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CONTENTS
Volume 14, Number 4, July 2011
 

Abstract
Researchers at the International Hurricane Research Center (IHRC), Florida International University (FIU), are working in stages on the construction of a large state-of-the-art Wall of Wind (WoW) facility to support research in the area of Wind Engineering. In this paper, the challenges of simulating hurricane winds for the WoW are presented and investigated based on a scale model study. Three wind profiles were simulated using airfoils, and/or adjustable planks mechanism with and without grids. Evaluations of flow characteristics were performed in order to enhance the WoW

Key Words
Wall of Wind; atmospheric boundary layer; wind profile simulation; pressure coefficient; blockage.

Address
Aly Mousaad Aly : Department of Mechanical Engineering, Alexandria University, Alexandria, Egypt
Arindam Gan Chowdhury : Laboratory for Wind Engineering Research, International Hurricane Research Center, Department of Civil and Environmental Engineering, Florida International University, Miami, Florida 33174, USA
Girma Bitsuamlak: Laboratory for Wind Engineering Research, International Hurricane Research Center, Department of Civil
and Environmental Engineering, Florida International University, Miami, Florida 33174, USA

Abstract
The full-scale measurements are compared with the wind tunnel test results for the long-span roof latticed spatial structure of Shenzhen Citizen Center. A direct comparison of model testing results to full-scale measurements is always desirable, not only in validating the experimental data and methods but also in providing better understanding of the physics such as Reynolds numbers and scale effects. Since the quantity and location of full-scale measurements points are different from those of the wind tunnel tests taps, the weighted proper orthogonal decomposition technique is applied to the wind pressure data obtained from the wind tunnel tests to generate a time history of wind load vector, then loads acted on all the internal nodes are obtained by interpolation technique. The nodal mean wind pressure coefficients,root-mean-square of wind pressure coefficients and wind pressure power spectrum are also calculated. The time and frequency domain characteristics of full-scale measurements wind load are analyzed based on filtered data-acquisitions. In the analysis, special attention is paid to the distributions of the mean wind pressure coefficients of center part of Shenzhen Citizen Center long-span roof spatial latticed structure. Furthermore, a brief discussion about difference between the wind pressure power spectrum from the wind tunnel experiments and that from the full-scale in-site measurements is compared. The result is important fundament of wind-induced dynamic response of long-span spatial latticed structures.

Key Words
long-span; spatial latticed structure; wind tunnel test; wind load; full-scale measurement.

Address
Hui Liu and Wei-lian Qu :Hubei Key Laboratory of Roadway Bridge and Structure Engineering, Wuhan University of Technology,Wuhan, Hubei 430070, P. R. China
Qiu-sheng Li : Department of Building and Construction, City University of Hong Kong, Hong Kong, P. R. China

Abstract
The vulnerability of roofing components of contemporary houses built in cyclonic regions of Australia is assessed for increasing wind speeds. The wind loads and the component strengths are treated as random variables with their probability distributions derived from available data, testing, structural analysis and experience. Design details including types of structural components of houses are obtained from surveying houses and analyzing engineering drawings. Wind load statistics on different areas of the roof are obtained by wind tunnel model studies and compared with Australian/New Zealand Standard, AS/ NZS 1170.2. Reliability methods are used for calculating the vulnerability of roofing components independently over the roof. Cladding and batten fixings near the windward gable edge are found to experience larger negative pressures than prescribed in AS/NZS 1170.2, and are most vulnerable to failure.

Key Words
vulnerability; reliability; wind loads; houses; wind tunnel; strength; probability.

Address
N.C. Jayasinghe and J.D. Ginger : Cyclone Testing Station, School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4811, Australia

Abstract
The collection of wind speed time series by means of digital data loggers occurs in many domains, including civil engineering, environmental sciences and wind turbine technology. Since averaging intervals are often significantly larger than typical system time scales, the information lost has to be recovered in order to reconstruct the true dynamics of the system. In the present work we present a simple algorithm capable of generating a real-time wind speed time series from data logger records containing the average, maximum, and minimum values of the wind speed in a fixed interval, as well as the standard deviation. The signal is generated from a generalized random Fourier series. The spectrum can be matched to any desired theoretical or measured frequency distribution. Extreme values are specified through a postprocessing step based on the concept of constrained simulation. Applications of the algorithm to 10-min wind speed records logged at a test site at 60 m height above the ground show that the recorded 10-min values can be reproduced by the simulated time series to a high degree of accuracy.

Key Words
wind speed; time series; gusts; kaimal distribution; constrained simulation; autocorrelation function.

Address
Javier Amezcua: Department of Atmospheric and Oceanic Science University of Maryland, College Park 20742-2425, USA
Raul Munoz and Oliver Probst : Physics Department,Instituto Tecnologico y de Estudios Superiores de Monterrey,Eugenio Garza Sada 2501 Sur, Monterrey, N.L., CP 64849, Mexico

Abstract
This paper deals with the flutter instability problem of flexible bridge decks in the framework of bimodal-coupled aeroelastic bridge system analysis. Based on the analysis of coefficients of the polynomials deduced from the singularity conditions of an integral wind-structure impedance matrix, a set of simplified formulations for calculating the critical wind velocity and coupled frequency are presented. Several case studies are discussed and comparisons with available approximated approaches are made and presented, along with a conventional complex eigenvalue analysis and numerical results. From the results, it is found that the formulas that are presented in this study are applicable to a variety of bridge cross sections that are not only prone to coupled-mode but also to single-mode-dominated flutter.

Key Words
bridges; eigenvalue; flutter; flutter derivatives; instability; simplified formulations.

Address
Tan-Van Vu and Hak-Eun Lee : School of Civil, Environmental and Architectural Engineering, Korea University, Seoul, South Korea
Young-Min Kim :Institute of Construction Technology, DAEWOO E&C Co., Ltd., Suwon, South Korea
Tong-Seok Han : School of Civil and Environmental Engineering, Yonsei University, Seoul, South Korea


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