Wind Load Model Research Articles

Probabilistic modeling of multivariate extreme non-Gaussian wind loads and its applications in envelope engineering

Probabilistic modeling for non-Gaussian wind load fields under extreme winds is crucial to the quantitative risk and reliability analysis of envelope structures. Based on the multi-point synchronous wind load data during typhoons, a probabilistic model is proposed to characterize multivariate non-Gaussian wind loads to improve the accuracy of the risk analysis considering data dimension reduction. In the proposed model, the Pareto distribution function is utilized to fit the marginal distribution, and the copula function is employed to construct the dependent structure of wind loads from different locations. In the marginal fitted results, the extreme wind load value in the edge region is about 0.10–0.15 higher than those from inner measurement points at quantile p = 95 %. In addition, the variation gradient from the different variable directions is approximately equal, and a sharp variation occurs at the point (0.10, 0.10) for bivariate joint distributions. Engineering applications given in this article are composed of three parts: calculating regional exceeding probability, estimating wind load vector under a specific regional exceeding probability, and determining the location of joint extreme wind loads using the joint gradient value. Finally, risk analysis of existing roof coverings is carried out, the edge corner region is weaker, and two engineering recommendations are given. For determining the regional design wind load, a comprehensive calculation framework considering the temporal dependence of different locations is established, and the reduction rates are in the range (5 %, 25 %).

Heliostat Consortium: Gap Analysis on State of the Art in Wind Load Design

Abstract Wind loads are a major driver of heliostat cost. Standardized methods and tools are needed for a more detailed understanding of the static and dynamic loads of a heliostat design. This will enable cost reduction of wind-dependent heliostats to avoid unnecessarily conservative heliostat designs and increase field efficiency and reliability to reduce the risk of component failures due to high-wind events. Gaps related to wind load include lack of site characterization for wind measurements, insufficient critical load cases for heliostat design, insufficient understanding of turbulence impacts on heliostat tracking error, lack of knowledge on wind load under various heliostat array configurations, and underexplored heliostat field wind-load reduction and operating strategies. Recommended pathway forward is to develop wind load and site characterization guidelines for heliostat design and develop heliostat field wind-load models with optical performance impacts.

Digital twin‐driven online intelligent assessment of wind turbine gearbox

AbstractRemaining useful fatigue life monitoring of wind turbine drivetrains is important. However, the implementation of real‐time monitoring often faces efficiency and accuracy challenges. In order to resolve this, this paper proposes a vibration‐based damage monitoring digital twin (VBDM‐DT) that enables the online intelligent evaluation of wind turbine gearboxes, using gear tooth surface durability as an example fatigue mode. The VBDM‐DT integrates a random wind load model, a high‐fidelity dynamics model, and a fatigue damage model. The random wind load model takes the wind speed from the supervisory control and data acquisition (SCADA) as input to estimate the input torque of the drivetrain in real time. Simultaneously, VBDM‐DT uses the vibration signals from the condition monitoring system (CMS) to intelligently calibrate the dynamics model, allowing it to be continuously adjusted and optimized in response to actual vibrations. The fatigue damage model takes the real‐time dynamic loads estimated by the high‐fidelity dynamic model as input to achieve real‐time fatigue damage monitoring of key components in the wind turbine gearbox. Applying the VBDM‐DT model to a 2 MW wind turbine gearbox, the results indicate that the model provides satisfactory accuracy in estimating input loads and good adaptability in intelligent calibration of the dynamic model. Based on this model, the fatigue life estimation for gears and bearings is more credible and reliable.

Copula-based estimation of directional extreme wind speeds: Application for wind-resistant structural design

Accurate probabilistic modelling of wind loads has important implications to the wind-resistant design of structures. Whereas, most previous studies merely concerned the statistical analysis of wind speed, while the effect of wind direction was usually neglected in the wind load modelling. This paper thereby proposes a novel copula-based approach to construct the joint distribution of wind speed and direction for determining the directional extreme wind speed. Based on the wind records at six typical sites in Hong Kong, a series of parametric and nonparametric copula models are applied to model the joint probability density function (JPDF) of wind speed and direction. The goodness-of-fit test indicates that the Bernstein copula is the best model to describe the correlation between variables. Furthermore, by applying the superior copula model, directional extreme wind speeds with a 10-year return period at the six selected sites are determined on basis of the conditional probability theory. The results show that the estimated extreme wind speeds vary obviously among different directions. And, the estimated directional extreme wind speed may be unreliable in some directions when ignoring the joint effect of wind speed and direction in wind load modelling. Notably, the presented method is an effective and practical tool to estimate the directional extreme wind speed with a certain return period. This paper aims to provide useful reference for the wind-resistant design in tropical cyclone-prone regions.

Wind Load Model and Response Spectra of Overbridges Subjected to Train-Induced Wind Loads

The vibration of pedestrian overbridges due to train-induced wind loads (TIWLs) during the passage of a high-speed train threatens the overbridge safety and causes pedestrian discomfort. To incorporate the structural dynamic magnification effect on overbridges under TIWLs in the design process, a framework to calculate the structural dynamic response, equivalent static TIWLs and response spectra of overbridges is established. A new simplified TIWL model with a “three-segment” wind pressure time history described by harmonic functions is proposed. This model facilitates the acquisition of analytical solutions for the structural dynamic response, streamlining the analysis process. The dynamic response and equivalent static TIWLs based on dynamic magnification factors (DMFs) of overbridges are obtained from the analytical method. The DMFs are primarily affected by the structural natural frequency and the characteristic frequency of TIWLs. Furthermore, based on the analytical solution of the overbridge dynamic response, parametric analysis is performed, and the response spectra representing the dynamic displacement and acceleration of overbridges are developed. The response spectra can be used to quickly calculate the displacement, internal force, and acceleration of the overbridges during engineering applications, which is more convenient but slightly less accurate than the analytical method.

Effect of Distributed Loading and Refined Modeling on Wind-Induced Stress Analysis of Long-Span Bridges

Wind-induced stress analysis is essential for evaluating the local failure and fatigue damage of long-span bridges in wind-prone regions. Nevertheless, the accuracy of stress-level analysis can be affected by the choice of wind loading and structure models. This study formulates three scenarios to calculate the wind-induced response of a long-span bridge, incorporating two types of wind load models (lumped force or distributed force) and two types of finite element (FE) models (spine-beam or substructure). Specifically, Case 1 employs the lumped force and beam model, Case 2 adopts the lumped force and substructure model, and Case 3 utilizes the distributed force and substructure model. The aerodynamic parameters for forces and POD pressure modes are obtained through wind tunnel tests. By comparing the wind-induced structural response in terms of global behavior (displacement, acceleration) and local behavior (stress), the influence of wind loading and structure models is discussed. The findings reveal that employing a simplified beam model underestimates local stress, and neglecting wind load distribution leads to further underestimation. Therefore, the refined FE model and distributed wind load models are recommended for the precise assessment of wind-induced stresses in long-span bridges.

Fault‐tolerant attitude tracking control of tandem rotor helicopter considering internal actuator saturation and external wind gust

SummaryTandem rotor helicopter is configured with two main rotors distributed along the longitudinal direction and without anti‐torque tail rotor. Therefore, the control strategy of tandem rotor helicopter can be quite different from that of traditional helicopter systems. In this article, a fault‐tolerant attitude tracking controller is presented for tandem rotor helicopter, with considerations of external wind disturbance and internal actuator problem. First, attitude control oriented dynamic model of the tandem rotor helicopter is constructed, in which both actuator fault and saturation are involved. Base on statistical characteristics of practical wind condition as well as aerodynamic properties of the helicopter rotors, a detailed wind load model is further established. Then, a fault‐tolerant attitude tracking controller is proposed for the tandem rotor helicopter system by incorporating nonsingular terminal sliding mode control with an adaptive super twisting algorithm, which allows a simultaneous regulation of the three angular motions via two propeller rotors. Finally, based on Quanser's 3‐dof helicopter system, comparative simulation tests are performed to demonstrate the effectiveness as well as advantages of the proposed fault‐tolerant controller design.

The influence of ASCE 7–16 wind load provisions on a vulnerability model of Florida residential construction

The Florida Public Hurricane Loss Model is a probabilistic risk model designed to estimate wind induced insurance losses to residential infrastructure in Florida. In the physical damage estimation module, Monte Carlo simulation is employed to generate damage matrices as a function of wind speed by comparing probabilistic building component capacities to wind loads. These damage matrices are input to a repair cost algorithm, ultimately producing damage ratios as a function of wind speed for different building classes. It is required that the inventory of residential building models reflect the history of construction practice within Florida. Differing eras of construction are represented by developing component-wise options for probabilistic capacities and load paths, resulting in a suite of hundreds of model variants. Regarding loads, the probabilistic wind load model is based on a directionalized adaptation of ASCE 7, and its representation in the model is kept current with the version adopted by the Florida Building Code (FBC). In 2020 the Florida Building Code adopted by reference ASCE 7–16, which contains important changes to the wind-load provisions. These changes have implications for both the loading and resistance aspects of the physical damage model, thus influencing insured loss projections. This study discusses the development and implementation of these changes within the model and investigates the impacts on the modeled vulnerability of residential structures in Florida. Comparing vulnerability estimates of structures designed before and after the FBC adoption of ASCE 7–16 provide insight into the potential effectiveness of such changes to improve community resilience.

Reliability-Based Collapse Assessment of Wind-Excited Steel Structures within Performance-Based Wind Engineering

As inelastic design for wind is embraced by the engineering community, there is an increasing demand for computational tools that enable the investigation of the nonlinear behavior of wind-excited structures and subsequent development of performance criteria. To address this need, a probabilistic collapse assessment framework for steel structures is proposed in this paper. The framework is based on the integration of a high-fidelity fiber-based nonlinear structural modeling environment with a wind-tunnel-informed stochastic wind load model to perform nonlinear time history analysis. General uncertainty is propagated using a stratified sampling scheme enabling the efficient estimation of reliabilities associated with rare events. The adopted models for simulating high-fidelity nonlinear structural behavior were found, in general, to be adequate for capturing phenomena, including progressive yielding, buckling, and low-cycle fatigue, that are essential for wind induced collapse analysis. In particular, the adopted fatigue model was found to be capable of predicting damage and potential fiber/section fracture associated with non–fully reversing stress-strain cycles that are characteristic of wind loading. Through illustration on a 45-story archetype steel building, critical discussions on the types of observed collapse mechanisms, the difference between along-wind and across-wind nonlinear behavior, reliabilities associated with first yield, and collapse are presented. A probabilistic description of the residual and peak story drifts is also provided through development of fragility functions.

Prediction of nonlinear structural response under wind loads using deep learning techniques

The wind actions on buildings are continuous in nature and could range from a few minutes to more than hours. Such long duration high intensity winds can push the structure to enter post elastic structural range and cause nonlinear behavior. Therefore, unlike performance-based earthquake engineering, where the structural simulations require seismic loads acting for a few seconds, the simulations for performance-based wind engineering (PBWE) requires wind load models acting for much longer durations. However, the nonlinear 3D model of a tall building will contain thousands of connections and structural members making it a complex finite element model. Dynamic time history analysis of such a model under loads lasting for hours can be tedious and often fail to achieve convergence. Using data-driven techniques that utilizes limited numerical and field data to obtain accurate structural responses under long duration loads is an exciting alternative. Deep learning techniques have been extensively used in the studies for structural health monitoring and earthquake engineering. However, the implementation of such data-driven techniques is very limited and has the potential for exploration in problems related to wind dynamics on tall buildings. This paper aims to predict the nonlinear structural response of tall buildings under sustained durations of wind loads using deep learning models. A Long Short-term Memory (LSTM) architecture is used to assess the efficiency of data-driven methods to replace computationally intensive 3D finite element analyses. The architecture will be tested on a 150 m tall building for response predictions under long duration wind loads. The robustness of the architecture will be further evaluated with predicting the acceleration response history of a scaled aeroelastic model based on experimental studies conducted at the Wind Simulation and Testing Laboratory (WiST) at Iowa State University.

Three-dimensional reynolds number effects and wind load models for cylindrical storage tanks with low aspect ratios

The wind loads of cylindrical storage tanks may be significantly affected by the Reynolds number (Re), while it is different from the infinite-length cylinder because the aspect ratios (H/D) of storage tanks are usually very low. The flow around tanks changes along the spanwise direction and presents a three-dimensional characteristic. In this study, the wind pressure on cylindrical storage tanks with 4 aspect ratios (H/D = 0.2–1.5) are measured by wind tunnel tests. Two kinds of flow field, uniform and atmospheric boundary layer (ABL) flow are set in the test with Re varying from 105 to 106. The drag and lift coefficients, wind pressure distributions and power spectra are analyzed to reveal the three-dimensional characteristics of the aerodynamic loads. Consequently, as the H/D of cylinder decreases, the Reynolds number effects are attenuated or even disappear gradually. The transition of separation occurs at Re in the range of 2.2 × 105–3.0 × 105 and 1.8 × 105–2.6 × 105 for tanks with H/D = 1.5 and 1.0 respectively, which is lower than that of two-dimensional cylinders. Moreover, the circumferential wind pressure distributions near the free end enter the critical Reynolds number region at lower Re than that at the middle sections. Parameters like the minimum pressure coefficient and separation angle are not exactly the same at different heights. Finally, a three-dimensional mean wind pressure distribution model of the storage tanks in the post-critical Re-independent region is proposed, the wind loads computed from which are accurate enough with only about 5% relative error to be used for design reference.

Dynamic characteristics of wheel–rail collision vibration for high-speed train under crosswind

ABSTRACT This paper focuses on the dynamic characteristics of wheel–rail collision vibration for high-speed train under crosswind. The wind load model is established by using fast Fourier transform harmonic synthesis method and Davenport coherence function, the lateral displacement of wheelset of high-speed train under crosswind is calculated, the dynamic model of wheel–rail collision vibration system of high-speed train under crosswind is established. The effects of vibration frequency, wheel–rail clearance and lateral damping on the characteristics of wheel–rail lateral clearance impact vibration system of high-speed train are discussed. Numerical simulation results show that the impact velocity of wheelset collision on left and right rails increases with the increase of vibration frequency. When ω > 3.3, the system changes from chaos state to single period stable state through inverse doubling bifurcation; when b < 0.0033, it is in a chaos state, and with the increase of b, the inverse doubling bifurcation occurs until the hunting motion of the wheel–rail system is in a stable state; when , the system is in a stable single period operation state, and with the continuous increase of , it begins to have hop bifurcation, enters a multi-period and chaos state, and finally it is in a stable single period operation state.

Architectural Glass

Recent decades have seen growing and widespread adoption of glass as an architectural material that can be used not only as window panes but also as facades, walls, and roofs. This is despite glass traditionally being considered a brittle material, not readily capable of handling the high loads required of architectural materials. Architectural glass has enabled the vaulted, transparent structures of many modern airport terminals and eye-catching buildings, such as the ubiquitous all-glass Apple Stores found around the world. Glass has enabled architects to expand their visions of buildings, using light and space to create wonderful new designs. As described in this review, these dramatic new possibilities for how glass is used in architecture have been the result of a convergence of many developments, including a better understanding of the fracture of glass, new processes for strengthening glass, confidence in large-scale finite element modeling of gravitational and wind loads, advances in the lamination of glass sheets, and the availability of ever larger individual sheets of float glass. The concurrent evolution of standards for the use of glass in buildings has also played a role in advancing the use of architectural glass. Advances in the architectural use of glass have their roots in the traditional uses and physical understanding of the properties of glass that have developed over hundreds of years.

Hidden safety in structural design codes

Structural design codes are deliberately kept simple to facilitate the design process. To ensure sufficient safety with simplified models, parameters of these models are often chosen conservatively. This leads to additional “hidden safety” in the design. But what happens if one utilizes more advanced design models without the implicit conservatism of the simple models? On one hand, an advanced design method has the potential to result in more optimized designs. On the other hand, it will affect the structural safety. While the advanced models might be associated with smaller uncertainty, which increases reliability, the loss of hidden safety can decrease the reliability. We comprehensively discuss the role of hidden safety in codified structural design and its effects on the reliability and material consumption. Based on this, we develop a framework for adapting the safety concept to ensure that advanced models lead to the same level of safety as standard models. The framework is exemplarily applied to the wind load model of the Eurocode.

Numerical and physical modeling of wind loads on long-span shell structures

Introduction. Wind load has a significant impact on buildings and structures. It triggers the evolution of the stress-strain state that causes various kinds of deformations. Requirements, applicable to the serviceability limit state, are important for the construction of long-span structures. In some cases, the analysis of the distribution of wind effects over the surface of a construction facility may be a challenging task. The purpose of the study is to identify the pattern of the wind load distribution over the shell of a long-span structure using physical and numerical methods, compare and analyze the obtained results.&#x0D; Materials and methods. In the course of the study, a model of the shell structure was tested in the wind tunnel in the course of the physical testing. The model was made of polymer materials using the 3D printing technology. In addition, the article addresses the procedure for conducting full-scale tests in a wind tunnel. Numerical modeling was performed using various software and numerical software packages, such as Ansys CFX, SOLIDWORKS.&#x0D; Results. The article presents the results of physical tests conducted in a wind tunnel, demonstrates the tables that have the values of aerodynamic coefficients and wind pressures, on the basis of which colour pressure isofields are made. Also, the article presents the results of iterative calculations of numerical models made using various software and numerical software packages. In addition, wind flow distributions were analyzed, since the object of the study has such a characteristic feature as an open-air shell, which allows the air flow to reach the structure from below.&#x0D; Conclusions. The authors analyzed the data obtained as a result of the research; the convergence between the results of physical tests and numerical modeling in Ansys CFX was identified, a great discrepancy between numerical and physical studies was identified as a result of the application of other software packages. When designing buildings and structures, having intricate geometric shape, both physical and numerical modeling should be conducted.

부공력감쇠를 고려한 와류하중모델의 진동예측성능

The negative aerodynamic damping is a very crucial parameter in estimating the vortex induced resonance(VIR) in the across-wind direction. Aerodynamic damping is a major factor constituting so-called motion induced load or feedback load, and it is also a tool to explain the rapid manifestation of VIR. In this study, a mathematical model of aerodynamic damping are evaluated, and a process for predicting vortex induced vibration(VIV) along with vortex induced load model is proposed. By performing aeroelastic model test of a slender structure with a rectangular section, the aerodynamic damping and vortex-induced load are identified from the measured acceleration, based on these results, the mathematical models for aerodynamic damping and vortex induced load with respect to the wind speed were constructed. Finally, vibration estimation performance was evaluated by comparing the measured acceleration with the acceleration response obtained through re-analysis using the aerodynamic damping model and the vortex induced load model. From the numerical results, it was found that mathematical model of across wind load model are able to reliably predict VIV with a high reliability.

Proposal Of Simplified Way of Applying Wind Load on Circular Cross-Section

Wind action on circular cross section was described in many publications. It finds an application for flue gas ducts, pipelines, silo or chimneys. This study concentrate on elements with diameter greater than 1m. There are well recognized analytical solutions of static calculation with uses Fourier-series for wind distribution. Although during last 10 years numerical methods of solving problems get more popular, especially among young engineers. For surface structures ability of analytical finding internal forces disappears, and Finish Element Method substitutes analytical calculation. Modelling of wind load in FEM programs cause several problems. Using wind load distribution proposed in Eurocode 1-4, or from laboratory test, it is usually necessary to divide circular cross-section into 32 up to 72 rectangular elements. Applying load in that way is the most accurate method to imitate wind load in FE model. From the other hand that take much time, and requires preparing data about distribution before modelling. Applying wind on complicated model, with many independent parts of piping, for at least 2 load cases cause faults and slows down work. This paper shows and compares a few proposal wind load models for numerical calculation. Those models were built to obtain accurate internal forces in compare to Eurocode procedure. Proposed models offers simplification of Geometry in numerical model, and saves of time. It also helps to make FE mesh become independent from structural nodes, lines or divisions. This paper concern on one case of one Reynolds number, with refers to 2m wide cylinder, wind velocity of 22m/s and surface roughness of steel plate – 0,05 mm. This paper compares different wind load distributions, in terms of required number of division of model, time consuming, precision of results. Author selected one proposal load distribution, with give equivalent internal forces as wind load distribution obtained from Wind Flow simulation (for example CFD method). Proposed model is useful for structural engineers and statics in offer stage of project. With some safety factor it can be also used as wind load as case for detailing cylindrical structures.

Development of nonlinear framework for simulation of Typhoon-induced buffeting response of Long-span bridges using Volterra series

This paper presents a nonlinear time-domain analysis framework to simulate the buffeting response of long-span bridges subjected to the typhoon winds. The analysis framework separates the aerodynamic forces generated on the bridge deck into low- and high-frequency components modelled by the quasi-steady and Volterra series-based wind load models, respectively. The aerodynamic nonlinearity and non-stationary wind effects existing in the wind-bridge interaction are incorporated in the analysis framework in terms of the ① static force coefficients measured at low-frequency effective angle of attack, ② flutter derivatives identified at varying angles of attack, ③ higher order fluid memory terms of the Volterra series and ④ time-varying mean wind speed. The efficacy of the proposed framework is verified by presenting the numerical example of a suspension bridge fully immersed in the typhoon winds with aerodynamic characteristics sensitive to the effective angle of attack. The dynamic analysis results show good agreement in the simulation of the typhoon-induced buffeting response of the bridge deck. Moreover, the simulation results are also compared with the measurements, and the existing linear and nonlinear wind load models to elucidate the efficiency of the proposed framework.

DEFORMATION AND BUCKLING ANALYSIS OF SHALLOW CONICAL SHELLS BASED ON IMPROVED MODEL OF WIND LOAD USING ENVIRONMENT ANSYS

The process of deformation and buckling of shallow thin-walled elastic conical shells has been investigated for the case of significantly non-uniform stress-strain state due to the action of wind load based on improved model of pressure application schema to the surface of shallow shell and for hinged hedge of border. An improved model of wind load was based on data presented in terms [5, 6] and was a logical continuation of previous investigation of wind action on shallow conical shells based on model of first approach [3]. Deformation and buckling process investigation has been carried out using software ANSYS which effectivity was approved by the fact of being used by NASA for its aerospace projects. A model of shallow conical shell has been made using four-corner finite element SHELL 281 with 8 nodes that let us obtain not only symmetrical relatively to the axis of rotation buckling form but an asymmetrical too. Two types of computation have been made during numerical modeling – linear bifurcation computation with determination of linear pressure qcr value and corresponding to it buckling form, and computation of geometrically non-linear problem of deformation with determination of limit pressure qlim and corresponding buckling form. Obtained buckling forms have been compared to the deformed shape of shell surface when aerodynamic computations have been carried out using software ANSYS. An estimation analysis has been made for case of application of improved model of wind load in comparison to the previous investigation according to the values of baring capacity and buckling shape coherence during resolution of static tasks and comparison to the results of aerodynamic solution. An analysis of base parameter influence has been carried out for the model of first approach and current improved model according to the bearing capacity value and local extremums on schema of pressure intensity distribution of wind load. Specific moments of deformation process computations based on improved model using environment ANSYS have been mentioned and of further analysis on the basis of improved model with it specifics have been given too.

The flow fields generated by stationary and travelling downbursts and resultant wind load effects on transmission line structural system

In many non-cyclone areas around the world, severe thunderstorm downbursts can produce annual gust peaks that are the design wind speeds of general structures, and the resultant wind loads pose a major potential threat to critical infrastructure, such as transmission line structural system. The flow fields generated by downbursts are different from those by the synoptic winds in the atmospheric boundary layer. In order to obtain a wind load model of downburst, scholars have made many attempts to study the flow characteristics of downburst-like events. However, in previous studies, the effects of different experimental setup parameters on distribution of downburst wind speed have not been fully discussed. In this paper, an experimental study is conducted using a pulsed wall jet experimental simulator located at Tohoku University, Japan, to analyse the flow fields of stationary and travelling downbursts, and the resultant wind load effects on transmission line structural system. The comparison results show that different experimental settings will affect the maximum wind speed obtained and the height providing the maximum wind speed. The translational speed ratio defined by the ratio of moving speed to jet inlet speed will affect the wind speed distribution in the longitudinal direction of the generated flow field of the travelling downburst. In addition, the comparative studies show that the wind speed distribution of travelling downburst cannot be simply expressed as the vector sum of stationary downburst wind speed distribution and the jet moving speed, and that speed of the travelling downburst can intensify the non-uniform wind loading relaying to the transmission line structural system. For the analysis of the downburst flow fields, a multi-degree-of-freedom analysis is needed to consider its three-dimensional effect, that is, the distributions of wind speeds along the three coordinate axes, and the comprehensive effects of influencing parameters.