2021 Fiscal Year Final Research Report

A Study for Systematizing Calculation Method of Tornado-induced Loads Considering Roughness Condition Near the Ground

Research Project

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Project/Area Number	19H02293
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 23010:Building structures and materials-related
Research Institution	National Institute for Land and Infrastructure Management
Principal Investigator	KIKITSU Hitomitsu 国土技術政策総合研究所, 建築研究部, 室長 (10370694)
Co-Investigator(Kenkyū-buntansha)	奥田泰雄国立研究開発法人建築研究所, 構造研究グループ, シニアフェロー (70201994)
Project Period (FY)	2019-04-01 – 2022-03-31
Keywords	竜巻 / 地表面粗度
Outline of Final Research Achievements	This study examines the load due to the tornado-like wind (tornadic load) considering the roughness effect near the ground surface. First, the relationship between surface roughness and wind characteristics of the tornado was analyzed through technical papers on the tornado observations near the ground. It was confirmed that the tendency of the observation record is almost consistent with the wind speed distribution obtained in the flow visualization experiment using the tornado-like wind generator. Next, wind pressure experiments were conducted to grasp drag characteristics of the roughness blocks on the floor, and it was confirmed that the absolute value of the drag force increases as the swirl ratio increases. Furthermore, assuming that the external force term of the Euler equation is balanced with the drag of the roughness blocks, a pressure dip model that reflects the roughness effect was examined by reflecting the above qualitative tendency.
Free Research Field	建築構造、風工学
Academic Significance and Societal Importance of the Research Achievements	一般に建築物への竜巻による作用は、小スケールかつ急激な気圧降下を伴う点で台風等の強風による作用と異なる。したがって、竜巻荷重の体系化においては現行の風荷重と異なる観点でモデル検討をする必要があり、本研究はその一助となることを目的に実施したものである。竜巻による顕著な建築物被害が報告されている近年の状況を踏まえ、本研究での地表面粗度を考慮した検討の成果は、より竜巻作用の実状に近い荷重モデルの整備に寄与でき、被害の軽減に資する可能性もある点において学術的、社会的な意義があると考える。