Wind-resistant Design Research Articles

Experimental study on wind load characteristics of rooftop canopies of low and medium rise buildings

Rooftop canopy is popular in buildings, and it is prone to wind induced damage due to its light weight and slender configuration. However, investigation on the wind load on this kind of structure has not been conducted, leading to a wind resistant design without a firm basis. This study measures the wind pressure acting on the rooftop canopy considering 4 different underneath building heights, whose prototype vary from 6m to 24m. The mean, fluctuating, and extreme wind pressure coefficients are examined. The correlation coefficients between the pressures at different positions are also checked. Results show that the underneath building height has significant effect on the wind load coefficients of the canopy. The correlation between wind pressures on both the upper and lower surfaces decreases gradually with the increase of the building height. The most unfavorable height of building found in this study is 12m, with the largest uplift net pressure coefficient of the canopy close to −7.0. Comparison with the design values for claddings of free roof in ASCE 7–22 shows that the rooftop canopy can practically have much larger uplift (negative) net pressure in the edge region.

Stability analysis of long-span bridge under static wind load

With the maturity of various technologies and the vigorous development of advanced materials, the design and construction of suspension bridges require larger spans and lighter structures, but at the same time, the problems arising from the dynamic and static responses of the system under wind loads have become more and more prominent. The phenomenon of wind-induced static response occurring before the emotional response has been found in wind tunnel tests at home and abroad. Static instability is also a vital issue in the wind-resistant design of large-span suspension bridges, so studying the static behavior and instability law of large-span suspension bridges under strong winds is of high practical value for the construction of large-span bridges in the future. In this paper, relevant research results of previous researchers based on static wind stability of suspension bridges are sorted out and summarized. Their corresponding fundamental theories are introduced in detail. In addition, the related analysis program is prepared by using the APDL language of ANSYS.

Bayesian uncertainty quantification of modal parameters and RRF identification of transmission towers with limited measured vibration data

The resonant response factor (RRF) sensitive to modal parameters, including the damping ratio and frequency, is a critical parameter for wind-resistant design of extra high voltage (EHV) transmission towers, because it directly affects the calculation of the wind vibration coefficient. However, the research on operational modal analysis (OMA) of in-service EHV transmission towers is limited due to the high risk of field monitoring. Therefore, it is critical to determine the size of sufficient data samples or minimum monitoring duration for the OMA of a transmission tower. In this study, an investigation of uncertainty quantification in Bayesian OMA of EHV transmission towers with small data samples from the ambient dynamic test is carried out. The uncertainty of the resonant component factor for wind-resistance design is proposed and quantified, which could provide engineering designers with a reference for confidence levels. Firstly, a field test system is installed on a multipurpose EHV transmission tower with a closed-loop cat head and a pair of cross-arms, to gather the acceleration responses. Then, the OMA for the transmission tower is carried out by the fast Bayesian FFT (FBFFT) method to determine the modal parameters as well as the associated posterior uncertainty. The small sample analysis of OMA for the transmission tower is further performed to obtain sufficient data samples and minimum monitoring duration. Finally, the distribution of the RRF is presented with the different confidential levels. It is found that a sampling length of 600 s could fulfill the basic needs of accuracy in Bayesian OMA and the determination of RRF. The outcomes of this study may provide a reference for the wind-resistance design parameter selection of the similar type of transmission towers.

Displacement estimation for a high-rise building during Super Typhoon Mangkhut based on field measurements and machine learning

Knowledge of displacement responses of high-rise buildings under harsh wind excitations is essential for their wind-resistant structural design. This paper develops a machine learning model named long short-term memory (LSTM) to estimate the displacements of a 420-m-high building during Super Typhoon Mangkhut based on available field measurements. The developed model is trained and validated using the field measurements on the building during typhoon events, and the performance of the model is assessed against several evaluation criteria. Then, the trained LSTM model is employed to estimate the displacements of the skyscraper during Mangkhut. The accuracy of the estimated displacements is validated in time and frequency domains. Moreover, the background and resonant components of the estimated displacements during the extreme windstorm are analyzed. This paper aims to provide valuable reference for the wind-resistant design of high-rise buildings in tropical cyclone-prone regions.

Gust Factor Approach for Estimating Maximum Response and Control Force in High-Rise Base-Isolated Buildings with Active Structural Control

This paper devises a new method for estimating the maximum response and maximum control force for high-rise base-isolated buildings with active structural control (active base isolation) to simplify the conventional complex design procedure. While active base isolation has emerged as a prominent solution for achieving high control performance, its design process is inherently complex, particularly when applied to high-rise buildings where wind loads become prominent. To address this problem, we propose a streamlined method inspired by the gust factor methodology widely used in conventional passive wind-resistant designs. This method estimates the maximum response and maximum control force without the need for numerical simulations. We first construct an equivalent passive model of a multi-degree-of-freedom control system to theoretically compute the dynamics of the system. Based on the constructed equivalent passive model and then propose a method to calculate the mean displacement and mean control force using only the static equilibrium of this model. Furthermore, we extend the conventional gust factor approach to active base isolation to estimate the maximum displacement and maximum control force for active base isolation without the need for numerical simulations. We validate our methods through a series of numerical examples, incorporating key parameters such as feedback gain, aspect ratio of building, return period of wind force, and stiffness of isolation. Numerical verifications show that the mean response and mean control force are estimated by the static equilibrium of the proposed equivalent passive model. Moreover, the maximum response and maximum control force can be estimated by the proposed gust factors. Our methods can be applied for feedback control systems using a given feedback gain.

Experimental study on the aerodynamic characteristics of combined angle transmission tower subject to skew wind

The transmission towers served as crucial carriers in the process of power transmission. The combined angle transmission tower of dual-angle steel with cruciform section are relatively a novel type of angle tower, which is being more widely used in transmission lines. The studies on aerodynamic characteristics of combined angle tower in skewed wind are limited. In this paper, the wind tunnel tests are conducted to investigate the aerodynamic characteristics of the combined angle tower, and the high frequency force balance (HFFB) test is introduced to obtain the transverse and longitudinal forces on the tower using the direct force measurement (DFM) method. The drag coefficients and wind load-distribution factors of the combined angle tower are obtained from the wind tunnel tests, and the effects of interference and tower leg spacing on the wind loads of the tower legs are fully explored. It can be found that the aerodynamic coefficients and drag coefficients of the combined angle steel tower leg tend to decrease with the increase of interference members and it also decreases with the decrease of the tower leg spacing. The test wind load-distribution factors of the isolated leg are generally larger than those defined by seven typical codes (e.g., US, EU, Japanese, and Chinese codes) and significantly exceed the code-specified values under partial wind angles. The observations obtained from this study may provide helpful guidance on the wind-resistant design of this relatively novel type of combined angle tower.

Semi-Analytical Formula for Estimating Variance Response of Megawatt Wind Turbine Tower Under Parked Condition

As the supporting structure of the wind turbine, the tower is important for the safety of the wind turbine. The accurate estimation of tower response is critical for the wind turbine tower design. In the preliminary design, lots of calculations are necessary to determine design parameters. The traditional time domain calculation suffers its low efficiency and hinders the design progress. To overcome this difficulty, the frequency domain analysis should be developed, especially for the large wind turbine which may be significantly affected by the aerodynamic damping. In this study, a semi-analytical formula for the variance of the tower base bending moment is developed from the frequency domain analysis at parked condition. First, based on the quasi-steady theory and the three-component (mean, background and resonant components) method commonly used in the wind-resistant design of structure, the analytical formula of the variance for the tower base bending moment is presented considering the three components of the wind velocity. Second, the analytical formula is corrected based on the comparison with the calculation result by FAST. In the correction, the empirical aerodynamic damping is adopted. Finally, the applicability of the developed semi-analytical formula is verified by 5[Formula: see text]MW, 10[Formula: see text]MW and 15[Formula: see text]MW wind turbines.

Experimental investigation of wind pressures on photovoltaic (PV) panel installed parallel to residential gable roof

The study was conducted to investigate the wind pressures on PV panels installed parallel to a 30° pitched gable roof, with a special focus on the effects of roof clearance. The wind pressures on the two sides of the scaled panels with four clearances, i.e., ranging from 5 cm to 20 cm with an interval of 5 cm, were tested. The pressure coefficients over taps and zones were examined and discussed. The results show that the most critical positive and negative area-averaged peak net pressure coefficients were comparable in magnitude. With a clearance of 10 cm, the critical positive and negative values were 1.13 and −1.08, respectively, and both occurred at θ = 0°. With effective area of 3.7 m2, the critical positive values increased 26.6 %, 8.3 % and 11.7 % as clearance ranged from 5 cm to 10 cm, 10 cm to 15 cm, and 15 cm to 20 cm, respectively, while the critical negative values changed little when clearance was less than 15 cm, but increased 18.8 % when clearance increased from 15 cm to 20 cm. However, the associated unfavorable wind directions of critical positive and negative values were at θ = 0°, and oblique wind, respectively, remaining nearly unchanged with the increasing of clearance. The tested critical positive and negative area-averaged peak net pressure coefficients were smaller than the values calculated by standards, indicating that the wind resistant designs of roof-mounted PV panels according to the mentioned standards are quite conservation.

Numerical study of wind characteristics at a long-span bridge site in mountain valley

Wind loads play an important role in the design and construction of long-span bridges, especially for that built in mountain valley, and wind characteristics in mountain terrain are still unclear. To further understand the wind characteristics at a bridge site in a mountain valley, large eddy simulations were employed to comprehensively study the wind characteristics at the bridge site in an L-shaped canyon. Different wind directions consisting of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° were considered, and the wind characteristics on the main girder and towers, as well as the flow field, were comprehensively investigated. The results indicate that the mean and fluctuating wind characteristics are significantly different from those specified in the relevant specifications, and it is inappropriate to apply the specifications directly to mountainous terrain. When wind flows along a channel, it leads to a large wind speed amplification factor, strong non-Gaussianity, and large kurtosis and skewness. The steeper the slope of the mountain, the stronger the non-Gaussianity of the fluctuating wind. The coherence function remains nearly unchanged when the distance between the two points is constant, regardless of the location. The wind characteristics at the main girder and towers are so different that they should be considered separately and taken into account in engineering practice. This study provides a reference for the wind-resistant design of bridges and structures built on mountainous terrains.

Wind-Induced Vibration Analysis of a Pentagonal Three–Four Strut Hybrid Open-Type Cable Dome

Previous research has confirmed that the newly proposed pentagonal three–four strut hybrid cable dome exhibits superior static performance compared to traditional cable domes, though its dynamic characteristics still require further study. Cable domes are wind-sensitive structures, and the results of a wind-induced vibration analysis are beneficial for the selection and construction of cable domes. In this study, a finite element model of a new open-type cable dome with a span of 120 m is established. The MATLAB 2017a programming language is employed to simulate pulsating winds, followed by a nonlinear dynamic analysis to analyze the wind-induced vibrations of the structure. The reliability of the pulsating wind model is confirmed by comparing the simulated spectrum with the target spectrum. Moreover, a wind-induced vibration time history analysis is performed to obtain the node displacement and internal force of components wind vibration coefficients, aiding in the approximation of pulsating winds with average winds in a wind-resistant design. Furthermore, a parametric analysis is carried out, ranking nodes and components based on sensitivity. The result shows that the structure exhibits the strongest wind resistance when the rise–span ratio is f/l=0.07 and the thickness–span ratio is h/l=0.08. Notably, the outer upper chord node, 2a, and the inner lower chord hoop cable, H1, are identified as the most sensitive node and component within the structure, respectively. Overall, the structure demonstrates excellent wind resistance performance, and the maximum wind vibration coefficient value remains below 3.

Wind-Induced Response Assessment of CAARC Building Based on LBM and FSI Simulation

It is very important for the wind-resistant design of high-rise buildings to assess wind-induced vibrations efficiently. The Lattice Boltzmann Method-based Large Eddy Simulation and Fluid–Structure Interaction techniques are used to identify the surface wind pressure and wind-induced dynamic response of a CAARC standard high-rise building. Compared with wind tunnel tests, a detailed analysis of the accuracy of simulated wind pressures and base moments of the CAARC model are discussed under multiple wind direction angles. The differences between one-way and two-way Fluid–Structure Interaction simulations are compared under two different reduced wind velocities. The research results show that the simulated mean surface wind pressures of building under seven wind direction conditions have an error within 15% compared to probe measurements, and the average and root mean square base bending moments agree well with the wind tunnel tests. The top transverse wind-induced vibrations of the buildings are significantly larger when the reduced wind velocity reaches 4.6, indicating that aerodynamic damping effects on structural responses should not be overlooked. The research findings of this article provide valuable technical references for the application of LBM methods in the wind load effect assessments of high-rise buildings.

Extreme Wind Speed Estimation for Wind-Resistance Design of a Transmission Line Situated in a Typhoon-Prone and Hilly Area

The southeastern coast of China is annually threatened by typhoons originating from the northwestern Pacific Ocean, posing a risk of severe damage to coastal transmission lines. This study employs the random forest-based typhoon full-track simulation method and YM wind field to assess the wind-resistance reliability of transmission lines. The obtained extreme wind speeds of a transmission line site in Wenzhou are 33.7m/s and 35.8m/s under the 50-year and 100-year return periods, respectively. The effects of micro-topography on the extreme typhoon wind speed are further analyzed, and the extreme wind speed distribution maps of Wenzhou City and Yueqing City are plotted, respectively. The results indicate a decreasing trend in typhoon wind speed within inland regions, while micro-topography displays a substantial effect on enhancing the typhoon wind speed.

The Return Period Wind Speed Prediction of Beijing Urban Area Based on Short-Term Measured Wind Speed

To predict and explore the return period wind speed distribution in Beijing urban area, based on the short-term measured wind speed record, the measured independent storm peak samples are extracted and the Monte–Carlo numerical simulation method is used to randomly generate pseudo-independent storm peak samples with the same distribution as the independent storm peak samples. In addition, the appropriate threshold is used to select and extract the over-threshold independent storm peak samples from the measured samples. And, then, the return period wind speed of the whole wind direction is predicted. Further, the traditional Cook method is used to predict and analyze the return period wind speed of each wind direction according to the measured wind speed data. The results show that the return period wind speed prediction results of the whole wind direction corresponding to the simulated pseudo samples and the measured over-threshold samples are basically close to each other, and the maximum relative deviation is less than 7%. The mean relative deviation of the return period wind speed prediction results is about 10.6% between each wind direction and the whole wind direction, and the mean relative deviation is about 9.4% between the RPWS prediction result of each wind direction and the design value of the code. In addition, the return period wind speed prediction values of the west by southwest, northwest and north by northeast wind directions exceed the design value of the code, while the predicted values of the other wind directions are within the envelope range of the design value of the code. Finally, the research content of this paper can provide some reference for the wind resistance design analysis of building structures in Beijing area.

A numerical study on load effects of low-rise buildings in a wind-blown sand environment

The transportation process of wind-blown sand, represented by sandstorms, occurs frequently in arid and semi-arid regions. The combined action of wind and sand impact load in a wind-sand environment poses a serious threat to the safety of construction, transportation and other engineering structures. However, most of the current structural designs only considers the effect of wind, and there is little detailed research on the surface load distribution of structures caused by sand impact, which leads to uncertainty in the safety assessment of engineering structures in wind-sand areas. In this paper, low-rise buildings which are easily damaged in strong wind-sand environments are taken as the research object. A numerical model of coupling turbulent wind field and particle motion was then established, and the reliability of the numerical simulation results was verified through wind tunnel experiments. Finally, the wind-sand movement around the low-rise building model and the load distribution characteristics on the building surface are simulated under different wind speed and sand concentration conditions. The results show that the edges and corners of engineering structures are subject to more severe particle erosion-abrasion. As the sand concentration increases in the flow field, the wind speed and the wind load acting on the structures weakens. Whereas the sand impact load increases with the increment of wind speed and sand concentration. The increased effect of sand particles on the total load can be considered by amplifying the wind load shape coefficient on the windward side. This study is helpful to understand the mechanism of sand wind-induced damage on low-rise buildings, and provides basic tools and a theoretical basis for the wind and wind-blown sand resistance design and performance optimization of engineering structures.

Generalized bivariate mixture model of directional wind speed in mixed wind climates

Probabilistic modeling of the directional wind speed has been an important topic in the fields of wind energy assessment as well as structural wind-resistant design. The mixture model is required for the probabilistic modeling on the directional wind speed as the wind climates often show the mixture nature. For accuracy and robustness concerns in engineering applications, a generalized bivariate mixture (GBM) model of the directional wind speed is developed by using the copula-based bivariate distribution function. In this model, the marginal distributions and connection function for each sub-model can be flexibly defined. In parametrizing the model, the data-driven parametric estimation including a data preprocess and an automatic unsupervised fitting process is presented. The performance of GBM model is verified using two data sets and compared with the offset elliptical normal mixture (OENM) model. The robustness of GBM model is found for its good performance in fitting to the targets with or without smoothing process, and in tackling directional wind speed with the extremely complex probability characteristic.

Two-year wind field measurements near the ground at a site of the Tibetan Plateau

A nearly two-year wind field measurement in the plateau has been conducted in the south of Tibet. High-frequency anemometric data of the distinctive plateau wind field was obtained. Combining the non-stationary model and test, wind samples are classified into three types of 10-min samples based on the level of stationarity. Analysis reveals the strong non-stationarity, turbulence intensity, gust factor, and integral length scale of the synoptic wind in the plateau, which differ from the ones at low altitudes. The stationary samples are recommended to represent the plateau synoptic wind for characterizing the fluctuating wind. At smaller time scales, high-frequency records capture some intense gust events. Based on the different influences of wind on the structures from the perspective of structural wind resistance, the plateau transient intense gust events are divided into thunderstorms and front, and short-rise-time gusts. Representative gust events are defined, sifted, and extracted. With the combination analysis of 10-min fluctuating wind characteristics and intense non-stationary gust events, the measurement data assist the structural wind-resistance design in the plateau.

Multimodal analysis of saddle micro-terrain prone to wind disasters on overhead transmission lines

Pervasive micro-terrain is a significant contributor to wind disasters on transmission lines. This study explores the effect of saddle micro-terrain on the wind field of transmission lines and proposes relevant models and analysis methods. Firstly, the characteristic elements and parameters of saddle micro-terrain are extracted using DEM and established representative cross-sections for classification. Subsequently, a multimodal computational model is developed, considering the geographical and meteorological features and the sag model of transmission lines under micro-terrain. This study calculates wind field distribution and conductor wind loads for three types of saddle micro-terrain conditions, revealing an exponential growth trend of wind loads with increasing wind speeds. The results indicate that in transmission lines at saddle areas, the sag region does not intrude into the boundary layer, with a wind speed growth rate of only 0.18, resulting in relatively stable wind loads. In contrast, for transmission lines at saddle areas in secondary mountain ranges and dual-mountain saddle regions, wind speed growth rates reach 0.97 and 1.53, respectively, indicating higher disaster risks. This research provides a basis for distinguishing and disaster prevention in mountainous transmission lines' micro-terrain variations, offering significant contributions to enhancing wind-resistant design standards in mountainous regions.

Super-long-span bridges: wind-resistant design developments and open issues

Suspension bridges with spans exceeding 1500 m were only achieved in 1998 with completion of the Akashi Kaikyo Bridge in Japan and the Great Belt Bridge in Denmark. The most recent record is the 1915 Çanakkale Bridge in Turkey, with a main span of 2023 m. A slightly longer bridge is currently under construction in China and significantly greater spans are in planning, such as the Messina Strait Bridge, aiming for an impressive 3300 m span connecting Sicily with mainland Italy. Three critical challenges associated with such ambitious designs are addressed in this article. The first challenge centres on the significance of vortex-induced vibrations, particularly in multi-box girders. The prediction of these vibrations before construction relies on wind tunnel tests with scaled-down models characterised by inherent uncertainties. The second issue involves non-synoptic winds, such as downbursts. Although these events are relatively small and short-lived, they have a non-negligible probability of occurrence on large structures and may induce damage and loss of serviceability due to their intensity and the presence of vertical velocity components. Finally, the importance of robust design practices is underlined, emphasising the potential risks of relying solely on aerodynamic cross-section optimisation without providing additional structural stiffness and damping resources in these critical structures.

Analysis of wind pressure characteristics of typical agricultural greenhouse buildings on tropical islands

Existing studies about wind pressure on agricultural greenhouse buildings concentrate on the mean wind pressure while ignoring the systematic research on fluctuating wind pressure characteristics and the influence of roof shape on the wind pressure characteristics, which are closely associated with the wind-induced damage mechanism. In this study, two typical agricultural greenhouse buildings on tropical islands are selected as prototypes to conduct pressure measurement experiments in the wind tunnel. Based on the wind pressure time series for the two greenhouses, the mean and fluctuating wind pressure distribution pattern and the localized high-pressure generation mechanism are analyzed. Then, the shape coefficient of the two greenhouses is compared in depth to the standards from four countries. Besides, wind pressure non-Gaussian determination criteria for agricultural greenhouse buildings considering the roof shape and wind directions are proposed. Lastly, the differences in wind pressure spectra on the roofs and walls of the two greenhouses are summarized. The results indicate the roof shape has a significant influence on the wind pressure characteristics. Compared with the pitched roof, the vaulted roof will increase the suction effect on the windward front zone and the middle area, mitigate the suction impact on the leeward roof, and weaken the wind pressure non-Gaussian characteristics. The experimental shape coefficient of the pitched-roof greenhouse is basically consistent with the standard from the U.S., while that of the vaulted-roof greenhouse has some deviation from the existing standards. The results provide a theoretical basis for the wind-resistant design of agricultural greenhouse buildings on tropical islands.

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.