JP7519948B2 - Wind noise reduction structure for lattice structure - Google Patents

Description

The present invention relates to a wind noise reduction structure for reducing the volume of noise (hereinafter referred to as wind noise) generated by lattice structures consisting of handrails installed on windows, verandas, balconies, rooftops, emergency stairs, etc. of buildings, or fences installed on the boundaries of land, houses, etc., when exposed to wind.

The lattice structure has multiple balusters that extend in one direction, vertically, horizontally or diagonally, at intervals from each other. In the lattice structure, when the dominant frequency of the wind matches the natural frequency of the balusters, the balusters resonate, generating wind noise.

A wind noise reduction structure proposed for reducing the magnitude of the wind noise in a vertical lattice handrail, which is one of the lattice structures, has been one that has two upper and lower plate- or rod-shaped horizontal members that connect multiple balusters to each other. The upper and lower horizontal members serve to reduce the magnitude of the wind noise generated by each baluster by catching the wind.

The above-mentioned lattice structures are installed in familiar locations related to people's lives and activities, so their appearance is important. In the above-mentioned conventional wind noise reduction structures, the horizontal members impair the orderly arrangement of the multiple balusters extending vertically, which may mar the appearance of the vertical lattice handrail. They also obstruct the view from inside the building.

JP 2000-265543 A

In consideration of the above-mentioned conventional situation, the present invention provides a wind noise reduction structure that can avoid damaging the appearance of a lattice structure.

The present invention relates to a wind noise reduction structure for a lattice structure consisting of a handrail or fence and having multiple balusters. The wind noise reduction structure comprises at least one plate member that is fixed to each baluster at at least one point and extends on the surface of each baluster in the extension direction of the baluster. Here, the "surface" of the baluster refers to the peripheral surface that is exposed to the outside air.

In the present invention, when the lattice structure is installed and each baluster vibrates due to wind pressure, each plate member vibrates due to the external force caused by the vibration from each baluster. Here, the vibration parameters of each baluster (mass, rigidity, damping coefficient of baluster) and the wind pressure are different in magnitude from the vibration parameters of each plate member (mass, rigidity, damping coefficient of plate member) and the external force. For this reason, energy is required to vibrate each plate member. Since the sum of the energy is almost equal to the external force applied to the baluster, the energy to vibrate the baluster is reduced compared to when no plate member is installed, and vibration can be suppressed. This reduces the magnitude of wind noise caused by the vibration of each baluster. Each plate member extends on the surface of each baluster in the extension direction of the baluster. In other words, each plate member extends in the extension direction within the range of the width of each baluster or to the extent that it slightly protrudes into the space between two adjacent balusters. This maintains the orderly arrangement of the multiple balusters, and maintains the appearance of the lattice structure defined by the arrangement. The plate members do not obstruct the view from the building. Furthermore, when the lattice structure is made up of balusters installed on a building, the vibrations of the balusters that cause the wind noise can propagate to the building's framework, generating noise inside the room. According to the present invention, the vibrations of the balusters can be suppressed, thereby reducing the noise generated inside the room.

The plate members can be in contact with the surface of each balusters. In this way, when each plate member vibrates relative to each balusters, frictional forces are generated between each balusters and each plate member due to the phase difference, and this frictional force can further reduce the volume of wind noise generated by each balusters. Also, each plate member can be positioned on the windward side when viewed in a state in which the lattice structure is installed. In this way, each plate member is subjected to wind pressure, so the frictional force of each plate member relative to each balusters is further increased, and the volume of wind noise from each balusters is further reduced.

Instead of placing each plate member on the surface of each balusters, it is possible to place it inside each hollow balusters. That is, at least one plate member can be fixed to each hollow balusters at at least one point and extend in the extension direction of each balusters. This makes it possible to reduce the intensity of wind noise caused by vibration of each balusters, or to reduce the intensity of wind noise caused by both the vibration and the frictional force, while avoiding exposure of each plate member to the outside of each balusters and preventing them from being affected by wind.

The plate member can extend over almost the entire length of each balusters and be fixed to the balusters at two points on both ends. This ensures a relatively long distance between the two points, which generates a larger frictional force between each balusters and each plate member, and can achieve a higher reduction in the amount of wind noise from each balusters. The plate member is made of, for example, metal, glass, wood, synthetic resin, or rubber.

FIG. 1 is a perspective view of a vertical lattice handrail, which is an example of a lattice structure to which a wind noise reduction structure is applied. FIG. 2 is a partially enlarged view showing a part of FIG. 1 . FIG. 1 is a cross-sectional view that shows an example of a plate member disposed on a surface of a balustrade having a rectangular cross section. FIG. 11 is a cross-sectional view showing another example of a plate member arranged on a surface of a balustrade having a rectangular cross section. FIG. 13 is a cross-sectional view that shows an example of a plate member disposed inside a balustrade having a rectangular cross section. FIG. 11 is a cross-sectional view that shows roughly another example of a plate member disposed inside a balustrade having a rectangular cross section. 1 is a graph showing a result of a verification performed in a wind tunnel experiment. 13 is a graph showing other verification results from a wind tunnel experiment.

The present invention is applicable to lattice structures such as vertical lattice handrails, horizontal lattice handrails, diagonal lattice handrails, etc. installed on building windows, verandas, balconies, rooftops, emergency stairs, etc., or fences installed on the boundaries of land, houses, etc.

The lattice structure has a number of balusters that extend in one direction at intervals. The balusters usually have a polygonal or circular cross-sectional shape and are either hollow or solid.

Figure 1 shows a vertical lattice handrail 10, which is an example of the lattice structure, and a wind noise reduction structure 12 attached to it.

The illustrated vertical lattice handrail 10 comprises a pair of posts 14 extending vertically (up and down), two upper and lower chord members 16, 18 fixed to the posts 14 and extending horizontally, and a number of hollow, i.e. tubular, balusters 20 spaced apart between the chord members 16, 18. The balusters 20 are fixed at their upper and lower ends to the upper chord member 16 and the lower chord member 18, respectively. Each of the posts 14, each of the chord members 16, 18, and each of the balusters 20 is made of, for example, an extruded aluminum material.

In the illustrated example, each balusters 20 has a rectangular cross-sectional shape and includes four side plate portions 22, 24 that are perpendicular to each other, i.e., two opposing side plate portions 22 and two opposing side plate portions 24 (see Figs. 2 to 6). The four side plate portions 22, 24 have four side surfaces (outer surfaces) _A1 , _B1 on the outside of the balusters 20 and four side surfaces (inner surfaces) _A2 , _B2 on the inside of the balusters 20, which define the rectangular cross-sectional shape. More specifically, one side plate portion 22 has an outer surface _A1 and an inner surface _A2 , and the other side plate portion 24 has an outer surface _B1 and an inner surface _B2 . Here, the outer surfaces _A1 and _B1 respectively form the surfaces of the balusters 20 that are exposed to the outside air. Each of the outer surfaces _A1 , _B1 and each of the inner surfaces _A2 , _B2 has a planar shape of an elongated rectangle. The outer surface _A1 and the inner surface _A2 of the side plate portion 22 have width dimensions _a1 and _a2 , respectively (see FIG. 3), and the outer surface _B1 and the inner surface _B2 of each side plate portion 24 have width dimensions _b1 and _b2 , respectively ( _a1 < _b1 , _a2 < _b2 ) (see FIG. 4). In the illustrated example, both outer surfaces _A1 of each balusters 20 face the front and back of the vertical lattice handrail 10, respectively. The balusters 20 of the vertical lattice handrail 10 may have a cross-sectional shape of a rectangle as shown in the figure, or may have a cross-sectional shape of another polygon such as a triangle, a square, or a pentagon.

The wind noise reduction structure 12 attached to the vertical lattice handrail 10 comprises a number of plate members 26. Each plate member 26 is disposed outside each balusters 20 (Figs. 1 to 4) or inside each balusters 20 (Figs. 5 to 6).

The plate member 26 is made of a flat plate made of metal such as aluminum or steel, or a flat plate made of glass, wood, synthetic resin, or rubber. The illustrated plate member 26 has a long, narrow rectangular planar shape, with an upper end 26a and a lower end 26b consisting of both ends. The illustrated plate member 26 also has a length (vertical length) that is slightly shorter than the mutual distance between the upper and lower chord members 16, 18, and a thickness of 0.5 to 3.0 mm. However, the length and thickness of the plate member 26 can be set to any size.

Each plate member 26 is fixed to each balusters 20 at at least one point (two points consisting of one point on the upper end 26a and one point on the lower end 26b in the illustrated example) and extends in the vertical direction along each balusters 20. More specifically, each plate member 26 is fixed to at least one of the four side plate portions 22, 24 of each balusters 20 at its upper end 26a and lower end 26b using tapping screws 28, and extends in the vertical direction on the outer surface _A1 , _B1 or the inner surface _A2 , _B2 of that one side plate portion 22, 24. However, the plate member 26 arranged inside the balusters 20 is not affected by wind, so it can be fixed to the side plate portions 22, 24 at any one point, for example, only one point on the upper end 26a. The plate member 26 can be fixed to the balusters 20 by fasteners such as rivets, bolts and nuts instead of tapping screws 28, by dotted adhesive, or by welding for the plate member 26 made of a metal plate. The plate member 26 can be fixed to the balusters 20, for example, at one point on one end or one point on the center in the longitudinal direction, or at multiple points spaced apart from one another in the longitudinal direction.

Each plate member 26 is in contact with each balusters 20. More specifically, the plate members 26 shown in Figs. 1 to 3 and Fig. 4 arranged outside the balusters 20 are in contact with the outer surface _A1 of the side plate portion 22 and the outer surface _B1 of the side plate portion 24, respectively. The plate members 26 shown in Fig. 5 and Fig. 6 arranged inside the balusters 20 are in contact with the inner surface _A2 of the side plate portion 22 and the inner surface _B2 of the side plate portion 24, respectively. Note that the plate members 26 arranged outside the balusters 20 can be fixed at their upper end portion 26a and lower end portion 26b to the upper and lower chord members 16, 18 (not shown) instead of being fixed to the balusters 20. Here, the plate member 26 is preferably selected to have a length dimension such that its upper end 26a does not protrude upward from the upper chord member 16 and its lower end 26b does not protrude downward from the lower chord member 18.

Instead of the illustrated example, the plate member 26 can be in a non-contact state with one outer side surface _A1 , _B1 of the balusters 20 between the upper and lower ends 26a, 26b by, for example, interposing spacers (not shown) between the upper and lower ends 26a, 26b and the side plate portions 22, 24 of the balusters 20. Also, even in an example in which the plate member 26 is fixed only at its upper end portion 26a, the portion below the upper end portion 26a can be in a non-contact state with one outer side surface _A1 , _B1 of the balusters 20 in the same manner.

With the wind noise reduction structure 12, when the vertical lattice handrails 10 are installed in required locations and receive wind pressure (F ₀ ), causing vibrations in each balusters 20, more specifically, when the dominant frequency of the wind matches the natural frequency of the balusters, the balusters resonate and generate wind noise. At this time, each plate member 26 receives an external force (F') from each balusters 20 due to the vibrations, and vibrates between its upper and lower ends 26a, 26b. Here, the vibration parameters of each balusters 20 (mass ( _m0 ), rigidity ( _k0 ), damping coefficient ( _c0 ) of the balusters) and the wind pressure ( _F0 ) are different in magnitude from the vibration parameters of each plate member 26 (mass (m'), rigidity (k'), damping coefficient (c') of the plate member 26) and the external force (F' (= _{m0a0 , a0} : vibration acceleration of the balusters 20)).

For this reason, energy is required to vibrate each plate member 26. Since the sum of the energy is approximately equal to the external force acting on the balusters 20, the energy that vibrates the balusters 20 is reduced compared to when the plate members 26 are not installed, and the vibration can be suppressed. This reduces the magnitude of wind noise caused by the vibration of each balusters 20. In addition, the vibration of the plate member 26 is out of phase with the vibration of each balusters 20. When the plate member 26 is placed in contact with one of the outer surfaces A1, B1 of each balusters 20, or one of the inner surfaces A2, B2, a frictional force is generated between each balusters 20 and each plate member 26 due to the phase difference, along with the vibration of each plate member 26 relative to each balusters 20. The frictional force further reduces the magnitude of wind noise generated by each balusters 20.

The results of wind tunnel tests conducted to verify this for three vertical lattice handrails are shown in the graph in Figure 7. The wind tunnel tests were conducted using a vertical lattice handrail with 17 tubular balusters. The width, depth, thickness and length of the balusters were 20 mm, 40 mm, 1.1 mm and 1165 mm, respectively. The plate members used were made of aluminum. The width, length and thickness of the plate members were 20 mm, 1150 mm and 2.0 mm, respectively. The graph shows A-weighted sound pressure levels for wind speeds of 5 to 20 m/s. In the figure, vertical lattice handrails to which no wind noise reduction structure 12 was attached are marked "none." Also, a vertical lattice handrail to which a wind noise reduction structure 12 is attached, in which a plate member 26 is attached at both upper and lower ends 26a, 26b to one side plate portion 22 of a balusters 20 and contacts the outer surface _A1 of the side plate portion, is marked as "Countermeasure (upper and lower end stop)". Furthermore, a vertical lattice handrail in which a plate member 26 is bonded over its entire surface to the outer surface _A1 of one side plate portion 22 of a balusters 20 and therefore cannot vibrate against one side plate portion 22, is marked as "Countermeasure (full surface stop)".

As shown in Figure 7, the sound pressure level of "Countermeasure (top and bottom end stop)" is lower than the sound pressure level of "none" in almost the entire range of wind speeds from 5 to 20 m/s, and is also lower than the sound pressure level of "Countermeasure (full stop)" at the relatively high wind speed of 13 to 17 m/s, showing that "Countermeasure (top and bottom end stop)" is relatively effective in reducing the volume of wind noise. In particular, the wind noise reduction effect of "Countermeasure (top and bottom end stop)" is evident at wind speeds of 13 to 17 m/s.

The width dimension of the rectangular plate member 26 is set to be equal to or smaller than the width dimensions _a1 , _b1 of the outer side surfaces _A1 , B1 of ₁ that the plate member 26 faces, preferably ₅₀ to 100% of the width dimensions a1, _b1 of the outer side surfaces _A1 , B1, and equal to or smaller than the width dimensions _a2 , _b2 of the inner side surfaces _A2 , _B2 of ₁ , preferably 50 to 100% of the width dimensions _a2 , _b2 of the inner side surfaces A2, B2. The plate member 26 extends in the vertical direction on the outer side surfaces _A1 , B1 of ₁ that it faces, within said outer side surfaces, and on the inner side surfaces _A2 , B2 of ₁ that the plate member 26 faces, within said inner side surfaces.

According to this, the plate member 26 arranged outside the balusters 20 does not protrude outside one of the outer faces _A1 , _B1 of each balusters 20, and therefore can be placed in a state where it extends in the extension direction together with each balusters 20 without protruding into the space 30 (see FIG. 2) between two adjacent balusters 20. However, for the rectangular plate member 26 arranged outside the balusters 20, it is possible to use one having a width dimension slightly larger than the width dimensions _a1 , b1 of one outer face _A1 , _B1 that the plate member faces, for example a width dimension 10% larger than the width dimensions _a1 , _b1 of the outer faces A1, _B1 .

This maintains the orderly arrangement of the multiple balusters 20, and the appearance of the vertical lattice handrail 10 defined by the arrangement is maintained. Also, since the plate members 26 arranged inside the balusters 20 are not exposed to the outside of the balusters 20, the orderly arrangement of the multiple balusters 20 is maintained, and the appearance of the vertical lattice handrail 10 defined by the arrangement is maintained.

In addition, in a vertical lattice handrail 10 in which the plate member 26 is placed outside the balusters 20, the plate member 26 can be placed so that it is located on the windward side when viewed in the installed state of the vertical lattice handrail 10. In this way, the plate member 26 is pressed against the balusters 20 by the wind pressure, so the frictional force of the plate member 26 against the side plate parts 22, 24 of one is further increased, and the amount of wind noise generated by each balusters 20 is further reduced.

The results of wind tunnel testing conducted on three vertical lattice handrails to verify this are shown in the graph in Figure 8. The wind tunnel testing was conducted using a vertical lattice handrail with 17 tubular balusters, as described above. The width, depth, thickness and length of the balusters were 20 mm, 40 mm, 1.1 mm and 1165 mm, respectively. The plate members used were made of aluminum. The width, length and thickness of the plate members were 20 mm, 1150 mm and 1.0 mm, respectively. The graph shows sound pressure levels in the 1/3 octave band at 2000 Hz for wind speeds of 5 to 20 m/s. In the figure, a vertical lattice handrail that does not have a wind noise reduction structure 12 attached is labeled "none," a vertical lattice handrail 10 that has a wind noise reduction structure 12 attached and is installed so that its plate member 26 is located on the windward side is labeled "countermeasures (installed upwind)," and a vertical lattice handrail 10 that has a wind noise reduction structure 12 attached and is installed so that its plate member 26 is located on the leeward side is labeled "countermeasures (installed downwind)."

As shown in Figure 8, the sound pressure level of "Countermeasure (Installation upwind)" is lower than the sound pressure level of "None" over almost the entire range of wind speeds from 5 to 20 m/s. Also, in the high-frequency range such as the 1/3 octave band 2000 Hz band, the sound pressure level of "Countermeasure (Installation upwind)" is lower than the sound pressure level of "Countermeasure (Installation downwind)" at wind speeds of 12 m/s or more, and it can be seen that the wind noise reduction effect of "Countermeasure (Installation upwind)" is relatively high.

In the above, a balusters 20 having a polygonal cross-sectional shape is given as an example of an attachment target of the wind noise suppression structure 12, and a plate member 26 made of a flat plate is attached to the balusters. However, when the balusters have a circular cross-sectional shape, a curved plate with a circular arc shape is used as the plate member. More specifically, for a solid balusters, at least one curved plate having a curvature approximately equal to the curvature of the circumferential surface that defines the surface of the balusters is arranged so as to face the circumferential surface and extend in the extension direction of the balusters, in accordance with the above, and fixed to the balusters at at least one point. When there are multiple curved plates, the multiple curved plates are arranged at intervals from each other in the circumferential direction. For a hollow balusters, the curved plates are arranged and fixed on the outer peripheral surface, which is the surface, in the same manner as for the solid balusters. For the plate member arranged inside the hollow balusters, a curved plate having a curvature approximately equal to the curvature of the inner peripheral surface of the balusters is used. At least one of these curved plates is also positioned and fixed on the inner circumferential surface in the same manner as on the outer circumferential surface.

The plate members can also be attached to railings with multiple balusters extending vertically, railings and fences with multiple balusters extending horizontally, and railings and fences with multiple balusters extending diagonally in the same manner as for the balusters of the vertical lattice railing and the balusters with a circular cross section.

10 Vertical lattice handrail 12 Wind noise reduction structure 16, 18 Upper and lower chord members of vertical lattice handrail 20 Balusters 22, 24 Side plate portion of balusters 26 Plate members 26a, 26b Upper and lower ends of balusters 28 Tapping screw 30 Space between balusters _A1 , _A2 Outer and inner surfaces of one side plate portion _B1 , _B2 Outer and inner surfaces of the other side plate portion

Claims (6)

A wind noise reduction structure for a lattice structure consisting of a handrail or fence having a plurality of handrails,
A wind noise reduction structure comprising at least one plate member fixed to each balustrade at at least one point and extending on a surface of each balustrade in the extension direction of the balustrade. The wind noise reduction structure of claim 1, wherein the plate member is in contact with the surface of each balustrade. The wind noise reduction structure according to claim 2, wherein the plate member is located on the windward side when viewed in a state in which the lattice structure is installed. A wind noise reduction structure for a lattice structure consisting of a handrail or fence having a plurality of hollow handrails,
A wind noise reduction structure comprising at least one plate member disposed within each balustrade and fixed to the balustrade at at least one point, and extending in the extension direction of each balustrade. The wind noise reduction structure according to claim 4, wherein the plate member is in contact with the balustrade. 6. A wind noise reduction structure according to claim 1, wherein the plate member extends over the entire length of each balustrade and is fixed to the balustrade at two points on both ends thereof.

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