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Volume 1990 (1990)
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Volume 1990, Issue 45
Displaying 1-9 of 9 articles from this issue
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Development of a System and an Attempt to Observe Paths of Particle of Wind Flowing over BuildingsHiroto HAGURA, Toshio KOIZUMI1990 Volume 1990 Issue 45 Pages 1-14
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSIt is important in the study of winds to three-dimensionally determine on site the flow of winds near the ground surface.
The authers developed a system to measure the data of wind flow in both thehorizontal and vertical directions utilizing aerial photographs.
This system uses two cigar-shaped kite balloons to which is mounted a 35mm still camera, which stereophotographs a third balloon released as a tracer, thereby threedimensionally analysing the third balloon's path of particle.
This time, we utilized a system in observing the paths of particle of wind flowing over a building, and obtained the following results. With the effectiveness of the system thus confirmed, we report herewith.
1) It was experimentally confirmed that, using this system, the paths of particle in both the horizontal and the vertical direction could be observed on site simultaneously.
2) It was confirmed that the system was suitable for fixed point observation at any altitude and that unskilled personnel could utilize the system simply and safely.
Consequently, the photographing of urban areas, etc, can be made, and the system is conceivably suitable for three dimensionally observing winds including those flowing over buildings.
3) From the charts of the paths of particles obtained, it was found that it is possible to confirm the behaviors of winds the velocity of which increases at the. windward eaves of a building as the data observed on site.View full abstractDownload PDF (2831K) -
Yoshiharu IWATANI, Masao SHIOTANI1990 Volume 1990 Issue 45 Pages 15-22
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSMeasurements of turbulent winds were made at the height of about 100m over the city of Tokyo. Power spectra, intensities of turbulence, gust factors and peak factors were calculated and were classified in terms of wind speeds, wind directions, weather conditions and day or night.
Gust factors and intensities of turbulence decreased with wind speed and varied with weather condition by day and night though they were nearly constant in the range of wind speed more than 7-8 m/s without relation to weather conditions and day and night. Gust factors were nearly equal to 1.40 to 1.42 in this range of wind speed. In clear night, gust factors and intensities of turbulence were not depend on wind speed. On the other hand, peak factors were almost independent of wind speed, weather condition and day and night, and nearly equal to 2.7 to 3.0.
Power spectra in strong wind conditions were able to be approximately expressed by the equation suggested by Fichtl and McVehil (1970). The integral scale obtained from the above approximation was about 384m under the frozen turbulence hypothesis.View full abstractDownload PDF (1663K) -
Hang CHOI, Jun KANDA1990 Volume 1990 Issue 45 Pages 23-43
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSMany mathematical models which represent the height dependence characteristcs of mean wind speed and turbulence intensity in the neutral atmospheric boundary layer have been proposed and conventionally adopted in practical loading codes.Basic parameters in those models are closely related with the surface condition, then different values have been commonly assumed based on a few previous works conducted before 1970. However, the change of the surface condition, especially in urban, can be anticipated and many reliable measurement results in recent years differ from in the previous ones. And then, some reconsiderations of those mathematical models and parameters are inevitable and, consequently, will be useful for the rationale evaluation of wind loads.
In this study, mathematical models and basic parameters such as power exponent, roughness length and atmospheric boundary layer depth etc, are carefully examined by using full-scale measurement results reported mainly after 1970, and compared with the values in previous proposals and loading codes, in oredr to propose a possible revision for parameters.View full abstractDownload PDF (1696K) -
Shuzo MURAKAMI, Shinsuke KATO, Shin-ichi AKABAYASHI, Takeo TAKAHASHI, ...1990 Volume 1990 Issue 45 Pages 45-55
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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Yoshiharu IWATANI1990 Volume 1990 Issue 45 Pages 57-64
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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Tokunosuke FUJITANI1990 Volume 1990 Issue 45 Pages 65-70
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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Shuzo MURAKAMI, Tadahisa KATAYAMA, Nobuyuki KOBAYASHI, Koichi IKEDA, M ...1990 Volume 1990 Issue 45 Pages 71-113
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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Taiichi HAYASI1990 Volume 1990 Issue 45 Pages 115-116
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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Low Speed Aerodynamics Laboratory National Research Council of Canada Ottawa, Ontario, Canda K1A 0R6Junji MAEDA1990 Volume 1990 Issue 45 Pages 117-120
Published: October 31, 1990
Released on J-STAGE: September 28, 2010
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