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CONTENTS
Volume 2, Number 2, June 1999
 

Abstract
The EARP(1)/UPS was first developed by Seong (1993) and has been tested for wind pressure time series simulations (Seong and Peterka 1993, 1997, 1998) to prove its excellent performance for generating non-Gaussian time series, in particular, with large amplitude sharp peaks. This paper presents a parametric study focused on simulation of extreme value statistics based on the synthetic realizations of the EARPG(1)/UPS. The method is shown to have a great capability to simulate a wide range of non-Gaussian statistic values and extreme value statistics with exact target sample power spectrum. The variation of skewed long tail in PDF and extreme value distribution are illustrated as function of relevant parameters.

Key Words
extreme value distribution; synthetic realizations; non-Gaussian statistics.

Address
School of Mechanical Engineering, Pusan National University, Pusan 609-735, Korea

Abstract
The dynamic properties of one-span or multi-span reinforced concrete footbridges of catenary form (see e.g., Fig. 1) include the very low fundamental natural frequency, usually near the step-frequency of pedestrians, and the low damping of bending vibrations. The paper summarized the results of model as well as full-scale measurements with particular reference to the influence of torsional rigidity of the stress-ribbon on the magnitude of aerodynamic response, the results of measurements on footbridges of catenary form being completed by results obtained on footbridges of some other types. Additionally the influence of the local broadening of the bridge deck on the bridge response was tested. Starting from these results the criterion has been drived for the decision, whether the flutter analysis is necessary for the design of the footbridge.

Key Words
footbridge; aerodynamic stability; bending-torsional vibration; wind-excited vibrations; wind-tunnel in civil engineering.

Address
Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Praha 9, Czech Republic

Abstract
The various spectral density functions of wind are applied in the wind process simulation by the spectral representation method. In view of the spectral density functions, the characteristics of the simulated processes are compared. The ensemble spectral density functions constructed from the simulated sample processes are revealed to have the similarity not only in global shape but also in the maximum values with the target spectral density functions with a high accuracy. For the correlation structure to be satisfied in the circumferential direction on the cooling tower shell, a new formula is suggested based on the mathematical expression representing the circumferential distribution of the wind pressure on the cooling tower shell. The simulated wind processes are applied in the dynamic analysis of cooling tower shell in the time domain and the fluctuating stochastic behavior of the cooling tower shell is investigated.

Key Words
simulation; spectral density function; spectral representation; cooling tower shell.

Address
Department of Civil Engineering, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea

Abstract
The ZG Bridge(preliminary design), with unfavorable aerodynamic stability characteristics, is a truss-stiffened suspension bridge, its critical wind speed of flutter instability is much lower than that of code requirement. In the present paper, based on both aerostatic and aeroelastic section model wind tunnel test, not only effects of some aerodynamic means on aerodynamic stability of its main girder are investigated, but also such effective aerodynamic means of it as flap and plate-like center stabilizer are concluded.rn

Key Words
flutter; wind tunnel test; flap; plate-like center stabilizer.

Address
Xiangdong He and Shaozhong Xi : Experiment & Research Center for Wind Engineering, Southwest Jiaotong University, Chengdu, 610031, China

Abstract
This paper describes probabilistic characteristics of damping in a tall building based on the results of full-scale measurement. It is found, through statistical analysis of the damping data, that the probability density function(PDF) of damping at the high amplitude plateau can be well represented by Normal distribution ( Gaussian distribution). A stochastic damping model is proposed to estimate amplitude-dependent damping for practical application.

Key Words
damping; tall building; full-scale measurement.

Address
J.Q. Fang, Q.S. Li, A.P. Jeary, D.K. Liu and C.K. Wong : Department of Building and Construction, City University of Hong Kong, Tat Chee Ave. Kowloon, Hong Kong


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