Journal of Wind Engineering
Online ISSN : 1349-340X
Print ISSN : 1349-3507
ISSN-L : 1349-340X
Volume 27 , Issue 4
[No. 93]
Showing 1-2 articles out of 2 articles from the selected issue
Technical Paper
  • Akihisa KAWAGUCHI, Makoto KANDA, Eizo MARUTA
    2002 Volume 27 Issue 4 Pages 93_93-93_101
    Published: 2002
    Released: August 05, 2005
    The Hybrid vibration technique, which was proposed by Dr. Kanda, is combined a movable mechanical system with a personal computer for simulating the wind-induced vibration of structures in wind tunnel tests. Authors attempted to investigate the wind-induced response of scale models with various-type of elasto-plasticity by means of Hybrid vibration system. The results of wind tunnel tests shows as follows: (1) Hybrid vibration system can simulate wind-induced vibration of models with a elasto-plasticity or a non-linear elasticity, (2) the across-wind response of models with a hysteretic damper was always reduced, (3) the across-wind response of models with a non-linear elasticity was increased around the wind condition of just below the vortex-excitation and decreased in the vortex-excitation, (4) the along-wind response of models was not controlled, and was remarkably increased, when the mean response was in the second stiffness and (5) the event of which the response was increased and/or decreased is explained in a viewpoint of frequency domain.
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  • Kazuyo FUKUDA
    2002 Volume 27 Issue 4 Pages 93_103-93_113
    Published: 2002
    Released: August 05, 2005
    The vertical structures of nocturnal drainage winds that blow onto the Fukuoka Plains from mountains behind were examined on the basis of echo intensity and wind velocity obtained by using a Doppler sodar. Air and soil surface temperatures, wind velocity and net radiation near the ground surface were also measured to estimate the heat budget between the air and the ground. Though the nocturnal drainage winds have the depth of 250 m to 300 m, the shape of the fronts varies with the sea breeze and the surrounding flow. Twice in the nighttime, the occurrence of the horizontal wind with the maximum speed of 4 to 6 ms-1 was observed at the height about 150 m above the ground surface. Though the ascending currents with the speed of 0.2 to 0.4 ms-1 were also seen twice with the occurrence, the second current ascended higher than the first one. These phenomena may be due to the intermitted supply of cold air mass from a basin being in the upstream side. After the first occurrence, the air temperature near the ground surface reaches to the air temperature at a height of 30m. This reason is that the cold air near the ground surface formed by the radiational cooling is replaced with the upper warm air by the advection of the drainage winds. After then, the decreasing rate of the air temperature becomes smaller because the heat fluxes from the air toward the ground suppress the radiational cooling.
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