| 摘要 |
PROBLEM TO BE SOLVED: To reduce wind sound such as pressure wind sound or buzz sound generated by wind from all directions by using a round bar having an elliptical cross section and twisted in the longitudinal direction for the step sections and major sections of a ladder. SOLUTION: This low-wind sound ladder 1 is constituted of step sections 2 and major sections 3, and the step sections 2 and major sections 3 are made of a twisted elliptical round bar. A proper round bar with an elliptical cross section constituted of a minor axis diameter and a major axis diameter is spirally twisted along the longitudinal direction to form the twisted elliptical round bar. The step sections 2 and the major sections 3 are assembled by bolts and nuts, welding or coupling to form the low-wind sound ladder 1. For the degree of twisting, the number of twists per unit length is determined in consideration of wind direction and wind quantity so that no wind sound occurs. Even if wind is applied to the ladder 1 orthogonally or in parallel, the wind sound can be reduced because the ladder 1 is made of the twisted elliptical rod.
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