Full-scale Measurements Of Wind Effects Research Articles

Wind effects on a cable-suspended roof: Full-scale measurements and wind tunnel based predictions

Full-scale measurements of wind effects on a long-span cable-suspended roof were carried out. The wind-induced response data were analyzed in the time-frequency domain based on the wavelet transformation, and modal frequencies and amplitude-dependent damping ratios were identified with the random decrement technique. The damping ratios were noted larger with increasing response amplitude especially in the fundamental mode. The identified modal frequencies from the full-scale measurements were lower than those from the original finite element model (FE model). The identified modal parameters were then used to update the FE model with an artificial neural networks (ANNs) based scheme. The dynamic response from the roof was computed from the updated FE model of the structure where the wind loads input was obtained from simultaneous pressure measurement in wind tunnel tests. In view of the uncertainties surrounding both full scale measurements and wind tunnel based predictions, these comparisons show good agreements at least at two locations. Both the dynamic response from full-scale measurements and numerically predicted analyses demonstrated significant contributions from multi-mode effects. The computed response spectra at selected locations were similar to those from the full-scale measurements, suggesting a validation of the predictions.

Full-scale measurements of wind effects and modal parameter identification of Yingxian wooden tower

The Yingxian wooden tower in China is currently the tallest wooden tower in the world. It was built in 1056 AD and is 65.86 m high. Field measurements of wind speed and wind-induced response of this tower are conducted. The wind characteristics, including the average wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and velocity spectrum are investigated. The power spectral density and the root-mean-square wind-induced acceleration are analyzed. The structural modal parameters of this tower are identified with two different methods, including the Empirical Mode Decomposition (EMD) combined with the Random Decrement Technique (RDT) and Hilbert transform technique, and the stochastic subspace identification (SSI) method. Results show that strong wind is coming predominantly from the West-South of the tower which is in the same direction as the inclination of the structure. The Von Karman spectrum can describe the spectrum of wind speed well. Wind-induced torsional vibration obviously occurs in this tower. The natural frequencies identified by EMD, RDT and Hilbert Transform are close to those identified by SSI method, but there is obvious difference between the identified damping ratios for the first two modes.

Full-scale measurements of wind effects on Guangzhou West Tower

Field measurements of wind characteristics and wind effects on Guangzhou West Tower (GZWT) were conducted when Typhoon Megi affected this super tall building on October 22, 2010. Based on the measured wind data such as wind speed and wind direction, statistical analysis of wind characteristics including turbulence intensity, gust factor, power spectral density of wind speed at about 450m height in urban area was first conducted. The simultaneously measured wind-induced acceleration was adopted to evaluate the dynamic characteristic and wind effect on this super tall building. The damping ratio with amplitude-dependent behavior was found by the random decrement method, and the serviceability performance level for different return period was estimated for this tall building. The wind-induced pressure on the building surface atop the building was investigated to evaluate the characteristic of the measured local wind pressure. Finally, the measured wind-induced acceleration and wind pressure were further compared with those obtained from the wind tunnel test to evaluate the accuracy of the model test results. The research output is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.

Full-scale measurements of wind effects on the Jin Mao building

The Jin Mao Building located in Pudong New Area, Shanghai, which has a height of 420.5 m and 88 floors, is currently the tallest building in Mainland China. This paper presents some selected results obtained from the full-scale measurements of wind effects on the Jin Mao Building during the passage of Typhoon Rananim in August, 2004. The field data including acceleration responses, wind speed and wind direction were simultaneously and continuously recorded during Typhoon Rananim. Detailed analysis of the field data was conducted to investigate wind effects on the super tall building. The characteristics of typhoon-generated wind and wind-induced responses of the 88-storey building are presented and discussed. Dynamic properties of the building are determined based on the field measurements, and comparison with those calculated from the finite element model of the building is made. The amplitude-dependent characteristics of damping that were obtained using the random decrement technique on the basis of the field measurements are investigated. Furthermore, wind tunnel experiment is conducted to study wind effects on the Jin Mao Building through force balance model test, and the full-scale measurements are compared with the wind tunnel test results for verification of wind tunnel test techniques. Finally, the serviceability of the super tall building under typhoon conditions is discussed.

Wind tunnel and full-scale study of wind effects on China’s tallest building

The Jin Mao Building with a height of 420.5 m and 88-storeys, located in Shanghai, is the highest tall building in Mainland China. This paper presents selected results from a combined wind tunnel and full-scale study of wind effects on the super tall building. In the wind tunnel test, mean and fluctuating force components on the building model for the cases of an isolated Jin Mao Building and the building with existing surrounding condition were measured by a high-frequency force balance technique under suburban and urban boundary layer wind flow configurations, respectively. Force coefficients, power spectral densities, displacement and acceleration responses were then presented and discussed. A detailed comparative study was conducted to investigate the influences of incident wind direction, upstream terrain conditions and interferences from the surroundings on the wind effects on the building. Serviceability of the super tall building under strong wind action was analyzed on the basis of the experimental results. On the other hand, full-scale measurements of wind effects on the Jin Mao Building were conducted under typhoon conditions. The field data, such as wind speed, wind direction and acceleration responses were simultaneously and continuously recorded during the passage of Typhoon Rananim in August, 2004. Analysis of the field data was carried out to investigate typhoon effects on the super tall building. Finally, the wind tunnel test results were found to be in good agreement with the full-scale measurements, illustrating that the wind tunnel tests can provide satisfactory predictions of wind-induced vibrations of the super tall building under typhoon conditions.

Field measurements of typhoon effects on a super tall building

Di Wang Tower located in Shenzhen has a height of approximately 325 m and was the tallest building in Mainland China when it was built several years ago. The aspect ratio between the building’s height and transverse width is about 9, which has largely exceeded the criteria in the current design codes and standards in China. This super tall building may be susceptible to severe vibration induced by strong winds. This paper describes some results obtained from the full-scale measurements of wind effects on Di Wang Tower under typhoon condition. The field data, such as wind speed, wind direction and acceleration responses were simultaneously and continuously measured from this building during the passage of Typhoon Sally in 1996. Detailed analysis of the field data was conducted to investigate the typhoon effects on the super tall building. The characteristics of the typhoon-generated wind and the structural responses of the building are presented and discussed in detail. Dynamic characteristics of the building are reported, and comparisons with those from the analysis of the three-dimensional finite element model of Di Wang Tower are made. The serviceability of this super tall building under typhoon conditions is assessed based on the field measurements. The damping ratios of the building during the typhoon are evaluated, and the amplitude-dependent characteristics of damping that were obtained using the random decrement technique are presented on the basis of the field measurements. Furthermore, the full-scale measurements are compared with the wind tunnel test results to verify the reliability of wind tunnel experimental techniques.

The effect of amplitude-dependent damping on wind-induced vibrations of a super tall building

Full-scale measurements of wind effects on a 70 storey tall building have been conducted. The tall building that has a height of 367 m is the second tallest structure in Hong Kong. The amplitude-dependent characteristics of damping have been obtained by using the random decrement technique from the field measurements of acceleration responses. The objective of this study is to present detailed investigations into the effects of amplitude-dependent damping on the wind-induced responses of the super tall building based on the measured non-linear damping and wind action characteristics. An efficient and less time consuming digital simulation technique is developed to generate time series of turbulent wind loads acting on the tall building based on the measured wind speed records. The predicted dynamic responses of the building using the actual amplitude-dependent damping characteristics are compared with those computed by using constant damping parameters assumed by the structural designers or estimated from the field measurements in order to evaluate the adequacy of current design practices and to apply that knowledge to structural design of tall buildings. It is observed from this study that the effect of amplitude-dependent damping on the dynamic responses of such a super tall building is significant and knowledge of actual damping characteristics is very important in the accurate prediction of wind-induced vibrations of a tall building.

Wind effects on a very tall building and wavelet analysis

This paper describes the results obtained from full-scale measurements of wind effects on a 70-storey building which has a height of approximately 370 m and is the second tallest structure in Hong Kong. The field data presented include the wind speed, wind direction and wind-induced response, which were measured at the top of this building during the passage of Typhoon Sally in 1996. Application of a wavelet transform to analyse the field data of wind velocity and wind-induced response is presented and discussed. The variation in the local energy content, not accounted for in Fourier spectral analysis, is noted. The comparison of the Fourier spectrum and wavelet scalogram is made.

WIND EFFECTS ON A VERY TALL BUILDING AND WAVELET ANALYSIS.

This paper describes the results obtained from full-scale measurements of wind effects on a 70-storey building which has a height of approximately 370 m and is the second tallest structure in Hong Kong. The field data presented include the wind speed, wind direction and wind-induced response, which were measured at the top of this building during the passage of Typhoon Sally in 1996. Application of a wavelet transform to analyse the field data of wind velocity and wind-induced response is presented and discussed. The variation in the local energy content, not accounted for in Fourier spectral analysis, is noted. The comparison of the Fourier spectrum and wavelet scalogram is made.

Evaluation of wind effects on a supertall building based on full-scale measurements

This paper describes the results obtained from the full-scale measurements of wind effects on a 70-storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The field data such as wind speed, wind direction and wind-induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the field data is conducted. The full-scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude-dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated. Copyright © 2000 John Wiley & Sons, Ltd.