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CONTENTS
Volume 7, Number 5, September 2004
 

Abstract
The Dongting Lake Bridge is a cable-stayed bridge crossing the Dongting Lake where it meets the Yangtze River in southern central China. Several intensive wind-rain induced vibrations had been observed since its open to traffic in 1999. To investigate the possibility of using MR damping systems to reduce cable vibration, a series of field tests were conducted. Based on the promising research results, MR damping system was installed on the longest 156 stay cables of Dongting Lake Bridge in June 2002, making it the worlds first application of MR dampers on cable-stayed bridge to suppress the wind-rain induced cable vibration. As a visible and permanent aspect of the bridge, the MR damping system must be aesthetically pleasing, reliable, durable, easy to maintain, as well as effective in vibration mitigation. Substantial work was done to meet these requirements. This paper describes field tests and the implementation of MR damping systems for cable vibration reduction. Three-years reliable service of this system proves its durability.

Key Words
cable-stayed bridges; stay cable; wind-rain induced vibration; MR dampers; vibration mitigation.

Address
Z. Q. Chen; School of Civil Engineering, Hunan University, Changsha, Hunan 410082, P. R. ChinarnX. Y. Wang; Department of Civil and Structural Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, P. R. ChinarnJ. M. Ko and Y. Q. Ni; Faculty of Construction and Land Use, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong KongrnB. F. Spencer and G. Yang; Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USArnJ. H. Hu; School of Civil Engineering, Hunan University, Changsha, Hunan 410082, P. R. Chinarn

Abstract
In this study, a wind tunnel, that has been developed for experiments of wind turbine rotor blades, has been considered. The deviations of the measurements have been examined after this wind tunnel had been introduced and the measurements on it had been explained. Two different wind turbine rotor blades miniatures have been used for getting better results from the experiments. The accuracy of measurements have been experimented three times repetitively and examined statistically. As a result, wind speed values which this type of wind tunnel and wind turbine rotors need for starting, wind speed in the tunnel, temperature and moisture values, the number of rotor

Key Words
wind turbine; rotor blade; rotor; rotor experimented; wind tunnel.

Address
Ali Vardar and Bulent EkerrnDepartment of Agricultural Machinery, Faculty of Agriculture, University of Trakya,rn59030, Tekirdag / Turkey

Abstract
Wind tunnel experiments were conducted under highly turbulent and disturbed flow conditions over a solid/perforated plate with a long splitter plate in its plane of symmetry. The effect of varied level of perforation of the normal plate on fluctuating velocities and fluctuating pressures measured across and along the separation bubble was studied. The different perforation levels of the normal plate; that is 0%, 10%, 20%, 30%, 40% and 50% are studied. The Reynolds number based on step height was varied from 4

Key Words
RMS fluctuating pressures; two dimensional perforated plates; normal plate; bluff body; splitter plate; shear layer; flow separation; reattachment; wind tunnel testing.

Address
Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, PO: Srinivasnagar - 575 025, Mangalore, India

Abstract
This paper illustrates application of the proper orthogonal decomposition (POD) and the autoregressive (AR) model to simulate large wind pressures due to gusts on a low-rise building. In the POD analysis, the covariance of the ensemble of large wind pressures is employed to calculate the principal modes and coordinates. The POD principal coordinates are modeled using the AR process, and the fitted AR models are employed to generate the principal coordinates. The generated principal coordinates are then used to simulate large wind pressures. The results show that the structure characterizing large wind pressures is well represented by the dominant eigenmodes (up to the first fifteen eigenmodes). Also, windpressures with large peak values are simulated very well using the dominant eigenmodes along with the principal coordinates generated by the AR models.

Key Words
proper orthogonal decomposition; autoregressive model; large wind pressure; pressure simulation.

Address
Department of Civil Engineering, Yonsei University, Seoul 120-749, Korea

Abstract
In the 1990s, four strong typhoons hit the Kyushu area of Japan and inflicted severe damage on power transmission facilities, houses, and so on. Maximum gust speeds exceeding 60 m/s were recorded in central Kyushu. Although the wind speeds were very high, the gust factors were over 2.0. No meteorological stations are located in mountainous areas, creating a deficiency of meteorological station data in the area where the towers were damaged. Since 1995 the authors have operated a network for wind measurement, NeWMeK, that measures wind speed and direction, covering these mountainous areas, segmenting the Kyushu area into high density arrays. Maximum gusts exceeding 70 m/s were measured at several NeWMeK sites when Typhoon Bart (1999) approached. The gust factors varied widely in southerly winds. The mean wind speeds increased due to effects of the local terrain, thus further increasing gust speeds.

Key Words
NeWMeK; winds measurement; transmission tower; typhoon damage; gust factor; terrain effect.

Address
Eriko Tomokiyo, Junji Maeda and Nobuyuki Ishida; Depertment of Archtecture, Kyushu University, JapanrnYoshito Imamura; Kyushu Electric Power Co., Inc., Japan


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