Wind Resistant Design for Buildings
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Model for wind tunnel experiment at Shinjuku Shintoshin |
In wind-resistant design of buildings, wind loads are calculated according to the design wind speed based on the external pressure and wind force coefficients obtained from the Building Standards Law, AIJ Recommendations for Loads on Buildings, wind tunnel experiments, and numerical fluid calculations. Wind loads include structural frame wind loads for the design of main structural members such as columns and beams, and exterior wind loads for the design of exterior finish materials such as glass. Wind tunnel tests and numerical fluid dynamics simulations, like wind tunnel models, reproduce not only the building under study but also the surrounding buildings over a wide area, making it possible to evaluate wind loads in a realistic manner. |
Wind Resistant Design for Bridges
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Wind tunnel test on the Akashi Kaikyo Bridge (1991) |
Wind effects cannot be ignored in bridge design. Especially for long-span bridges such as the Akashi-Kaikyo Bridge, it is necessary to verify not only the effects of wind loads, which are static effects, but also aerodynamic vibration phenomena, which are dynamic effects. To avoid a repeat of the 1879 collapse of the Tay Bridge in England and the 1940 collapse of the old Tacoma Bridge in the U.S., numerous studies on aerodynamic characteristics of bridge girders, towers, and suspension members have been conducted to date through wind tunnel tests, computational fluid dynamics (CFD), field observations, and so forth. |
Wind Resistant Design for Overhead Transmission Lines
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Helicopter line extension under construction |
Many of Japan's power transmission towers are located in mountainous areas where the topography is rugged. Because mountainous areas are subject to strong winds caused by the undulations of the terrain, it is important to consider the geographical characteristics of each region when designing wind-resistant transmission towers. In addition, overhead power lines sway and vibrate in strong winds, and if the wires are too close to each other, insulation breakdown (flashover) may occur, making it impossible to transmit power. |
Numerical simulation of flow
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Turbulence in the approaching flow and the 3-D prismatic column Interference with wake vortex |
Wind is a flow of air, and air is a fluid. Computational Fluid Dynamics (CFD), which predicts approximate flows by computer simulation based on the Navier-Stokes equations of motion of fluids, is widely applied to wind engineering. The three-dimensional flow information obtained by CFD not only complements experiments and observations and helps in understanding phenomena, but is also beginning to be used in practice to predict wind loads acting on buildings, bridges, and other structures, as well as the wind environment in urban pedestrian spaces. |
Air Pollution, Diffusion, Ventilation, Ventilation
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Visualization of high-temperature exhaust gas from a plant Visualization of diffusion properties |
Wind carries substances and heat. For example, air pollution problems such as pollutants released into the air from factories and exhaust gases from automobiles, diffusion of heat from air conditioning equipment, ventilation that maintains the indoor environment by bringing pollutants, heat, and odors generated indoors out and fresh air indoors in, and ventilation that brings outdoor air into the room to reduce the temperature of the body. Ventilation brings outdoor breezes into the room to lower the temperature. Air pollution, diffusion, ventilation, and ventilation are also research topics in wind engineering. |
Wind disaster investigation
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Damage to the five-story pagoda of Muroji Temple caused by Typhoon No. 9807 Damage to the five-story pagoda of Muroji Temple (1998) |
When a strong wind disaster occurs, experts in meteorology, architecture, transportation, and other areas related to wind engineering conduct field investigations. The main purpose of the field survey is to collect data to analyze the cause of the damage. In the field, we will assess the damage situation of the surveyed area. The survey results are complemented by interviews with witnesses, victims, and local authorities at the time of the disaster. In addition to the collected field survey results, meteorological data, video footage, and information from the media will be analyzed to clarify the situation at the time of the disaster. The survey results will be compiled into papers, reports, etc., and utilized for future countermeasures against strong wind disasters. |
Tornado
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Chitose Tornado(1988) |
Tornado are caused by updrafts associated with strongly developing cumulonimbus clouds. They occur and develop in an extremely short period of time and produce fierce wind gusts tens to hundreds of meters wide and several kilometers to tens of kilometers across, causing extensive damage to local properties. Since it is difficult to observe directly, wind speed is estimated from the state of damage to estimate the strength and scale of Tornado. In addition to working to improve the accuracy of the Japanese modified Fujita scale (JEF) used for this purpose, we also use experiments and numerical fluid analysis to investigate the flow structure of a tornado, the characteristics of the wind loads generated therein, and the flight characteristics of flying debris to ensure the safety of important structures and other objects against wind gusts such as tornadoes. |
Wind energy
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Hachijojima Wind Farm |
Wind energy is expected to play an important role in the power supply structure, and is being deployed onshore and offshore around the world. Research and development covers a wide range of areas, including R&D on wind turbine structures and control to improve power generation efficiency, wind-resistant design to protect wind turbines from strong winds, and evaluation and prediction of wind capacity and value as a resource, such as wind abundance, topography, and regional characteristics. These R&D activities are conducted using wind tunnel experiments, numerical simulations, monitoring and statistical analysis, and are the subject of active discussions. |
