Standard Tall Building Research Articles

Effects of turbulence integral scale on the fluctuating pressures on side face of the standard tall building model

Effects of turbulence integral scale on the fluctuating pressures on side face of the standard tall building model

Nonlinear dynamic analysis of wind pressure variability on standard tall building

Understanding the variability of wind pressure on tall building surfaces is of essential importance regarding the control of wind-induced response. In this study, advanced time series analysis techniques, e.g., phase space reconstruction and recurrence analysis, were applied to diagnose the wind pressure variability from a nonlinear dynamic perspective. It is shown that, the wind pressure acting on tall building surfaces exhibit distinct chaotic nature. Due to the complex flow patterns around the building, the underlying dynamics of wind pressure is subject to pronounced region-to-region variability. For windward surface, the wind pressure dynamics at the stagnation region is more deterministic than those of downstream. For the side surfaces, the distribution of recurrence quantification analysis (RQA) indicators follows a clear pattern, where the values are larger at the near-front edge, and decreases towards the rear. The distribution of RQA indicators on the leeward surface is opposite to that of windward surface, in which larger values occur more often at near-ground level. Further upstream, the values are found to decrease. The outcomes provide valuable insights to the wind-structural interaction, thus could help wind-resistant design.

Aerodynamic loads of tapered tall buildings: Insights from wind tunnel test and CFD

Tapered modifications have been widely utilized for tall buildings to reduce their wind effects in practical engineering. However, the flow mechanisms caused by tapering and relevant empirical models for wind loads estimations of tapered tall buildings are still unknown. In this study, both wind tunnel test and CFD were used to study the aerodynamic performance of tapered tall buildings. Taken the CAARC standard tall building model as the benchmark model, another four modified models with taper ratio of 0.05, 0.10, 0.15 and 0.20 were designed and tested by pressure measurements and large eddy simulation (LES). The variations of wind pressure coefficients, local wind force coefficients, base moment coefficients, wind load power spectrum and vertical coherence function of five models with different taper ratios were discussed and compared. Also, the streamline of mean and fluctuating velocity around tapered tall building models are provided for better understanding of the flow mechanisms. The results showed that aerodynamic performance of the tapered tall buildings has been improved effectively, especial for across-wind effects. This study aims to provide reference for aerodynamic optimization design of tapered tall buildings.

Characterizing wind pressure on CAARC standard tall building with various façade appurtenances: An experimental study

Tall buildings are usually considered as wind-sensitive structures. While extensive studies have been conducted concerning the wind load characteristics on tall buildings, the effect of façade appurtenances has not been fully understood. In this study, a 1:300 scaled CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building was tested in wind tunnel to diagnose the effect of various façade appurtenances on wind pressure characteristics. It is shown that, the change of façade appurtenances can significantly influence the fluctuating wind pressure on the windward and leeward surfaces, with the maximum reduction reaching 21%. By contrast, the effect of façade appurtenance on mean wind pressure is somewhat less pronounced. The results also indicated that adding vertical strips is likely to reduce the horizontal coherence of surface wind pressure, with the maximum reduction of horizontal coherence coefficient reaching 38%. Comparatively, the effect of façade appurtenance on vertical coherence is less significant.

Machine learning based algorithms for wind pressure prediction of high-rise buildings

In recent years, machine learning (ML) techniques have been used in various fields of engineering practice. In order to evaluate the feasibility of machine learning algorithms for prediction of wind-induced effects on high-rise buildings, four ML algorithms including ridge regression, decision tree, random forest and gradient boosting regression tree are adopted in this study to predict wind pressures on Commonwealth Advisory Aeronautical Research Council standard tall building. The gradient boosting regression tree model is proved to be well performed in predicting both mean wind pressures and fluctuating wind pressures. Compared to expensive wind tunnel tests and time-consuming computational fluid dynamic simulations, it is expected that the gradient boosting regression tree model is an efficient and economical alternative for predicting wind pressures on high-rise buildings.

Numerical-experimental study of neighboring wind effects on tall buildings related to serviceability via reliability

abstract: In this paper a reliability analysis was carried out, regarding the dynamic responses of displacements and accelerations in the x and y directions at the top of CAARC standard tall building, determined by the numerical-experimental High Frequency Pressure Integration technique (HFPI). The building was studied on distinct angles, subjected to dynamic wind load, isolated and with the presence of different neighbors. Tendency curves and its equations for reliability indices and maximum responses, in relation to the directions adopted to the CAARC, were presented. With the results found, it was noticed that the existence of neighborhood affects the responses of maximums and the reliability indexes, both for increase and decrease compared to the isolated building, depending on the situation and the type of dynamic response.

Reduction of wind loads on rectangular tall buildings with different taper ratios

To explore the influence of different taper ratios on wind loads reduction on rectangular tall buildings, the CAARC standard tall building model is selected as the benchmark model and four other rigid models with different taper ratios ranging from 5% to 20% are tested for pressure measurement in a boundary layer wind tunnel. Based on the test results, the distribution of wind pressure coefficients, local wind force coefficients, base moment coefficients and their power spectral densities from the five models are compared and discussed. Moreover, correlation factors for base moment coefficients and their power spectral densities concerning the effects of different taper ratios are provided. It has been proved that the aerodynamic performance of the rectangular tall building has been improved by the increasing of taper ratio. This study aims to provide useful information for the wind-resistant design of rectangular tall buildings.

Influence of Small Vehicle on Transiting Test Method for Measuring Building Wind Pressure Coefficients

The transiting test method is a new approach for structural wind resistance research. However, traffic on the test road inevitably influences test results. In this study, the symmetrical CAARC standard tall building model was used to investigate the influence of a small vehicle near the test vehicle. A small vehicle was set up as an interference vehicle to drive around the test vehicle under different cases during the test. Results indicate that the mean wind pressure coefficient during the overtaking period is higher than that during the no overtaking period. The enlarged relative velocity and the small test vehicle velocity increase the overtaking interference and the data calculation time required to eliminate the overtaking influence. The overtaking influence only occurs if the test vehicle is overtaken by the small vehicle in the adjacent lane. The influence of the overtaking behavior of a small vehicle can be eliminated after the data calculation time exceeds 26 s. Moreover, the wake of small interference vehicle no longer influences the transiting test results after the spacing reaches 24 m.

HFBB model test for tall buildings: A comparative benchmark with a full-aeroelastic model

A novel approach to full-aeroelastic model design is presented, considering continuous structures and coupled modes. Its validity is proven by building a full-aeroelastic CAARC standard tall building model featuring 12-degrees-of-freedom at 1:360 scale. A complete description of its design, manufacturing, tuning, and dynamic identification is reported. The model is tested in a novel wind-tunnel experimental campaign performed at the CRIACIV facility (Prato, Italy). A comparative study of aerodynamic and full-aeroelastic response in terms of base moment and accelerations shows that the aerodynamic model tends to overpredict the response along the broader side of the model. The contribution of second modes is found to be relevant for induced acceleration at the rooftop.

Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications

This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.

Layered Stochastic Approximation Monte-Carlo method for tall building and tower fragility in mixed wind load climates

Performance-based wind engineering has emerged as an active research field due to potential applications into design standards [e.g., by the American Society of Civil Engineers (ASCE) in the United States of America]. Therefore, novel and accurate methodologies are necessary to successfully implement practice-oriented guidelines. This study will systematically examine the use of the Layered Stochastic-Approximation Monte-Carlo method, recently explored to assess of wind-induced structural dynamic analysis of vertical structures. The study will utilize a standard tall building and a monopole tower structure to investigate maximum response in terms of lateral displacement and acceleration, and the behavior of a structural member in terms of demand-to-capacity index. Both serviceability and ultimate limit states will be considered. The proposed method will be verified against standard Monte-Carlo sampling to assess its adequacy, accuracy and potential limitations. Particular consideration will be devoted to the study of wind loads and response in mixed wind climates, characterized by the presence of both tropical cyclones (hurricanes) and extra-tropical depressions.

Numerical investigation of interference effects on the critical wind velocity of tall buildings

The main aim of this study is to evaluate the upstream and downstream interference effect of two CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall buildings using Computational Fluid Dynamics (CFD). To that end, the Large Eddy Simulation (LES) turbulence model is employed for the three-dimensional simulations of turbulent wind flow with Reynolds numbers of 1.4×104<Re<8×104. The aerodynamic response of the principal building in different interference cases is investigated using mean and fluctuating coefficients of lift and drag forces, pressure distribution and Strouhal number. To better understand the involved physics, streamlines and vorticity contours are presented and their relationship with the aerodynamic results is interpreted. In addition, an isolated CAARC standard tall building is considered for comparison with interference cases and to validate our results compared to previous experimental and numerical studies. In contrast with the isolated case, in most of the interference cases, the shielding effect of the interfering building results in a lower mean drag coefficient of the principal building. Also, compared to the isolated building and, depending on the location of the interfering building, the fluctuating lift coefficient either increases or decreases. While the mean pressure coefficient at the windward surface is not significantly sensitive to the interference states, it is strongly influenced by the different states of the interference at the lateral and leeward surfaces. Also, the principal building’s Strouhal numbers for different interference states and different Reynolds numbers are calculated using spectral analysis of lift signals. It is then shown that Strouhal numbers are highly dependent on the location of the interfering building and are inversely related to the width of the wake region. Our results, furthermore, demonstrate that the aerodynamic parameters have little sensitivity to Reynolds number variations in the considered range. Finally, the critical wind velocity corresponding to the aeroelastic instabilities is estimated based on Strouhal numbers and it is shown that upstream interference cases, will increase the critical velocity of the wind, thereby reducing the likelihood of occurrence of aeroelastic instabilities.

The effect of soil–structure interaction on the along-wind response of high-rise buildings

Rapid population growth tends to lead to the construction of tall buildings. It is thus necessary to study the influential parameters on the behaviour of tall structures due to wind action. Soil deformability is one parameter that can affect the aerodynamic behaviour of tall structures. In this work, the impact of wind on the standard tall building of the Commonwealth Advisory Aeronautical Research Council, placed on a raft footing, was numerically modelled using Abaqus software. The wind was defined by a power function in the boundary layer of the atmosphere. Stream turbulence was modelled using the implicit large eddy simulation technique and a co-simulation was used to exchange non-uniform loads from the fluid domain to the structural domain. The mechanical reaction of the footing–soil framework was modelled using a direct strategy. Infinite boundary conditions were added to the numerical model for simulation of free boundaries and appropriate contact elements for sliding and separation between subsurface components were considered. The fluid and structural solutions were compared with the mean and root mean square values of experimental estimations for an extensive range of reduced speeds. Numerical results for the framework with soil–structure interaction (SSI) were compared with those without SSI. The dynamic properties and reactions of the building subjected to wind loading were affected by the SSI and therefore engineers should consider these parameters to guarantee practical designs.

Wind-resistant optimal design of tall buildings based on improved genetic algorithm

Modern tall buildings are likely sensitive to wind excitations due to their increasing height and structural flexibility. Proper or optimal wind-resistant structural design of such high-rise buildings is required or sometimes necessary to meet the requirement of safety and serviceability. Combining a genetic algorithm (GA) with improved penalty function and calculation method for equivalent static wind loads (ESWLs), this paper presents an optimal procedure for the wind-resistant design of tall buildings, which aims to minimize the total weight of the designed building subject to the constraints of top acceleration and lateral drifts. A penalty function is utilized to deal with the implicit expressed constraints of optimization. The ESWLs can be instantaneously updated due to the change of structural dynamic properties during the optimal design process. A 60-story rectangular reinforced concrete frame structure with the same geometric shape of the CAARC standard tall building is adopted to verify the feasibility of the presented method. The example demonstrates that the proposed optimal design procedure is an effective tool for the wind-resistant optimal design of tall buildings.

Aerodynamic performance of CAARC standard tall building model by various corner chamfers

This paper takes CAARC standard tall building as example to investigate the effects of corner chamfers on the aerodynamic performance of tall buildings. Five rigid tall building models including CAARC standard tall building as benchmark model and four corner chamfered models with different modification rates from 5% to 20% are tested for pressure measurements in a boundary layer wind tunnel. Based on the experimental results, wind pressure coefficients, local wind force coefficients, base moment coefficients and their power spectral densities from the five models are compared and discussed. The results show that the aerodynamic performance of the tall building models can be effectively improved as the corner chamfer rate increases. The correlation factors for base moment coefficients and power spectral densities are proposed to assess the aerodynamic performance improvement. This paper aims to provide useful information for the wind-resistant optimal design of rectangular tall buildings.

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.

The Effect of Wind-Soil-Structure Interaction on the Longitudinal Response of High-Rise Buildings

In this work, the modelling of the wind impact on the standard tall building of CAARC (Commonwealth Advisory Aeronautical Council), which is placed on a surface spread footing, is done numerically utilizing the ABAQUS program. The wind is demonstrated as an exponential way in the boundary layer of the atmosphere. Then, stream turbulence is modeled by the ILES technique and a cosimulation is accepted to exchange non-uniform loads from fluid to structural nodes. Damping of the structure is controlled by the Rayleigh strategy. Mechanical reaction of the footing-soil framework is modeled utilizing direct strategy. Infinite boundary conditions have been added to the numerical model for the simulation of free boundaries, and reasonable contact elements for sliding and separating between subsurface components are considered. Finally, fluid solutions and structural reactions are compared with the mean and root mean squares of experimental estimations on an extensive range of reduced speeds. Numerical results for the framework of soil-structure systems were compared with base conditions without association of soil-structure interaction. It is concluded that dynamic properties and reactions of the building influence soil-structure interaction and accordingly the planners should consider these parameters keeping in mind to guarantee the practical designing.

LES evaluation of wind-induced responses for an isolated and a surrounded tall building

Aerodynamic response of a standard tall building (commonly known as the CAARC model) is investigated using LES. The LES employs the Consistent Discrete Random Flow Generation (CDRFG) technique to generate the inflow boundary condition allowing accurate depiction of the turbulence spectra and coherency. The building aerodynamic behavior is investigated for two configurations (an isolated building and a building with complex surrounding buildings) and the results are compared with a previous wind tunnel test. It is found that pressure and other wind-induced responses, such as top displacement, top acceleration and base moments, obtained from the LES are in a good agreement with those in the wind tunnel. The average difference between LES and wind tunnel results is found to be 4% for the pressures and 6% for the dynamic responses for the simulated wind directions, which emphasizes the accuracy of the employed model. As expected, comparison between the results for the isolated and the complex surrounding configuration showed 50% and 40% difference for mean and rms pressure coefficients, respectively. The employed LES model leads to an acceptable estimation for the wind pressure distribution and responses of the study building in a time-efficient manner. Therefore, it is expected to encourage the use of CFD in similar wind engineering applications in the future.

CFD를 이용한 박스형 건물의 풍압분포 분석에 관한 연구

Abstract This paper studies the wind pressure distribution over the Commonwealth Advisory Aeronautical Council buildingmodel (CAARC model) using CFD. We also considered the interaction between the CAARC model and other buildings.The Reynolds number based on the building height was 380,000. The number of sells for the simulation was about 500,000.The wind pressure was lowest when the wind direction was blowing at an angle 45 degrees of the CAARC model. Whenthe gap between the two buildings in front of the CAARC was over 1/2 the horizontal length of the CAARC model, thewind pressure was higher than the pressure without the two buildings. When the distance between the two front buildingsand the CAARC was less than 1.5 times the vertical length of the CAARC model, the wind pressure increased. Accordingly,the relative distance between two buildings or the distance from the CAARC model should be considered when extra windexists due to other buildings. Key words CFD(전산유체역학), Standard tall building(CAARC 모델), Wind pressure(풍압), Building wind(빌딩 풍), Standard k-epsilon turbulence model(표준 k-ϵ 난류 모델)†Corresponding author, E-mail:

Una metodología de cálculo para la determinación de la respuesta dinámica longitudinal de estructuras altas bajo la acción del viento

The optimization of computing methods along with the advance of construction technology of civil structures, allow nowadays to design and build lighter and low stiffness and damping structures, turning them into elements of high sensitivity against wind-induced dynamic effects. The purpose of this work is to describe and to apply a simple calculation methodology that enables the determination of the longitudinal dynamic response of tall buildings in time domain. The wind velocity field is reproduced by velocity series that incorporate the coherence function which then are transformed into fluctuating nodal forces using the quasi-static loading model. Furthermore, to include the effect of imperfect averaging associated with the discretized nodes, the aerodynamic admittance function is added.Through the proposed methodology two structures widely studied by other authors are analyzed: a steel tower and the CAARC Standard Tall Building. The results thus obtained show agreement with those reported in the literature.