Showing papers by "Qiusheng Li published in 2000"
TL;DR: In this article, an exact approach for free longitudinal vibrations of one-step non-uniform rods with classical and non-classical boundary conditions is presented, and the fundamental solutions that satisfy the normalization conditions are derived and used to establish the frequency equations for 1-step rods.
61 citations
TL;DR: In this article, two models of damping in a tall building, the artificial neural network (ANN) model and the auto-regressive (AR) model, are established by employing ANN and AR methods, and used to predict the damping values at high amplitude level, which are difficult to obtain from field measurements.
54 citations
TL;DR: In this article, the influence of shear lag for thin-walled curved box girders, including longitudinal warping, was investigated, and closed-form solutions of the equations were derived, and Vlasov's equation was further developed.
Abstract: This note investigates the influence of shear lag for thin-walled curved box girders, including longitudinal warping. The longitudinal warping displacement functions of the flange slabs are approximated by a cubic parabolic curve instead of a quadratic curve of Reissner’s method. On the basis of the thin-walled curved bar theory and the potential variational principle, the equations of equilibrium considering the shear lag, bending, and torsion (St. Venant and warping) for a thin-walled curved box girder are established. The closed-form solutions of the equations are derived, and Vlasov’s equation is further developed. The obtained formulas are applied to calculate the shear lag effects for curved box girder bridges. Numerical examples are presented to verify the accuracy and applicability of the present method.
54 citations
TL;DR: In this article, the amplitude-dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated, and full-scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University.
Abstract: 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.
53 citations
TL;DR: In this paper, the fine structures of the crust and upper mantle of the basin-and-range juncture on the northwestern margin of the Qinghai-Tibetan Plateau are first delineated by the deep seismic reflection profile across the juncture zone between the Tarim Basin and the West Kunlun Mountains.
Abstract: Fine structures of the crust and upper mantle of the basin-and-range juncture on the northwestern margin of the Qinghai-Tibetan Plateau are first delineated by the deep seismic reflection profile across the juncture zone between the Tarim Basin and the West Kunlun Mountains Evidence is found for the northward subduction of the northwest marginal lithosphere of the Qinghai-Tibetan Plateau and its collision with Tarim lithosphere beneath the West Kunlun Mountains The lithosphere image of the face-to-face subduction and collision determines the coupling relationship between the Tarim Basin and the West Kunlun Mountains at the lithosphere scale and reflects the process of continent-continent collision
44 citations
TL;DR: In this article, the free flexural vibration of a one-step bar with variable cross-section under various axial loads is reduced to Bessel's equations or ordinary equations with constant coefficients by selecting suitable expressions, such as power functions and exponential functions, for the distributions of stiffness and mass as well as for the axial forces acting on the bars.
35 citations
TL;DR: In this article, two groups of reliable reflective seismic phases of the Moho (Pm1 and Pm2) are recognized on the shot record section of the Kuytun area.
Abstract: The deep seismic sounding profile across the Tianshan Mountains revealed a two-layer crustal structure in the Tianshan region, namely the lower and upper crusts. Lateral variations of layer velocity and thickness are evidently shown. Low-velocity layers spread discontinuously at the bottom of the upper crust. The Mono depth is 47 km in the Kuytun area and 50 km in the Xayar area. In the Tianshan Mountains, the Moho becomes deeper with the maximum depth of 62 km around the boundary between the southern and northern Tianshan Mountains. The average velocity ranges from 6.1 to 6.3 km/s in the crust and 8.15 km/s at the top of the upper mantle. Two groups of reliable reflective seismic phases of the Moho (Pm1 and Pm2) are recognized on the shot record section of the Kuytun area. A staked and offset region, 20–30 km long, is displayed within a shot-geophone distance of 190–210 km in Pm1 and Pm2. Calculation shows that the Moho is offset by 10 km in the northern Tianshan region, 62 km deep in the south while 52 km deep in the north, and plunges northwards. In comparison with typical collisional orogenic belts, the structure of the Moho beneath the Tianshan Mountains presents a similar pattern. This can be used to explain the subduction of the Tarim plate towards the Tianshan Mountains. This intracontinental subduction is considered the dynamic mechanism of the Cenozoic uplifting of the Tianshan Mountains. The discovery of seismic phases Pm1 and Pm2 serves as the seismological evidence for the northward subduction of the Tarim plate.
25 citations
TL;DR: In this paper, an exact solution approach is presented to study the buckling of a non-uniform column with spring supports under combined concentrated and distributed loads, and the obtained exact solutions are used to derive the eigenvalues equation for buckling for a multi-step non-informal column with support by using the transfer matrix method.
22 citations
TL;DR: In this paper, the exact analytical solutions for longitudinal vibration of non-uniform rods with concentrated masses coupled by translational springs were derived by using Bessel's equation or an ordinary differential equation with constant coefficients.
22 citations
TL;DR: An analytical procedure for the elastic buckling of a multi-step non-uniform column subjected to concentrated axial compressive forces is presented in this paper, where the governing differential equation for the buckling problem is estab- lished.
Abstract: An analytical procedure for the elastic buckling of a multi-step non- uniform column subjected to concentrated axial compressive forces is presented in this paper. The governing differential equation for the buckling problem is estab- lished. Special solutions of the governing equation for five different types of non- uniform columns are given. The procedure for determining the fundamental solu- tions that satisfy the normalization conditions is proposed. Using the fundamental solutions and a recurrence formula developed in this paper, the bending moment function that includes only one unknown parameter for each step column can be easily determined. Thus, it is convenient to establish the eigenvalue equation for buckling of a multi-step non-uniform column in terms of the normalized funda- mental solutions of the governing equation. The eigenvalue equations for three gen- eral boundary conditions are given. A numerical example shows that the proposed procedure for determining the critical buckling force of a multi-step non-uniform column with general boundary conditions is a simple, efficient and exact method.
22 citations
TL;DR: In this article, the function for describing the distribution of mass of a non-uniform rod is expressed as a functional relation with the mass distribution and vice versa, and simple formulas to predict the longitudinal vibration frequencies and mode shapes of one-step rods with continuously varying cross-section are presented.
TL;DR: In this article, a transfer matrix method and closed-form solutions of one-step non-uniform bars are combined to obtain a single frequency equation for any number of steps, which is suitable for describing the distributions of stiffness and mass of typical tall buildings.
TL;DR: In this paper, an integrated approach to the modelling and optimization of structural control systems in tall buildings is proposed, in which an artificial neural network is applied to model the structural dynamic responses of tall buildings subjected to strong earthquakes, and a genetic algorithm is used to optimize the design problem, which constitutes a mixeddiscrete, nonlinear and multi-modal optimization problem.
Abstract: This paper proposes an integrated approach to the modelling and optimization of structural control systems in tall buildings. In this approach, an artificial neural network is applied to model the structural dynamic responses of tall buildings subjected to strong earthquakes, and a genetic algorithm is used to optimize the design problem of structural control systems, which constitutes a mixed-discrete, nonlinear and multi-modal optimization problem. The neural network model of the structural dynamic response analysis is included in the genetic algorithm and is used as a module of the structural analysis to estimate the dynamic responses of tall buildings. A numerical example is presented in which the general regression neural network is used to model the structural response analysis. The modelling method, procedure and the numerical results are discussed. Two Los Angeles earthquake records are adopted as earthquake excitations. Copyright © 2000 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors present an analytical approach to determine natural frequencies and mode shapes of non-uniform flexural-shear plates with line translational spring and rotational spring supports and line masses under action of axial forces.
TL;DR: In this article, a new exact approach which combines the basic solutions with unit matrix property and recurrence formula for determining natural frequencies and mode shapes of non-uniform shear beams is presented.
TL;DR: In this article, a new exact approach for analyzing free vibration of single degree of freedom (SDOF) systems with non-periodically time varying parameters is presented, where the function for describing the variation of mass of a SDOF system with time is an arbitrary continuous real-valued function.
Abstract: A new exact approach for analyzing free vibration of single degree of freedom (SDOF) systems with nonperiodically time varying parameters is presented in this paper The function for describing the variation of mass of a SDOF system with time is an arbitrary continuous real-valued function, and the variation of stiffness with time is expressed as a functional relation with the variation of mass and vice versa Using appropriate functional transformation, the governing differential equations for free vibration of SDOF systems with nonperiodically time varying parameters are reduced to Bessel's equations or ordinary differential equations with constant coefficients for several cases, and the corresponding exact analytical solutions are thus obtained A numerical example shows that the results obtained by the derived exact approach are in good agreement with those calculated by numerical methods, illustrating that the proposed approach is an efficient and exact method
TL;DR: In this article, an analytical model of a flexural-shear plate is proposed and the governing differential equation for vibration of such a plate with variably distributed mass and stiffness considering the effects of damping and axial forces is established.
TL;DR: In this article, the governing equations for free vibration of multi-step orthotropic shear plates with variably distributed mass, stiffness, and viscous damping are established, and the general solutions of the governing equation with various boundary conditions 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.
Abstract: The governing differential equations for free vibration of multi-step orthotropic shear plates with variably distributed mass, stiffness and viscous damping are established. It is shown that a shear plate can be divided into two independent shear bars to determine the natural frequencies and mode shapes of the plate. The jk-th natural frequency of a shear plate is equal to the square root of the square sum of the j-th natural frequency of a shear bar and the k-th natural frequency of another shear bar. The jk-th mode shape of the shear plate is the product of the j-th mode shape of a shear bar and the k-th mode shape of another shear bar. The general solutions of the governing equations of the orthotropic shear plates with various boundary conditions 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. A numerical example demonstrates that the present methods are easy to implement and efficient. It is also shown through the numerical example that the selected expressions are suitable for describing the distributions of stiffness and mass of typical multi-storey buildings.
TL;DR: In this article, the authors treated multi-storey buildings with narrow rectangular plane configuration (narrow buildings) as cantilever flexural-shear plates in analysis of free vibration.
TL;DR: In this paper, a new exact approach that combines the general solutions and recurrence formula was developed for determining natural frequencies and mode shapes of multistep flexural beams with varying frequencies and modes.
Abstract: A new exact approach that combines the general solutions and recurrence formula developed in this paper for determining natural frequencies and mode shapes of multistep flexural beams with varying ...
TL;DR: In this paper, a spatially placed passive tuned liquid column damper system was proposed to suppress coupled lateral-torsional responses of tall buildings in a 3D stochastic model.
Abstract: The possible application of a spatially placed passive tuned liquid column damper system forrnsuppressing coupled lateral-torsional responses of tall buildings is investigated in this paper The windrnloads acting on rectangular tall buildings are analytically expressed as 3-D stochastic model Meanwhile,rnthe 3-D responses of tall buildings may be coupled due to eccentricities between the stiffness and massrncenters of the buildings In these cases, torsional responses of the buildings are rather larger, and a TLCDrnsystem composed of several TLCD located near the sides of the buildings is more effective than the samernTLCD placed at the building center in reducing both translational and torsional responses of the buildingsrnIn this paper, extensive analytical and numerical work has been done to present the calculation methodrnand optimize the parameters of such TLCD systems The numerical examples show that the spatiallyrnplaced TLCD system can reduce coupled along-wind, across-wind and torsional responses significantlyrnwith a fairly small mass ratio
TL;DR: In this article, the equation of motion for free longitudinal vibration of a non-uniform one-step bar is reduced to an analytically solvable equation by selecting suitable expressions, such as power functions and exponential functions, for the area variation.
Abstract: Using appropriate transformations, the equation of motion for free longitudinal vibration of a nonuniform one-step bar is reduced to an analytically solvable equation by selecting suitable expressions, such as power functions and exponential functions, for the area variation. Exact analytical solutions to determine the longitudinal natural frequencies and mode shapes for a one step nonuniform bar are derived and used to obtain the frequency equation of multi-step bars. The new exact approach is presented which combines the transfer matrix method and closed form solutions of one step bars. A numerical example demonstrates that the calculated natural frequencies and mode shapes of a television transmission tower are in good agreement with the corresponding experimental data, and the selected expressions are suitable for describing the area variation of typical high-rise structures.
TL;DR: In this article, an analysis of free vibration of single-degree-of-freedom (SDoF) systems with nonperiodically varying parameters, such as variable mass and stiffness, is presented and discussed.
Abstract: An analysis of free vibration of single-degree-of-freedom (SDoF) systems with nonperiodically varying parameters, such as variable mass and stiffness, is presented and discussed in this paper The vari ations, relative to time, of mass and stiffness are expressed by the selection of suitable expressions such as power functions and exponential functions, and the general governing differential equation for free vi bration of SDoF systems with nonperiodically varying parameters is established. The exact solutions for free vibration of such time-varying systems are derived. The obtained solutions demonstrate that free vibra tion of several undamped systems with nonperiodically varying parameters cannot be induced by an initial disturbance.
TL;DR: In this article, the buckling behavior of flexural-shear plates with and without considering shear deformation of shear-wall structures is analyzed for tall buildings with shearwall structures and with narrow rectangular plane configuration.
Abstract: In this paper, tall buildings with shear-wall structures and with narrow rectangular plane configuration are modeled as flexural-shear plates for buckling analysis. The differential equations that govern the buckling behavior of flexural-shear plates, with and without considering shear deformation of shear-wall structures, are established. The general solutions of uniform flexural-shear plates with various end conditions are derived and used to obtain the eigenvalue equation for multistep flexural-shear plates. The new exact approach that combines the transfer matrix method and the derived closed-form solutions is presented for the buckling analysis of multistep flexural-shear plates. The exact solutions for buckling of nonuniform flexural-shear plates are derived for two types of distributions of variable stiffness. It is proved that a flexural-shear plate with two edges free in the longitudinal direction can be simplified as a flexural bar and that a multistep uniform flexural-shear plate may be treated...
01 May 2000
TL;DR: In this article, 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...
Abstract: 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 ...
TL;DR: In this article, the authors treated multi-storey buildings with narrow rectangular plane configuration (narrow buildings) as one-step or multi-step flexure-shear plates in analysis of free vibration.
TL;DR: In this article, transfer matrix method and recurrence formula method are proposed to determine the natural frequencies and mode shapes of multistep shear plates. But the method is not suitable for the case of a single shear plate.
Abstract: The governing differential equations for free vibration of a one-step shear plate and a multistep shear plate are established. It is shown that a shear plate can be divided into two independent shear bars to determine the natural frequencies and mode shapes of the plate. The jkth natural frequency of a shear plate is equal to the square root of the square sum of the jth natural frequency of a shear bar and the kth natural frequency of another shear bar. The jkth mode shape of the shear plate is the product of the jth mode shape of a shear bar and the kth mode shape of another shear bar. In this paper, two methods—transfer matrix method and recurrence formula method—are proposed to determine the natural frequencies and mode shapes of multistep shear plates. A numerical example shows that the present methods are easy to implement and are efficient.