Showing papers by "Qiusheng Li published in 1999"
52 citations
TL;DR: In this article, the effects of free-stream turbulence on streamwise surface pressure fluctuations on two-dimensional rectangular cylinders were investigated and the possible effects of turbulence integral scale on fluctuation and peak pressures were given.
Abstract: This paper presents the effects of free-stream turbulence on streamwise surface pressure fluctuations on two-dimensional rectangular cylinders. Particular attention is given to possible effects of turbulence integral scale on fluctuation and peak pressures. The mean, standard deviation, peak pressure coefficients, spectra and cross-correlation of fluctuating pressures were measured to investigate the nature of the separation and reattachment phenomenon in turbulent flows over a wide range of turbulence intensity and integral scale.
25 citations
TL;DR: In this paper, a set of parameter optimization methods is proposed to determine optimal parameters of passive tuned mass dampers under wind excitation, and simplified formulas for determining the optimal parameters are proposed so that the design of a TMD can be carried out easily.
Abstract: The most common used control device on tall buildings and high-rise structures is active and passive tuned mass damper (ATMD and TMD). The major advantages of ATMD and TMD are discussed. The existing installations of various passive/active control devices on real structures are listed. A set of parameter optimization methods is proposed to determine optimal parameters of passive tuned mass dampers under wind excitation. Simplified formulas for determining the optimal parameters are proposed so that the design of a TMD can be carried out easily. Optimal design of wind-induced vibration control of frame structures is investigated. A thirty-story tall building is used as an example to demonstrate the procedure and to verify the efficiency of ATMD and TMD with the optimal parameters.
19 citations
TL;DR: In this paper, the authors presented a new exact approach which combines the transfer matrix method and closed form solutions of one-step cantilever bars to obtain the frequency equation of multi-step bars, which is suitable for describing the distributions of stiffness and mass of typical tall buildings and high-rise structures.
Abstract: Using appropriate transformations, the differential equation for flexural free vibration of a cantilever bar with variably distributed mass and stiffness is reduced to a Bessel\'s equation or an ordinary differential equation with constant coefficients by selecting suitable expressions, such as power functions and exponential functions, for the distributions of stiffness and mass. The general solutions for flexural free vibration of one-step bar with variable cross-section are derived and used to obtain the frequency equation of multi-step cantilever bars. The new exact approach is presented which combines the transfer matrix method and closed form solutions of one step bars. Two numerical examples demonstrate that the calculated natural frequencies and mode shapes of a 27-storey building and a television transmission tower are in good agreement with the corresponding experimental data. It is also shown through the numerical examples that the selected expressions are suitable for describing the distributions of stiffness and mass of typical tall buildings and high-rise structures.
19 citations
TL;DR: In this article, artificial neural networks are employed to model and predict amplitude dependent damping in buildings based on full-scale measurements of buildings, and the performance of the models is evaluated and discussed by tests and predictions including self-test, one-lag, and multi-lag prediction.
Abstract: In this paper, artificial neural networks, a new kind of intelligent method, are employed to model and predict amplitude dependent damping in buildings based on our full-scale measurements of buildings. The modelling method and procedure using neural networks to model the damping are studied. Comparative analysis of different neural network models of damping, which includes multi-layer perception network (MLP), recurrent neural network, and general regression neural network (GRNN), is performed and discussed in detail. The performances of the models are evaluated and discussed by tests and predictions including self-test, "one-lag" prediction and "multi-lag" prediction of the damping values at high amplitude levels. The established models of damping are used to predict the damping in the following three ways : (1) the model is established by part of the data measured from one building and is used to predict the another part of damping values which are always difficult to obtain from field measurements : the values at the high amplitude level. (2) The model is established by the damping data measured from one building and is used to predict the variation curve of damping for another building. And (3) the model is established by the data measured from more than one buildings and is used to predict the variation curve of damping for another building. The prediction results are discussed.
18 citations
TL;DR: The complexity, discreteness and non-linearity of the optimal design problems of actuator placement are investigated and an optimal control algorithm and active tendon controllers are applied to control the response of a 16-storey building under earthquake loads.
Abstract: Optimal placement of actuators in actively controlled structures is a mixed-discrete optimization problem; it has the characteristics of nonlinear, non-continuous, and so on. For this type of optim...
14 citations
TL;DR: In this article, the uncertainties associated with structural parameters and dynamic loading are identified and discussed, and the calculated results demonstrate that the variation in structural parameters indeed influences the dynamic response and the first passage probability evaluation of structures.
Abstract: The uncertainties associated with structural parameters and dynamic loading are identified and discussed. Structural parametric uncertainties are treated as random variables and dynamic wind load is simulated as a random process. Dynamic wind-induced responses of structures with parametric uncertainties are investigated by using stochastic finite element method. The formulas for structural dynamic reliability analysis considering the randomness of structural resistance and loading are proposed. Two numerical examples of high-rise structures are presented to illustrate the proposed methodology. The calculated results demonstrate that the variation in structural parameters indeed influences the dynamic response and the first passage probability evaluation of structures.
12 citations
TL;DR: In this paper, the general solutions of free vibrations of one-step cantilever shear plates with variably distributed mass and stiffness are derived by selecting suitable expressions, such as power functions and exponential functions, for the distributions of stiffness and mass along the height of the plates.
11 citations
TL;DR: In this article, a new active control design of structures is proposed and investigated, which preserves the decoupling property of the modal vibration equation and eliminates the spillover problem, which is the main shortcoming in the independent modal space control algorithm.
Abstract: In this paper, a new algorithm for active control design of structures is proposed and investigated. The algorithm preserves the decoupling property of the modal vibration equation and eliminates the spillover problem, which is the main shortcoming in the independent modal space control(IMSC) algorithm. With linear quadratic regulator(LQR) control law, the analytical solution of algebraic Riccati equation and the optimal actuator control force are obtained, and the control design procedure is significantly simplified. A numerical example for the control design of a tall building subjected to wind loads demonstrates the effectiveness of the proposed algorithm in reducing the acceleration and displacement responses of tall buildings under wind actions.
5 citations
TL;DR: In this paper, an analysis of free vibrations of shear-type buildings is presented and discussed, and the differential equations for the free vibration of buildings with variably distributed free vibrations are presented.
Abstract: In this paper, an analysis of free vibrations of shear-type buildings is presented and discussed. The differential equations for the free vibration of shear-type buildings with variably distributed...
3 citations
TL;DR: In this paper, a dynamic condensation method has been applied to the model reduction of a television transmission tower and comparisons between the performance of the models produced and that produced by the Guyan method are conducted.
TL;DR: In this article, a new function transform, based on the differential recurrence function series, is proposed, and its computational characteristics are investigated in order to investigate the computational accuracy and efficiency of the proposed algorithm, two numerical examples are given.
TL;DR: In this paper, the governing differential equations for vibration of flexural-shear plates considering the effects of flexur, shear deformation and axial forces are established and a numerical example demonstrates that the calculated natural frequencies and mode shapes of a tall building that is treated as a two-step flexural shear plate are in good agreement with the experimentally measured data.
Abstract: The governing differential equations for vibration of flexural-shear plates considering the effects of flexural, shear deformation and axial forces are established. The general solutions of a one-step flexural-shear plate are derived and used to obtain the eigenvalue equations of a multi-step flexural-shear plate with various boundary conditions. The new exact approach which combines the transfer matrix method and closed form solutions of a uniform flexural-shear plate with various boundary conditions is presented. A numerical example demonstrates that the calculated natural frequencies and mode shapes of a tall building that is treated as a two-step flexural-shear plate are in good agreement with the experimentally measured data. It is also shown that the effect of shear deformation on the fundamental natural frequency can be ignored, but its effect on the higher natural frequencies should be considered. On the contrary, the effect of axial force (N) on the higher natural frequencies is not significant, ...
TL;DR: In this article, the authors describe probabilistic characteristics of damping in a tall building based on the results of full-scale measurement and find that damping at the high amplitude plateau can be well represented by Normal distribution ( Gaussian distribution).
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.