A CONVERGENCE AREA EFFECT OF WIND SPEED TO WIND RESISTANCE PERFORMANCE EVALUATION OF STRUCTURES

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A layr grid having 300 openings of 90mm*37mm was prepared. Using the layr grid wind fields of a uniform distribution and a straight gradient profiles were genrated. The turbulence characteristics of the 3 components of the wind fields were examined. A wind tunnel test device in Department of Architecture, Faculty of Engineering, Kyushu University was used. The measurement section area is 1.5m*1.5m. The measurement position is the lower stream 1,500mm of the grid. The following results were obtained.(1) Mean wind distribution in the condition where all openings of the layr grid are open :(a) A longitudinal component (a component in mean wind direction) is uniform distribution. The wind speed in testing is 15m/s.(b) The mean wind speeds of lateral components in vertical and horizontal directions are uniform distribution of an about 0m/s.(2) Turbulence characteristics in the condition where all openings of the layr grid are open :(a) A ratio of the intensity of turbulence of the longitudi … More nal, vertical lateral and horizontal lateral components became 1.0 : 0.09 : 0.78.(b) A ratio of the scale of turbulence of the longitudinal, vertical lateral and horizontal lateral components became 2 : 1 : 1.(c) Power spectra of the three components agree with Karman's spectrum in the theory of isotropic turbulence for the most part except the wall neighborhood inside the measurement section.(3) Mean wind distribution in condition of a straight line profile by adjusting the width of the openings :(a) The wind profile of he longitudinal component (component in mean wind direction) shows a straight line distribution in 1/3 range area of the center inside the measurement section.(b) The mean wind speeds of vertical and horizontal lateral components are uniform distribution of nearly zero m/s.(4) Turbulence characteristics in condition of a straight line profile :(a) The intensities of turbulence of 3 components show a straight line slope.(b) Scales of turbulence are larger than those in uniform distribution in all of 3 components.(c) In the about half range of a straight line slope range of average wind velocity, scales of turbulence of 3 components becomes big in proportion to a wind velocity value. The longitudinal component is most obvious.(d)The turbulence spectra in all of 3 components are similar with those of the longitudinal component. Less