Characteristics Of Wind Loading On Roofs Of National Stadium

As an innovative style of structure, large span roofs differ significantly from conventional buildings, especially in the consideration of wind loading during design. The decision of wind loads acting on large span roofs is usually the key and challenging problem for this kind of structure. The complexity of wind loading acting on long span roofs arises from the variety of the building shapes, the randomness of fluctuating wind pressure and the time/space and spatial correlation of wind pressure fluctuations. Combining with these factors, the statistics characteristics of wind pressure is not only related to the characteristics of oncoming flow, but also mostly to the signature turbulence which induced by the building itself. Therefore, there does not exist a mature method to describe the gust loading on roofs yet.Based on above thinking, studies on the characteristics of wind loading on roofs have been carried out in time domain and frequency domain respectively, and a analytical method of peak value of wind pressure is proposed, by using wind tunnel tests result. The main contents in this paper are shown as following:(1)Wind tunnel test of National Stadium is introduced. Based on test result, the characteristic of mean and fluctuating features of wind pressures on roofs is also investigated. And the characteristic of wind pressures distribution is discussed in signature turbulence.(2)The characteristics of fluctuating wind pressures in time domain is carried out. The method of chi-square test for goodness of fit is proposed to study the characterize non-Gaussian feature of wind pressures. Spatial correlations of wind pressure on different roofs and the same roof are studied, and the effort of correlations on fluctuating value of wind pressures is analyzed.(3)The statistical theory of extreme is studied, two different method is proposed to definite factor of peak value in non-Gaussian region and non-Gaussian region. And the distribution of factor of peak value and extreme value of wind pressures is also investigated.(4) The characteristics of fluctuating wind pressures in frequency domain is carried out. Combining with vortex under different wind directions, the characteristics of wind pressure spectra in different position on roofs are studied. The theories of wavelet transform and wavelet packet analysis are introduced, the energy distribution is studied by using wavelet packet energy spectra. Finally, the coherence functions of wind pressures are studied in different directions and roof edge.