JP2018172961A - Lattice body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lattice body capable of inhibiting a vibration and noise due to wind.SOLUTION: A plurality of lattice members 1,1,... are provided with interval and a lattice member 1 has an identical cross section from one end 1a to an intermediate position 1b and a range Y from the intermediate position 1b to the other end 1c is twisted and an orientation of the cross section is altering due to a twist gradually.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lattice used for a handrail or the like.

  For the railing of the bridge and the railing of the veranda, a lattice body in which thin rod-shaped lattice members are attached at intervals is used. Such a lattice body has a problem that vibration and noise are generated in a strong wind. The mechanism for generating vibration and noise will be described. As shown in FIG. 10, when the grid material 90 is hit by the wind, regular vortices 91 are discharged alternately to the leeward side, and the grid material 90 is instantaneously released. Since the pressure in the vicinity of is reduced, the lattice material 90 is displaced to the side from which the vortex 91 is released. By periodically discharging the vortex 91 alternately left and right, the lattice material 90 is also periodically displaced to the left and right (in the direction perpendicular to the wind flow), resulting in vibration. In the grid member 90 having a uniform cross section, the vortex 91 is released from any position in the same state. Therefore, the vortex 91 is aligned with the entire length in the longitudinal direction of the grid material 90, and the excitation force acts in the same direction over the entire length. Becomes larger. Further, when the lattice member 90 having a uniform cross section is supported at both ends, it is most likely to vibrate in the primary mode (see FIG. 11) in which the amplitude between the support points is just the maximum.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a lattice body that can suppress generation of vibration and noise due to wind.

  In order to achieve the above object, a lattice body according to the first aspect of the present invention comprises a plurality of lattice materials at intervals, and the lattice material has the same cross section from one end to an intermediate position, and the other from the intermediate position. The range to the end is twisted, and the direction of the cross section is gradually changed by twisting.

  In the grid body according to the first aspect, the cross section of the grid material is the same from one end to the intermediate position, the range from the intermediate position to the other end is twisted, and the direction of the cross section gradually changes due to torsion. Therefore, the generation of vibration and noise due to wind can be suppressed. This is because the lattice material is twisted, the position where vortices are released gradually in the longitudinal direction of the lattice material when receiving wind, and the vortices are not aligned in the longitudinal direction of the lattice material. Depending on the position, the left or right non-uniform force acts on the lattice material at the same time, and the left and right forces cancel each other out or twist to twist the wind in a direction perpendicular to the wind. The rigidity of the grid material is intermediate between the support points because the rigidity of the lattice material changes, the twisted part is closer to one side (the other end), and the twisted part is more rigid than the untwisted part. This is considered to be due to a decrease in the amplitude of the primary mode.

It is a front view showing one embodiment of a lattice object of the present invention. 1A is a cross-sectional view taken along line AA in FIG. 1, FIG. 1B is a cross-sectional view taken along line BB in FIG. 1, FIG. 1C is a cross-sectional view taken along line CC in FIG. FIG. 2E is a cross-sectional view taken along line EE in FIG. It is the schematic of a test apparatus. It is a graph which shows the relationship between a wind speed when a wind is applied to the lattice body of Example 1, and a vibration acceleration level. It is a graph which shows the relationship between a wind speed when a wind is applied to the lattice body of Example 2, and a vibration acceleration level. It is a graph which shows the relationship between a wind speed when a wind is applied to the lattice body of Example 3, and a vibration acceleration level. It is a graph which shows the relationship between a wind speed when a wind is applied to the lattice body of Example 4, and a vibration acceleration level. It is a graph which shows the relationship between the wind speed and vibration acceleration level when a wind is applied to the lattice body (what the lattice material is not twisted) of the comparative example 1. It is a graph which shows the relationship between the wind speed and the vibration acceleration level when a wind is applied to the grid | lattice body (what the grid | lattice material twisted full length) of the comparative example 2. FIG. It is a figure which shows a mode that a vibration generate | occur | produces when a wind hits the conventional lattice material. It is a figure which shows typically the vibration mode of a lattice material.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an embodiment of the lattice body 2 of the present invention. The grid 2 is used for a handrail of a veranda, and includes a pair of pillars 3 and 3, a headboard 4 erected at the upper ends of the pillars 3 and 3, and a lower chord member 5 erected at the lower part of the pillars 3 and 3. And a plurality of lattice members 1, 1,... Mounted between the headboard 4 and the lower chord member 5 at intervals in the left-right direction.

  As shown in FIG. 2, the lattice material 1 is formed of a hollow aluminum extruded shape having a rectangular (square) cross section. As shown in FIG. 1, the lattice material 1 has the same cross section as the range X from the lower end 1a to the intermediate position 1b as shown in FIG. 2E, and the range Y from the intermediate position 1b to the upper end 1c. The center of the cross section is twisted about the axis, and the direction of the cross section is gradually changed by twisting as shown in FIGS.

As shown in Table 1 below, the lattice body 2 with different twist angles and twist ratios (the ratio of the twisted range of the total length of the lattice material) is created, and as shown in FIG. Noise is generated when the wind with the wind speed changed in steps of 2 m / s in the range of 2 to 20 m / s is applied to the grid 2 in the direction of wind (α in the figure) in the range of 0 ° to 90 ° in steps of 15 °. Tested to see if. Specimen No. Nos. 1 to 15 have a twist ratio of 75%, and the twist angle was changed between 15 ° and 165 ° (in increments of 15 ° from 15 ° to 75 ° and from 105 ° to 165 °, 75 ° to 105 ° Until then, it was changed in 5 ° increments.) Specimen No. In Nos. 16 to 24, the twist angle was 90 °, and the twist ratio was changed from 55% to 95% in increments of 5%.
As a result of the test, the test specimen No. whose twist angle was changed was changed. From the results of 1 to 15, it was found that noise was not generated when the twist angle was 85 ° or 90 °. Further, from the results of the test bodies 16 to 24 in which the twist ratio was changed, it was found that noise was not generated when the twist ratio was 65% to 95%.

  Next, a twist angle of 90 ° and a twist rate of 75% (Example 1), a twist angle of 90 ° and a twist rate of 65% (Example 2), a twist angle of 90 ° and a twist rate of 95% (Example 2) Example 3) For a sample having a twist angle of 85 ° and a twist ratio of 75% (Example 4), the wind direction (α in the figure) is 0 °, 30 °, 60 ° as shown in FIG. As shown in FIG. 3B, the vibration acceleration level of the acceleration pickup 6 attached to the intermediate position of the lattice material 1 was measured when the wind speed was changed between 2 and 20 m / s. For comparison, the lattice material 1 that was not twisted (Comparative Example 1) and the lattice material 1 that was twisted full length (Comparative Example 2) were also measured (in Comparative Example 2, only the wind direction was 0 °). The measurement results are shown in FIGS.

As shown in FIG. 8, in Comparative Example 1 in which the lattice material 1 is not twisted, the vibration acceleration level becomes 130 db or more when the wind speed exceeds 10 m / s at a wind direction of 0 °, and the vibration acceleration level becomes higher when the wind speed exceeds 16 m / s. In the first to fourth embodiments in which the lattice material 1 is partially twisted, the vibration acceleration level is 130 db in any measured wind direction and speed as shown in FIGS. It was never over.
Further, as shown in FIG. 9, in Comparative Example 2 in which the lattice material 1 is twisted over its entire length, the vibration acceleration level was 130 db or more when the wind direction was 0 ° and the wind speed was 10 m / s, whereas the twist was partially twisted. In Examples 1 to 4, the vibration acceleration level did not become 130 db or higher in any measured wind direction and wind speed.
Comparing the magnitude of vibration acceleration level when the wind direction is 0 ° with partial torsion (Examples 1 to 4), full-length torsion (Comparative Example 2), and no torsion (Comparative Example 1), no torsion> full length The vibration acceleration level decreased in the order of torsion> partial torsion.
In addition, it is known from the test for the comparative example that there is a relationship as shown in Table 2 below between the vibration acceleration level and sensory evaluation (evaluation performed by human hearing). When the level is less than 130 db, noise is not felt or is a level that does not matter even if it is heard.

  As described above, the grid body 2 has the same cross section from one end 1a to the intermediate position 1b of the grid material 1, and the range Y from the intermediate position 1b to the other end 1c is twisted. Is gradually changing, it is possible to suppress the generation of vibration and noise caused by wind. This is because the lattice material 1 is twisted so that the position where vortices are released in the longitudinal direction of the lattice material 1 gradually changes when the wind is received, and the vortices are not aligned in the longitudinal direction of the lattice material 1. The excitation force acting on the grid material 1 is also not uniform, and depending on the position, the left or right non-uniform force acts on the grid material at the same time, and the left and right forces cancel each other or twist according to the direction of the cross section. The change in rigidity in the direction perpendicular to the wind, and the fact that it is less likely to vibrate than what is twisted over the entire length, the twisted part is closer to one side (the other end), and the twisted part is not twisted Since the rigidity of the lattice material becomes asymmetric with respect to the intermediate point between the support points, the amplitude of the primary mode is reduced, so that it is considered that sound and vibration due to wind can be suppressed.

  When the lattice material 1 has a substantially square cross section, the twist angle is preferably approximately 85 ° to 90 °, and the ratio of the twisted range is preferably 65% to 95%. Thereby, the effect which suppresses said vibration and noise is exhibited reliably. The substantially square cross section includes, for example, a square corner chamfered in an R shape.

  The present invention is not limited to the embodiments described above. Even if the torsion angle is an angle other than approximately 85 ° to 90 °, vibration and noise can be reduced as compared with those not twisted. The twisted range may be asymmetric with respect to the longitudinal center of the lattice material, and the lower end side may be twisted. The lattice material is not limited to a square cross section, but may be a rectangular cross section or the like, and is not limited to a hollow material, and may be a solid material. The present invention is not limited to handrails and can be widely applied to lattice bodies having lattice materials at intervals.

1 Lattice material 2 Lattice body

Claims (1)

  A plurality of lattice materials are provided at intervals, and the lattice material has the same cross section from one end to the intermediate position, and the range from the intermediate position to the other end is twisted, and the direction of the cross section gradually changes due to torsion. A lattice body characterized by being.