Research And Application Of Wind Characteristics Measurement System On Long-span Structures

With the improvement of the structural system, construction materials, design and the technology of construction, high height and large-span structure are becoming popular in modern architectures, which show the characteristics of low weight, high flexibility, low damping ratio and low vibration frequencies. As a result, wind load becomes one of the main loads in structural design controlling.At present, wind tunnel test is still the main way to do the wind-induced design research. Since the test is the scale model experiment, the simulated turbulence intensity in the wind tunnel test is rather hard to meet the true value, and Reynolds number, which is the key parameter to describe the characteristics of fluid, is also lower by2-3magnitudes than that of the true value. Field measurement is the most direct and reliable way to effectively verify the results of the wind tunnel test and CFD, and to improve the simulation method of this two measurements, so as to develop the whole research measurements of wind engineering.Firstly, the paper lists the several examples of large-span roof structure suffered from wind at home and abroad. From the analysis of the large-span roof structure, its characteristics of the low weight, low damping ratio and low vibration frequencies lead to a high sensitivity to the wind load. Thus, the wind-induced design of the structure is significant. As there are some limitation and shortage in the traditional usual wind-induced measurement (wind tunnel test and CFD method), it is essential to promote the wind field measurement of the prototype structure. Due to the limitation of manpower and resources cost and the problem of arrangement in the wind field measurement, only little research has been involved the field measurement of lage-span roof structure around the world. The wind field measurement system based on the wireless-sensor network which is developed by our workgroup can solve the above problems and promote the large-scale researches on wind field measurement of large-span spatial structure, which is a great progress in the wind engineering.Secondly, the paper introduces the basic theories of the wind field measurement system. The fluctuating wind velocity is the driving force of wind speed which is random no matter from macroscopic aspect or from microscopic aspect. Consequently, the way of random vibration is used in wind engineering to analyze the wind speed. The paper introduces the basic knowledge of random vibration and the analytical way such as FFT, correlation analyzing, etc. It also introduces the definition of several parameters like turbulent intensity and gust response factors, and some classical PSD function. At the same time, the wind load distribution characteristics of the large-span roof structure attained from the wind tunnel test and CFD value simulation are also introduced in this paper.Thirdly, the paper shows the constitution of the wind field measurement system developed by our workgroup, which consists of the relative parameters of wind speed sensors, wind direction sensors, and wind pressure sensors, and the topological structure of the wireless-sensor network and networking technology, and the system structure, function and key principle of field measurement software. Finally, according to the systematic verified tests done by our groups, when this wind field measurement system is under the cycle changing wind from fans, the wind speed, wind direction and wind pressure power spectrum of all the measure points reach the peak value at the same frequency, which verifies the correction of the system. Moreover, the system is applied to the wind speed and wind direction test on National Stadium large-span roof, which gains plenty of valuable data. The paper will analyze the field measurement data to draw some valuable conclusions.