Aerodynamic drag force of a sphere in uniform flow is measured using Magnetic Suspension Balance System of Fukuoka Institute of Technology. The result of CD is well coincident with well known CD value in the Reynolds number range of 10000 to 100000. Wake interference effects are also measured by inserting a supporting shaft from rear part of the sphere.

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Drag and wake of sphere has been measured with MSBS (Magnetic Suspension and Balance System) at NAL (National Aerospace Laboratory of Japan). MSBS is an ideal way of supporting a model for wind tunnel tests because the force to supporting a model is generated by the magnetic field, which is controlled by coils arranged outside the test section. It can be shown the effect of model support interference. The experiments, are carried out in the wind tunnel of NAL at Reynolds numbers ranging from 100,000 to 347,000. The turbulence intensity is less than 0.08%.
A comparison of present data with other investigations of sphere including free flight and other MSBS data is given. The results of drag measurement indicate that the tendency for critical Reynolds number to higher than other data of sphere with model support is shown.
The hot-wire measurements of vortex shedding from sphere indicate that the signals recorded at two places which are different in the position of a center of sphere to 225mm (x/D=1.5) show a phase shift. An attempt is made to interpret this experimental evidence.

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An RTK-GPS (Leica MC1000) has a nominal accuracy of 1cm +1ppm for horizontal displacements with a sampling rate of 10Hz. The object of this paper is to demonstrate the feasibility of RTK-GPS for wind-induced response measurements and its efficiency in measuring the displacement of a full-scale tower and to study the feasibility of hybrid use of FEM analysis and RTK-GPS for detecting the integrity of structures during strong typhoons. The efficiency of RTK-GPS is demonstrated in the full-scale measurement of an actual steel tower. According to the feasibility study of RTK-GPS for measuring wind-induced responses of buildings, the responses with amplitudes larger than 2cm and natural frequencies lower than 2Hz can be detected by RTK-GPS. Hybrid use of RTK-GPS and FEM analysis for real time monitoring of the integrity of structures is proposed and its efficiency is demonstrated.

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This Paper describes the fundamental aerodynamic characteristics of two edge girders, which would be used for the bridge girders of future long span cable stayed. For the purpose of the aerodynamic stabilization of two edge girders, we considered the girder, which was inclined low flanges for controlling the flow field around lower side of two edge girder sections, because the vertical and horizontal plates on lower side was effective for aerodynamic instability through various wind tunnel tests. Therefore, the aerodynamic effect of two-edge girders with inclined lower flange was investigated by unsteady aerodynamic characteristic based on measurement of aerodynamic forces.

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Further expansion of span length of a suspension bridge is necessary to realize long-span bridge projects in the world. Effects of basic parameters of a suspension bridge such as sag ratio, side-span ratio, deck aspect ration and cable strength on its aeroelastic characteristics were analytically studied.

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Flutter stabilization of girders is one of major subjects in design of long- spanned bridges, since the onset of flutter oscillation directly leads to structural failure. In the previous studies, it has been clarified that the reduction of unsteady aerodynamic force and the flow separations at two different points on the side surface of the body are effective in the control of flutter from the point of flow mechanism. The aim of this paper is to improve the flutter characteristics of separate box girders by these methods. For this purpose, wind tunnel tests are conducted under the condition of installation of vertical plate.

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Unsteady aerodynamic forces on bridge deck are usually expressed by vertical, torsion and their velocity proportional components, and linear superposition of them is assumed. Setting a spring-mounted bridge deck model for which amplitude ratio of vertical and torsion, and their phase are arbitrarily controlled, linear superposition of unsteady aerodynamic forces is studied by measurement of surface pressure around the model.

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There are instances of erecting parallel bridges because of complying with increase of traffic etc. We have known aerodynamic response of parallel bridges is different from one of single bridge and is complex. But, we have not still found effect of parallel distance on aerodynamic response of parallel bridges. In this study, we examined the effect by wind tunnel experiment using 2-dimensional model of parallel cable-stayed bridges. As a result, it was found that a tendency to effect of parallel distance changed by wind direction, natural mode of vibration, position of box girder being windward or leeward.

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It is likely to become a parallel bridge for the correspondence of traffic to the increase and the reasons for the construction efficiency etc. Not being understood enough is a current state in the characteristic though the wind behavior becomes a single bridge and complex the difference when becoming a parallel bridge. Moreover, it is possible that the wind behavior becomes complex by the wind affected by surrounding small-scale terrain around the bridge construction point. In this research, wind tunnel experiment was conducted in order to clarify the influence which surrounding small-scale terrain exerted on the response of parallel box girder bridges to the wind. It has been understood that the response characteristics of parallel box girder bridges are different when surrounding small-scale terrain exists. Effects of the water level of a vertical shore protection, and existence and the slope of an embankment are tested.

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We carried out numerical simulation of a separated flow that installed the wall height field of the rod in the rectangular section. The flow field that is almost equal to basic section is formed, when the protrusion of the rod was established, when three dimensionality of a separated flow of digit upper surface was noticed. By installing the wall in half interval of the span direction, it could be confirmed that the three dimensionality of a separated flow strengthened.

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This paper describes wind-induced vibration of inclined cables of cable-stayed bridges.This vibration may not be expressed by only galloping type vibration but also the vortex-related phenomena. To clarify this phenomenon, wind tunnel tests are carried out from the view point of applying the quasi-steady theory to inclined cable aerodynamics and span-wise upper water rivulet locations related to the characteristics of Karman vortex shedding.

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A large-scale inclined cable model was installed in the southernmost cape of the Japan main island and its behaviors have been observed all the year round to investigate the mechanisms of wind-induced vibrations of inclined stay cables. Using a few types of the cable models, their responses have been measured and analyzed especially under seasonal wind of winter and typhoon wind of summer. Then, the rain-wind induced vibration and the galloping like vibration was observed. The mechanism of the second vibration was not completely proved as galloping. However, this result may show the possibility of divergent type vibration on the stayed cables.

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The aim of this study is to clarify the reason why the span-wise coherence of fluctuating pressures on two-dimensional bluff sections is larger than that of fluctuating wind velocities. The surface pressure and the velocity fluctuation around a 2-D model with rectangular section of B/D=1(B:chord length, D:depth of the section) were measured in grid turbulence and in the artificially generated 3-D fluctuating flow.

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To discuss the validity of the assumption for the analytical formulation of the Sears function, surface pressure of 2-D flat rectangular cross section was measured. Deviation of waveform from sinusoidal signal is clearly captured by applying the phase averaging technique to the measured data. It was confirmed that the difference between upper and lower surface shows more sinusoidal waveform, then the assumption is concluded to be satisfied.

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The interferences between different aerodynamic phenomena must be an important subject in bridge aerodynamics, for example the case of Tacoma Narrows Bridge Failure. Generally, wind tunnel tests with sectional bridge models are conducted using same modes of heaving and torsional motion. However, it may be possible that the aerodynamic vibrations of different modes of heaving and torsional motion occur simultaneously or interfere each other. It is rather significant to investigate the aerodynamic interferences to understand behaviors of real bridge decks. Then, in this study, the aerodynamic interferences of B/D=2 rectangular section was investigated by wind tunnel tests as a fundamental research. Using this model, following aerodynamic interferences are observed, 1) coupled flutter, 2) suppression of galloping by torsional flutter, 3) suppression of torsional flutter by galloping, 4) suppression of galloping by torsional vortex-induced excitation.

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The characteristics of a flow around a cubic model are experimentally studied by a wind tunnel test. The flow around the model was measured by PIV method. And simultaneous multi-pressure measurements on the model surface were also performed. By using this two method synchronously, simultaneous data set of the flow and the wind pressure on model were obtained. As a result of the measurements, instantaneous reattachment was observed on the side surface of the cubic model.

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This paper discusses the applicability of LES to turbulent flows and pressures on a cube in natural wind. Examples of comparative studies between the numerical simulation and the full-scale observations are few. The turbulent flow around a cube is simulated using LES, and compared with the full-scale measurement data for a 6m cube in the meadow by R.P.Hoxey et al. of Silsoe Research Institute. In this research for simulating the characteristics of the natural wind at SRI, we assumed the ratio of the roughness length to the boundary layer thickness to be universal. On the basis of the computed flow patterns, the characteristic of pressure on the roof are discussed. We continue LES computation with the following modification. 1. Higher resolution for the upwind region of a cube as well as near-cube region. 2. For sufficient turbulence intensity of the boundary layer, the larger ratio of the boundary layer thickness to cube height. The instantaneous reattachment is seen and it is expected that the separated flow be reattached by sufficient time passing.

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The wind flow around a cylinder of large aspect ratio and the wind pressure acting on it were measured synchronously by Particle Image Velocimetry (PIV) and simultaneous multi-pressure measurements. The results are as follows. The correlations between perpendicular flow and lift force were highest. The correlations between main flow and lift force were second. There was a spatial periodic change like a sine function in the correlation between lift force and perpendicular flow on the center axis of main flow. It can be considered that the change was a result of the action of vortices, because of a high correlation between the spatial period and the reciprocal of Strouhal number.

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In this experiment unstable aerodynamic oscillation of a rectangular cylinder with small side ratio was examined under homogeneous turbulent flow. Using turbulence-producing grids created 2 kinds of turbulent flows. The obtained velocity fluctuating spectrum is almost same with the Karman type spectrum. Using the results of square cylinder we checked the accuracy of the system. Then we study the behavior of the unstable aerodynamic oscillation of the rectangular cylinders with side ratio 0.2, 0.5, 0.6 in uniform flow and homogeneous turbulent flows (turbulence intensities are Iu=6% in Weak Turbulent flow and Iu=14%% in Strong Turbulent flow). Observing the Velocity-Amplitude curves, turbulence effects on galloping phenomena are discussed.

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Characteristics of wind forces acting on a building with curved surfaces greatly change around the critical Reynolds number. Therefore, it is afraid that characteristics of wind forces measured by wind tunnel test are different from those for an actual building. However, it is difficult to reproduce the Reynolds number corresponding to an actual building in wind tunnel test. To solve this problem and reproduce artificially wind force characteristics in the high Reynolds number region, roughness is attached on curved surfaces. This paper investigated the characteristics of wind forces and the Strouhal number for two 3D circular cylinders with several patterns of surface roughness. As the results, it was clarified that the effect of inconsistency of the Reynolds number on the wind forces and the Strouhal number could be eased when the surface roughness of which size was over 0.9% of the cylinder diameter was attached on the curved surface.

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The flow past a circular cylinder, which is often encountered in the industrial field, is important to be clarified from an engineering point of view. At the region of Re=O(10³), transition of the separated shear layers begin earlier as Re increases. Appropriate simulation technique and condition must be chosen. Here we carry out LES of wake flows past a circular cylinder in the region of Re=O(10³), and clarify the instability of shear layers and relation between wake structures and aerodynamic characteristics.

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The objective of this paper is to show the applicability and the efficiency of the present LES method to the flow around a circular cylinder, oscillating with linear-mode, in smooth and turbulence flows. First, we investigate the reproductivity of the computed results about the response amplitude through the comparison with the experimental results. Next, we study the vortex motion around a cylindrical tower, oscillating with linear-mode. As a results, the computed response amplitude in smooth flow show good agreement with experimental data. On the other hand, in the case of turbulent boundary layer, the computed results can not simulate quantitatively the response values of the experiments though qualitative agreement can be recognized. It might be considered that finer resolution for perpendicular direction is necessary to simulate quantitatively the response amplitude in turbulent boundary layer.

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The baseball pitcher throws many kinds of balls. For example, straight, curve, fork, knuckle, and sinker ball. In many kinds of balls, there is a vertical slider famous for being thrown by Daisuke Matsuzaka, Seibu Lions and Randy Johnson Diamondbacks. The axis of this ball oriented to advance direction - so called gyro-ball-with 140[km/h] speed and less lift force. As a result of this ball trajectory is vertically sink as same as fork ball.The mechanism of change of a vertical slider is explored in this research. First, the aerodynamic force of a rotation ball is measured by high precision wind tunnel experiment. It carries out based on the result, and flight orbital analysis of a ball is performed.

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The research is conducted to measure the aerodynamic characteristics of highly spinning golf ball immersed in uniform flow of a wind tunnel. The balls, which are used in this study, are two kinds of balls, Skyway and Callaway. The drag and the lift in the uniform flow of a wind tunnel, of which the maximum wind velocity is 44m/s, are measured in the maximum revolution of the golf ball up to 210rps. Present, experiment data of Skyway ball is already applied to the machine named Pythagoras by Mizuno Inc. for 3-D trajectory of ball flight, after mesuring of ball initial conditions. The final stage of this paper is focused on the 3-D flight trajectory formulation of golf ball passing through atmospheric boundary layer.

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A series of wind tunnel experiments have been conducted in order to investigate the effect for wind-induced vibration by jets from the leading edges of a rectangular cylinder. The inside of the rectangular cylinder is designed in order to obtain uniform and plenty amount of jet from the slit along the leading edges. The jet is propelled by two AC servomotor controled wind blowers. Various velocity of steady jets flows and various period and velocity level of pulsated jets are generated. The vibration displacement of the cylinder is measured by laser sensor. In cases of the steady jets, higer velocity jets are more effective to suppress vortex-induced vibration. In cases of the pulsated jets, either longer period case or the natural period case is effective.

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Effect of correlation length on Aerodynamic sound from cylinder is considered based on Curle's equation. Correlation length using coherence, root-coherence and co-coherence respectively was compared with experimental data of back-flow fluctuation velocity for rectangular cylinder with aspect ratio 1 and 3. It is observed that Correlation length highly depends on coherence function.

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A purpose of this study is to examine habitability of a wooden house to wind-induced vibration.In this study, a wind-force model is a quasi-steady wind-force expression taken the Vickery's formula as aerodynamic admittance, and reproduces wind-force characteristics obtained a wind tunnel test.Time-history response analyses are carried out for wind action of 1-year return period.Obtained results can't be make use of estimation of the habitability of a wooden house to wind-induced vibration, because criteria for the habitability of several countries are out of 1 Hz over domains which 1st natural frequencies of subjected houses are.In future, the habitability of a wooden house to wind-induced vibrations is required establishing a new criterion.

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This paper discusses the quasi-static wind load effect combination to be considered in structural design of low-, middle- and high-rise building models. Various load effect combinations, e.g. across-wind base shear and torsional base moment accompanied by maximum along-wind base shear, are analyzed and discussed.

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Fluctuating surface pressure measurements are made for four flat-roofed building models with square or rectangular plans in order to examine wind load combinations. The fluctuating pressures are integrated over all their surfaces and results are obtained of along-wind force, across-wind force, vertical force, along-wind overturning moment, across-wind overturning moment and torsional moment on their frames. This paper discusses the combination of the maximum level of quasi-static and resonant wind load components for low-, middle- and high-rise building models. It then examines the peak normal stresses in columns of frame models to assess the effects of wind load combinations on rigid buildings.

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In this study, a numerical simulation around a high-rise building, whose aspect ratio is 4, in an atmospheric turbulent boundary layer was performed and wind pressure distribution on the building were compared with experimental data. The turbulent inflow data were generated by the method, in which a turbulent boundary layer was numerically simulated using quasi-periodic boundary condition. In the early studies using CFD, the predictions of wind pressure on high-rise buildings did not agree with the results of wind tunnel tests, because they could not duplicate the target characteristics of approaching flows. To predict the wind pressure on a building properly, we attempts to simulate an atmospheric flow using the method achieving the similitude of turbulence characteristic between in the laboratory/atmosphere flow and in the CFD flow. The height of the building is about one-fifth of the thickness of the boundary layer and it is within the inner layer over which the logarithmic law holds.
The mean velocity profile of the generated inflow fits with the power law whose exponent is 0.2. An upwind UTOPIA scheme is applied to the area nearby the building, but in the rest of the area a 2nd-order central differencing is used. The dynamic procedure is employed to identify the Smagorinsky coefficient of LES. The Reynolds number based on the building height and wind velocity at the roof height is about 1.2x10⁵. The mean wind pressure profiles on the front surface are 10% compared to wind tunnel data. The wind pressure on the side and the rear surface are in good agreement with wind tunnel data.

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This paper examines the effect of corners cut and balconies for wind-induced response of a high-rise RC housing, through wind tunnel tests. The shape of the model is rectangular building with the side ratio (depth/breadth) of 1, and the aspect ratio is 5.3. The mass density of the model is 398kgf/m3. The damping constant of the model is 0.015, 0.02 and 0.03. As a result, the wind-induced response reduction of the model with corners cut was confirmed. The wind-induced response of the model with balconies was larger than without balconies, in case of the model with low-damping (damping constant equal to 0.015) and corners cut.

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Various types of vibrations in consideration of motion-induced wind forces and dynamics characteristics of structures have been clarified by the technique of Computational Fluid Dynamics (CFD). The aim of this CFD study is to examine coupled unstable aerodynamic vibration across-wind and torsion on an elasto-plastic structure Obtained results are as follows; 1) Aeroelasto-plastic response usually suppressed by hysteretic damping effects comparing with the elastic response. 2) However, in spite of the effect of hysteresis damping, the response in case of small value of the yield displacement ratio is larger than the elastic response. Because the natural frequency tends to shift lower. Therefore, a possibility that unstable aerodynamics vibrations will occur increases.

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In many cases of the wind load estimates, the fluctuating components of wind force are treated to be proportional to fluctuating components of wind. Because the fluctuating components of the wind are much smaller than the mean wind velocity and the quadratic term of the component in the wind force expression is omitted. Some of recent reports of strong wind observation, however, indicate that the gust factor becomes over 2 or that intensity of turbulence reaches to 30%. In this paper, the influences of the quadratic term on the overall wind force in high gust factor are discussed.

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The characteristics of the external pressures acting on spherical domes have been investigated based on the data obtained from a series of wind-tunnel measurements in simulated atmospheric boundary layers. The dome surface is divided into three or four areas, based on the characteristics of pressure distribution. The external pressure coefficients for designing the structural frames and cladding are proposed as functions of the rise/span and eaves-height/span ratios for each area. The effect of the turbulence intensity of approach flow is taken into account for the windward area when the rise/span ratio is high.

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Wind loading is a very important external action to single-layer reticulated shells since this structural system is sensitive to the external loading distribution and stability is a dominant problem for structural design. Usually an equivalent static method is used for wind-resistant design of such shells. However, the estimated equivalent static wind loading may not reflect the actual effect of fluctuating wind loading on the stability of shells. In this paper, at first, a framework of the effective static loading distribution method to estimate the effective wind loading distribution for such shells was introduced. Then, a new method from the stability point of view was presented to determine a suitable reference response variable used in the effective static loading distribution estimation, as well as to estimate the effect of wind loading on structural stability conservatively. Finally, with comparative analyses, the efficiency of the presented method was proved.

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Previous studies of wind loads on free-standing canopy roofs have been surveyed. Focus is on the data obtained from wind-tunnel measurements in simulated atmospheric boundary layers as well as from full-scale measurements. Comparisons are made between these studies for some aerodynamic characteristics, such as mean and peak wind force coefficients. The wind load provisions in the current Building Standard Law of Japan are also compared with the experimental data. Based on the results, new provisions of the design wind force coefficients are proposed both for the main wind force resisting systems and cladding/components. A discussion is made of the subjects to be investigated for making the provisions more appropriate.

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The parallel-member attachment method is a cost-effective construction method for wind load reinforcement of a transmission steel-tube tower in operation. We apply, however, just a drag factor of angle bar (Cd = 2.0) to the design wind load of the reinforced member for safety reasons. We have clarified the drag factor and aerodynamic properties of this reinforced member by wind tunnel test. The results have shown that drag factors in all cases are less than 2.0. We are able to estimate more cost-effectively the design wind load of the member reinforced by the parallel-member attachment method using the results.

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