Simulation Of Wind Loads Research Articles

Characterizing lower tail components of multivariate non-Gaussian wind loads under typhoon climate: using the Huang-Cui triangular pulse function model

Wind loads at the edge and corner areas of the roof surface of low-rise buildings under extreme winds exhibit intensive non-Gaussianity, especially a high degree of negative skewness. The cumulative effect of negative wind loads below a specific threshold u0 in the time domain is the direct cause of structure destruction under extreme winds. Therefore, this study proposes a triangular pulse function model to quantitatively characterize lower tail components of wind loads with negative skewness via equal cumulative integral on time. In this model, the two critical factors are the intensity for the absolute value of the threshold u0 and the minimum continuous duration T0. Additionally, this article investigates the dependence structures of the lower tail components from multivariate wind loads, and their values vary from 0.65 to 0.80 at quantiles (0.25,0.25). In characterizing the peak locations, a position function combining Poisson pulses and periodic pulses is established, and the period T for generating periodic pulses is a constant. Through analysis, the median value of storm lengths varies from 7.0 to 8.5, and 95% are in the interval (5.0, 15.0). Finally, an example is given to illustrate the effectiveness of the continuous integral by the proposed model. For wind loads measured from different locations, the dependence of pulse locations, lower tail storm length, and intensity are investigated comprehensively. In the end, a physical perspective to understand the generation mechanism of lower tail storms is provided via the fractal dimension. The proposed model and analyzed results are of significant engineering guidance value in time-domain numerical simulation of multi-point synchronous non-Gaussian wind loads to improve simulation accuracy.

Wind load simulation for the analysis of the antenna dual-purpose poles aerodynamics

Introduction. In addition to the location of cellular communication equipment, dual-purpose poles perform the function of a lighting pole. Since dual-purpose pole are located on the central streets of the city, they have strength margins and minimum dimensions. The growing number of urban dual-purpose poles makes the correct calculation very relevant for ensuring their safe operation.Aim. Analysis of the change in the wind load on the dual-purpose pole with panel antennas and its effect on the strength of the dual-purpose pole structure. In order to achieve this, the following tasks were formulated: to deter-mine the dependence of the aerodynamic coefficient and the magnitude of the wind load on the dimensions of panel antennas and their location; to formulate recommendations for the installation of panel antennas on the upper dual-purpose pole section with a diameter of 114 mm.Materials and methods. An analysis of changes in the wind load and aerodynamic coefficient of the dual-purpose pole section, 114 mm in diameter, with panel antennas, installed thereon, depending on the dimensions of antennas and their location.Results. The aerodynamic coefficient was established to decrease at an increase in the projection of the panel antennas beyond the pipe rack, regardless of their dimensions. The more the panel antennas are pressed against the pipe rack, the closer they are to the neighboring antennas, thereby making it difficult to blow the cross-section in the center. Despite the fact that the aerodynamic coefficient decreases with an increase in the projection beyond the pipe rack, the value of the wind load remains almost constant.Conclusions. Panel antennas on a pipe rack with a diameter of 114 mm must be designed taking into account the cross-section dimensions of panel antennas. If the panel antenna width and thickness exceed 350 and 150 mm, respectively, the installation of such panel antennas should be as close as possible to the considered pipe rack in order to reduce the wind load on the dual-purpose pole. In other cases, the projection of panel antennas will have no significant effect on the change in the wind load.

A new probability-distribution scale synthetic eddy method for large eddy simulation of wind loads

The accurate generation of inflow turbulence in large eddy simulation (LES) plays a crucial role in assessing the wind loads on buildings. To faithfully recreate turbulent flow fields, the inflow turbulence must accurately replicate vortex structures. In this study, we propose a novel method for generating turbulent inflow called the probability-distribution scale synthetic eddy method (PDSSEM). PDSSEM utilizes a random generation of eddy positions, with the length of each eddy scale determined by its probability density function (PDF). This approach ensures that PDSSEM maintains consistency in the mean wind speed profile, turbulence integral length, turbulence intensity profile, and wind speed spectra of the atmospheric boundary layer (ABL). The PDSSEM method can be more easily applied compared with multi-scale synthetic eddy method (MSSEM), making it highly versatile and adaptable. The self-sustaining characteristics of the flow field generated by PDSSEM are validated, revealing abundant vortex structures and good agreement with targeted values for turbulence flow characteristics. Furthermore, comparing the wind pressures of a tall building with the experimental data, the accuracy and feasibility of PDSSEM are comprehensively demonstrated. Thus, it indicates the great potential of the proposed method for broader computational wind engineering applications, including wind load evaluation and flow pattern investigation.

Computational Simulation of Wind Loads on Three Curved Eave Models with Different Height-Width Relationships

This work deals with the effects of wind loads on two industrial shed models with curved eaves aspect of different height-to-width ratios. Using Ansys Workbench software, the external pressure coefficients for the entire roof by applying refinement levels were determined. Also were studied the quality of the unstructured and tetrahedral grid according to recommendations to ensure greater efficiency in the simulation results. The results generated provided evidence that the wind in the transverse direction is more damaging in the windward region: for a wind at 45º the most critical region appeared both windward and leeward in the model with a ratio of h/b=0.5 (Model 1) and to windward in the models with a ratio of h/b=1 (Model 2) and h/b=1.5 (Model 3). The leeward suctions increased due to the reduction in the height-width ratio considering a wind direction of 45º. The increase in this ratio intensified the values of the external pressure coefficients in the windward region for the 90º wind direction.

CFD simulation of wind loads of kilometer‐scale super tall buildings with typical configurations in veering wind field

SummaryThe atmospheric boundary layer (ABL), whose total height is about 1–1.5 km, is composed of the atmospheric surface layer (ASL) and the Ekman layer, which typically account for the lower 10% and the upper 90% of the ABL, respectively. The wind veering angle in the Ekman layer can be between 10° and 30°, which may be an important influence factor for the wind‐resistant design of kilometer‐scale super‐tall buildings. Unfortunately, there is very little research on this issue so far due to the difficulty in simulations of veering wind in wind tunnels and computational fluid dynamics (CFD) simulation platforms. In this study, the simulations of non‐veering and veering wind fields are presented, and furthermore, the wind loads of kilometer‐scale super tall buildings with several typical configurations in veering wind fields are numerically investigated. Specifically, the large eddy simulations (LES) of unsteady flow around three buildings, namely, a square building, a tapered building (tapering ratio: 6.6%), and a 4‐layer setback building with the same height and the same aspect ratio of 9:1, are systematically performed for the cases of veering wind and non‐veering wind. The wind pressures and wind forces on these buildings are obtained and comprehensively analyzed. The differences in the wind loads among the building configurations are highlighted, and the mechanisms are discussed based on the time‐averaged and instantaneous flow fields.

Uncertainty Quantification and Simulation of Wind-Tunnel-Informed Stochastic Wind Loads

The simulation of stochastic wind loads is necessary for many applications in wind engineering. The proper-orthogonal-decomposition-(POD)-based spectral representation method is a popular approach used for this purpose, due to its computational efficiency. For general wind directions and building configurations, the data-informed POD-based stochastic model is an alternative that uses wind-tunnel-smoothed auto- and cross-spectral density as input, to calibrate the eigenvalues and eigenvectors of the target load process. Even though this method is straightforward and presents advantages, compared to using empirical target auto- and cross-spectral density, the limitations and errors associated with this model have not been investigated. To this end, an extensive experimental study on a rectangular building model considering multiple wind directions and configurations was conducted, to allow the quantification of uncertainty related to the use of short-duration wind tunnel records for calibration and validation of the data-informed POD-based stochastic model. The results demonstrate that the data-informed model can efficiently simulate stochastic wind loads with negligible model errors, while the errors associated with calibration to short-duration wind tunnel data can be important.

Development of software based on spectral characteristics for wind load

A method is proposed for processing data from experimental or numerical simulation of wind loads and impacts in order to obtain spectral characteristics, which will make it possible to more correctly calculate the response of a structure, in particular, take into account the resonant and turbulent components that affect the stress-strain state of structures. In the Python programming language, the WIND SPECTRUM software module was written, designed to process simulation data based on spectral characteristics, which implements the developed technique. Examples of processing the wind effect obtained from the results of numerical simulation in the ANSYS CFX software package are also given.

Large-eddy simulation of wind loads on a roof-mounted cube: application for interpolation of experimental aerodynamic data

Failure of roof-mounted equipment in extreme wind events such as hurricanes is a significant contributor to wind-related property loss. Proper understanding of the nature and magnitude of wind-induced loads on these structures is essential to ensure their safety during severe storm conditions. Previous studies showed that wind loads on roof-mounted equipment vary significantly depending on the shape, size, location, and elevation relative to the roof surface. In this study, using large-eddy simulation (LES), wind loads on cube-shaped equipment mounted on the roof of a low-rise building are investigated to study the effect of equipment elevation on the wind loads aiming to complement existing experimental aerodynamic data. The accuracy and reliability of the LES results are assessed stage by stage. First, the characteristics of the incident wind profiles reported in the experimental study are reproduced in LES. Then, surface pressure distribution and force coefficients found from the LES are validated against the experimental aerodynamic data for selected representative cases. Finally, the variations of peak drag and uplift force coefficients with different equipment elevations are investigated in detail with the help of the flow field acquired from the LES near the rooftop equipment. The results from the current work show that the peak uplift force coefficients are significantly reduced for elevated equipment. However, considering all the cases studied, the peak drag force coefficients remain relatively unchanged with equipment elevation.

Evaluation of wind loads on high-rise buildings at various angles of attack by wall-modeled large-eddy simulation

This study is to validate the accuracy of large-eddy simulation (LES) of wind pressures and loads on high-rise buildings at various angles of attack based on approaching flow simulation framework with synthetized inflow turbulence. The wake flow field and pressure distribution on building surfaces are quite different at different angles of attack due to sensitivity of flow phenomena (separation, vortex, wake effects, etc.). To better capture such complex flow features around the building, local octree mesh refinement is proposed as an efficient meshing strategy to improve the simulation of wind loads statistics with acceptable additional computational cost. Its accuracy is demonstrated by comparing the simulation results from progressive levels of mesh refinement with experimental data. It is shown that octree mesh refinement can improve the prediction of skewness and kurtosis of wind pressures, which are important for the prediction of peak pressures. Moment-based Hermite model approach is introduced for better assessment of probability distribution of peak pressures from short duration of simulation samples.

Numerical simulation of wind loads and aerodynamic characteristics of streamlined bridge decks under tornado-like vortices

This paper mainly investigates interactions between a tornado and a streamlined single-box bridge deck using large-eddy simulation (LES). Simulation is carried out with respect to an ISU-type tornado vortex simulator with an embedded bridge deck model. Aerodynamic loading characteristics of the bridge deck are compared with available experimental data, in forms of surface pressure coefficients as well as sectional aerodynamic load coefficients. The presence of the bridge deck as well as the horizontal distance from tornado center to bridge deck are then taken into account to reveal the interference of the bridge deck with the tornado flow field. It is shown that the numerical results fit well with the experimental data in most cases, while discrepancies recorded in some cases are potentially due to the limitations of experimental measurement and uncontrollability of flow field similitude. The presence of the bridge deck would destroy the vortex structure generated in an empty simulator and form two new flow regimes with distinct vortex structures above and below the deck. The effects of the variation of spatial relationship between the bridge deck and the tornado-like vortices on two newly formed flow regimes appear to be different, and the difference between the pressure deficits of these two flow regimes result in discrepancies between the surface pressures on the upper and lower surfaces of the bridge deck. The angle of attack and the magnitude of velocity of incoming wind flows are determined for the further purpose of simple parameterization of tornadic effects on bridge decks, and both seem to be influenced by the presence of the bridge deck.

Practical Approach to Digitally Simulate Nonsynoptic Wind Velocity Profiles and Its Implications on the Response of Monopole Towers

AbstractIn the numerical simulation of stochastic nonstationary wind loads, rapidly varying wind speed fluctuations about a deterministic mean value typically represent the sole source of random va...

A high-efficiency simulation method of wind field and its application on transmission line

Generally, the fluctuating wind is simplified as several independent one-dimensional multivariate stationary Gaussian processes in simulating a natural wind field. The correlation in the lateral, longitudinal and vertical directions should all be considered in the simulation of longitudinal wind field for the large-span spatial structures. In fact, this type of structure has lots of simulation points. The calculation amount of wind field simulation by the harmonic superposition method depends on the scale of cross-spectral density matrix, which is directly related to the number of simulated points, leading to a low efficiency when generating the time-varying wind speed. This paper innovatively proposes a high-efficiency simulation method for the longitudinal wind field based on Taylor's hypothesis. Subsequently, the effectiveness of the proposed wind field method was verified by the numerical simulation. Finally, the dynamic responses of a transmission tower-line system under the wind loadings generated with the new method and traditional method are calculated and compared. The percentages difference of the mean and maximum axial force at the main tower members are less than 0.02% and 1%, respectively, indicating the effectiveness of the proposed time delay method. The results also show that the proposed simulation method of wind field can not only ensure the simulation accuracy, but also significantly improve the efficiency of wind speed generation, which is suitable for the wind load simulation of large-span spatial structures.

Wind Load Electrically Controlled Automatic Assembly through Computer BIM Model

In recent years, many Chinese construction enterprises began to use building information modeling technology (hereinafter referred to as BIM). This is a global trend designed to maximize automation and speed up the design process and document approval. This paper presents the key advantages of the BIM approach and discusses the possibility of using digital building models for wind load simulation (the automation of this process) to expand the "profit margin". At present, it is possible to automate application-based wind impact analysis methods. Possible application scenarios are listed and the advantages of wind load automatic assembly are described. At the same time, a possible method for load analysis in BIM design process is proposed.

Flaw Resistance and Mode - I Fracture Energy Redistribution in Bamboo - A Correlation

Bamboo is a unidirectional fibre-reinforced composite with radially graded and almost transversely isotropic elastic properties. The cracks originated in bamboo under bending due to wind loads propagate along the fibre direction. This process is controlled by interlaminar fracture toughness. In order to observe the spatial distribution of the fracture toughness in bamboo, energy release rate is theoretically deduced from the general equations for crack-tip stress fields in anisotropic bodies. The analysis shows that the fracture toughness has graded distribution and the trend is opposite to that of axial modulus. To verify this, the energy release rate (or fracture toughness) is experimentally calculated for double cantilever beam specimens (with a crack placed in different fibre density region) in mode-I i.e. crack opening mode. It is observed that the crack propagation parallel to fibres (splitting) develops easily and the energy release rate decreases with increased density of fibre bundles. The observed trend closely corroborates the results from theoretical analysis. From the results of real-time wind load simulations (reported elsewhere) on tapered bamboo-like structure it is concluded that with the help of radially graded fracture toughness bamboo converts flaws of all orientations into splitting mode.

Multidisciplinary design optimization for sustainable design using building information modeling

This paper illustrates the application of computational design using Rhinoceros software and Grasshopper plugin to investigate a real accommodation with respect to the solar radiation reduction. The paper also introduces the basic concepts of Building Information Modelling (BIM) utilization in construction. The multidisciplinary BIM model show that the Computable BIM Model can be used for Architecture, Structure, Mechanical - Electrical -Plumbing (MEP) to help architects, designers do sustainable design such as acoustic comfort, lighting design on effective cost manner with many rapid design options from the conceptual design phase, to facilitate wind load simulation, predict structural behaviour under fierce conditions, to estimate heat load, HVAC systems performance for energy saving and sustainable design.

Numerical simulation of wind loads on an offshore PV panel: the effect of wave angle

ABSTRACTThis numerical simulation determines the wind loads on a stand-alone solar panel in a marine environment. The initial angle of tilt is 20° and 40° and the wind is incident at an angle of 0–180° (in increments of 45°). The wave angle affects the motion of a pontoon. For a wave angle of 0–180° (in increments of 45°), the variation in the surface pressure pattern and the lift coefficient with the angle of incidence of wind and waves in a single period is determined. The lift force is determined by competing the tilt angle for the upper surface with respect to wind and variation in roll angle for a specific wave angle. The data are pertinent to structural design for photovoltaic systems in a marine environment.

Automatic assembly of wind load from BIM-model

In recent years many Russian construction companies have started using technologies of building information modelling (hereinafter – BIM). It’s a global trend aimed at maximum automation and acceleration of a design process and documentation approval. This article shows main advantages of the BIM approach, discusses the possibility of expanding “the space of benefits” by using digital building models for wind load simulation (automatization of this process). Currently, applied methods of wind impact analysis based on which automation is possible are described. Potential application scenarios, describing the advantages of automatic wind load assembly, are listed. Also, possible approach to the analysis of loads in process of BIM-design is shown.

Estimation of full-scale ship manoeuvrability in adverse weather using free-running model test

The ship manoeuvrability in actual seas with both wind and waves, especially in adverse weather conditions, for a full-scale tanker with different maximum available power of the engine is studied. It is directly evaluated based on the result of a free-running model test (FRMT) under a course-keeping manoeuvre in long-crested and short-crested irregular waves of Beaufort scale force (BF) 7–10. The FRMT combines rudder effectiveness and speed correction considering the operational limit of an engine, and a wind load simulator, both of which were previously proposed by the authors. Therefore, not only the effect of waves but also effect of wind, rudder effectiveness of the full-scale ship, and the engine limit for continuous operation are considered in the FRMT. To validate the reliability of the direct evaluation method in FRMT and the measured data in irregular waves of large amplitude, the time-averaged manoeuvring motion of the FRMT at BF 9 is compared with ship manoeuvring motion under steady equilibrium conditions estimated using numerical simulation based on a modular mathematical model. The wave drift forces and moment in the simulation are determined on the basis of the results of the captive model test in regular waves, which is carried out using the same tanker model before the FRMT, so that we can eliminate the estimation errors in the manoeuvring motion caused by the imprecision in the wave drift forces as much as possible. The comparison shows the FRMT results acceptably agree with the simulation results, although a discrepancy is observed in the rudder angle in beam seas for the tanker with a low engine output. Further, FRMT data themselves show that full-scale rudder effectiveness, operational limit of an engine, and the engine with lower power cause the ship speed to decrease and the drift angle and the rudder angle to increase in head, bow, or beam seas because of the difference in the propeller rotational speed in each model control condition. In addition, it was clarified that operational limit of an engine also affects the significant single amplitudes of the fluctuating components of them and the oscillatory ship motion. Next, the authors assess the manoeuvring limit in adverse weather by comparing the FRMT data of the time-averaged values of the longitudinal ship speed, as well as the drift and rudder angles in short-crested irregular waves at BF 7–10 with their thresholds. The assessment clarifies that the tanker becomes unmanoeuvrable at BF 9–10 and in head, bow, or beam seas owing to a lack of sufficient advancing speed. However, the limit is not attributable to the drift or rudder angle, although the lower-power engine worsens the course-keeping ability owing to the decrease in the ship speed and the increase in the drift and rudder angles. Furthermore, the tanker is manoeuvrable in any wind and waves directions at BF 8, which is defined as adverse weather conditions for this subject ship in the interim guideline (IMO, 2013). It indicates that the tanker has sufficient margin of the engine power to keep manoeuvrability in adverse weather conditions. In summary, these findings reflect the possibility that FRMT can replace numerical simulation as a direct evaluation method of full-scale ship manoeuvring motion and limits in adverse weather.

Research on Windage Yaw Flashovers of Transmission Lines under Wind and Rain Conditions

Windage yaw flashovers under strong wind and rain conditions leave a negative impact on the safe operation of transmission lines. However, the mechanism behind this is not well known yet. Therefore, this paper proposes a systematic method, including three basic parts described as simulation of wind and rain loads, calculation of windage yaw, and flashover analysis, to analyze windage yaw flashovers of transmission lines. The YanMeng-particle swarm optimization (YanMeng-PSO) algorithm is proposed to enhance the simulation accuracy. Unlike the conventional approach, the windage yaw status of conductors and insulator strings is dynamically described with key nodes and the breakdown voltage of their clearances rather than windage yaw angle. Furthermore, in the second part, a new method named key-node method (KNM) is proposed to calculate the conductors’ windage yaw. Moreover, the rain effect is also considered in this paper. This paper then presents a case study on a 110 kV double-circuit transmission line section that suffered severe collapse when the typhoon Rammasun landed in Hainan island. Particular focus was placed on the windage yaw flashover before the structural failure of the transmission line. The results validated the significant rain effect and found that conductors/ground suffer more severe windage yaw flashover than insulator strings. Finally, constructive solutions such as interphase spacers, reasonable conductor arrangement in the design phase, and regular measurements and adjustments of conductor sag in the maintenance phase are proposed to improve the design of transmission lines to enhance their capacity against windage yaw flashovers.

Structural Analysis of Large-Scale Vertical-Axis Wind Turbines, Part I: Wind Load Simulation

When compared with horizontal-axis wind turbines, vertical-axis wind turbines (VAWTs) have the primary advantages of insensitivity to wind direction and turbulent wind, simple structural configuration, less fatigue loading, and easy maintenance. In recent years, large-scale VAWTs have attracted considerable attention. Wind loads on a VAWT must be determined prior to structural analyses. However, traditional blade element momentum theory cannot consider the effects of turbulence and other structural components. Moreover, a large VAWT cannot simply be regarded as a planar structure, and 3D computational fluid dynamics (CFD) simulation is computationally prohibitive. In this regard, a practical wind load simulation method for VAWTs based on the strip analysis method and 2D shear stress transport (SST) k-ω model is proposed. A comparison shows that the wind pressure and aerodynamic forces simulated by the 2D SST k-ω model match well with those obtained by 2.5D large eddy simulation (LES). The influences of mean wind speed profile, turbulence, and interaction of all structural components are considered. A large straight-bladed VAWT is taken as a case study. Wind loads obtained in this study will be applied to the fatigue and ultimate strength analyses of the VAWT in the companion paper.