Integrated aerodynamic load determination and stiffness design optimization of tall buildings

Modern tall steel buildings are wind sensitive and are prone to dynamic serviceability problems. Although wind tunnel techniques have emerged as valuable tools in providing reliable prediction of the wind‐induced loads and effects on tall buildings, current design practice normally considers the wind tunnel‐derived loads as constant static design loads. Such practice does not take into account the change in wind‐induced structural loads while the dynamic properties of a building are modified during the design synthesis process. This paper presents a computer‐based technique that couples together an aerodynamic wind tunnel load analysis routine and an element stiffness optimization method to minimize the cost of tall steel buildings subject to the lateral drift design criteria, while allowing for instantaneous prediction and updating of wind loads during the design synthesis process. Results of a full‐scale steel building framework with the same geometric shape of the Commonwealth Advisory Aeronautical Research Council (CAARC) standard building indicate that not only is the proposed technique able to produce the cost‐effective element stiffness distribution of the structure satisfying the serviceability wind drift design criteria, but a potential benefit of reducing the design wind loads can also be achieved by the stiffness optimization method. Copyright © 2007 John Wiley & Sons, Ltd.     

Mode shape linearization and correction in coupled dynamic analysis of wind‐excited tall buildings

The three‐dimensional mode shapes found in modern tall buildings complicate the use of the high‐frequency base balance (HFBB) technique in wind tunnel testing for predicting their wind‐induced loads and effects. The linearized‐mode‐shape (LMS) method was recently proposed to address some of the complications in the calculation of the generalized wind forces, which serve as the input to modal analysis for predicting wind‐induced dynamic responses of tall buildings. An improved LMS method, called the advanced linearized‐mode‐shape (ALMS) method, is developed in this paper by introducing torsional mode shape corrections to account for the partial correlation of torques over building height. The ALMS method has been incorporated into the accurate complete quadratic combination method in the coupled dynamic analysis to form a comprehensive procedure for the determination of equivalent static wind loads (ESWLs) for structural design of complex tall buildings. The improved accuracy in the prediction of generalized forces by the ALMS method has been validated by a 60‐storey benchmark building with multiple‐point simultaneous pressure measurements. A practical 40‐storey residential building with significant swaying and torsional effects is presented to demonstrate the effectiveness of the proposed wind load and response analysis procedure based on the HFBB data. Copyright © 2010 John Wiley & Sons, Ltd.     

The wind‐induced response characteristics of atypical tall buildings

A tall building reacts sensitively to winds because the wind force increases according to the height and shape of the building. Various shapes of tall buildings and their aerodynamic characteristics have been studied extensively. For structural design and occupant comfort, the dynamic displacement of a tall building must be maintained within the criteria for acceptable levels of wind‐induced motion. An aerodynamically appropriate building shape needs to be selected at the design stage of a tall building. In this study, wind‐induced vibration responses were investigated, according to the criteria for maximum acceptable displacement and acceleration. Copyright © 2007 John Wiley & Sons, Ltd.     

Evaluation of wind loads on super‐tall buildings from field‐measured wind‐induced acceleration response

With the nonstationary wind‐induced acceleration data from full‐scale measurements, an approach for estimation of the wind‐induced overturning bending moments for super‐tall buildings was proposed in this paper. The empirical mode decomposition was employed to decompose the measured acceleration data into a set of intrinsic mode functions and a residual component. To remove the baseline offset, the residual component and the intrinsic mode function components with long‐period were eliminated before their integrations into velocity and displacement components. Then, the intrinsic mode function components, which have the same dominant periods as the natural periods of the studied tall buildings, were extracted from the original signals, and the natural frequency and damping ratio for the first vibration mode of the building were identified. Finally, the wind‐induced overturning bending moments of the building were obtained from the generalized wind loads for the first vibration mode, which could be obtained from the time history analysis of dynamic equation. The Hilbert spectrum of wind‐induced overturning bending moments was utilized to observe its characteristics in both time and frequency domains, and the Strouhal number was thus identified. The proposed scheme and some selected results may be helpful for further understanding of wind effects on super‐tall buildings. Copyright © 2012 John Wiley & Sons, Ltd.     

高层建筑钢结构基于风振响应和动力特性的优化设计

高层建筑的风致响应和等效静力荷载虽然可以通过风洞试验和动力分析有效的加以确定,在结构设计的整个过程中这些等效风力却往往被当作常数来应用。本文提出了一个结合气动风力分析和结构刚度优化的自动化技术。在结构设计中利用这个技术,可以在优化结构刚度和最小化结构造价的同时,实时检查和更新作用在建筑结构上的等效风荷载。一个几何尺度与航空研究共同顾问理事会(CAARC)建议的建筑模型一致的钢框架结构被用来进行风力分析和结构优化的例子。结果表明这个技术不但能在满足位移设计要求的情况下优化结构刚度降低造价,而且也降低了作用在结构上的等效风力。     

Spectral characteristics and correlation of dynamic wind forces on a super‐tall building

The 88‐storey Jin Mao Building located in Shanghai has a height of 420·5m and is the highest building in mainland China. Dynamic wind force components on the super‐tall building were measured by high‐frequency force balance technique in a boundary layer wind tunnel for the cases of an isolated Jin Mao Building and the existing surrounding condition under suburban and urban boundary layer flow configurations. Spectral characteristics of along‐wind and across‐wind components and, in particular, the cross‐correlation and coherence among various wind loading components are presented and discussed in detail. Furthermore, the effects of upstream terrain conditions and surrounding buildings on the spectra, cross‐correlation and coherence are investigated. The experimental results show that such effects are significant. Finally, an empirical formula for estimation of the across‐wind overturning moment spectrum for the super‐tall building is presented. Comparisons of the spectra determined by the proposed formula and those obtained from wind tunnel tests are made to examine the applicability of the proposed formula. Copyright © 2007 John Wiley & Sons, Ltd.     

Structural design and analysis of vertical double‐layer space structures in super‐tall buildings

This paper investigates the potential of double‐layer space structures to be applied vertically as a new structural system in super‐tall buildings. The investigation using case studies covers four stages: structural designs of 100‐storey buildings in order to obtain internal force distributions and determine appropriate structural member sizes, analyses of the impacts of wind and seismic loads on the structures, sensitivity of structural weight ratios and lateral deflection constraints to changing structural geometry, and comparison of the lateral deflected shapes and structural weights per unit area with those of other current tall structural systems. The results show that changing the angles of diagonal members to make them span two storeys rather than one storey reduces structural weight and has little impact on lateral deflection. Compared with other current tall structures, vertical double‐layer space structures are relatively efficient structurally. The study concludes that double‐layer space structures can be applied vertically as a structural system of super‐tall buildings. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification of Wind Loads and Estimation of Structural Responses of Super‐Tall Buildings by an Inverse Method

This article presents a Kalman‐filter‐based estimation algorithm for identification of wind loads on a super‐tall building using limited structural responses. In practice, acceleration responses are most convenient to be measured among wind‐induced dynamic responses of structures. The proposed inverse method allows estimating the unknown wind loads and structural responses of a super‐tall building using limited acceleration measurements. Taipei 101 Tower is a super‐tall building with 101 stories and a height of 508 m. Field measurements and numerical simulations of the wind effects on Taipei 101 Tower are conducted. The wind loads acting on the super‐tall building are estimated based on the wind‐induced responses determined from the numerical simulations and the refined finite‐element model of the structure, which are in good agreement with the exact results. The stability performance of the proposed algorithm is evaluated. The influence of noise levels in the measurements and covariance matrix of noise on the identification accuracy are investigated and discussed based on the L‐curve method. Finally, the wind loads and structural responses are reconstructed based on the field‐measured accelerations during Typhoon Matsa. The accuracy of the identified results is verified by comparing the reconstructed acceleration responses with the field measurements. The results of this study show that the proposed inverse approach can provide accurate predictions of the wind loads and wind‐induced responses of super‐tall buildings based on limited measured responses.     

Field measurements of amplitude‐dependent damping in a 79‐storey tall building and its efects on the structural dynamic responses

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 approximately 324 m. Field measurements including wind speed, wind direction and wind‐induced acceleration responses have been made. The amplitude‐dependent characteristics of damping are obtained by using the random decrement technique from the detailed analysis of the field acceleration measurements. The main objective of this paper is to present detailed investigations into the effects of nonlinear damping on the dynamic responses of the tall building subjected 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 were compared with those computed by using constant damping parameters assumed by the structural designers. It is concluded from the investigations that knowledge of actual damping characteristics are very important in the accurate prediction of the dynamic responses of a tall building when the major harmonic components of the applied loads overlap with the lowest natural frequencies of the building. The design damping level for tall building structures currently used by structural engineering practitioners appears to be high and not conservative. Copyright © 2002 John Wiley & Sons, Ltd.     

A combined tuned damper and an optimal design method for wind‐induced vibration control for super tall buildings

The wind‐induced vibrations of super tall buildings become excessive due to strong wind loads, super building height and high flexibility. Tuned mass dampers (TMDs) and tuned liquid column dampers (TLCDs) have been widely used to control vibrations for actual super tall buildings for decades. To fully use both the economic advantage of the TLCD system and the high efficiency of the TMD system, an innovative supplemental damping system including both TLCD and TMD and called combined tuned damper (CTD), which can substantially decrease the cost of the damper, was proposed to control the wind‐induced vibrations of tall buildings. The governing equations are generated for the motion of both the primary structure and the CTD and solved to anticipate the dynamic response of the CTD‐structure system. Moreover, an optimal design method of human comfort performance is proposed, in which the life cycle cost of the damper‐structure system is considered as the quantitative index of the performance. The life cycle cost includes the initial cost, the maintenance cost and the failure cost. The failure cost can be calculated using the vibration‐sensation rate model, which is based on the Japanese code AIJES‐V001‐2004. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

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.     

Field measurements of wind and structural responses of a 70‐storey tall building under typhoon conditions

This paper describes the results obtained from the full‐scale measurements of wind effects on a 70‐storey tall building in Hong Kong. The objective of the experiment is to measure wind action on and wind‐induced response of the tall building. Simultaneous and continuous data of wind speeds, wind directions and acceleration responses have been recorded at the top of the tall building since 1995. The field data presented in this paper were measured during the passage of four typhoons—Typhoon Kent (1995), Typhoon Ryan (1995), Typhoon Sibyl (1995) and Typhoon Sally (1996). The characteristics of the typhoon wind and the structural responses of the building are investigated. The serviceability of this tall building under typhoon conditions is discussed on the basis of the field measurements. Copyright © 2000 John Wiley & Sons, Ltd.     

Experimental study on wind load characteristics of high‐rise buildings with opening

For investigation of the wind load characteristics on high‐rise buildings with opening, a series of rigid rectangular high‐rise building models with opening were tested by synchronous multi‐pressure sensing system (SMPSS) in a boundary wind tunnel. Influence parameters including different opening heights, opening rates, opening patterns, and terrain categories are studied in detail. Based on the test results, the local wind force coefficients, base moment coefficients, and power spectral densities were discussed. The results indicated that the opening could affect the wind loads acting on high‐rise buildings to different extent. The distinct reduction of wind loads on high‐rise buildings was found at along‐wind direction, which could be evaluated by a proposed simplified expression accordingly. This study aims to provide useful information for the wind‐resistant design of high‐rise buildings with opening.     

Wind tunnel test and field measurement study of wind effects on a 600‐m‐high super‐tall building

Ping An Finance Center with a height of 600 m and 118 storeys, located in Shenzhen, is currently the second tallest building in China. This paper presents a comprehensive study of wind effects on the supertall building through wind tunnel testing and field measurement. The wind‐induced loads and pressures on the skyscraper were measured by high‐frequency force balance technique and synchronous multipressure sensing system, respectively. In the wind tunnel study, a whole range of characteristic properties, including mean and r.m.s force coefficients, power spectral densities, coherences, correlations, and phase‐plane trajectories, wind‐induced displacement, and acceleration responses were presented and discussed. In addition, a field measurement study of the dynamic responses of Ping An Finance Center was conducted during a tropical cyclone, which aimed to verify the design assumptions and further the understanding of the dynamic properties and performance of the 600‐m‐high supertall building, including natural frequencies, damping ratios, and wind‐induced structural responses. Then, the serviceability of the skyscraper is assessed on the basis of the experimental results and field measurements. The outcomes of this combined model test and field measurement study are expected to be useful for the wind‐resistant design of future supertall buildings.     

Optimal lateral stiffness design of tall buildings of mixed steel and concrete construction

This paper presents an optimal sizing technique for the lateral stiffness design of tall steel and concrete buildings. The minimum structure cost design problem subject to lateral drift constraints is first mathematically formulated and then solved by a rigorously derived Optimality Criteria (OC) method. The emphasis is particularly placed on the practical applicability of the optimization technique in engineering practice. Once the structural form of the lateral load resisting system of a building is defined, the optimal steel and concrete element sizes are then sought while satisfying all serviceability lateral stiffness and practical sizing requirements. The effectiveness and practicality of the optimization technique is illustrated through an actual application to the preliminary design of an 88‐storey building in Hong Kong. When complete, the building will be 420 m tall and will become the tallest building in Hong Kong. Copyright © 2001 John Wiley & Sons, Ltd.     

山地风场中超高层建筑风荷载幅值特性试验研究

针对山地风场中超高层建筑风荷载特点,在1.4m×1.4m风洞中进行了11个不同高宽比、厚宽比矩形截面和圆形截面超高层建筑表面测压风洞试验,分析了阻力系数平均值、均方根值和升力、扭矩系数均方根值受来流风湍流度、建筑高宽比、厚宽比和层相对高度等因素的影响。结果表明：矩形截面建筑各气动力幅值特性明显随湍流度、建筑高宽比、厚宽比、层相对高度的改变而变化,而圆形截面建筑各气动力幅值特性仅随湍流度、层相对高度的改变而变化。根据风洞试验结果,建立了正方形截面和圆形截面风荷载幅值特性的数学模型,通过比较说明与风洞试验结果吻合较好,可为山地风场中的超高层建筑风致响应计算提供依据。图11表5参10     

Optimum seismic design of steel framed‐tube and tube‐in‐tube tall buildings

The relatively large number of structural elements and the variety of design code requirements complicate the design process of tall buildings. This process is exacerbated when the target is to obtain the seismic code‐compliant optimal design with minimum weight. The present paper aims at providing a practical methodology for the optimal design of steel tall building structures considering the constraints imposed by typical building codes. The applicability of the proposed approach is demonstrated through the determination of the optimal seismic design for 20‐, 40‐, and 60‐story buildings with a framed tube as well as a tube‐in‐tube system. Such a design gives rise to a basis for the fair comparison of the behavior of the framed tube with that of the tube‐in‐tube system under applied loads. The optimal weight of the buildings with the tube‐in‐tube system turns out to be slightly less than that of the buildings with the conventional framed‐tube system.     

Influence of soil‐structure interaction on performance of a super tall building using a new eddy‐current tuned mass damper

Tuned mass dampers (TMDs) can be used as vibration control devices to improve the vibration performance of high‐rise buildings. The Shanghai Tower (SHT) is a 632‐m high landmark building in China, featuring a new eddy‐current TMD. Special protective mechanisms have been adopted to prevent excessively large amplitude of the TMD under extreme wind or earthquake loading scenarios. This paper presents a methodology for simulating behavior of the new eddy‐current TMD that features displacement‐dependent damping behavior. The TMD model was built into the SHT finite element model to perform frequency analysis and detailed response analyses under wind and earthquake loads. Furthermore, soil‐structure interaction (SSI) effects on wind and seismic load responses of the SHT model were investigated, as SSI has a significant impact on the vibration performance of high‐rise buildings. It was found that SSI has more significant effects on acceleration response for wind loads with a short return period than for wind loads with a long return period. Some of the acceleration responses with SSI effects exceed design limits of human comfort for wind loads with shorter return periods. As to the seismic analyses, it was found that SSI slightly reduces the displacement amplitude, the damping force, and the impact force of the TMD.     

Wind‐induced interference effects between twin tapered skyscrapers

Twin high‐rise buildings, that is, two closely located tall buildings with identical or similar geometrical features, are inevitably under wind‐induced interference effects. Most previous studies employed rectangular or circular prisms as twin tall buildings to investigate the interference effects. Therefore, these findings need further verification and modification for twin high‐rise buildings with more complex exterior geometries. This study uses wind tunnel pressure measurement tests to investigate the interference effects on typical twin super‐tall buildings with a tapered shape and recessed corners. Structural overall overturning moments and surface wind pressures applied on the twin skyscrapers are analyzed and discussed in detail. The interference effects on the twin skyscrapers are further compared with those on paired square prisms with the same height and footprint breadth. The results show that the interference effects on the twin tapered super‐tall buildings differ considerably from those on the square prisms, and the critical building configurations that need cautious treatment in the designs of twin skyscrapers are specified.