Wind excitation of neighbouring tall buildings

There is a growing concern about the importance of interaction effects between neighbouring tall buildings subjected to wind loading. Available results indicate that both the peak dynamic response as well as the mean wind loads may increase substantially due to building interaction.An extensive wind-tunnel study of the interaction between two square prisms with a height-to-base length equal to six was undertaken at the LAC, UFRGS. Fifteen relative prism positions were studied, for wind orientations at every 15°, under smooth-uniform as well as turbulent-shear wind. Mean force and torsional moment coefficients for uniform flow were reported in previous publications. Herein, complete results for turbulent wind are given. In addition, the most important interaction effects observed under both flow conditions are discussed in detail.     

靠近深基坑高耸构筑物的加固与纠偏技术

结合杭州某地铁车站高耸构筑物的保护,通过分析具体的施工过程,分析了城标发生较大偏移的原因,并针对性的提出了城标的加固措施,形成了系统的靠近深基坑构筑物的加固保护方案,论证了在设计阶段设计合理加固措施的重要性。     

地貌对高层建筑(群)风效应影响数值分析

高层建筑(群)风效应与地貌条件相关,分析掌握其内在关系是建筑布局规划和抗风设计的重要前提。基于雷诺时均模拟方法(RANS),引入具有分离流预测优势的SST k-ω湍流模型,以某高层建筑单体及群体风场为对象,模拟4类地貌条件下的风效应场,侧重分析人行高度(2m)风速场以及建筑立面的风压分布特性。分析结果表明,地貌除对人行高度的风速场影响明显外,对高层建筑表面风压系数影响也较为可观,实际工程应适当考虑地貌效应。     

Wind conditions around The Rock of Gibraltar

Full-scale data from two sources, structural damage to the East Side Water Catchment and a survey of turbulence on the approach flightpath to the airfield at Gibraltar, are compared with the results of wind-tunnel tests on a scale model of the Rock. The comparisons show that wind-tunnel simulation of the flow around large sharp-edged topographical features is practical at scale factors as high as $\text{1}\text{5000}$ for conditions of strong wind and neutral stability. The Rock is shown to behave as one half of a narrow-delta lifting body on an infinite ground plane.     

低矮房屋迎风屋面局部风压特性研究

基于尺寸比为1.5:1:1(长:宽:高)的低矮房屋的风洞试验数据,分析了9类不同坡角的低矮房屋在5个不同风向的风场环境下,迎风屋面屋檐、屋脊等局部区域测点的平均、脉动及峰值风压系数.通过对比低矮房屋在不同坡角、不同风向作用下屋面的风压变化规律,总结了坡角及风向对低矮房屋屋面局部风压的影响规律.结果表明,低矮房屋在45....     

Cross-wind response of tall buildings

A design procedure was developed using random vibration theory and uses mode-generalized cross-wind force spectra and aerodynamic data to calculate the cross-wind displacement and acceleration responses of tall buildings. The force spectra of a number of building shapes and sizes in both suburban and city centre type wind flow are presented. The proposed design procedure gives reasonable estimates of the cross-wind response, compared with wind tunnel measurements, at reduced wind velocities and at structural damping values consistent with modern habitable tall building design. This allows assessment of the structural requirements of tall buildings to be made at an early design stage, and also allows the designers to assess the need for more detailed and expansive wind tunnel model tests.     

高层民用建筑的应急照明

论述了高层建筑的应急照明灯具、光源及供电电源，通过分析目前应急照明设计状况及存在的问题，总结了高层建筑应急照明的几点认识，供同行参考借鉴。     

Vibration control of tall buildings

Objectionable vibrations have been experienced in modern tall buildings. To alleviate the vibrations one may increase the structural stiffness and damping or use a passive control device such as a ‘tuned mass damper’. The drawback of the above mentioned methods is the greatly increased cost. An alternative approach is to use active control devices providing control forces based on the feed back control theory. This paper presents a systematic approach of first reducing a multistorey structure to a simpler equivalent system. Then a pole placement method is developed to obtain the conrol forces. A successive approximation method is used to reduce the responses to permissible magnitudes. An example is presented to demonstrate the feasibility of the method.     

Designing tall buildings in Moscow

The trend towards industrialisation is described in this article by engineer Dihovichney, who comments on the relative effectiveness of different structural and design solutions adopted.     

Wind-induced motion of tall buildings

Modern buildings designed such that their lateral drifts under statically applied wind loads are less than some fraction of building height, may vibrate excessively during winds and cause occupant discomfort. Methods are presented for evaluating the vibration characteristics of buildings using random vibration theory to relate the fluctuating wind forces to structural response. These methods can be used to evaluate serviceability or to plan wind tunnel tests of buildings.     

Designing tall buildings in Moscow

The trend towards industrialisation is described in this article by engineer Dihovichney, who comments on the relative effectiveness of different structural and design solutions adopted.     

Core-frame interaction in tall buildings

A method is presented for solving by hand structural systems comprising frames and shear walls coupled together through floor slabs. The coupled system is viewed as a shear-flexure cantilever which resists the lateral loads by its combined actions and the coupled governing equations are solved by the Galerkin technique. The contribution of each term from the assumed displacement field is uncoupled by choosing appropriate admissible functions. This uncoupling condition is valid when the structure is uniform throughout the height.     

高层民用建筑中水泵结合器的设置

就高层民用建筑消防设计中水泵结合器的设置问题，从水泵结合器与消防车的配套设置、水泵结合器在自喷消防系统中的设置、安全阀的设置等方面介绍了具体方法，以合理设置并消除故障。     

Interference excitation of twin tall buildings

The enhanced dynamic response of a tall square building under interference excitation from neighbouring tall buildings has been studied in a series of wind-tunnel model tests. In a low-turbulence wind environment and under normal strong wind conditions, the dynamic loads on the upstream of an identical pair of tall buildings may increase by a factor of up to 4.4. The dynamic loads on the downstream building of the pair may increase by a factor of up to 3.2 due to “resonant buffeting”. Measurements of along-wind and cross-wind force spectra and a number of wake spectra provide an explanation for the observed behaviour. Possible excitation mechanisms are discussed and critical building arrangements presented. The large interference loads found in this study indicate that interference excitation should be carefully considered in the design of tall buildings.     

Across-wind loads of typical tall buildings

Previous studies have indicated that the across-wind dynamic responses of super-tall buildings are usually larger than the along-wind ones. With the increase of heights, the across-wind dynamic response of super-tall buildings has been a problem of great concern. In this paper, 15 typical tall building models are tested with high-frequency force balance technique in a wind tunnel to obtain the first-mode generalized across-wind dynamic forces. New formulas for the power spectra of the across-wind dynamic forces, the coefficients of base moment and shear force are then derived. Parametric analyses of the effects of factors on the across-wind loads of the buildings are performed. Besides, a SDOF aeroelastic model of a square tall building with an aspect ratio of 6 is selected from the above buildings and is tested to investigate its across-wind dynamic response and aerodynamic damping characteristics. The power spectrum of the across-wind force of the square building is employed to compute its across-wind dynamic responses with and without considering the effect of the aerodynamic damping. The computed responses are then compared with the corresponding responses from the aeroelastic model test to verify the present formulas of the across-wind loads of buildings.     

Vibration analysis of tall buildings with narrow rectangular plane configuration

In this paper, tall buildings of narrow rectangular plane configuration are treated as one-step or multi-step cantilever flexural-shear plates for the analysis of their free vibrations. The governing differential equations for the vibration of flexural-shear plates considering the effects of both flexural and shear deformation are established. The general solutions for one-step flexural-shear plates are derived and used to obtain the eigenvalue equation for multi-step cantilever flexural-shear plates. A new exact approach is presented which combines the transfer matrix method and a closed-form solution for a uniform flexural-shear plate. A numerical example demonstrates that the calculated natural frequencies and mode shapes of a tall building 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. Copyright © 1998 John Wiley & Sons, Ltd.     

Propagation of seismic waves in tall buildings

A discrete-time wave propagation formulation of the seismic response of tall buildings is introduced. The building is modeled as a layered medium, similar to a layered soil medium, and is subjected to vertically propagating seismic shear waves. Soil layers and the bedrock under the foundation are incorporated in the formulation as additional layers. Seismic response is expressed in terms of the wave travel times between the layers, and the wave reflection and transmission coefficients at the layer interfaces. The equations account for the frequency-dependent filtering effects of the foundation and floor masses. The calculation of seismic response is reduced to a pair of simple finite-difference equations for each layer, which can be solved recursively starting from the bedrock. Compared to the commonly used vibration formulation, the wave propagation formulation provides several advantages, including simplified calculations, better representation of damping, ability to account for the effects of the soil layers under the foundation, and better tools for identification and damage detection from seismic records. Examples presented show the versatility of the method. Copyright © 1998 John Wiley & Sons, Ltd.     

高层建筑结构整体稳定性研究

结构的侧向刚度和重力荷载之比即刚重比,是反映结构整体稳定性的关键参数。当高层建筑的高宽比足够大时,结构的刚重比一般接近规范规定的下限值,甚至低于下限值,计算的刚重比的准确性就显得非常重要。着重分析了弯剪型结构整体稳定性验算时存在的问题,比较结构顶点位移在考虑重力P-Δ效应前后的变化,以及其与刚重比及结构屈曲临界荷载系数的关系,提出了补充验算结构整体稳定性的建议。     

Drift control and damage in tall buildings

The interstorey drift limitations in earthquake codes of various countries around the world, have been reviewed. It is emphasized that, the aseismic safety of a tall building as well as its susceptibility to nonstructural damage are primarily indexed to its ability to restrict the relative storey displacements, in addition to its adequate strength, ductility and toughness. A moment resisting frame building satisfying all requirements of strength and ductility may still be subject to severe nonstructural damage, if the interstorey drifts are not restricted properly by means of shear walls. Several stringent deflection criteria as well as a damage control index are introduced to be conscientiously determined and checked during the design calculations for the purpose of controlling damage especially to nonstructural elements.