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Experiments on the rectangular prisms with side ratios of 2. 0, 2.5, 3.0, 3.5 and 4. 0 are reported. Wind pressure measurements were carried out on five rectangular prisms for the testing Reynolds number Re ranging from l. 1 x 105 to 6. 8 x 105. The Reynolds number effects on the wind pressure distributions and the base pressure coefficients were studied, then the mechanisms of Reynolds number effects on rectangular prisms were described by analyzing the variation of the flow around the model. The results are summarized as follows; wind pressure distributions of five rectangular prisms are all sensitive to Re, and the Reynolds number affects the wind pressure distributions not only in the reattachment region, but also in the separation bubble. The sensitivity to the Reynolds number effects is changed with the side ratio of the rectangular prism, and the B/D = 4 .0 rectangular prism appears to be the most sensitive to the Re. Its separated shear layer is easier to reattach to the body at high Re, and the flow reattachment point moves towards the leading edge suddenly at the critical Re = 6. 8 x 105. In addition, with the increasing of Re, the absolute value of base pressure coefficient for the B/D =4. 0 prism increases firstly, and then decreases rapidly. [ABSTRACT FROM AUTHOR]

Blockage effects of isolated rectangular tall buildings whose blockage ratios are 4. 1%, 6. 1%, 8. 4% and 10. 1% were respectively investigated in the uniform wind flow using the synchronous wind pressure measurement technique. Fluctuating forces along height and power spectral density, correlation and coherence of forces on each layer of models were compared. The results show that with the increasing of blockage ratio, fluctuating drag and lift of each layer increase, and the increase of fluctuating lift is more obvious. Peaks appear in power spectra of drag of each layer at the frequency which is two times of the Strouhal number. Peaks of lift power spectra are more prominent, and the Strouhal number increases. The correlation and coherence of lift of each layer increase as well as the coherence of drag of each layer. However, above half height of the building, the correlation of drag of each layer decreases. [ABSTRACT FROM AUTHOR]

The aeroelastic response of a square section tall building with 1:6 width to height aspect ratio in atmospheric boundary layer was numerically simulated, using loosely coupled method. In the present study, large eddy simulation technique was adopted with consideration of inflow turbulence. The wind-induced along and across vibration responses were both considered. The present method was verified to be able to accurately predict wind loads on buildings at rest, by comparing large eddy simulation results with rigid model wind tunnel experiment. The simulated wind-induced along and across vibration responses were compared with corresponding aeroelastic model wind tunnel experiments. The comparison results show that the present method is applicable to a certain extent in solving wind-structure- interaction problems. Aeroelastic responses of the building model under high reduced wind velocities were also investigated. Variation of the along-wind and across-wind displacement responses at different reduced wind velocities was analyzed in detail. The aeroelastic response of the building composes of two parts, i.e. the along-wind buffeting induced by inflow turbulence and the across-wind vortex-excited vibration. The along-wind and across-wind displacement responses were small with almost the same amplitude at low reduced wind velocities. With the increase of the reduced velocity, the displacement responses become large and the across-wind vortex-excited vibration becomes dominant, transferring from the beat-phenomena to the vortex-excited resonance. [ABSTRACT FROM AUTHOR]

It is important and valuable to estimate the interference effects of surrounding buildings on tall building in structure wind resistant design. In this paper, the research progresses of interference mechanism, interference effect on overall wind load and wind pressure are first summarized. Descriptions on wind-induced interference effect in wind load codes of several main countries are presented. Then additional remarks on interference effect in load code for design of building structures (GB 50009-2012) are given by combination of more than ten years of researches on tall buildings by the team of the authors. The quantitative method is emphatically introduced, and applicable condition of interference effect that the reduced velocity V, ≤ 7 is also emphasized. Finally, some recommendations such as interference mechanism, peak acceleration of building top, torsional responses and loads correlation, are made for further studies according to the problems in previous researches and requirements in practical engineering. [ABSTRACT FROM AUTHOR]

This paper studied the loads on the configuration details of low-rise building roofs by the rigid model pressure measurement tests, which were often destroyed in wind disasters. The pressure coefficients and drag coefficients of the ridge, protruding gable wall and eaves gutter were examined, which were of varied heights and with or without the other 2 types of configuration details. The results show that the negative pressure of interior surface ( the leeward surface for the ridge) of the configuration details end varies severely and the amplitude occurs when the wind obliquely blows to the exterior surface (the windward surface for the ridge) , which leads to the very large worst peak net pressure coefficient towards the roof. The worst peak net pressure coefficients of the protruding gable wall, ridge and eaves gutter are about 18.0, 10.5 and 7.0, respectively. However the peak pressure away from the roof ( towards the windward surface for the ridge) is relatively stable. The worst peak net negative pressure of the lower tap is 5 larger than that of the higher tap on the same vertical plan of the protruding gable wall, while that of the lower tap is only O. 8 larger than that of the higher tap for the eaves gutter. When the roof is equipped with the other 2 types of configuration details, the worst peak net negative pressure coefficients of the ridge and protruding gable wall decrease much to 7.5 and 6.0 from 10.5 and 18.0, respectively, while that of the eaves gutter decreases to 6 from 7. The worst peak drag coefficients of the ridge and eaves gutter are not affected by whether the roof is attached with the other 2 types of configuration details or not, while that of the protruding gable wall is smaller when the roof is attached with ridge and eaves gutter. The worst peak drag coefficients of the protruding gable wall and eaves gutter are larger with the increase of each height. [ABSTRACT FROM AUTHOR]

Based on measured wind speed and wind direction data at the height of 10 m, 20 m, 30 m and 40 m in Shanghai Pudong district, the comparison study of fluctuating near ground wind characteristics during typhoon Muifa with monsoon characteristics was developed. The results show that turbulence intensities and gust factors all decrease with wind speed during typhoon as well as monsoon. The only difference is that the change rate decreases with wind speed during typhoon Muifa but almost constant during monsoon. The values of turbulence intensities and gust factors at the same observation height during typhoon Muifa are less than those during monsoon, and the empirical fitting expression of turbulence intensities and gust factors profiles are also obtained. The auto-correlation coefficients decrease gradually with lag time r during both typhoon Muifa and monsoon, and the decay rate decreases with observation heights. At the same observation height, the value of decay rate during typhoon Muifa is larger than that during monsoon. [ABSTRACT FROM AUTHOR]

In this research, the wind data was measured from a tower of 40m in height during the mild typhoon 'Meari' and ultra strong typhoon 'Muifa' near Shanghai Pudong International Airport by the East China Sea. The characteristics of turbulence intensity, gust factors, peak factor and turbulence integral scale for various segment lengths were analyzed in detail. It shows that turbulence intensity decreases with the increase of segment lengths and agrees well with Durst's results. As expected, the value measured from the mild typhoon 'Meari' is larger than that of the ultra strong typhoon 'Muifa'. Gust factors measured at 10 m are larger than those of the above heights which agree well with ASCE/SEI 7-10. The peak factor also decreases with the increase of segment lengths and agrees well with those proposed by Durst. For segment lengths more than 100 s, the value of peak factor measured from 'Meari' is larger than that of 'Muifa' Furthermore, as the segment length increases, the turbulence integral scale will be larger, especially the lateral length scale will be larger than that of the longitudinal value, and all its components measured from 'Meari' are larger than those of 'Muifa' for various segment lengths. At a 10 m observation height, for instance, estimates of L vary from 27 m to 267 m for 'Meari' and 27 m to 205 m for 'Muifa', respectively. [ABSTRACT FROM AUTHOR]