Yoshiteru Iwasa

Aerodynamic shape effects of tall building for vortex induced vibration

Abstract The effects of building plan shape on aerodynamic forces and displacement response have been studied for super high-rise building with an assumed height of 600 m in a wind tunnel. Experiments have been carried out using rigid models with eight kinds of building plan shapes of equal area ( = 6400 m 2 ) , equal building height ( = 600 m ), and equal density ( = 125 kg/m 3 ). The measurement model force had been combined analytically with a computer model of the building to provide estimates of the actual building response. The dynamic response behavior of a super high-rise building under strong wind due to vortex shedding and the aerodynamic damping effect of vibration by changing the cross section of building were clarified from these results.

Study on acceptable criteria for assessing wind environment at ground level based on residents' diaries

Abstract This paper describes a method for assessing the wind environment at ground level. Around a high-rise apartment building located in a built-up area in Tokyo, long-term observations of wind-induced troubles were conducted, in cooperation with many inhabitants of the area. Analysis of wind environment in this paper is based on these observations. Since the observations of wind were conducted simultaneously, the relationships between impressions of wind environment or wind-induced troubles and wind speed may be clarified. Considering these relationships, criteria are proposed to determine the acceptable frequency of strong wind.

Aerodynamic damping effects of tall building for a vortex induced vibration

Abstract The influences which are induced upon the wind-induced response of the plane shape of a super high-rise building with an assumed height of 600m, as well as the dynamic effects of the vibration were studied. For this study, results obtained from the measurements of the wind force using a force balance, the response using a dynamic motion model, and the wind pressure of the face were used. From the result obtained from the response analysis made through the use of the measured result of the aerodynamic force and the result gained from the measurement of the response using the dynamic model, the change of the response, caused by a difference in the shape of a building and by the dynamic effect, have been clarified. Furthermore, as for the square shape which is a representative plane, the change of the pressure properties induced by the vibration of the building has been indicated.

Internal pressure of double composite exteriors

Abstract An analytical approach for predicting the mean and fluctuating internal pressure induced by wind between double walls when the outer wall is provided with openings has been investigated. The method of analysis was based on jet simulated air-flow through the openings and a model of pressure flow between parallel planes. The analytical results were compared with wind tunnel results, and they matched closely.

Wind induced response of low-profile cable-reinforced air-supported structures

Abstract Presented is an analytical method to obtain the dynamic response on roof deflections and cable tensions of low-profile cable-reinforced air-supported structures under strong winds. This method is based on a quasi-static theory and results are obtained by using the data from wind tunnel tests and the theoretical dynamic characteristics of the structure. The analytical results are compared with the measured dynamic behavior of a large scale field model (25m × 25m) during a typhoon. It is shown that the calculated and the measured results are in good agreement.

Full-scale measurement of environmental wind in the shinjuku new metropolitan center

Abstract This study was an attempt to specify quantitatively the effects of tall buildings upon the properties of sorrounding winds. In the Shinjuku New Metropolitan Center in Tokyo, where six tall buildings each measuring∼200 m in height were located, cup anemometers were installed near the ground at 17 locations. Observations began in October 1975. Typical ground-level wind phenomena are illustrated in the results obtained from measurements made during two years. Moreover, wind-tunnel simulations corresponding to these full-scale measurements were also carried out. Comparisons of the velocity ratio, the deviation of wind direction and the gust factor between full-scale and wind-tunnel measurements are dealt with in this paper. Generally, the data resulting from both varieties of tests show marked correspondence.

Structural characteristics and wind resistant design of low-profile cable-reinforced air-supported structures

In general, air-supported structures are designed primarily against wind load which causes the greatest stresses in the environmental condition.Furthermore, the wind pressure distribution is variable and extremely complex in contrast to the load caused by internal pressure or dead load.This paper deals with following wind resistant characteristics of low-profile cablereinforced air-supported structure.1) The structural characteristics based on results of wind-load loading tests and periodically forced vibration tests by using a large-scale model.2) Wind pressure distribution of the roof measured in the field-test and the wind tunnel tests.3) The analytical determination methods of wind load and dynamic deformation of the roof.

A New Wind Tunnel of Technical Research Laboratory, Takenaka Komuten Co., LTD

We have installed a new wind tunnel of closed return type for carrying out our research in wind environment around tall buildings, aerodynamic stability of structures, atmospheric diffusion and design of a ventilation.The working section of this wind tunnel is 1.3m m height, 2.0min width and 16m in length. Wind velocity is able to vary from 1m/s to30m/s, and the uniformity of the velocity distribution is within±0.6%.The characteristics and performance of the wind tunnel are presented in this paper.