Evaluation of peak resultant response for wind-excited tall buildings

The traditional peak factor approach and combination rules developed for Gaussian scalar combination effects are not applicable for vectorial combination effects which feature non-Gaussian characteristics. This paper addresses the evaluation of the peak value of a vectorial resultant response of a wind-excited tall building resulting from correlated three-dimensional responses with a special focus on building acceleration. The peak value of the resultant response over a given duration is analyzed based on the upcrossing theory for non-Gaussian processes and for vector-valued Gaussian processes. A parametric study including the correlation of response components and their derivative processes is conducted to identify the controlling parameters in estimating the upcrossing rate and peak resultant response. The accuracy of the current empirical combination approaches is evaluated. A practical combination scheme is proposed and demonstrated using a wind-excited tall building with three-dimensional mode shapes. The results show that the existence of eccentricity leads to coupled alongwind, crosswind and torsional accelerations, and considerably amplifies the peak resultant acceleration.     

Study on occupant comfort evaluation mode of tall buildings in wind excitation based on fuzzy probability method

Occupant comfort mode in wind‐induced vibration was proposed and studied based on fuzzy probability method (FPM). First, the predictions of the comfort mode were compared with the studies of other researchers to verify the reliability of the method proposed in this paper. Second, vibration comfort of 4 types of buildings was investigated and assessed respectively with the proposed mode. Third, parameters of influencing the occupant comfort, such as coefficient of variation and membership function (MF), were discussed, and optimal results were found. Finally, application of the comfort mode was investigated with a true super tall building. This study shows that the FPM is a feasible and reliable way of establishing the occupant comfort mode, and good predictions can be obtained, especially for FPM with MF1 and MF2. The quantitative story and total comfort ratios can be evaluated effectively for tall buildings in wind excitation. The proposed occupant comfort mode based on FPM provides a new and reliable way of investigating the comfort ratio of tall buildings quantifying vibration comfort and guiding structural comfort design.     

Mode shape linearization for HFBB analysis of wind-excited complex tall buildings

The high-frequency base balance (HFBB) testing technique has been developed and continuously improved for two decades. A number of researches have been devoted to the development of mode shape correction factors to account for the significant uncertainties in the prediction of generalized wind forces due to the non-ideal mode shapes. However, these correction factors are mostly derived based on presumed wind loading distributions and/or correlations, which introduce inherent uncertainties associated with the inappropriate modelling of the actual wind loads influenced by the site specific characteristic of the surrounding proximity. This paper proposes a new HFBB analysis method independent of the information of the wind load distributions, referred to as the linear-mode-shape (LMS) method, to minimize the discrepancy in the estimation of generalized wind forces due to nonlinearity of mode shapes. The uncertainties of the translational components of the generalized wind forces prediction are eliminated by linearizing the three-dimensional (3D) coupled mode shapes.A series of wind tunnel pressure tests was conducted at the CLP Power Wind/Wave Tunnel Facility, The Hong Kong University of Science and Technology to determine the distribution of wind loads on an example building, from which an “exact” wind-induced response was computed and used as a reference for the comparison of the LMS method and the conventional HFBB method. The accuracy of the generalized forces prediction, and hence the estimation of structural responses, for buildings with 3D coupled mode shapes was improved. In addition, a parametric study was carried out to examine the robustness and reliability of the LMS method for a range of practical mode shape power exponents. The detailed formulation of the LMS method is outlined in this paper.     

焦作夏季居住建筑人体热舒适现场研究

采用环境参数测量与问卷调查同步进行的方式,研究了混合供冷模式下人们的热舒适性。结果显示,该地区夏季实测热中性温度为27.7℃,预测热中性温度为25.4℃,由热感觉法和直接询问法得到的80%可接受温度范围的上限分别为28.8℃和29.2℃,由这两种方法得到的期望温度分别为27.4℃和24.0℃;在混合供冷模式下,由于存在由空调环境进入非空调环境的情况,所以对热环境的不满意率要高于自然通风状态,可接受温度上限比自然通风状态低。     

焦作市冬季居住建筑室内人体热舒适现场研究

为了研究寒冷地区中小城市冬季室内的热环境状况,对焦作市44户住宅的冬季室内热环境进行了现场调查.对99名居民的热感觉、热舒适等进行了主观问卷调查,同时测试了温度、相对湿度、风速等室内外环境参数,对测试与调查结果进行了统计回归分析.结果表明,焦作市居住建筑冬季实测的热中性温度为19.2℃,预测热中性温度为24.3℃,两者相差5.1℃;居民期望温度为21.0℃;该地区冬季居民的热适应模型为tcomf=0.317tout+18.19,80％居民可接受温度范围为11.6～24.2℃.     

Control of wind-induced vibration of long-span bridges and tall buildings

With the rapid increase in scales of structures, research on controlling wind-induced vibration of large-scale structures, such as long-span bridges and super-tall buildings, has been an issue of great concern. For wind-induced vibration of large-scale structures, vibration frequencies and damping modes vary with wind speed. Passive, semiactive, and active control strategies are developed to improve the wind-resistance performance of the structures in this paper. The multiple tuned mass damper (MTMD) system is applied to control vertical bending buffeting response. A new semiactive lever-type tuned mass damper (TMD) with an adjustable frequency is proposed to control vertical bending buffeting and torsional buffeting and flutter in the whole velocity range of bridge decks. A control strategy named sinusoidal reference strategy is developed for adaptive control of wind-induced vibration of super-tall buildings. Multiple degrees of freedom general building aeroelastic model with a square cross-section is tested in a wind tunnel. The results demonstrate that the proposed strategies can reduce vibration effectively, and can adapt to wind-induced vibration control of large-scale structures in the uncertain dynamic circumstance.     

Effect of axial deformation on vibration of tall buildings

In this paper, the governing equations of a frame‐core wall building are formulated through the continuum approach and the whole structure is idealized as a shear–flexural cantilever. The effect of axial deformation in the frame is considered and incorporated in the formulation of the governing equations. The Bubnov–Galerkin method is used to transform the governing differential equations into a set of algebraic equations. Numerical examples are solved and the results compared with the values obtained from the finite element package ‘ETABS’. The study indicates that the effect of axial deformation should be considered especially for tall and/or slender buildings. The proposed method is simple and efficient, provides reasonably accurate results and can be easily implemented on any personal computer. Copyright © 2001 John Wiley & Sons, Ltd.     

Thermal comfort and workplace occupant satisfaction—Results of field studies in German low energy office buildings

The issues of comfort and workspace quality in buildings have gained much importance with the European “Energy Performance of Buildings Directive” of 2001. New energy efficient building concepts and technologies require a revision of comfort standards, which were developed for air-conditioned buildings only. Particularly, the question of recommendable upper indoor temperature limits needs further investigation. In addition, a broader approach to occupant satisfaction in buildings is necessary with respect to overall building performance.     

Torsional vibration of wind-excited symmetrical structures

A method for estimating the torsional dynamic response of a symmetrical structure subjected to a normally-incident wind is presented. The procedure is based on random-vibration concepts and parallels the gust factor approach currently used in engineering design. An analytical expression is derived for the torsional aerodynamic admittance function, and an approximate expression is presented for computing the expected maximum torsional response. Numerical examples are presented which indicate that the torsional response depends on the width of the structure and its torsional natural frequency.     

Sopite syndrome in wind-excited buildings: productivity and wellbeing impacts

Tall buildings vibrate in response to strong winds at frequencies below 1?Hz, which can cause motion sickness and sopite syndrome in humans. Sopite syndrome is characterized by sleepiness, low motivation and low mood that can reduce productivity in office workers. This paper uses recent multidisciplinary research to estimate the cost of building motion on organizations in tall buildings, and provides a framework for future research. The potential costs of wind-induced building motion to organizations are highly variable, depending on the local weather climate, but are likely to be significant in the long-term. It is argued that wind-induced building motion is a negative externality, a cost of inadequate design passed to building users. A three-factor approach towards reducing adverse impacts of wind-induced building motion is discussed: (1) further research investigating the characteristics of motion that provoke sopite syndrome, (2) create a new generation of serviceability criteria, and (3) regulations setting the maximum acceptable motion dose for office workers. This three-factor approach will likely produce comprehensive, yet usable, guidelines to develop strategies that reduce the adverse effects of motion on occupants in both new and existing buildings.     

高层建筑结构的风振阻尼控制分析与设计方法

本文首先分析了阻尼比对结构风振反应的控制效果,重点讨论了阻尼比对风振脉动增大系数的减小效果和具体计算方法,给出了便于工程实际应用的阻尼比为10%～30%的风振脉动增大系数随基本风压和结构基本周期变化的计算图表。结果表明,结构阻尼比增大,风振脉动增大系数明显减小。其次,分析了结构耗能减振系统的附加阻尼特性,给出了调频质量阻尼器(TMD)、调频液体阻尼器(TLD)和速度线性相关型耗能器附加给结构阻尼比的实用计算公式。最后给出了100层钢结构分别设置TMD和线性粘滞阻尼器的风振控制分析和设计实例。实例结果表明,两种被动阻尼控制系统对结构最大位移和最大加速度控制效果相同,可以达到40%～55%,同时说明了本文提出的方法可以方便地用于大型结构的风振阻尼控制分析和设计。     

Unified dynamic absorber design formulas for wind-induced vibration control of tall buildings

The objective of this paper is to establish some unified design formulas for various kinds of passive dynamic absorber for wind-induced vibration control of tall buildings. A total of five different passive dynamic absorbers (TMD, TLCD, LCVA, C-TLD and R-TLD) are considered in this study. Firstly, unified equations of motion for the building–absorber system under wind-induced excitation are presented. A set of unified formulas for the optimal properties and the equivalent damping ratios for these five dynamic absorbers are then derived analytically. The Shanghai Central Plaza, which is a thirty-nine-story reinforced-concrete building, is used as an example to demonstrate the procedure and to verify the accuracy of the unified approach. The results show that these unified formulas provide direct performance evaluation and comparison between the five dynamic absorbers for the control of wind-induced vibration of tall buildings. © 1998 John Wiley & Sons, Ltd.     

The effects of axial deformation and axial force on vibration characteristics of tall buildings

A tall building comprising frames and shear walls coupled together is idealized as a shear–flexure cantilever through the continuum approach. The effects of axial deformation as well as axial force in the frames are considered and incorporated in the formulation of the governing equations. Numerical examples are solved through the Galerkin method and the results compared with finite element solutions. The study indicates that the effect of axial deformation in the frame should be considered for tall and/or slender buildings while the effect of axial force in the column should be included for buildings with soft‐storeys resulting from the termination of core walls in the lower portion of the building. Copyright © 2002 John Wiley & Sons, Ltd.     

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。     

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.     

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.     

Simulation and visualization of energy-related occupant behavior in office buildings

In current building performance simulation programs, occupant presence and interactions with building systems are over-simplified and less indicative of real world scenarios, contributing to the discrepancies between simulated and actual energy use in buildings. Simulation results are normally presented using various types of charts. However, using those charts, it is difficult to visualize and communicate the importance of occupants’ behavior to building energy performance. This study introduced a new approach to simulating and visualizing energy-related occupant behavior in office buildings. First, the Occupancy Simulator was used to simulate the occupant presence and movement and generate occupant schedules for each space as well as for each occupant. Then an occupant behavior functional mockup unit (obFMU) was used to model occupant behavior and analyze their impact on building energy use through co-simulation with EnergyPlus. Finally, an agent-based model built upon AnyLogic was applied to visualize the simulation results of the occupant movement and interactions with building systems, as well as the related energy performance. A case study using a small office building in Miami, FL was presented to demonstrate the process and application of the Occupancy Simulator, the obFMU and EnergyPlus, and the AnyLogic module in simulation and visualization of energy-related occupant behaviors in office buildings. The presented approach provides a new detailed and visual way for policy makers, architects, engineers and building operators to better understand occupant energy behavior and their impact on energy use in buildings, which can improve the design and operation of low energy buildings.     

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.     

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.