Wind Load Characteristics Research Articles

Study on wind load characteristics of gable roof under tornado

This research simulates the behavior of a tornado on a double-slope roof using the Ward tornado generator and the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$SS{T_{k - \\omega }}$$\\end{document} turbulence model. The effects of different ground roughness, slope angle, and wind field position on the tornado load characteristics of gable roofs were studied. The tornado-generating device established the tornado field under various working conditions, and the simulation results were compared with the experimental data to verify the reliability of the simulation results. The wind pressure distribution of gable roofs with four different slope angles was analyzed to find the most unfavorable roof condition of the tornado field. The gable roof’s aerodynamic and wind pressure characteristics at various places in the tornado field were explored by comparing the wind pressure coefficients at five distinct positions on smooth and rough ground. The lift-drag and wind pressure coefficients of five kinds of ground roughness were calculated to determine the influence of different ground roughness on the aerodynamic force and partial pressure distribution of the gable roof. The ground roughness reduces the vortex ratio because the ground roughness reduces the maximum tangential wind speed and the radius of the vortex core. Therefore, the gable roof’s suction increases as the updraft increases.

Investigation of the wind loads and flow patterns of a high-rise building under twisted wind flows based on LES

The twisted wind effect has attracted increasing attention among scholars due to its significant influence on the wind loads and wind induced responses of high-rise buildings. Nowadays, it is still challenging to simulate twisted wind flows (TWFs) with larger wind twist angles (WTAs) in the wind tunnel test. Compared to wind tunnel test limitations, the large eddy simulation (LES) offers an effective tool to simulate a broader WTA range. Several state-of-the-art numerical studies have generated TWFs that rely on multiple velocity inflow boundary (MVIB), but it results in vast computational domains and substantial abnormal pressure fluctuations. This paper proposes a single velocity inflow boundary (SVIB) method for modeling TWFs, which can significantly reduce the computational domain size without losing accuracy. Based on the SVIB method, we simulate TWFs with four WTAs (i.e., 0°, 25°, 35°, 45°) and conduct a comprehensive analysis of the influence of WTA and wind direction angle on both the wind load characteristics of and the flow patterns around a high-rise building. The results show that the TWFs will twist the vortex topology and trajectory, and the maximum extreme local resultant force coefficient under 35TWF is larger than that under SWF by around 10 %. The positive and negative wind pressures can simultaneously occur on a special surface at large WTAs (e.g., 35°, 45°), which may impose significant shear forces on the intermediate layers. The wind veering effect enhances the contribution of vortex shedding to the longitudinal fluctuating wind loads and the influence of incoming turbulence on lateral fluctuating wind loads. This study contributes to providing a more effective LES method to simulate TWFs with large WTAs and to reveal the effect of large WTA on the wind load characteristics of high-rise buildings under TWFs and the underlying flow mechanism, which is beneficial to the future wind-resistant design of skyscrapers.

The balance issue of the proportion between new energy and traditional thermal power: An important issue under today's low-carbon goal in developing countries

The stability of the new power system depends on the balance between controllable flexible resources and uncontrollable uncertain resources. For many developing countries and regions lacking advanced flexible resources, thermal power is the main force in solving the problem of new energy consumption. Finding the balance between new energy and traditional thermal power is the key for today's low-carbon goal. To solve this problem, this paper calculates the power range and climbing rate range of thermal power based on physical principles and actual data, and characterizes the characteristics of wind power, photovoltaic power, load and net load based on the five proposed volatility indicators. Then, a logically clear method for determining the required number of thermal power units based on the volatility indicators of new energy from the mechanism and principle perspective is proposed. Finally, under the premise of meeting the power balance and flexibility balance of the power system, the reasonable ratios between the installed capacity of new energy and the number of thermal power units are calculated in four seasons. The results indicate that the judgment system can provide guidance for the energy structure of developing regions.

The Impact of Installation Angle on the Wind Load of Solar Photovoltaic Panels

In order to explore the wind load characteristics acting on solar photovoltaic panels under extreme severe weather conditions, based on the Shear Stress Transport (SST) κ-ω turbulence model, numerical calculations of three-dimensional incompressible viscous steady flow were performed for four installation angles and two extreme wind directions of the solar photovoltaic panels. The wind load characteristics on both sides of the photovoltaic panels were obtained, and the vortex structure characteristics were analyzed using the Q criterion. The results indicate that, under different installation angles, the windward side pressure of the solar photovoltaic panel is generally higher than the leeward side. The leeward side is prone to forming larger vortices, increasing the fatigue and damage risk of the material, which significantly impacts the solar photovoltaic panel. As the installation angle increases, the windward side pressure of the solar photovoltaic panel also gradually increases. Therefore, optimal installation methods include installing the panel facing the wind at angles of 30° and 45°, or installing it facing away from the wind at a 60° angle, to minimize the impact of wind load on the solar photovoltaic panel.

Partitioning of wind pressure coefficients on a tall building under interference effect: A cluster analysis approach

This study proposed a cluster analysis-based approach for partitioning wind pressure on tall buildings in densely-packed areas, considering interference effects. By utilizing a modified GK cluster algorithm and leveraging the coordinate positions of pressure taps along with their corresponding wind pressure coefficients (WPC), the study aimed to distinguish different parts of the building surface exhibiting varying wind load characteristics. The adoption of cluster validation indices (CVIs) allowed for the determination of the optimal number of clusters, enhancing the accuracy and reliability of the partitioning process. The resulting clusters effectively captured the distribution of wind pressure, providing valuable insights for wind-resistant design considerations. Overall, the proposed approach demonstrates promising potential in facilitating the design and analysis of tall buildings subjected to complex wind loads in urban environments.

Experimental study of turbulent inflow on the aerodynamic performance of a wind turbine with Gurney flaps

Nowadays, wind turbines operate within complex inflow environments. Meanwhile, installing Gurney flaps on existing wind turbines could enhance wind energy efficiency. However, limited research has been conducted on the variation of aerodynamic characteristics of a wind turbine equipped with Gurney flaps under turbulent inflow conditions. Hence, wind tunnel test comparisons were made between the output power, wind load, and wake characteristics of a model wind turbine with and without Gurney flaps. The results demonstrated a correlation between the additional power increase in the wind turbine equipped with Gurney flaps and the aerodynamic variation of the corresponding airfoil. Gurney flaps could be effective at higher tip speed ratios, and the power enhancement efficiency initially increased but then decreased as turbulence intensity increased from a low value to 19.0%. Installing Gurney flaps resulted in significant pulsation peaks within the original inertial sub-range. The time-averaged thrust coefficient shifts upward, but the difference decreases slightly under turbulent conditions. Wake analysis revealed that the presence of additional wake velocity deficits primarily concentrated within the near-wake region, which extends along the spanwise direction. These findings could enhance a better understanding of the aerodynamic performances of wind turbines installing Gurney flaps under varying turbulent flow conditions.

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.

Day-Ahead and Intraday Two-Stage Optimal Dispatch Considering Joint Peak Shaving of Carbon Capture Power Plants and Virtual Energy Storage

The anti-peaking characteristics of a high proportion of new energy sources intensify the peak shaving pressure on systems. Carbon capture power plants, as low-carbon and flexible resources, could be beneficial in peak shaving applications. This paper explores the role of carbon capture devices in terms of peak shaving, valley filling, and adjustment flexibility and constructs a virtual energy storage model utilizing various flexible loads on the demand side. Also, it proposes a joint peak shaving strategy involving carbon capture devices and virtual energy storage. Considering the predictive error characteristics of wind power and load across different time scales, this study establishes a day-ahead and intraday two-stage rolling regulation peaking model based on carbon capture power plants and virtual energy storage to fully leverage the diverse response speeds and peak shaving capabilities of various types of flexible loads. Initially, the model calculates the net load curve after implementing a demand response system, aiming to minimize the load peak–valley difference. Subsequently, within the intraday period, it seeks to minimize system operating costs by precisely allocating peak shaving resources as per demand, thus aiming for economic efficiency while ensuring the system’s peak shaving capability.

Analysis of the Influence of Antenna Arrangement Parameters on the Aerodynamic Performance of Telecommunication Towers

With the widespread adoption of 5G telecommunication networks, to reduce construction costs, it has become necessary to add new equipment or antennas to existing 4G and 3G telecommunication towers. This significantly changes the original aerodynamic shape of the towers, leading to a substantial increase in the wind load, which may exceed the original structure’s bearing capacity and pose a threat to the structure’s safety. This study employed three-dimensional numerical simulation methods to systematically investigate the impact of various antenna arrangement parameters, such as the arrangement number, arrangement form, and arrangement layers, on the wind load characteristics of telecommunication towers. The findings revealed that the antenna arrangement form significantly affects the sensitivity of the telecommunication tower’s wind load to the wind direction, with more uniform antenna arrangements resulting in less sensitivity. Compared to the drag coefficient and the windward base overturning moment coefficient, the tower’s lateral force coefficient and the crosswind base overturning moment coefficient are more sensitive to changes in the wind direction. The change patterns in the tower’s overturning force coefficient and overturning moment coefficient with the antenna arrangement number are essentially the same. However, as the antenna arrangement number increases, the growth rate of the tower’s overturning moment coefficient is about twice that of the overturning force coefficient. The tower’s overturning force coefficient increases approximately linearly with the increase in antenna arrangement layers, while the tower’s overturning moment coefficient exhibits a nonlinear increase with the increase in antenna arrangement layers. The rate of increase in the wind load with the antenna arrangement layers is significantly greater than that with the antenna arrangement number. Thus, to reduce wind load, it is advisable in practical engineering applications to increase the antenna arrangement number per layer, thereby reducing the antenna arrangement layers. The study also summarized a calculation method for the structural wind load of telecommunication towers, taking into account the influence of antenna arrangement parameters, providing a reliable basis for the structural design and safety assessment of telecommunication towers in practical engineering.

Flow around single and two tandem rectangular cylinders with various single-side fairings

The shape of single-side wind fairing, which is the longitudinal triangular prism that tailors the outer side of a bridge deck, is key to the aerodynamic performances of double streamlined box girders used in long-span bridges. Uniform flow past single and double 4:1 rectangular cylinders with various single-side fairings are investigated using large-eddy simulation at a Reynolds number of 1.1 × 104. Various fairing nose angles and heights are compared. The wind loading and flow characteristics of the cylinders are discussed. The upstream fairing shows a larger reduction of mean drag and fluctuating lift on double cylinders than on a single cylinder. The fairing nose angle has a stronger influence on the wind loading than the nose height. By adding the fairing, sharpening the fairing nose, or lifting the fairing nose, the lateral recirculation zones are shortened while the rear recirculation zone barely changes, leading to different influences on the surface pressure. The upstream fairing is effective in reducing the vertical range and complexity of vortex structures around single and double cylinders.

Average surface wind pressure surrounding tall buildings with cruciform shapes

Abstract Building shape affects wind pressure on building surfaces, while limited studies have examined how building shape affects the wind pressure on cruciform-shaped tall buildings. This article investigated the variation of the average wind pressure coefficient (AWPC) on cruciform-shaped tall buildings with the height–width ratio (HWR) and height–thickness ratio (HTR). The results demonstrated the occurrence of building blockage, wind separation, wind re-circulation, and wind re-attachment on building surfaces. The frontal surface of the main building was always the windward surface with positive wind pressure. At 2/3 of the building height (H), the peak AWPCs in all scenarios were ~0.70. However, in the case with an HWR of 3.66, the side surfaces of the main building and the frontal surfaces of the branch building, wind pressure was all negative. With the HWR reduction by building width increase, wind pressure on these surfaces became positive, where the AWPCs in the HWR = 1.41 case were 0.60–0.63 and 0.64–0.69 on side and frontal surface, respectively. With the HWR decrease, both positive and negative wind pressure intensified. Along the central axis (M1) in the vertical direction, wider buildings had stronger positive wind pressure on the frontal surfaces below 0.10H, while narrower buildings had stronger positive wind pressure above 0.82H. In comparison, HTR made limited differences to the wind pressure on the frontal surface. Overall, vertical results showed that scenarios with smaller HWR underwent stronger positive and negative wind pressures. On the HTR cases, wind pressure on top surfaces showed complicated results, while thicker buildings had weaker negative wind pressure on the back surface. Overall, this study is important to understand the characteristics of wind load on cruciform-shaped tall buildings and generate implications for wind resistance, natural ventilation design, and wind electricity generation over tall buildings.

Numerical study on wind-loading characteristics of a high-speed train running over the bridge under tornado-like vortices

With global warming intensifying, weather patterns become more volatile and extremes more common. Tornadoes are the most destructive natural disasters causing significant damage to infrastructure. Meanwhile, high-speed railways now face greater risks from tornado events as the national railway network and mass transit trains expand. Thus, studying the tornado flow characteristics and associated effects on high-speed trains is necessary. A study is presented regarding the wind-loading characteristics of a high-speed train running over a railway bridge induced by a tornado belonging to the future railway network. The wind-loading characteristics analyses are performed using the improved delayed detached eddy simulation method. After verifying the numerical approach and mesh strategy, computational studies are conducted to produce a tornado-like vortex and investigate the tornado-induced wind-loading characteristics of a high-speed train running on the bridge by combining a tornado simulation with a moving mesh technique. For the wind-loading parameters studied herein, the selected train's velocity range is between 50 and 350 km/h, the typical operation speed of either regular or high-speed trains. The numerical results show that the time histories of aerodynamic forces on the train revealed a pattern in tornadic flow variability, the time evolutions of the wind loads on the train were affected by train speeds, and the fluctuation was the greatest when the train ran at 50 km/h. Moreover, the train is subjected to larger aerodynamic forces and moments when it operates along with the rotating vortex flow, especially in the core region, and the train is more dangerous when it runs at a lower speed. The results in this study provide references for assessing operation safety, while a train running on the bridge encounters tornadoes.

Study on Wind Load Characteristics of Typical Structure Based on Reynolds Average Method

Study on Wind Load Characteristics of Typical Structure Based on Reynolds Average Method

外立面突出构件对高层建筑风荷载特性影响研究

外立面突出构件对高层建筑风荷载特性影响研究

Overall and Local Wind Loads on Post-Installed Elevator Shaft of Existing Buildings

The glass curtain walls of post-installed elevator shafts in existing buildings can be damaged by local wind loads, and the serviceability of an elevator may be affected by excessive overall wind loads, especially in hurricane-prone areas. The overall and local wind load characteristics of elevator shafts with different arrangements (E-type, H-type, I-type) were studied using wind tunnel tests and computational fluid dynamics (CFD) numerical simulations. Firstly, high-frequency base balance wind tunnel tests of these elevator shafts with three arrangements were carried out to obtain the overall wind loads on the elevator shafts. Secondly, a CFD simulation was performed on the post-installed elevator shafts with three arrangements, obtaining the surface local wind pressure distribution of the elevator shafts under different wind directions. Finally, the wind-induced displacement responses of post-installed elevator shafts were analyzed. The results show that the aerodynamic interference of different elevator arrangements (E-type, H-type, I-type) and wind directions have significant effects on the overall local wind loads and wind-induced responses of the post-installed elevator, while the local wind loads on the area of the elevator door are less influenced by the elevator arrangement type than local wind loads on the surface and the overall wind loads of the elevator shafts. The results and conclusions may be helpful for developing the wind-resistant design of a post-installed elevator shaft.

Study on low-cycle hysteresis properties of seawater corroded steel considering loading history effects

To investigate the combined effects of wave loading history and time-dependent corrosion damage on the hysteresis mechanical properties of long-term serviced marine engineering materials, this study conducted hysteresis mechanical experiments and a generalized mechanical model research on corroded steel, considering the influence of high-cycle loading history. Steel corrosion was pre-generated by accelerated electrochemical corrosion method. Developing the early-stage high-cycle fatigue loading system and later-stage low-cycle hysteresis loading system based on the dynamic characteristics of wave loads, seismic actions, and typhoon-level pulsating wind loads. Analyze the influence of the independent and combined effects of early-stage load stress levels, cycle times, and corrosion damage on the steel capacity to withstand low-cycle high-stress hysteresis loading. Based on test results and mechanical properties, an improved generalized hysteresis mechanical model was established that encompassed monotonic tension curves, skeleton curves, and well-defined loading and unloading rules. The validity and universality of the model were verified through various loading systems and hysteretic tests of corroded steel. The results indicated that the early-stage high-cycle fatigue history led to a reduction in the material's elastic range, causing the material to transition into plasticity earlier. The combined effects of early-stage loading history and corrosion damage resulted in a significant degradation of the material's hysteresis mechanical properties.

Study on wind load characteristics of stadium under tornado

The stadium is a wind-sensitive structure, and the tornado has a greater damage to the stadium. The Ward tornado generating device was used to simulate the wind load characteristics of the stadium during tornado action in order to investigate the wind load characteristics of the stadium. The results of this paper are compared with the experimental results to verify the accuracy of the simulation method. The wind load characteristics of the stadium and its most vulnerable location during a tornado are ascertained by examining the wind pressure coefficient and wind speed distribution law of the stadium’s upper and lower surfaces with different swirl ratio. The influence of uniform wind and wind profile on the wind load of the stadium is explored by comparing and analyzing the wind pressure coefficient of the stadium surface with and without wind profile at the entrance of the wind field. The impact of varying ground roughness on the stadium is compared in order to ascertain how it affects the wind speed, stadium wind pressure, and vortex core radius. The vorticity of the stadium in the tornado wind field with different swirl ratios was compared and analyzed, and the influence of the stadium on the vorticity development of the wind field was explored. This study reveals the effects of swirl ratio, ground roughness and wind profile on the wind pressure, wind speed and vorticity of the stadium under tornadoes, and determines the most vulnerable location and the most unfavorable factors. The above research is helpful to provide reference for disaster prevention and mitigation of stadium structure design.

Experimental Study on Wind Load and Wind-Induced Interference Effect of Three High-Rise Buildings

Wind loads of high-rise buildings are a key parameter in architectural design. The magnitude and distribution characteristics of wind loads are of great importance for the safety and economy of structural design. The wind loads of high-rise buildings are quite different from those of monomer buildings. The wind-induced interference effect could significantly increase the local wind pressure of buildings, causing potential safety hazards for the main structure and enclosure structure. For the three common high-rise buildings, we adopted the wind tunnel test method to measure the surface pressure of each building. The corresponding Re number was 8.2×106. This paper studied the shape coefficients, fluctuating wind pressure coefficients and base bending moment coefficient of each building with different wind direction angles and different spacing ratios, and the maximum value of each parameter and the corresponding working condition were statistically analyzed. The results showed that, under any wind direction angle, the fluctuating wind pressure coefficients on all sides of the building were affected by the spacing ratio, and the fluctuation range was large. When the wind angle was 180º, the fluctuating wind pressure coefficients on the sides of Building 1 were most affected by the slope ratio. At this wind angle, the maximum value was 0.43 at a slope ratio of 5.0, which was 65% different from the minimum. Partition shape coefficients of some sides and top surfaces changed significantly with the spacing ratio. When the spacing ratio was 5.0, the base bending moment coefficients in the downwind and crosswind directions reached their maximum values, and the wind direction angles where the maximum values of the base bending moment coefficients in the downwind direction were 40º and 50º, respectively, and the wind direction angle where the maximum value of the base bending moment coefficients in the crosswind direction was 10º. Due to the influence of the wind angle and the building spacing ratio, the wind loads on the facades of the pyramidal group of buildings varied greatly, and the wind-induced interference effect was evident. The wind load between the building facades in the three buildings was different, and the wind disturbance effect was evident. Therefore, the most unfavorable stress state and interference state of the structure should be comprehensively considered in the wind resistance design of the three buildings. The building spacing ratio should preferably be set to 3.0, and wind angles of 10º, 40º, and 50º should be avoided whenever possible.

Large eddy simulation on wind-induced interference effects of staggered chamfered square cylinders

Chamfered corners in buildings are the main means to reduce the control effect of wind load on the structure, and the interference effect of chamfered buildings cannot be ignored. At present, only the mutual interference coefficients of square and rectangular section buildings are given in the Chinese code, without the interference effect of chamfered buildings being specified. Therefore, in this paper, aerodynamic force and wind pressure coefficients of chamfered square cylinders of different spacing are obtained by the large eddy simulation method. Wind load characteristics, non-Gaussian characteristics and interference effects of chamfered square cylinders with different arrangements are studied based on aerodynamic coefficients, wind pressure coefficients and interference coefficients. The results show that when the wall y plus value is 1, the large eddy simulation is the most accurate to simulate the wind load and wind field parameters. Besides, the aerodynamic effects, non-Gaussian characteristics and interference effects between the chamfered square cylinders are mainly controlled by the cross-wind interval and the spacing (4.0, 4.0) is the characteristic coordinate. That means, when the spacing is smaller than this coordinate, the interference effect of the square cylinder is more obvious. When the spacing coordinate is greater than (4.0, 4.0), the aerodynamic coefficients and non-Gaussian regional distributions of the principal square cylinder and the isolated cylinder are the same, and the interference factor approaches 1.

Fundamental Characteristics of Wind Loading on Vaulted-Free Roofs

The present paper investigates the fundamental characteristics of wind loading on vaulted (cylindrical) free roofs based on a wind tunnel experiment and a computational fluid dynamics (CFD) analysis using Large Eddy Simulation (LES). In the wind tunnel experiment, wind pressures at many points, both on the top and bottom surfaces of rigid roof models, were measured in a turbulent boundary layer. The wind tunnel models, including the tubing system installed in the roof and columns, were made using a 3D printer, which made the roof thickness as small as 2 mm, whereas the span B was 150 mm and the length L ranged from 150 to 450 mm. The rise-to-span ratio f/B ranged from 0.1 to 0.4. Pressure taps were installed along the center arc and an arc near the roof edge (verge) of an instrumented model with a length-to-span ratio of L/B = 1. The value of L/B of the tested models was changed from 1 to 3 using one or two dummy models, which had the same configuration as that of the instrumented model but no pressure taps. The wind direction θ was changed from 0° (perpendicular to the eaves) to ±90° (parallel to the eaves). The CFD simulation was carried out only for limited cases, that is, f/B = 0.1 and 0.4 and θ = 0° and 45°, considering the computational time. The effects of f/B, L/B, and θ on the mean (time-averaged) and fluctuating wind pressures acting on the roofs were investigated. In particular, the flow mechanism generating large wind forces on the roof was discussed. An empirical formula was provided for the distribution of mean wind force coefficients along the center arc (Line C) at θ = 0° and 30° and along the edge arc (Line E) at θ = 40° for each f/B ratio. Note that these wind directions provided the maximum and minimum mean wind force coefficients within all wind directions for Lines C and E. Furthermore, the maximum and minimum peak wind force coefficients on the two arcs were presented. The effect of turbulence intensity of approach flow on the maximum and minimum peak wind force coefficients was investigated. The experimental results were compared with those estimated using a peak factor approach, which showed a relatively good agreement between them. The data presented here can be used to guide the design of the main wind force-resisting systems and the cladding/components of vaulted-free roofs.