By investigating acrosswind forces on rectangular cylinders withvarious side ratios atnormal attack angle in a boundary layer wind tunnel, this paper presents empirical formula ofacrosswind force spectra, RMS lift coefficients and Strouhal numbers of rectangular tallbuildings, and coherence functions of acrosswind force are also probed. Thus, a completeanalytical model of acrosswind dynamic loads on rectangular tall buildings is established. Thismodel is in good agreement withth e experimental results obtained by wind tunnel tests; so it isreliable and applicable. A calculation method based on this model can be developed toevaluate wind-induced acrosswind responses of rectangular tall buildings in frequencydomain.

本文对于u形渡槽槽体结构模型进行了风漏实验研究，得出了u形渡槽槽体结构的风压分布和风载体型系数。风洞试验结果表明u形渡槽槽体的风压分布和风载体形系数同槽体的高宽比和流场状况有关，在同一流场状况下槽体的风载体形系数随着槽体的高宽比变化。本文的试验结果为渡槽结构的抗风设计提供了参考依据。

The magnitude of the vertical component of earthquake ground motion is often aboutone-third of the horizontal component. Thus, it is necessary to calculate vertical dynamic charac-teristics of tall buildings and high-rise structures in design stage for certain cases. In analysing freevibrations of tall buildings and high-rise structures, it is possible to regard such structures as acantilever bar with variable cross-section. In this paper, the differential equations of free longitudinalvibrations (in vertical direction) of bars with variably distributed mass and stiffness consideringdamping effect are established. The damping coefficient of a bar is assumed to be proportional toits mass, and the general solutions of mode shapes of damped distributed parameter systemsare reduced to Bessel's equations by selecting suitable expressions, such as power functions andexponential functions, for the distributions of stiffness and mass. An approach to determine thenatural frequencies and mode shapes in vertical direction for tall buildings with variably distributedstiffness and variably distributed mass is proposed. The presented method is also applicable to thefree longitudinal vibration analysis without considering damping effect (damping coefficient invibration equations is equal to zero). A numerical example shows that the computed values of thefundamental longitudinal natural frequency and mode shape by the proposed method are close tothe full scale measured data. It is shown through the numerical example that the selected expressionsare suitable for describing the distributions of stiffness and mass of typical tall buildings. A com-parison between undamped structural dynamic characteristics and damped natural frequencies,mode shapes is made in this paper.

This paper describes some results obtained from full-scale measurements of wind effects on a super-tall building,Di-Wang Tower, located in Shenzhen, China. This tall building has 79-storeys with a height of approximately324 m. Field measurements including wind speed, wind direction and wind-induced acceleration responses havebeen made. The amplitude-dependent characteristics of damping are obtained by using the random decrementtechnique from the detailed analysis of the field acceleration measurements. The main objective of this paper is topresent detailed investigations into the effects of nonlinear damping on the dynamic responses of the tall buildingsubjected to various types of applied loads based on the measured amplitude-dependent damping characteristics.The predicted dynamic responses of the building obtained by using the measured damping characteristics werecompared with those computed by using constant damping parameters assumed by the structural designers. It isconcluded from the investigations that knowledge of actual damping characteristics are very important in theaccurate prediction of the dynamic responses of a tall building when the major harmonic components of theapplied loads overlap with the lowest natural frequencies of the building. The design damping level for tallbuilding structures currently used by structural engineering practitioners appears to be high and not conservative.Copyright

Wind-induced dynamic torque on rectangular cylinders with various side ratios is investigated through a series of model tests ina boundary layer wind tunnel. Based on the experimental investigation, this paper presents empirical formulae of torque spectra,RMS torque coefficients and Strouhal number, as well as coherence functions of torque. An analytical model of wind-induceddynamic torque on rectangular tall buildings is established accordingly. Comparisons of the results from the proposed model andthe wind tunnel measurements verify the reliability and applicability of the developed model for evaluation of torsional dynamicwind loads on rectangular tall buildings. A calculation method is presented based on the proposed model to estimate wind-inducedtorsional responses of rectangular tall buildings in the frequency domain.

The results of full scale measurements of damping as well as other researches on damping show that damping in buildings exhibits randomness and amplitude dependent behaviour in the case of tall buildings subjected to dynamic loading. In this paper, based on full scale measurements of damping in a tall building, a time series analysis method (TSA) is employed to obtain the relationship between damping and vibration amplitude. Then, 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. In order to get high accuracy, a genetic algorithm strategy is employed to aid in training the ANN. Comparison analysis of the neural network model and the AR model of damping is made, and the results are presented and discussed.

The necessary conditions for the occurrence of 2D coupled galloping oscillations and adescription of the set of general differential equations for 2D coupled galloping vibrations are estab-lished in this paper. A procedure to predict the 2D coupled galloping oscillalions is proposed. Windloading was treated as a stochastic process including mean and fluctuating components caused by at-mospheric turbulence. The formulae and the procedure presented permit a better assessment of gallop-ing oscillations of a prismatic structure which has the same natural frequencies in the directions of thetwo orthogonal horizontal axes. The effects of turbulence on 2D coupled galloping are investigated. Itis shown that 2D coupled galloping oscillations mainly occur in the cross-wind direction. The effect ofthe turbulence integral scale on the onset wind velocity of 2D coupled galloping oscillations is negli-gible. However, the turbulence integral scale has certain influences on the rms response both in thealong-wind and the cross-wind directions when the wind velocity is equal or close to the onset wind vel-ocity for galloping. An increase in the turbulence integral scale in the range of 10--40 m considered inthis paper increases the galloping response.

Central Plaza has a height of approximately 374m and is 78-storeys tall. It is the tallest structure in Hong Kongand was the highest reinforced-concrete building in the world when it was built several years ago. This paperdescribes some results obtained from the full-scale measurements of wind effects on Central Plaza. The field datasuch as wind speed, wind direction and acceleration responses have been measured during the close passage ofseveral typhoons in recent years. Detailed analysis of the field data is conducted to investigate wind effects on thetall building. The full-scale measurements are compared with the wind tunnel results. The amplitude-dependentcharacteristics of damping that were obtained by using the random decrement technique are investigated on thebasis of the field measurements. Copyright

An analytical model of a flexural-shear plate is proposed herein for the purpose of buckling analysis. In this paper, tall buildingswith shear-wall structures and with narrow rectangular plane configuration are modeled as flexural-shear plates for buckling analysis.The governing differential equation for buckling of a flexural-shear plate with varying cross-section is established. Using appropriatetransformations, the equation is reduced to an analytically solvable equation by selecting suitable expressions, such as power functionsand exponential functions, for the distribution of stiffness along the height of the plate. The exact solutions for buckling ofa flexural-shear plate with variable stiffness are derived. A numerical example shows that the present methods are easy to implementand are efficient.