, comprising the steps of arranging a plurality of girders (12) so as to extend horizontally and parallel to each other below a floor slab (4) (FIG. 5(A)), a vibration-damping material (24) containing a large number of granular bodies, and a box (26) for accommodating the vibration-damping material, the box using a plurality of vibration-damping bodies (22) including a bottom plate (28) having a layer structure of at least two layers forming an air layer, and a pair of engagement pieces (42) extending horizontally in a direction away from each other. The method includes the steps of: placing the vibration-damping body between a pair of adjacent rafters, engaging a pair of the engaging pieces with the pair of rafters from above, and temporarily supporting the vibration-damping body on the pair of rafters so that the bottom plate is positioned lower than the underside of the rafters (Figures 5(B) and (C)); and pressing a ceiling board (20) against the underside of the rafters from below, abutting the bottom plate against the upper surface of the ceiling board, and connecting the ceiling board to the rafters with the pair of engaging pieces positioned above the pair of rafters (Figure 5(D)).

[0020] According to this embodiment, the bottom plate of the box body has at least a two-layer structure forming an air layer, and the bottom plate is given elasticity, so that the vibration-damping material can vibrate freely on the bottom plate. This makes it possible to sufficiently attenuate vibration energy and effectively reduce floor impact noise. In addition, such a vibration-damping body can be easily temporarily supported on the rafters by engaging a pair of engagement pieces with a pair of rafters from above. This makes it easy to place the vibration-damping body on the ceiling board, and makes it easy to build the ceiling structure.

[0021] In the above-mentioned embodiment, when placing the vibration-damping body between a pair of adjacent rafters, the vibration-damping body is tilted and moved above the pair of rafters (Figure 5(B1)), and the vibration-damping body is vibrated above the pair of rafters to equalize the thickness of the vibration-damping material inside the box body (Figure 5(B2)), and then the vibration-damping material is horizontally lowered to be temporarily supported by the pair of rafters (Figure 5(B3)).

[0022] According to this embodiment, the thickness of the vibration-damping material inside the box can be easily made uniform, and the vibration energy attenuation effect of the vibration damper can be prevented from decreasing due to unevenness of the vibration-damping material. Also, the vibration damper can be temporarily supported by the joist in this state. When the ceiling board is attached to the joist, the vibration damper is simply pushed upward by the ceiling board and does not tilt, so the vibration-damping material does not become uneven inside the box. Effect of the Invention

[0023] According to the above aspects, it is possible to provide a ceiling structure and a method for constructing the same that can effectively reduce heavy floor impact noise propagating from an upper floor to a lower floor. [Brief description of the drawings]

[0024] [Figure 1] Plan view of the ceiling structure according to the first embodiment [Diagram 2] Cross-sectional view of II-II in Fig. 1 [Diagram 3] Enlarged cross-sectional view of III-III in Figure 1 [Figure 4] Plan view of the vibration damper with the lid open [Diagram 5] Diagram of the ceiling structure construction procedure [Figure 6] FIG. 5 is an enlarged cross-sectional view of a ceiling structure according to a second embodiment, corresponding to FIG. [Figure 7] FIG. 4 is an enlarged cross-sectional view of a ceiling structure according to a third embodiment, corresponding to FIG. [Figure 8] Graph showing the results of a comparative experiment on soundproofing performance based on box materials [Figure 9] A graph showing the results of an experiment comparing soundproofing performance based on the number of layers of bubble cushioning material [Figure 10] A graph showing the results of an experiment comparing soundproofing performance based on bubble size in bubble cushioning material [Figure 11] Graph showing the results of a comparative experiment on soundproofing performance depending on the height of the box [Figure 12] A graph showing the results of a comparative experiment on soundproofing performance depending on the number of internal space divisions of a box DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0026] First Embodiment Figures 1 to 5 show a first embodiment of the present invention. As shown in Figures 1 and 2, a ceiling structure 2 according to the first embodiment is provided in a building such as an apartment building, and is disposed below a floor slab 4 (Figure 2) on an upper floor. The floor slab 4 is formed from reinforced concrete. Instead of reinforced concrete, the floor slab 4 on the upper floor may be a deck plate floor, a cast-in-place concrete floor, a panel floor, or the like, disposed on floor beams made of H-shaped steel or the like.

[0027] The ceiling underlayment 6 is placed below and adjacent to the floor slab 4. The ceiling underlayment 6 comprises a pair of runners 10 fixed near the upper ends of opposing walls 8 of the lower floor, and a number of rafters 12 spanning between the pair of runners. The rafters 12 are placed horizontally and parallel to each other with equal intervals between adjacent rafters 12.

[0028] The pair of runners 10 are positioned near the upper ends of the walls 8, i.e., at a position spaced apart from the floor slab 4 of the upper floor. The pair of runners 10 are made of light-gauge steel with a channel cross-section, and are positioned parallel and horizontally with the open faces of the channel cross-section facing each other. The joists 12 are made of corner studs with a rectangular cross-section, and are bridged between the pair of runners 10 so as to be perpendicular to them. Both ends of the joists 12 are supported by the pair of runners 10 by protruding into the open faces of the channel cross-section of the pair of runners 10.

[0029] Above the middle part of the siding 12, a siding support 14 is arranged, which extends horizontally in a direction perpendicular to the siding 12 and supports the siding 12. That is, the siding support 14 is arranged parallel to the runner 10. The siding support 14 may be, for example, a square stud with a rectangular cross section or a lightweight steel with a channel cross section, and is suspended below the floor slab 4 by a suspension member such as a suspension bolt 16 fixed to the floor slab 4. The siding support 14 is supported by the suspension bolt 16 via a connection metal fitting 18 attached to the lower end side of the suspension bolt 16. In another example, the siding support 14 may be directly supported by the suspension bolt 16.

[0030] In the illustrated example, one siding support 14 is disposed in the middle of the siding 12 in the longitudinal direction. In other examples, multiple siding supports 14 may be provided depending on the length of the siding 12, or no siding support 14 may be provided. When multiple siding supports 14 are provided, the multiple siding supports 14 are arranged parallel to each other and so that the distance between the runner 10 and the adjacent siding supports 14 is approximately equal. In still other examples, the hanging bolt 16 may directly support the siding 12 without the siding support 14, or the hanging bolt 16 may not be provided.

[0031] A ceiling board 20 is attached to the underside of the joists 12. The ceiling board 20 is made of gypsum board or the like, and is fixed to the underside of the multiple joists 12 with screws. The ceiling board 20 is an interior material, and wallpaper or the like is applied to its underside to form the ceiling surface of the living room on the lower floor.

[0032] A plurality of vibration dampers 22 are placed on the ceiling board 20. The vibration dampers 22 are formed into a substantially rectangular parallelepiped shape. If the extension direction of the rafters 12 is defined as the vertical direction and the direction perpendicular to the extension direction of the rafters 12 is defined as the horizontal direction, the vibration dampers 22 are aligned in the horizontal direction and arranged every other one in the space between the rafters 12 defined by the plurality of rafters 12 in each row. Furthermore, the vibration dampers 22 arranged in each row are also aligned in the vertical direction and arranged at equal intervals in the vertical direction.

[0033] The arrangement of the vibration dampers 22 is not limited to this. In other embodiments, the vibration dampers 22 may be arranged alternately so as to be offset from one another in the vertical direction. Alternatively, the vibration dampers 22 may be arranged in all of the spaces between the sidings 12 defined by the plurality of sidings 12.

[0034] 3 and 4, the vibration damping body 22 includes a vibration damping material 24 and a box body 26 that houses the vibration damping material 24. The vibration damping material 24 attenuates vibration energy by vibrating within the box body 26 due to the vibration of floor impact sound propagating from the floor slab 4, and contains a large number of granular bodies. The vibration damping material 24 is housed approximately evenly within the box body 26 with a thickness that forms a gap in the upper part of the internal space of the box body 26.

[0035] The granular material may be, but is not limited to, plastic flakes made of irregularly shaped resin in plate form, plastic pellets made of round resin, plastic pieces made of cylindrical resin, stalks of charcoal or dried plants, etc. Among these, it is preferable to use plastic flakes as the granular material, as they have the greatest floor impact sound reduction effect in the 63 Hz band (1 / 1 octave band), which is the frequency band that determines the general heavy floor impact sound insulation performance.

[0036] The box 26 has a hollow structure including a bottom plate 28, a side plate 30 having a rectangular ring shape in a plan view, and a cover plate 32 that closes the upper end of the side plate 30. Inside the box 26, partition plates 34 (34a, 34b) are provided that divide the internal space in the horizontal direction. In the example shown, inside the box 26, one vertical partition plate 34a extending vertically and one horizontal partition plate 34b extending horizontally are provided. Therefore, the internal space of the box 26 is divided into four sections.

[0037] As shown in Fig. 3, the bottom plate 28 is an extrusion molded product of resin, and includes an upper plate 36, a lower plate 38 arranged below the upper plate 36 with a gap therebetween, and a plurality of connecting plates 40 connecting the upper plate 36 and the lower plate 38. The plurality of connecting plates 40 are arranged parallel to one another with a predetermined gap therebetween. The bottom plate 28 is made of so-called plastic corrugated cardboard. In this manner, the bottom plate 28 has a two-layer structure in which an air layer is formed between the upper plate 36 and the lower plate 38. In this embodiment, the plurality of connecting plates 40 extend vertically in parallel with the rafters 12.

[0038] The side plates 30 are formed from the same two-layer plate material as the bottom plate 28. The connecting plates 40 of the side plates 30 are arranged horizontally at intervals in the vertical direction. The cover plate 32 is also formed from the same plate material as the bottom plate 28. In other embodiments, the side plates 30 and the cover plate 32 may be formed from a plate material different from that of the bottom plate 28.

[0039] A pair of engagement pieces 42 are integrally provided on the upper part of the two plates extending in the vertical direction of the side plate 30 so as to protrude laterally from the side plate 30. The engagement pieces 42 are formed from the same two-layer plate material as the bottom plate 28. In other embodiments, the engagement pieces 42 may also be formed from a plate material different from the bottom plate 28. The engagement pieces 42 are formed by folding the plate material along three parallel fold lines to have a substantially triangular cross section, and are joined to the side plate 30 to be integrated with the box body 26. The engagement pieces 42 may be joined to the side plate 30 by bonding with an adhesive, adhesive tape, double-sided tape, or the like, welding, or fastening with staples, rivets, or the like. In other embodiments, the engagement pieces 42 may be joined to the cover plate 32 instead of the side plate 30. Alternatively, the upper part of the side plate 30 may protrude laterally, and the side plate 30 itself may constitute the engagement pieces 42.

[0040] The box body 26 is disposed between a pair of joists 12, and the width of the side panel 30 is smaller than the gap between the joists 12. Meanwhile, the dimension between the outer ends of the pair of engagement pieces 42 is larger than the gap between the joists 12. Therefore, at least a portion of the engagement piece 42 is located above the joists 12, and when there is no ceiling board 20 below, the engagement piece 42 can engage with the joists 12 from above.

[0041] The ceiling structure 2 is constructed as described above. When an impact is applied to the floor slab 4, the floor slab 4 vibrates, and the vibration of the floor impact sound propagates from the floor slab 4 through the wall 8 and the air, and further through the hanging bolts 16 if they are provided, and excites the joists 12 and the ceiling boards 20 fixed to the joists 12. The vibration damper 22 attenuates the vibration energy by the vibration damping material 24 vibrating within the box body 26, and reduces the vibration of the joists 12 and the ceiling boards 20, particularly the vibration of the frequency corresponding to the natural frequency of the vibration damper 22. This reduces the vibration of the joists 12 and the ceiling boards 20, and the sound radiated from the ceiling boards 20 becomes smaller.

[0042] In particular, in this embodiment, the bottom plate 28 of the box body 26 has a two-layer structure that forms an air layer, and the bottom plate 28 is provided with rigidity and elasticity. This makes it easier for the vibration-damping material 24 to bounce, and the vibration-damping material 24 can vibrate freely on the bottom plate 28. This sufficiently attenuates vibration energy, and effectively reduces floor impact noise.

[0043] In addition, the bottom plate 28 is an integral structure having an upper plate 36, a lower plate 38, and a plurality of connecting plates 40 that are arranged parallel to each other at a predetermined interval and connect the upper plate 36 and the lower plate 38. Since the bottom plate 28 is thus formed from an integral structure, the box body 26 can be easily manufactured and handled.

[0044] Furthermore, the box body 26 includes a pair of engagement pieces 42 arranged above the adjacent pair of rafters 12 so as to be able to engage with the pair of rafters 12 from above. In other words, by engaging the pair of engagement pieces 42 with the pair of rafters 12, the vibration damper 22 can be temporarily supported by the rafters 12. Therefore, as will be described in detail below, the vibration damper 22 can be easily placed on the ceiling board 20.

[0045] A specific procedure for constructing the ceiling structure 2 will be described with reference to Fig. 5. Prior to constructing the ceiling structure 2, a plurality of vibration dampers 22 having the above-mentioned configuration are prepared in advance.

[0046] At a building site, first, as shown in Fig. 5(A), a plurality of rafters 12 are arranged so as to extend horizontally and parallel to each other below the floor slab 4. Next, as shown in Fig. 5(B), a vibration-damping body 22 is arranged between a pair of adjacent rafters 12, and a pair of engagement pieces 42 are engaged with the pair of rafters 12 from above, so that the bottom plate 28 is positioned below the lower surface of the rafters 12, and the vibration-damping body 22 is temporarily supported by the pair of rafters 12.

[0047] At this time, as shown in Fig. 5 (B1), the vibration-damping body 22 is tilted and moved above the pair of rafters 12. Next, as shown in Fig. 5 (B2), the vibration-damping body 22 is vibrated above the pair of rafters 12 to equalize the thickness of the vibration-damping material 24 inside the box body 26. After that, as shown in Fig. 5 (B3), the vibration-damping material 24 is lowered horizontally so that it is temporarily supported by the pair of rafters 12.

[0048] By arranging the vibration damping body 22 in this manner, the thickness of the vibration damping material 24 inside the box body 26 can be easily made uniform, and the vibration energy attenuation effect of the vibration damping body 22 is prevented from decreasing due to unevenness of the vibration damping material 24. Also, the work of temporarily supporting the vibration damping body 22 on the joist 12 in such a state is easy. When attaching the ceiling board 20 to the joist 12, the vibration damping body 22 is simply pushed upward by the ceiling board 20 and does not tilt, so the vibration damping material 24 does not become uneven inside the box body 26.

[0049] A number of vibration-damping bodies 22 are placed in predetermined positions, resulting in the state shown in Fig. 5(C). Then, as shown in Fig. 5(D), the ceiling board 20 is pressed from below against the lower surface of the rafters 12. This causes the bottom board 28 to abut against the upper surface of the ceiling board 20, and the pair of engagement pieces 42 are positioned above the pair of rafters 12. By joining the ceiling board 20 to the rafters 12 in this state, the ceiling structure 2 configured as described above is constructed.

[0050] In this way, the bottom plate 28 of the box body 26 has at least a two-layer structure that forms an air layer, and the bottom plate 28 is given elasticity, so that the vibration-damping material 24 can freely vibrate on the bottom plate 28. This allows the vibration energy to be sufficiently attenuated to effectively reduce floor impact noise. In addition, such a vibration-damping body 22 can be easily temporarily supported on the rafters 12 by engaging the pair of engagement pieces 42 with the pair of rafters 12 from above. This makes it easier to place the vibration-damping body 22 on the ceiling board 20, and makes it easier to construct the ceiling structure 2.

[0051] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is an enlarged cross-sectional view of a ceiling structure 2 according to the second embodiment, corresponding to Fig. 3. As shown in Fig. 6, in the ceiling structure 2 of this embodiment, the configuration of the box body 26 is different from that of the first embodiment. Specifically, the box body 26 is made of corrugated cardboard (sheet). In this embodiment, the bottom plate 28, side plate 30, cover plate 32 and engagement piece 42 of the box body 26 are made of corrugated cardboard. In other embodiments, parts other than the bottom plate 28 may be made of a plate material other than corrugated cardboard.

[0052] The bottom plate 28 has a pair of sheets, i.e., an upper sheet 46 and a lower sheet 48, and a corrugated connecting sheet 50 disposed between the upper sheet 46 and the lower sheet 48 and bonded to the upper sheet 46 and the lower sheet 48. In this way, the bottom plate 28 has a two-layer structure in which an air layer is formed between the upper sheet 46 and the lower sheet 48. In other embodiments, the bottom plate 28 may have a layer structure of three or more layers.

[0053] Even if the box body 26 is constructed in this way, the bottom plate 28 has a two-layer structure that forms an air layer, so that the bottom plate 28 is given rigidity and elasticity. This makes it easier for the vibration-damping material 24 to bounce, and the vibration-damping material 24 can vibrate freely on the bottom plate 28. This sufficiently attenuates vibration energy, and effectively reduces floor impact noise.

[0054] Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is an enlarged cross-sectional view of the ceiling structure 2 according to the third embodiment, corresponding to FIG. 3. As shown in FIG. 7, the configuration of the box body 26 in the ceiling structure 2 of this embodiment is also different from that of the above embodiment. Specifically, the box body 26 is mainly formed of a base plate 52, which is a solid board material. The bottom plate 28 of the box body 26 includes the base plate 52, and the side plate 30, the cover plate 32, the partition plate 34, and the engagement piece 42 are each made of the base plate 52. The base plate 52 may be made of resin, for example, and provides a predetermined rigidity to the box body 26. Meanwhile, the bottom plate 28 of the box body 26 further includes, in addition to the base plate 52, a bubble cushioning material 54 placed on the base plate 52.

[0055] The bubble cushioning material 54 is formed by bonding two resin sheets (hereinafter, referred to as a first sheet 54a and a second sheet 54b) together so as to form a plurality of air bubbles. The bubble cushioning material 54 has a two-layer structure in which an air layer is formed by a plurality of air bubbles. The first sheet 54a is flat, and the second sheet 54b has an uneven shape so as to form air bubbles. In this embodiment, the bubble cushioning material 54 is placed on the base plate 52 with the flat first sheet 54a facing upward. Therefore, the entire area between the first sheet 54a and the base plate 52 forms an air layer, and the vibration-damping material 24 is accommodated on the first sheet 54a that forms an air layer over the entire area of ​​the bottom plate 28. In other embodiments, the bubble cushioning material 54 may have a layer structure of three or more layers.

[0056] The base plate 52 ensures the rigidity of the bottom plate 28 of the box body 26, and the air bubbles in the bubble cushioning material 54 form an air layer for imparting elasticity to the bottom plate 28. That is, the bottom plate 28 includes the base plate 52 having a predetermined rigidity and the bubble cushioning material 54 having a layered structure that forms an air layer, thereby imparting rigidity and elasticity to the bottom plate 28. Even if the box body 26 is configured in this way, the vibration damping material 24 is more likely to bounce, and can vibrate freely on the bottom plate 28. Therefore, vibration energy is sufficiently attenuated, and floor impact noise is effectively reduced.

[0057] Next, the floor impact sound reduction effect of the present invention will be described with reference to Figs. 8 to 12. The inventors of the present application constructed a ceiling structure 2 using various types of vibration-damping members, generated floor impact sounds, and measured the vibration acceleration level that decreased when the sounds passed through the ceiling structure 2. Figs. 8 to 12 are graphs showing the results of various experiments conducted by the inventors of the present application. The horizontal axis of the graph indicates the frequency of the floor impact sound, and the vertical axis of the graph indicates the vibration acceleration level difference, i.e., the amount of reduction in floor impact sound. The greater the vibration acceleration level difference, the greater the floor impact sound reduction effect (soundproofing performance).

[0058] 8 is a graph showing the results of a comparative experiment on soundproofing performance depending on the material of the box body 26. The experiment was carried out using, as the vibration-damping member, a gypsum board (PB), a damping material 24 placed in a bag (bagged), a damping material 24 placed in a thin acrylic case (AC), a damping material 24 placed in a cardboard box, i.e., the damper 22 of the second embodiment (DB box), and a damping material 24 placed in a plastic cardboard box, i.e., the damper 22 of the first embodiment (PB box).

[0059] As shown in Fig. 8, in the frequency band of 50 to 63 Hz, which indicates heavy floor impact noise, the gypsum board (PB) has the lowest soundproofing performance. The one placed in a bag (Bagged) and the one placed in an acrylic case (AC) showed higher soundproofing performance than the gypsum board. On the other hand, the vibration damper 22 of the second embodiment (DB box) and the vibration damper 22 of the first embodiment (PB box) showed even higher soundproofing performance.

[0060] 9 is a graph showing the results of a comparative experiment on soundproofing performance depending on the number of layers of bubble cushioning material 54. The experiment was carried out using, as the vibration-damping members, a vibration-damping material 24 placed in a bag (bagged), a vibration-damping material 24 placed in a bag made of bubble cushioning material 54 with a two-layer structure having small air bubbles (small-particle two-layer product), and a vibration-damping material 24 placed in a bag made of bubble cushioning material 54 with a three-layer structure having small air bubbles (small-particle three-layer product).

[0061] As shown in FIG. 9, in the frequency band of 50 to 63 Hz, which indicates heavy floor impact noise, bubble cushioning material 54 (two-layer small-particle product) and bubble cushioning material 54 (three-layer small-particle product) showed higher soundproofing performance than the bagged product.

[0062] 10 is a graph showing the results of a comparative experiment on soundproofing performance depending on the bubble size of bubble cushioning material 54. The experiment was carried out using, as the vibration-damping members, a vibration-damping material 24 placed in a bag made of bubble cushioning material 54 with a two-layer structure having small bubbles (small-particle two-layer product), a vibration-damping material 24 placed in a bag made of bubble cushioning material 54 with a two-layer structure having medium-sized bubbles (medium-particle two-layer product), and a vibration-damping material 24 placed in a bag made of bubble cushioning material 54 with a two-layer structure having large bubbles (large-particle two-layer product).

[0063] As shown in Figure 10, in the frequency band of 50 to 63 Hz, which indicates heavy floor impact noise, the soundproofing performance of the air bubble cushioning material 54 (medium grain two-layer product) was higher than that of the air bubble cushioning material 54 (small grain two-layer product). In the same frequency band, the soundproofing performance of the air bubble cushioning material 54 (large grain two-layer product) was even higher than that of the air bubble cushioning material 54 (medium grain two-layer product).

[0064] 11 is a graph showing the results of a comparative experiment on soundproofing performance depending on the height of the box body 26. In the experiment, a vibration damping body 22 was used in which the vibration damping material 24 was placed in a cardboard box similar to the vibration damping body 22 of the second embodiment. The experiment was carried out using a cardboard box having a height of 150 mm and containing the vibration damping material 24 (DB box H=150), a cardboard box having a height of 125 mm and containing the vibration damping material 24 (DB box H=125), a cardboard box having a height of 100 mm and containing the vibration damping material 24 (DB box H=100), and a cardboard box having a height of 70 mm and containing the vibration damping material 24 (DB box H=70).

[0065] In the vibration damping body 22 that attenuates vibration energy by vibrating the vibration damping material 24, it is necessary to allow the vibration damping material 24 to vibrate freely. Therefore, it is necessary to provide a space above the vibration damping material 24 so that the vibration damping material 24 does not collide with the cover plate 32, and if the height of the box body 26 is low, the soundproofing performance is reduced.

[0066] As shown in Fig. 11, the DB box H=70 exhibits high soundproofing performance in the frequency band of 50 to 63 Hz, which indicates heavy floor impact sound, but exhibits soundproofing characteristics different from those of Figs. 9 and 10. On the other hand, even if the height is increased to DB box H=150 or DB box H=125, there is no improvement in soundproofing performance compared to DB box H=100. This means that simply increasing the space does not contribute to improving soundproofing performance. Therefore, the height of the box body 26 may be large enough to ensure a space that allows the vibration-damping material 24 to vibrate freely, such as a cardboard box with a height of 100 mm.

[0067] 12 is a graph showing the results of a comparative experiment on soundproofing performance depending on the number of divisions of the internal space of the box body 26. In the experiment, a vibration damping body 22 was used, which was a plastic cardboard box containing a vibration damping material 24, similar to the vibration damping body 22 of the first embodiment. The experiment was carried out using a box body 26 whose internal space was not divided (no division), a box body 26 whose internal space was divided into 8, 9, 6, and 4 divisions.

[0068] As shown in Figure 12, in the frequency band of 50 to 63 Hz, which indicates heavy floor impact noise, the non-divided type had the lowest soundproofing performance. The other types showed significantly higher soundproofing performance than the non-divided type, but there was no significant difference depending on the number of divisions.

[0069] From the above, it can be seen that by including the partition plate 34 that horizontally divides the internal space of the box 26, floor impact noise can be reduced more effectively.

[0070] Although the description of the specific embodiment is finished above, the present invention is not limited to the above embodiment and the modified examples, and can be widely modified. For example, the specific configuration, arrangement, quantity, angle, material, etc. of each member or part can be appropriately changed within the scope of the present invention. On the other hand, all of the components shown in the above embodiment are not necessarily required, and can be selected appropriately. [Explanation of symbols]

[0071] 2: Ceiling structure 4:Floor slab 12: No-en 20: Ceiling panel 22: Vibration damper 24: Damping material 26: Box body 28: Bottom plate 34: Partition plate 34a: Vertical partition 34b: Horizontal partition plate 42: Engagement piece 46: Upper sheet (upper plate) 48: Lower sheet (lower plate) 50: Connecting sheet (connecting plate) 52: Base plate 54: Bubble wrap 54a: 1st sheet 54b: 2nd sheet

Claims

1. A ceiling structure for reducing floor impact noise in a building, a ceiling plate disposed below the floor slab with a gap therebetween; A plurality of vibration dampers are placed on the ceiling board, Each of the vibration damping bodies comprises a vibration damping material containing a large number of granular bodies and a box body that houses the vibration damping material, the box body including a bottom plate having a layered structure of at least two layers that form an air layer, and the bottom plate is an integral structure having an upper plate, a lower plate, and three or more connecting plates that are arranged parallel to each other at a predetermined interval and connect the upper plate and the lower plate.

2. A ceiling structure for reducing floor impact noise in a building, a ceiling plate disposed below the floor slab with a gap therebetween; A plurality of vibration dampers are placed on the ceiling board, Each of the vibration damping bodies comprises a vibration damping material containing a large number of granular bodies, and a box body that houses the vibration damping material, the box body including a bottom plate having a layered structure of at least two layers that form an air layer, the bottom plate including a base plate having a predetermined rigidity, and a bubble cushioning material consisting of two sheets placed on the base plate and forming a plurality of sealed air bubbles.

3. A ceiling structure for reducing floor impact noise in a building, a ceiling plate disposed below the floor slab with a gap therebetween; A plurality of vibration dampers are placed on the ceiling board, Each of the vibration damping bodies comprises a vibration damping material containing a large number of granular bodies and a box body that houses the vibration damping material, and the box body includes a bottom plate having a layered structure of at least two layers that form an air layer, and a partition plate that horizontally divides the internal space.

4. A ceiling structure for reducing floor impact noise in a building, a ceiling plate disposed below the floor slab with a gap therebetween; A plurality of vibration dampers are placed on the ceiling board, Each of the vibration dampers includes a vibration damping material including a large number of granular bodies and a box that contains the vibration damping material, the box including a bottom plate having a layer structure of at least two layers that form an air layer; The ceiling board is attached to the lower surface of a plurality of joists arranged to extend horizontally and parallel to one another below the floor slab, A ceiling structure, wherein the box body further includes a pair of engagement pieces arranged above the joists so as to be able to engage with a pair of adjacent joists from above.

5. A method for constructing a ceiling structure to reduce floor impact noise in a building, comprising: disposing a plurality of joists extending horizontally and parallel to one another below the floor slab; A step of preparing a plurality of vibration dampers, each of which includes a vibration damping material containing a large number of granular bodies and a box for accommodating the vibration damping material, the box including a bottom plate having a layer structure of at least two layers forming an air layer, and a pair of engagement pieces extending horizontally away from each other; A step of disposing the vibration damper between a pair of adjacent furring strips, engaging a pair of the engagement pieces with the pair of furring strips from above, and temporarily supporting the vibration damper on the pair of furring strips so that the bottom plate is positioned lower than the lower surface of the furring strips; A method for constructing a ceiling structure includes a step of pressing a ceiling board from below against the underside of the rafters, abutting the bottom board against the upper surface of the ceiling board, and connecting the ceiling board to the rafters while positioning a pair of the engaging pieces above a pair of the rafters.

6. A method for constructing a ceiling structure as described in claim 5, wherein when placing the vibration-damping body between a pair of adjacent rafters, the vibration-damping body is tilted and moved above the pair of rafters, the vibration-damping body is vibrated above the pair of rafters to equalize the thickness of the vibration-damping material inside the box body, and then the vibration-damping material is lowered horizontally to be temporarily supported by the pair of rafters.

Images