This paper describes wind effects for the accumulation of snow particles formed behind a 2D-fence. Wind tmnel tests that used model snow particles are carried out to examine the relationship between the accumulation of snowparticles and the shear stress behind a fence. The activated clay particles are used to simulate snow particles . The shear stress is measured by using a shear stress sensor that improved the hot-film anemometer . The experiment shows that the accumulation distributions of model snow particles and shear stress are almost similarity. This paper proves a fact that the shear stress is important for the evaluations of snow drifting behind a fence.
Annual maximum wind speed distributions caused by typhoons for 40 years from 1950 are plotted on the extremal probability papers at 28 weather stations of JMA (Japan Meteorological Agency). Corresponding distributions which are estimated by a probabilistic procedure based on the statistical properties of typhoons such as central pressure difference and travelling speed are compared with previous ones by introducing conversion factors from the gradient wind to the surface one. It may be said that so called indirect methods are convenient to avoid the effects due to not only increase of surface roughness in observation sites but also randomness of typhoons, since the both distributions seem to be nearly comparable. Effects of super-gradient wind are also investigated by a simulation.
The aerodynamic characteristics of tandem cables of cable-stayed bridges has become more and more serious problem with increment of span length. From the view point of reduction of construction cost and maintenance of cable, tandem cables have been adopted for cablestayed bridge. The tandem cables however, have aerodynamic response characteristics like wake-galloping. Therefore, it is required to develop the method for suppressing wake-galloping of tandem cables. The purpose of this study is to grasp the characteristics of wake galloping phenomenon on tandem cables of cable-stayed bridge using the numerical fluid flow analysis. The flow around the fixed tandem circular cylinders modeled for tandem cables is calculated varying the angle of tandem cylinders. Flow field is treated as incompressible viscous flow, and the selective lumping three-step explicit finite element method which is based on the sound speed method is adopted for the discretization method.
A membrane specimen, PTFE-coated glass fiber fabric, suspended between supports in the uniform air flow in wind tunnel began to flutter at a critical flow speed . This fluttering behavior was modeled as a sinusoidal travelling wave, and was analysed with an approximate method applying thin-airfoil theory and Hamilton's principle . By the analysis the flutter oscillation period-membrane stress curves were shown. The coincidence between the analytical and experimental results was confirmed by study on these curves, and the theoretical or practical region of the flow speed where the fluttering occurs was described. Some applied calculations were performed.
A closed circuit type boundary layer wind tunnel has been constructed at Hachiohji Laboratory, Housing and Urban Development Corp., It is the multipurpose wind tunnel which can be used for many researches on wind engineering. The working section of the wind tunnel is 2.1m in height, 2.8m in width and 17.5m in length. The range of wind speed is from 0.5 to 30.0m/s and the uniformity of mean wind speed and the turbulence intensity in the working section are within ±1.0%, 0.3% respectively. The characteristics of the boundary layer flow made by spires and roughness blocks in the wind tunnel are also described in this paper.