Cross Spectra of Wind Pressures on Domed Roofs in Boundary Layer Wind Tunnel

[[abstract]]This research intends to investigate the cross spectrum characteristics of wind pressure fluctuations on the surface along the meridian of domed roofs under turbulent wind flows. Wind pressure experiments of domed roofs are conducted considering two roof curvatures and three heights of side walls. From the experimental results, various distribution types of co-coherences are examined and the traditional exponential decaying form is shown insufficient to approximate the general characteristics of co-coherences. By combining the proposed models by Uematsu et al ([1]) and Kanda et al ([2]) and also a phase shift parameter included, the approxi-mation model is then improved to represent the observed coherences generally.[[conferencetype]]國際[[conferencedate]]20120902~20120906[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Shanghai, Chin

Characteristics of Power and Cross Spectra of Wind Fluctuation along Meridian on Dome-like Structures

[[conferencetype]]國際[[conferencedate]]20110710~20110715[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Amsterdam, Netherlan

Annual maximum wind simulation based on moment parameter of parent distribution

[[abstract]]It has been revealed that higher moments of parent distributions influence the tail characteristics of annual maximum wind speed distribution. Some studies have been conducted to show that once the standard deviations of skewness and kurtosis of yearly variation for the 10 minute mean wind speeds are properly estimated, a good probability model for the annual maxima can be obtained. However since the parameters for four moments have various effects on the location and scale parameters of estimated Gumbel distribution for annual maxima, it is interesting to see more general relationship between those parameters of parent distributions and the location and scale parameters of Gumbel models. This paper aims at examining the characteristics of the moment parameters and their effects on the Gumbel models. Once the relation between the moment parameters and approximate annual maximum statistics is known, even a short period statistics such as 5 years or 10 years may help to have an approximate estimation of annual maximum. It is expected that such examinations of probabilistic characteristics of 10 minute mean wind speeds may provide good information for wind hazard models for individual sites.[[conferencetype]]國際[[conferencedate]]20100614~20100616[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Edinburgh, U

Investigation on Coherence Characteristics of Wind Pressure on Hemispherical domes

[[abstract]]Systematic wind tunnel tests were conduct to investigate coherence characteristics of any two fluctuating wind pressures along the meridian on hemispherical domes under smooth and turbulent wind flows. Reynolds number was alternated from 6.6×104 to 1.9×106 for both flows. Contour plots of root-coherence values with respect to frequency and reference location were given to show only little inconsistency due to Reynolds number effect. On the other hand, approaching turbulence, simulated in turbulent flow, showed distinct differences, especially in the windward and dome apex region. A modified form proposed by Hui et al (2009) was applied for the approximation of root-coherences rather than Davenport’s proposed. It was concluded that not only the location of the reference tap but also the distance between two taps, can significantly determine the distribution features of coherences.[[sponsorship]]CSIR-Structural Engineering Research Centre[[conferencetype]]國際[[conferencedate]]20131210~20131214[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Chennai, Indi

Characteristics of Power and Cross Spectra of Wind Pressure Fluctuations on Dome-like Structures

[[abstract]]Experiments of four basic dome-like models were conducted for the wind pressure measurement. With the different ratios of height-to-span, characteristics of wind pressure fluctuations on the dome roofs can be categorized into three regions. It was indicated that different regions have different patterns of power and cross spectra. Therefore the wind loads may be evaluated with different contributions in three regions.[[conferencetype]]國際[[conferencedate]]20110307~20110308[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Tokyo, Japa

Spectrum Characteristics of Fluctuating Wind Pressures on Hemispherical Domes

[[abstract]]A large span roof is one of the common designs for modern structures, such as sport stadiums, coal/oil storage, museums, or certain symbolic structures standing for religious or national meanings. The most concerned of such design is its curved geometry and its sensitivity to wind loads. For the past three decades, many works have been published to investigate the aerodynamic characteristics on hemispherical domes. However, only limited description was given on discussing spectrum characteristics. Systematic wind tunnel tests were carried out to investigate the spectrum characteristics of fluctuating wind pressures on the surface of hemispherical domes due to Reynolds number effects in both smooth and turbulent wind flows. Reynolds number in this study varies from 6.6×104 to 1.9×106 to have a wider range for discussion. Instantaneous fluctuating wind pressures were measured and processed FFT for spectrum calculation. Power spectra and cross spectra between two pressures along the meridian were selected for examination. It was observed that not only the location but also the distance difference between two pressures can significantly affect the spectrum distribution. From upstream to downstream, power spectra vary gradually as separation occurs and forms a wake region. With the increase of Reynolds number, coherence varies significantly in the lower reduced frequency range. Oncoming turbulence intensities somehow enhance the wave form distribution over all frequency ranges. However, it is also mentioned that a quantitative description may help more in defining how spectrum characteristics affect the wind loadings on the surfaces.[[sponsorship]]Department of Civil and Architectural Engineering, City University of Hong Kong; 香港城市大學土木及建筑工程系; Beijing University of Technology, China; 北京工業大學[[conferencetype]]國際[[conferencedate]]20121212~20121219[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Macau, Chin

Application Range of Polynomial Translation Method and Its Modification of Estimation of Annual Maximum Wind Speeds

[[abstract]]Polynomial translation method for translating Gaussian random variables to non-Gaussian random variables has been proposed for more than half centuries. Application of this method has also been utilized to many aspects. However, the approximation of parameters of the polynomial form cannot provide good estimation when random variables are given large skewness and kurtosis. In this research, the approximation method used for the parameter estimation is investigated for wider ranges of given skewness and kurtosis, which are observed from the 10 minute mean wind speed samples of 155 sites from 1961 to 2002. The proposed simulation process of the estimation of annual maximum wind speeds is then modified based on the investigation results. For those extreme cases with large observed skewness or kurtosis, the modified simulation process can provide fairly good estimation results as normal cases.[[conferencetype]]國際[[conferencedate]]20091102~20091102[[booktype]]紙本[[iscallforpapers]]N[[conferencelocation]]東京, 日

Reynolds Number Effects on Wind Flows around Hemispherical Domes by Visualization Technique

[[abstract]]In general, visualization experiment in a conventional boundary layer wind tunnel for buildings is a difficult task to carry out. This research intends to conduct the visualization experiment through the direct observation on the surrounding wind flow. The occurrence of flow separation along the surface is preliminarily observed. By high-speed camera, the location of the separation point moves forward to the downstream as the Reynolds number increases.[[conferencetype]]國際[[conferencedate]]20130519~20130523[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Tainan, Taiwa

Effects of Higher Moments on Distributions of Annual Maximum Wind Speeds

[[abstract]]The relation between higher order moments of 10-minute mean wind speeds and the probability distribution of annual maximum wind speeds have been examined by utilizing observed wind data in Japan. It is found that the four moment parameters determine the tail characteristics of extreme value distributions and these moment parameters vary yearly and regionally. The variations of skewness and kurtosis play significant roles in particular. When the mean and the standard deviation of four moments of parent distribution are appropriately estimated, the simulation of annual maximum wind speeds provides a good correspondence to the distribution of observed annual maximum wind speeds. The possibility of good estimation of annual maximum wind speeds may be expected from a short period of data, such as 5 years when the variations of four moments are properly estimated as a representative one for long-term statistics.[[notice]]補正完畢[[incitationindex]]EI[[booktype]]紙

Application of Polynomial Translation Method to Prediction of Annual Maximum Wind Speeds

[[conferencetype]]國際[[conferencedate]]20110710~20110715[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Amsterdam, Netherlan