Tall Building Model Research Articles

A numerical-experimental investigation on the aerodynamic performance of CAARC building models with geometric modifications

This paper presents the results of a numerical-experimental investigation carried out with the purpose to evaluate the aerodynamic performance of CAARC tall building models with different cross-section configurations. A numerical model based on the Taylor-Galerkin two-step scheme and the Finite Element Method is adopted. Turbulence is described using LES and a synthetic inflow turbulence generator. Experimental tests were performed at the Prof. Joaquim Blessmann Boundary Layer Wind Tunnel considering CAARC tall building models with cross-section modifications based on chamfered and recessed corners. Some of the wind tunnel predictions obtained here are compared with results obtained from the numerical model proposed in this work, where two and three-dimensional meshes are utilized. Comparisons are also performed considering results obtained from other authors in similar studies. From the present investigation, it was observed that the wind action on tall buildings is significantly influenced by the geometric configuration of the building corners, which may lead to important reductions in the aerodynamic forces. Through a direct comparison of results between numerical and experimental simulation, we can see that both reach a convergence of results, thus indicating the potential of use of CFD in the modern aerodynamic investigation of buildings.

Simultaneous measurement of wind velocity field and wind forces on a square tall building

Vortex shedding from a tall building is known to be responsible for the quasi-periodic across-wind force exerted on the building. This article unveils the exact relationship between the vortex shedding pattern and the fluctuating across-wind force. Simultaneous particle-image velocimetry and pressure measurements are carried out on a square-plan tall building model in the wind tunnel toward an understanding of the velocity–pressure–force relation for across-wind force generation on the building. A collection of instantaneous wind flow patterns and synchronized wind pressure distributions suggests the existence of full periods of vortex shedding from the building. The results are further analyzed using the conditional sampling method by which the roles of development and shedding of large-scale vortices in the building wake on the generation of peak across-wind forces are evidently found. Furthermore, quasi-periodicity of across-wind excitation is clearly confirmed with Hilbert transform of the across-wind force signal. The phase averaging technique is applied to the particle-image velocimetry flow fields and distinct vortex shedding patterns from the building are observed for most of the measurement time, together with an evident phase relationship with the across-wind forces.

Sensitivity analysis of wind pressure coefficients on CAARC standard tall buildings in CFD simulations

Constructing tall buildings has been a common trend for many cities due to rapid increase of population, therefore, it is essential to analyze wind pressure around and over these tall buildings. CFD simulation is an effective approach to realize this, in which CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building has been a well-acknowledged model to validate and calibrate tall building models. Nevertheless, less work has been conducted to study sensitivity of wind pressures over CAARC standard tall building to geometric and computational parameters in CFD simulation. This paper is therefore designed to fill this gap by analysing impacts of various parameters like turbulence model, approaching-flow speed and grid type on wind pressure coefficients over CAARC buildings. In this paper, wind pressure coefficients over CAARC models subjected to four wind directions were numerically analyzed for validating the correctness and effectiveness of numerical model. Sensitivity of wind pressures to geometric and computational parameters was analyzed through comparisons of deviation and absolute deviation. Results indicated that various phenomena such as fluid separation, vortex, wake effect and reattachment were sensitive to wind direction, resulting in great variations in wind pressure. Maximum positive wind pressure coefficients emerged around 0.8–0.85H of windward surface, while maximum negative one occurred at foreside of top surface. Furthermore, turbulence model had significant influences on the accuracy of numerical results, where Realizable k-ε and SST were the most accurate turbulence models, and standard k-ε and RNG k-ε models were the second accurate ones, but BSL was not recommended for wind resistance design. Approaching-flow speed and grid type exerted insignificant influences on pressure coefficient distribution, while grid resolution had significant effects on negative wind pressure distribution. In general, conclusions obtained in this study can assist structural engineers to select practical geometric and computational parameters in predicting wind pressure distribution against tall buildings.

Estimation of Gust Response Factor for a Tall Building Model with 1:1.5 Plan Ratios

The purpose of structural analysis and design of structures as per the building codes and its corresponding standers is to ensure the safety of structure under maximum loads and remains functional under service load. The structure which is designed under consideration of codes should also satisfy the durability, economy and aesthetics. The primary purpose of this work is to understand and compare design wind loads according with the Gust Response Factor as per codes of practices. The paper is concerned with the calculation of design wind loads on a rectangular building model (1:300gemetric scale) of size 10cm x 15cm x 70cm with an aspect ratio of 1:1.5:7 at eight different levels over the height under sub-urban terrain category for 00 angle and 900 angle wind incidence. The experiment id conducted in an atmospheric boundary layer wind tunnel facility of CSIR-Structural engineering Research centre, Chennai. The measured pressures are integrated to evaluate mean and RMS (Root, Mean, Square). Further the variation of above mentioned loads and response factor along the heights of the building with respect to sub-urban terrain condition are discussed and summarized in addition, the codal values of various international standards [IS-875 part-3 1987, IS-875 part-3 draft, ASCE-07] have also considered for comparison.

Wind-induced responses of a tall building with a double-skin façade system

To date the engineering community has seen double-skin façade systems as non-structural elements on buildings for the aesthetic desire, improving the indoor environment, reducing the energy use, and even improving acoustics in buildings. In this study, the effects of a double-skin façade system on the wind-induced responses of a tall building were investigated via a program of wind tunnel tests. Two types of wind tunnel tests, i.e. aeroelastic test and pressure test, were performed. It was found that a double-skin façade with/without vertical openings installed in front of the windward face of the building model results in very different effects on the wind-induced responses in alongwind and crosswind directions. In the alongwind direction, the façade with/without openings induces negligible effects on the wind-induced response. However, in the crosswind direction, the façade with opening(s) reduces the wind-induced response significantly, whereas the façade without any opening increases the response, compared to the bare tall building model. Therefore, in addition to achieve the purposes of the aesthetic desire, improving indoor environment and reducing energy use, the double-skin façade system with vertical opening(s) can also be used to effectively reduce crosswind responses without inducing larger alongwind responses.

Utilizing cavity flow within double skin façade for wind energy harvesting in buildings

Efficient wind energy harvesting by utilizing small-scale wind turbines in the urban environment requires techniques to enhance the desirable flow characteristics, including velocity magnitude and uniformity, and diminish the unfavorable characteristics, including high turbulence and intermittence. This study proposed a Double-Skin Façade (DSF) system with strategic openings to harvest wind energy in the built environment. A series of wind tunnel tests and CFD simulations have been conducted to investigate the characteristics and related mechanisms of flow within the cavity of DSF integrated with a tall building model at different incident wind angles. The discrepancy between numerical and experimental results generally remains within an acceptable range of 15% which validates the capability and accuracy of the developed CFD simulations in predicting the flow characteristics. It was found that the flow becomes more uniform while the turbulence progressively decays as flow progresses through the cavity for all wind directions. Hence the regions in the middle of both the leading and trailing sides of the cavity are favorable locations for installing small-scale, building-mounted wind turbines. Overall, the DSF system with a strategic opening can effectively enhance the flow within the cavity for a wide range of incident wind angles and can be adapted for wind energy harvesting purposes.

High Performance Computing for Regional Building Seismic Damage Simulation

Modern cities are becoming integrated systems that consist of a high density of population and buildings. Once they are hit by earthquakes, the damage or collapse of buildings will result in huge economic losses and casualties. For the three key problems (i.e. modeling, computing and visualization) in regional building seismic damage simulation, a high-fidelity modeling method, a high-performance computing approach and a realistic visualization technique are proposed in this study, respectively. With respect to the modeling problem, a multi-degree-of-freedom (MDOF) shear model for multi-story buildings and a MDOF flexural-shear model for tall buildings are proposed. Also, the corresponding parameter determination methods are proposed. For the computing problem, a parallel computing method based on GPU (graphics processing unit) for regional building seismic damage simulation is proposed, leading to a speedup ratio of approximately 54 times. In regard to the visualization problem, a 3D-GIS data generation method using the widely accessible 3D urban polygonal model and a realistic visualization method are proposed for displaying the simulated urban earthquake disaster scenario. The above proposed methods have been used in a large-sized city and Beijing central business district (CBD). Accurate, efficient, and realistic simulations for regional building seismic damage have been achieved with these methods. The outcome of this study provides important technology for regional building seismic damage simulation, which can improve the ability of urban disaster prevention and mitigation.

高层建筑平均风压的阻塞效应试验研究

基于5组不同缩尺比的矩形高层建筑风洞试验模型，在两种不同湍流度强度风场下研究湍流度对高层建筑平均风压的阻塞效应影响。试验结果表明：同种风场下，阻塞效应对模型迎风面平均风压系数的影响较小，阻塞比的不同并没有引起迎风面压力分布的显著变化，阻塞比的增大使模型侧面和背风面平均风压系数降低较为显著。来流湍流增大会降低阻塞效应对平均风压系数的影响，湍流度增大对迎风面阻塞效应影响较小，但对高层建筑模型侧面、背面阻塞效应影响较大；最后，对低湍流度风场下阻塞效应修正公式进行了检验，并验证了高湍流度风场下阻塞效应修正公式的适用性。 Based on five groups of different scale wind tunnel test models, this paper researches the effect of turbulence on the blockage effect of mean wind pressure on tall buildings under two different tur-bulence intensity wind fields. The experimental results show that the effects of the blocking effect on the mean pressure coefficient on windward surface of the model are slight. The difference of the blocking ratio has little effect of the pressure distribution of the windward surface. The increase of the blocking ratio makes the mean pressure coefficient of the side surfaces and leeward surfaces decrease more obviously. However, the increase of the turbulence will reduce the effect of the blocking effect on the mean wind pressure coefficient, and the increase of turbulence intensity has little effect on the blocking effect of the windward surface but the turbulence increase has a great influence on the side surfaces and leeward surfaces of the tall building model. Finally, the correction results of the blocking effect are verified under the low turbulence wind field and the correction formula for mean pressure coefficient is proposed based on the high turbulence.

Wind tunnel tests of 3D wind loads on tall buildings based on torsional motion-induced vibrations

This paper presents the experimental results of the wind tunnel tests for three symmetric, rectangular, tall building models on a typical open terrain considering the torsional motion-induced vibrations. The time histories of the wind pressure on these models under different reduced wind speeds and torsional amplitudes are obtained through the multiple point synchronous scanning pressure technique. Thereafter, the characteristics of both the Root Mean Square (RMS) coefficients and the spectra of the base shear/torque in the along-wind, across-wind, and torsional directions, respectively, are discussed. The results show that the RMS coefficients of the base shear/torque vary in the three directions with both the reduced wind speeds and the torsional vibration amplitudes. The variation of the RMS coefficients in the along-wind direction results mainly from the change of the aerodynamic forces, but sometimes from aeroelastic effects induced by torsional vibration. However, the variations of the RMS coefficients in the across-wind and torsional directions are caused by more equal weights of both the aerodynamic forces and the aeroelastic effects. As such, for the typical tall buildings, the modification of the aerodynamic forces in the along-wind, across-wind, and torsional directions, respectively, and the aeroelastic effects in the across-wind and torsional directions should be considered. It is identified that the torsional vibration amplitudes and the reduced wind speeds are two significant parameters for the aerodynamic forces on the structures in the three directions.

아웃리거 댐퍼시스템의 감쇠와 강성 변화에 따른 지진응답제어 성능평가

In recent years, an outrigger damper system has been proposed to reduce dynamic responses of tall buildings. However, a study on outrigger damper system is still in its early stages. In this study, time history analysis was performed to investigate the dynamic response control performance of outrigger damper. To do this, a actual scale 3-dimensional tall building model with outrigger damper system has been developed. El Centro earthquake was applied as an earthquake excitation. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. Analysis results, on the top floor displacement response to the earthquake load, was greatly effected by damping value. And acceleration response greatly was effected by stiffness value of damper system. Therefore, it is necessary to select that proper stiffness and damping values of the outrigger damper system.

Accounting for soil nonlinearity in three-dimensional seismic structure-soilstructure-interaction analyses of adjacent tall buildings structures

The interactive effects of adjacent buildings on their seismic performance are not frequently considered in seismic design. The adjacent buildings, however, are interrelated through the soil during seismic ground motions. The seismic energy is redistributed in the neighboring buildings through multiple structure-soil-structure interactions (SSSI). For example, in an area congested with many nearby tall and/or heavy buildings, accounting for the proximity effects of the adjacent buildings is very important. To solve the problem of SSSI successfully, researchers indicate two main research areas where need the most attention: 1) accounting for soil nonlinearity in an efficient way, and 2) spatial analysis of full 3D soil-structure models. In the present study, three-dimensional finite element models of tall buildings on different flexible foundation soils are used to evaluate the extent of cross interaction of adjacent buildings. Soil nonlinearity under cyclic loading is accounted for by Equivalent Linear Method (ELM) as to conduct large parametric studies in the field of seismic soil-structure interaction, the application of ELM is preferred over other alternatives (such as application of complicated constitutive soil models) due to the efficiency and reliability of its results. 15 and 30 story steel structures with pile foundations on two sandy and clayey sites are designed according to modern codes and then subjected to several actual earthquake records scaled to represent the seismicity of the building sites. Results show the cross interaction of adjacent buildings on flexible soils, depending on their proximity, increases dynamic displacements of buildings and reduces their base shears.

Interference effects on aerodynamic wind forces between two buildings

Wind-induced interference effects on overall wind loads and local wind loads on two buildings were studied in a series of the wind tunnel test on typical tall building models using a pressure measurement technique. In this study, five types of adjacent building models were considered with height ratios (Hr=0.5, 0.7, 1, 1.5 and 2) and wind directions were considered from 0° to 355° in 5° steps. Aerodynamic interference effects on base moments and local wind forces along nine height levels of the principal building are presented and discussed. As a result, interference effects (MIFMD and RIFMD) on along-wind base moment coefficients with Hr=1 and 1.5 significantly increased when the interfering building was close to the principal building. Moreover, when a higher interfering building was located at (X/B, Y/B)=(1.5, 1), mean wind loads and fluctuating wind loads in the along-wind and across-wind directions simultaneously increased. Mean and RMS along-wind local force coefficients at z/H=0.975 were significantly increased when the interfering building was located at (X/B, Y/B)=(1.5, 0). Variations of along-wind and across-wind local force coefficients along the height levels depended on the locations and height ratios of the interfering building.

THE SEISMIC PERFORMANCE OF THE FRAME-SHEAR WALL TALL BUILDING WITH AND WITHOUT VERTICAL SETBACK

Recently, High-rise buildings are developed very quickly to satisfy the production and peoples’ living needs and development. There are so many reasons for large number of developments of the high- rise building, commercialization, industrialization and urbanization. This quick development of the high-rise building necessitates study and analysis of the seismic performance of highrise buildings, especially when the high-rise building has irregularity in its horizontal plan or vertical section. In this present study, main focus to analyze the relative earthquake performance for the tower portion of a 34 storey Reinforced Concrete (RC) with 103.4m total height frame-shear wall buildings with and without setbacks subjected to an earthquake excitation scaled down to be of peak ground acceleration appropriate for China, and analyze the setback influence on this high-rise building to identify weakness positions in the high-rise building structure. The comprehensive use of SAP2000 software V16.1 for the elastic calculations aid to assess nonlinear time history analysis for their applicability to tower models (first model with setbacks, second model without setback) of height-rise frame-shear wall building under same conditions of the site category, earthquake acceleration type and standards in structural design. This study is carried out first to judge the shear for the tall building model 1 belongs to which type of the torsion, second to study how the vertical (elevation) setback impact in tall building resisting seismic activity.

Physics-Based Method for the Removal of Spurious Resonant Frequencies in High-Frequency Force Balance Tests

AbstractThe high-frequency force balance (HFFB) test is a widely used method for estimating lateral turbulent wind loads on tall buildings in a wind tunnel. The method relies on use of a highly accurate force sensor placed at the base of the tall building model to measure base forces and overturning moments. Because the turbulent wind load excitation is broadband, it is important to adequately design the connection detail between the model and the sensor. Accurate design is needed to avoid contaminating the measurement of the lateral wind loads by the potential spurious resonant effect, which is induced by flexibility in the connection detail. This design often relies on the experience of the wind tunnel modeler. On occasion, because of the limitations of test setup and environment, the connection detail between the building model and the HFFB force sensor may not be sufficiently stiff. Consequently, resonant response caused by the flexible connection may affect the power spectral density function of the ...

Wavelet-Galerkin analysis to study the coupled dynamic response of a tall building against transient wind loads

The wavelet-Galerkin analysis approach is explored for the solution of the stochastic structural dynamic response of a tall building under transient nonstationary winds. The approach is obtained by combining the Galerkin expansion method with basis-functions selected from discrete orthonormal wavelets (namely, the compactly supported Daubechies wavelets). The expansion transforms the stochastic dynamic problem of the tall building, subjected to time-dependent turbulent-induced forces and motion-induced forces, into a system of random algebraic equations in the domain of the wavelet coefficients. A reduced-order model of a benchmark tall building is employed as a numerical example. Nonstationary wind time histories, simulating the loading of a downburst, are artificially generated at discrete points along the vertical axis of the building by using the notions of evolutionary power spectral density of the turbulence and time-dependent amplitude modulation function. Important aspects such as the treatment of boundary conditions are examined. The paper also aims at investigating the influence of the order of the wavelets and the wavelet resolution on the numerical accuracy of the building response. Even though the primary purpose of the study is to examine the feasibility of the proposed analysis method for studying the transient stochastic response of the tall building, a “frozen” thunderstorm downburst model (a first approximation of a slowly-varying time-dependent wind velocity profile with constant wind direction and negligible thunderstorm translation velocity) is also employed. Two time-independent synoptic wind velocity profiles (power-law models) and one non-synoptic downburst wind velocity profile (“Vicroy’s model”) are considered.

POD analysis of crosswind forces on a tall building with square and H-shaped cross sections

The shape of a tall building has significant impact on wind force generation and wind-induced dynamic response. To study the effect of recessed cavities, wind excitations on a wind-tunnel model of an H-section tall building were compared with those on a square-section building model. Characteristics of the fluctuating wind pressures on the side faces of the two tall buildings and their role in the generation of crosswind forces on the buildings were investigated with the space-time statistical tool of proper orthogonal decomposition (POD). This paper also compares the use of different pressure data sets for POD analysis in situations where pressures on two different surfaces are responsible for the generation of a wind force. The first POD mode is found to dominate the generation of crosswind excitation on the buildings.

Evaluation effects of establishment high rise building on urban water infrastructure)) case study: Qazvin city ((

Abstract. In this century establishment of tall buildings is the phenomenon that considered as solution for prevent the uncontrolled horizontal expansion and a way for provision hosing for urban household .Tall buildings in the city can act as a major factor in solving urban hosing problems, if they planned correctly. But this phenomenon if located on incorrect position can face the city with the numerous problems. This problems include traffic tie-ups, fracture in provision of urban infrastructure facilities and equipment that they needed by the resident of the city. Ecological pollution and impose of ecological pressure to the urban district. Final goal of this project is examining effects of establishment tall building on provision urban infrastructure consists of urban water. On this way two model of establishment tall building in the world (Chicago & conservectivism) and their case studies (Poonak site & Palestine site) in the Qazvin city are compared with each other and finally the optimization of each of two model distinct in provision of urban infrastructure facilities.

Reduced-order wavelet-Galerkin solution for the coupled, nonlinear stochastic response of slender buildings in transient winds

A tall building is prone to wind-induced stochastic vibration, originating from complex fluid–structure interaction, dynamic coupling and nonlinear aerodynamic phenomena. The loading induced by extreme wind events, such as “downburst storms”, hurricanes and tornadoes is naturally transient and nonstationary in comparison with the hypothesis of stationary wind loads, used in both structural engineering research and practice. Time-domain integration methods, widely applied for solving nonlinear differential equations, are hardly applicable to the analysis of coupled, nonlinear and stochastic response of tall buildings under transient winds. Therefore, the investigation of alternative and computationally-efficient simulation methods is important. This study employs the wavelet-Galerkin (WG) method to achieve this objective, by examining the stochastic dynamic response of two tall building models subject to stationary and transient wind loads. These are (1) a single-degree-of-freedom equivalent model of a tall structure and (2) a multi-degree-of-freedom reduced-order full building model. Compactly supported Daubechies wavelets are used as orthonormal basis functions in conjunction with the Galerkin projection scheme to decompose and transform the coupled, nonlinear differential equations of the two models into random algebraic equations in the wavelet domain. Methodology, feasibility and applicability of the WG method are investigated in some special cases of stiffness nonlinearity (Duffing type) and damping nonlinearity (Van-der-Pol type) for the single-degree-of-freedom model. For the reduced-order tall building model the WG method is used to solve for dynamic coupling, aerodynamics and transient wind load effects. Computation of “connection coefficients”, effects of boundary conditions, wavelet resolution and wavelet order are examined in order to adequately replicate the dynamic response. Realizations of multivariate stationary and transient wind loads for the building models are digitally simulated in the numerical computations.

Estudio para la optimización de mallas estructurales de acero envolventes de edificios en altura según sus solicitaciones, en base al análisis de sus líneas isostáticas

The aim of the present study is determinate if the steel space grid envelope structures, for tall buildings (framed tube), are more optimal and efficient if their design is based on the isostatic lines of their equivalents structural elements according to their solicitations. In this study, 600 models of tall buildings, for different triangled facades and geometric slenderness, are analyzed. The methodology employed consisted of detecting the wind loads that affects tall buildings applying the Equivalent Static Wind Loads (ESWL) in relation to the wind speed and turbulence result of the roughness terrain and the topographic. However, it was also needed to establish the frequencies and modes of vibration of each structure as well as defining the coefficients of pressure, force and moments produced by the wind. The results conclude that space grids are more efficient if they do adopt the trajectory of the main and dominant load, in this case the wind.

Predicting wind-induced vibrations of high-rise buildings using unsteady CFD and modal analysis

This paper investigates the wind-induced vibration of the CAARC standard tall building model, via unsteady Computational Fluid Dynamics (CFD) and a structural modal analysis. In this numerical procedure, the natural unsteady wind in the atmospheric boundary layer is modeled with an artificial inflow turbulence generation method. Then, the turbulent flow is simulated by the second mode of a Zonal Detached-Eddy Simulation, and a conservative quadrature-projection scheme is adopted to transfer unsteady loads from fluid to structural nodes. The aerodynamic damping that represents the fluid–structure interaction mechanism is determined by empirical functions extracted from wind tunnel experiments. Eventually, the flow solutions and the structural responses in terms of mean and root mean square quantities are compared with experimental measurements, over a wide range of reduced velocities. The significance of turbulent inflow conditions and aeroelastic effects is highlighted. The current methodology provides predictions of good accuracy and can be considered as a preliminary design tool to evaluate the unsteady wind effects on tall buildings.