An Experimental Study on Wind Environment caused by Building Group Structure

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1. For the grasping approach flow to a urban area, a vertical profile of wind velocity was measured by an observation balloon in the university campus. Although the purpose of this survey was finding the difference of the profile which occurs with the southern approach wind or northern one, sufficient results were not taken because the northern wind condition was poor. The measurement is planned to be continued.2. The experiment in the wind tunnel was conducted using a building group model and it examined following point. That is an influence of the building group density (building coverage and floor area ratio), an arrangement form and a building shape over the urban area air current and a building wind pressure coefficient. The results are shown as follows.(1) An air current below the height of the building eaves was affected by the arrangement form of buildings. Above the height of the building eaves, wind velocity become equal above a certain height, which is 1.5-3 times as high as the height of building eaves. The direction of street influenced the urban area air current up to fairly height.(2) When the building increased in height at the same building coverage, the thickness of surface boundary layer and roughness parameter : Z_0 increased proportionally with the building height in general.(3) When the building bottom length increased in the same building coverage, the growth of street wind was observed in case that the building coverage is low. And a little increase in wind velocity was observed above the height of eaves.(4) The influence of building group density (building coverage) were large and wind pressure on the wall was very different under the height of building eaves.(5) As examining the hight of standard wind velocity in which a wind pressure coefficient coincides on the conditions of the building groups of a various building shape and an arrangement form, its height was equal to or more than 5 times of a building eaves height.