設計基準風速についての一考察 : 建物密度の経年変化を考慮した年最大風速の均質化

概要

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The values of annual maximum windspeed measured at the weather stations in Japan have been decreased from 1960. Several investigators explain that this is due to the decrease of the number of severe typhoons afflicting Japan. However, this explanation is suspect because the reduction of windspeed also appears in the values of annual mean windspeed and daily maximum windspeed. The authors hypothesize that this tendency to reduced windspeed is closely related to the increasing of ground roughness. We investigated the total volume of the building around the weather stations in Japan and we assert that the yearly variation of the ground roughness is greater than we expected. We show that the building density has increased radically since I960 and is closely correlated with the yearly variation of windspeed. We suggest a possibility that the reduction of windspeed is mainly caused by the increasing of the ground roughness. Then the annual maximum windspeed is corrected taking into account the variation of the ground roughness, and the values for any return period are discussed.
社団法人日本建築学会の論文
1989-06-30