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

With the development of building materials, construction technology, and design concepts, suspended arched roofs (SARs) are becoming increasingly popular. The wind loads of arched roofs springing from ground level (ARSGL) and vaulted roofs on side walls (VRSW) have already been studied; however, the wind loads of SARs, which are very different from those of ARSGL or VRSW, have not received adequate attention. Based on the wind tunnel tests of a rigid model of an actual SAR design scheme, the mean value, root mean square (RMS) value, and most unfavorable value of the wind pressure coefficient and overall lift coefficient of this type of roof are analyzed. Furthermore, the influence of the buildings below or surrounding it is investigated and discussed. The test results indicate that the net wind pressure of the SAR is affected by the upper- and lower-surface wind pressures. Both the most unfavorable wind pressure (positive pressure) and suction (negative pressure) coefficients of the SAR are larger near the edge (arch foot) and smaller in the internal area. The maximum values of the most unfavorable pressure and suction coefficients of the tested SAR are 4.5 and 8.0, respectively, and these values are larger than those of ARSGL and VRSW. The buildings below cause airflow congestion under the SAR and eventually increase the net pressure coefficients near the windward edge of the SAR. The shielding effects of the surrounding buildings of the tested SAR reduce the wind pressure coefficient; however, the wind pressure in some areas of the tested SAR increases because of the narrow tube effects between surrounding buildings. The lift coefficient of the tested SAR significantly increases because of the presence of buildings below in some cases. [ABSTRACT FROM AUTHOR]

Summary: The wind direction in the atmospheric boundary layer (ABL) twists with height due to the Coriolis force; this phenomenon is called the Ekman spiral. However, this phenomenon is generally not considered in the present wind load estimation of super high‐rise buildings, which may lead to an incorrect estimation and affect the safety of structures. Therefore, this study considers and analyzes the influence of the Ekman spiral phenomenon in the wind direction reduction effect (WDRE) of the wind load of super high‐rise buildings. First, this paper proposes an empirical fitting equation for the twisted wind direction angle for a height of 100–800 m according to the classical Ekman spiral theory model (CE model). Subsequently, on the basis of twisted wind, this paper proposes a method for the correction of the wind direction reduction factors (WDRFs) of strong winds considering the influence of the Ekman spiral phenomenon in the design wind load estimation of super high‐rise buildings with heights of 400–800 m. A high‐frequency balance force measurement test of a square‐section super high‐rise building model was performed to analyze the influence of the Ekman spiral phenomenon on the WDRE of the aerodynamic force and wind‐induced response. Three Chinese cities (i.e., Beijing, Wuhan, and Kunming) are selected as case studies to illustrate the importance and necessity of the correction method. The results demonstrate that the proposed empirical fitting equation accurately determines the twisted wind direction angle at different latitudes and altitudes. Furthermore, estimating the design wind load while considering the WDRE and neglecting the influence of the Ekman spiral phenomenon may lead to a significant underestimation of the wind load of super high‐rise buildings, rendering the designed building structure more dangerous. [ABSTRACT FROM AUTHOR]

Slender structures are sensitive to wind loads, and aeroelastic effects during vortex-induced resonance have considerable influences on their survivability, serviceability, and habitability. However, the vortex-induced aeroelastic effects and the effects of turbulence intensity on unsteady aerodynamic forces of an aeroelastic prism remain far from been fully understood. In this study, a series of wind tunnel tests, including the pressure measurements of a rigid model and simultaneous measurements of the pressure and response of an aeroelastic model, were conducted in three different wind flows. The characteristics of unsteady aerodynamic forces and the effects of turbulence intensity on the unsteady aerodynamic forces were systematically investigated. The mechanism of aeroelastic effects and the variations of aerodynamic damping ratios were also discussed. Wind-induced responses were predicted by the unsteady aerodynamic forces and compared with the measured values. The experimental results show that vortex-induced aeroelastic effects on the wind-induced responses and the unsteady aerodynamic forces are significant. An increase in the turbulence intensity may result in a weak correlation of the unsteady aerodynamic forces and thus suppress the vortex-induced aeroelastic effects. Moreover, the amplitudes of the positive and negative peaks of the aerodynamic damping ratios decrease with the increase of the turbulence intensity. In addition, the wind-induced responses predicted by the unsteady aerodynamic forces measured from the aeroelastic model are the closest to the measured responses. [ABSTRACT FROM AUTHOR]

Due to the strike of wind-blown raindrops, the pressure caused by wind and rain on building facades is different from the action of wind-only. The wind–rain induced pressure during Typhoon Haikui (2012) was collected at three taps on the windward side of Tongji University experimental building which was located near the coast of East China Sea. The observed data during the storm was compared with both the data of normal wind events without rains and wind tunnel test. The results show that the presence of driving rains intensifies the wind effects acting on the windward side of the building. More specifically, the mean wind–rain induced pressure coefficients at the three locations of the experimental building are larger than those collected from the strong wind-only events and the wind tunnel test when the wind direction ranges from 110° to 130°. It was also found that the mean wind–rain induced pressure coefficients at each tap increase in magnitude with rainfall intensity and the distance between the pressure tap and the wall corner. Similarly, the fluctuating wind–rain induced pressure coefficients are larger in comparison to the wind-only pressure coefficients from the full-scale measurement and wind tunnel test. However, the coefficients decrease with the distance from the wall corner in the case of 80°–140° wind directions. In addition, it was found that Gamma distribution is a robust model to represent the probability distribution of the wind–rain induced pressure coefficients. High quality of pressure correlation was observed among three taps, regardless of the rainfall intensity. By contrast, the presence of driving rains slightly reduces the correlation of wind–rain induced pressure. [ABSTRACT FROM AUTHOR]

Gable roofs with overhangs (eaves) are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative (block) pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future’s modification of wind load codes. [ABSTRACT FROM AUTHOR]

A series of wind tunnel tests were conducted to investigate the effects of parapets of different configurations and various heights on the wind loading of a flat-roofed low-rise building. Local wind pressures, area-averaged peak pressures, and overall roof uplift force on the roof were determined. Spectral analysis was also performed to better understand the mechanism of how the presence of parapets affects the wind effects on the building. Additional attention was given to the power spectral density and non-Gaussian features of the area-averaged wind pressures. The results show that low parapets (h/H no more than 0.1) often increase suctions in the roof corner region. The presence of high parapets results in a decrease in the wind effects over the roof corners; however, it also leads to a growth of the uplift force over the entire roof. Comparisons among many different parapet configurations show that the ones with the raised and bottom-slotted corners help to efficiently alleviate the worst suction on flat roofs. In addition, the high parapet acts as a low-pass filter, filters out parts of the high-frequency energy in the approach flow, and stabilizes the wind pressure distribution on roof. [ABSTRACT FROM AUTHOR]

The effects of grid curtains on the local and overall wind loads of a high-rise building are investigated in detail according to a series of wind pressure and wind force tests on rigid model in a wind tunnel. The effects of grid curtains on the mean and fluctuating wind pressures on windward and sideward walls when the wind direction is parallel to the geometrical axes are investigated, along with the effects of the most unfavorable wind pressures for all wind directions. Furthermore, the effects of grid curtains on the mean and fluctuating aerodynamic forces on the entire building are also analyzed for various wind directions, along with the effects of grid curtains on the aerodynamic force spectra when the wind direction is parallel to the geometric axes. The test results indicate that grid curtains affect the mean and fluctuating windward pressure slightly but greatly influence the large sideward negative pressures. Grid curtains increase the mean and fluctuating windward aerodynamic forces and reduce the fluctuating aerodynamic torsions. According to the aerodynamic force spectra, grid curtains can mainly affect the wind forces in the low-frequency range. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Experiments on the rectangular prisms with side ratios of 2. 0, 2.5, 3.0, 3.5 and 4. 0 are reported. Wind pressure measurements were carried out on five rectangular prisms for the testing Reynolds number Re ranging from l. 1 x 105 to 6. 8 x 105. The Reynolds number effects on the wind pressure distributions and the base pressure coefficients were studied, then the mechanisms of Reynolds number effects on rectangular prisms were described by analyzing the variation of the flow around the model. The results are summarized as follows; wind pressure distributions of five rectangular prisms are all sensitive to Re, and the Reynolds number affects the wind pressure distributions not only in the reattachment region, but also in the separation bubble. The sensitivity to the Reynolds number effects is changed with the side ratio of the rectangular prism, and the B/D = 4 .0 rectangular prism appears to be the most sensitive to the Re. Its separated shear layer is easier to reattach to the body at high Re, and the flow reattachment point moves towards the leading edge suddenly at the critical Re = 6. 8 x 105. In addition, with the increasing of Re, the absolute value of base pressure coefficient for the B/D =4. 0 prism increases firstly, and then decreases rapidly. [ABSTRACT FROM AUTHOR]

Gable-roofed low-rise buildings with ridges, protruding gable walls and eaves gutters are usually found on the southeastern coast of China, which are often invaded by typhoons. The wind effects due to ridges, protruding gable walls and eaves gutters on low-rise buildings as well as the wind loads on the architectural details themselves have been studied through a series of wind tunnel tests. The mean block pressure coefficient and the negative peak block pressure coefficient on different roof regions were compared, and architectural details' single tap pressure coefficients and drag coefficients were investigated. The study shows that each of the architectural details reduces roof wind load impact to various extents, and their coexistence has a most significant effect on decreasing roof wind loads, up to the reduction of 56% on the 'Ru' windward region for the mean block pressure coefficient, and 47% and 45% on the 'C1' and 'C2' corner regions for the worst negative peak block pressure coefficient, respectively. The worst negative peak pressure at the interior surface of the architectural details occurs when the wind blows obliquely on the exterior surface of the architectural details. This condition leads to very large peak net pressure coefficients. The worst net pressure coefficients of the protruding gable wall, ridge and eaves gutter are about 18.0, 10.5 and 6.7, respectively. Finally, the drag coefficients on the architectural details were also examined, and the results are suitable for engineering application. [ABSTRACT FROM AUTHOR]

The wind-induced responses of a large-scale membrane structure, Expo Boulevard, are evaluated in this study. To obtain the wind pressure distribution on the roof surface, a wind tunnel test is performed. A brief analysis of wind pressure on the membrane roof is conducted first and then an analysis of the wind-induced responses of the structure is carried out using a numerical integral method in the time domain. In the process of calculation, the geometrical nonlinearity is taken into account. Results indicate that mean, RSM and peak values of the structure responses increase nonlinearly while the approaching flow velocity increases. Strong nonlinear characteristics are observed in the displacement responses, whereas the responses of nodal stress and cable axial force show minimal nonlinear properties when the membrane structure is subjected to wind loads. Different values of the damping ratio only have a minimal impact on the RSM response of the structure because the background component is a dominant part of the total dynamic response and the resonant component is too small. As the damping ratio increases from 0.02 to 0.05, the RMS responses of vertical displacement, nodal stress and cable axial force decrease by 8.1%, 6.7% and 17.9%, respectively. Since the mean component plays a significant role in the wind-induced response, the values of the gust response factor are not high for Expo Boulevard. [ABSTRACT FROM AUTHOR]

The cylindrical reticulated shell structures without side walls, which are normally arranged in pairs, are usually used as dry-coal sheds in a thermal power plant. The wind loads of these shells do not exist in standards or codes. Therefore, this study investigates the mean and fluctuating wind loads on a cylindrical reticulated shell with a rise-to-span ratio of 0.39 through a series of wind tunnel tests. The characteristics of the wind pressures on the upper and lower surfaces and the net pressures are presented. The results show that the wind direction and another shell structure significantly affect the wind loads on the principal shell. The most unfavorable wind direction is around 30°, whereas the effects of the wind field and the height of the coal stack are small. The surfaces of the shells are divided into nine blocks, and the block mean and fluctuating (rms) pressure coefficients suitable for engineering applications are given as references for wind load codes. [ABSTRACT FROM AUTHOR]

Using several formulas of across-wind aerodynamic forces and aerodynamic damping of rectangular super-high-rise buildings with side ratios smaller than 2 proposed previously by the authors, across-wind equivalent static loads and responses of super-high-rise buildings are evaluated through a proper combination of resonant and background components. The resonant component is computed according to the power spectral density of the base moment and the aerodynamic damping. The background component, whose vertical distribution is derived from background moment responses at different heights and then expressed as a cubic equation of the relative height, is computed using the base moment coefficients. Furthermore, comparisons are made for the equivalent static wind loads and responses of a hypothetical typical building between the present method and the AIJ (1996) method, which indicate the applicability of the present method. Finally, the effects of background component and aerodynamic damping on the equivalent wind loads and responses are also discussed. [ABSTRACT FROM AUTHOR]

Wind loading is one of the most important loads for controlling the design of large-span roof structures. Equivalent static wind loads, which can generally aim at determining a specific response, are widely used by structural designers. A method for equivalent static wind loads applicable to multi-responses is proposed in this paper. A modified loadresponse- correlation (LRC) method corresponding to a particular peak response is presented, and the similarity algorithm implemented for the group response is described. The main idea of the algorithm is that two responses can be put into one group if the value of one response is close to that of the other response, when the structure is subjected to equivalent static wind loads aiming at the other response. Based on the modified LRC, the grouping response method is put forward to construct equivalent static wind loading. This technique can simultaneously reproduce peak responses for some grouped responses. To verify its computational accuracy, the method is applied to an actual large-span roof structure. Calculation results show that when the similarity of responses in the same group is high, equivalent static wind loads with high accuracy and reasonable magnitude of equivalent static wind distribution can be achieved. [ABSTRACT FROM AUTHOR]

This paper discusses an investigation into the interference effects on the wind-induced responses of a dry coal shed structure used for depositing coal stacks. Two interference factors, a nearby shed and coal stacks inside the shed, are considered. A wind tunnel test was conducted to obtain wind pressure distributions on the roof surface of the shed, and the results are briefly analyzed. The characteristics of the wind-induced responses of the structure and the effects of interference factors are then illustrated. The paper places emphasis on wind-induced responses and interference factors variations, and points out the situations when the maximum interference effects occur. The effects of an adjacent shed and incident wind direction are more pronounced than the spacing of adjacent sheds and coal stacks inside the shed. The most unfavorable results appear when an oblique wind blows at 45° span-wise with no interfering shed nearby, but when there is low coal stack inside. Values of the interference factor are also slightly higher than 1.0 for the maximum absolute peak responses in all cases investigated. This indicates that interference conditions magnify the peak responses of an isolated roof only minimally. [ABSTRACT FROM AUTHOR]

Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy. [ABSTRACT FROM AUTHOR]

Wind-excited responses at different wind speeds and wind directions have to be acquired before analysis of wind-induced fatigue life reliability of structures. In this paper, wind-excited response of circular line-like structure is estimated at different wind speeds and directions, the excitations from along-wind fluctuating force, cross-wind fluctuating force and self-excited force are taken into account in course of wind-excited response estimation. Some primary effects such as Reynolds number, surface roughness on the aerodynamic forces are considered based on some interrelated database in ESDU. Finally, a steel antenna of circular section as a case is analyzed. The wind induced vibration responses of the antenna obtained from computation are compared with those from the wind tunnel test of the aeroelastic full antenna model, and the comparison shows that they match well. [ABSTRACT FROM AUTHOR]

Based on an improvement of LRC method, a modified LRC method that regards peak responses as the target is proposed in the present paper. For large-span roofs, it is well known that several mode shapes should be considered in the process of equivalent inertia forces of resonant components, so the time-consuming process of computing resonant components is proposed in the new method. For the sake of considering the resonant component, each original element in background component is multiplied by a modified coefficient. Based on the modified LRC method, the response grouping principle is present to calculate equivalent static wind loads for large-span roof. The main idea is that the responses whose equivalent static wind loads are similar to each other are selected in a same group. If the calculating error of one response when the structure subjected the equivalent static wind loads aiming at other response are small, the two responses could be chosen into a same group. And the universal equivalent static wind loads of the groups are calculated based on least square principles, which can reproduce simultaneously several peak responses. [ABSTRACT FROM AUTHOR]

The interference effects of neighboring dry-coal sheds and the internal coal stacks within the investigated dry-coal shed probably make the wind-induced responses of the dry-coal shed more complicated. In order to provide a systematic method to study the characteristics of dry-coal sheds with/without interference condition, wind-induced responses are calculated in this paper. The wind-induced dynamic responses are calculated in frequency domain using mode superposition method (CQC method), based on the wind pressure distributions on roof from wind tunnel tests on the rigid models. The wind-induced responses under no-interference conditions are firstly analyzed, and the results show that the responses of some typical nodes are largest when the structure is subjected to skew wind. Through the analysis of interference factors, the characteristics of interference effects under different interference conditions and wind directions are investigated, the cases where the interference effects are stronger are pointed Out. Meanwhile, it is found that interferences only had small effect on the largest total peak displacement for the control condition. [ABSTRACT FROM AUTHOR]

• A soil-large pile group-supertall building model (SSI model) is proposed. • The wind-induced responses of SSI models are computed and parametrically analyzed. • Empirical equations of SSI factors are developed for wind-induced responses. A simplified three-dimensional soil-structural interaction (SSI) model is established for large pile groups-supertall buildings (>300 m height) to simulate the dynamic response of the building to wind loading. The displacement and acceleration responses to wind loading at the top of the supertall building are calculated using the established model. The effects of SSI on the wind-induced mean displacement, root-mean-square (RMS) displacement and RMS acceleration are analyzed considering different values of soil shear wave velocity and material damping, and different total mass, first natural frequency and damping ratio of the superstructure as well as different terrain conditions. The results from the comprehensive parametric study are used to derive empirical equations of the mean displacement, RMS displacement and RMS acceleration SSI factors. The findings demonstrate that the mean displacement of the top of supertall building increases considering SSI. As the soil shear wave velocity decreases, the mean displacement SSI factor increases. It was also found that the mean displacement SSI factor increases with the increase in total mass and first natural frequency of the superstructure. In addition, the RMS displacement and acceleration SSI factors decrease with the increase of the soil shear wave velocity and material damping. Finally, the RMS displacement and acceleration SSI factors increase as the superstructure first damping ratio increases. [ABSTRACT FROM AUTHOR]

Blockage effects on the aerodynamics of rectangular prisms, which represented isolated tall buildings, under uniform turbulent flows were investigated experimentally. Wind tunnel tests were performed on models for four blockage ratios (BR ​= ​4.1%, 6.1%, 8.4%, and 10.1%) under the uniform flows for three turbulence intensities ((I U =0.1%, 4%, and 8%) using the synchronous pressure measurement technique. The blockage effects on the surface pressure coefficient, aerodynamic force coefficient, and Strouhal number (St) were evaluated in detail, and the blockage behaviours of the aerodynamics of models under the different uniform turbulent flows were analysed. The mechanisms of the blockage effects were then revealed. It is found that wind pressures, wind forces, and St increase monotonically with the increase of BR, and the blockage effects are more significant on the fluctuating wind pressures and forces than the time-averaged ones. Additionally, the blockage effects on wind pressures and forces are suppressed with the increase of the inflow turbulence intensity. • The effects of blockage on the aerodynamics of isolated tall building models are investigated under different uniform turbulent flows. • Blockage effects are more significant on the fluctuating wind pressures and forces than on the time-averaged ones. • Blockage effects on wind pressures and forces are suppressed with the increase of the inflow turbulence intensity. [ABSTRACT FROM AUTHOR]

Wind tunnel tests were performed in low-turbulence uniform flow to measure the wind pressures on the surfaces of sixteen 2D prisms with various side ratios and chamfered corners. First, the effects of chamfered corners on wind pressure coefficients and pressure correlation coefficients on the side surfaces of models with various side ratios are analyzed. Second, the mean drag coefficients, root-mean-square (RMS) drag coefficients and RMS lift coefficients of the 16 models are discussed. Third, power spectra of aerodynamic force coefficients of the 16 models are analyzed, and the Strouhal numbers are obtained by analyzing the power spectra of lift coefficients. Finally, three typical points on the surfaces of each model are selected, and the power spectra of pressure coefficients for these points are discussed. Based on the above analysis, physical mechanisms of the effects of chamfered corners on the aerodynamic characteristics of 2D prisms with various side ratios are revealed. • The effects of chamfered corners on the aerodynamic characteristics of prisms with various side ratios was studied. • The wind pressures acting on 16 prisms in the uniform flow with a low turbulence level was measured. • The experimental results can clarify the complicated behavior of the flow field around the bodies. • The physical mechanisms of the effects of chamfered corners on the aerodynamic characteristics can be revealed. [ABSTRACT FROM AUTHOR]

Summary: When a large super high‐rise building taller than the surrounding tall buildings is built in a dense urban area, the aerodynamic interference effects of the surrounding buildings on the proposed building attract much attention, while the interference effects of the taller high‐rise building on the nearby existing buildings are often ignored. Based on a series of wind tunnel tests, the interference effects of a proposed taller high‐rise building, an adjacent equal‐height partner building, and relatively short background buildings on the target building's local wind pressures are analysed in this paper. Two‐dimensional numerical simulation are carried out to further understand the interference mechanism in some cases. The test results show that the influence of a nearby proposed taller high‐rise building may lead to wind‐induced damage on the interfered shorter buildings' envelopes. The envelope structures of other surrounding buildings facing the side of the proposed building need to be given more attention. [ABSTRACT FROM AUTHOR]

In wind resistance research involving super high-rise buildings, most studies have concentrated on increases in the wind velocity with height, but Ekman layer effects, inducing wind veering, have rarely been considered. Therefore, the main objective of this paper is to investigate the Ekman layer effects on super high-rise buildings based on computational fluid dynamics (CFD). Numerical simulations were systematically performed on a 3D square cylinder with an aspect ratio of 9:1 using the large eddy simulation (LES) method. The simulation results for three different incident mean wind profiles, including a logarithmic profile without veering, a profile with an inflection point but without veering, and a profile with an inflection point and veering, were compared to illustrate the differences in the wind loads and flow fields with and without wind veering. The results reveal that the proposed method is capable of simulating the wind veering profiles. The local wind pressure distribution on the building is considerably affected by wind veering, especially at the upper portion of the building surface. The effects of wind veering on the mean aerodynamic forces for super high-rise buildings are mainly in the aspect of Y-axis force, X-axis and torsional moment, and the fluctuations of local wind forces and base moments decrease to various degrees. • Performed RANS simulations of wind veering profiles using a modified k - ε model. • Performed LES of wind effects on a super high-rise building considering veering. • Illustrated differences in wind loads and flow fields with and without veering. [ABSTRACT FROM AUTHOR]

A recent field survey provided eight typical soffits used in the residential houses within the typhoon-prone coastal region of southeastern China. Their aerodynamic effects in alleviating rooftop extreme wind pressures were evaluated via wind tunnel testing on a series of 1/20 gable roof house models. Local pressures, area-averaged pressures and uplift forces acting on roofs were examined. Results showed that in contrast to the model without soffits, the presence of these gutters or eaves gives a rise to a significant reduction of negative peak wind pressures at edges and corners near them. However, they hardly impact wind loads on the other roof surface. Some minor simple architectural elements attached to eaves, such as cantilevered spoiler and semicircular gutter, were observed to facilitate the reduction of extreme wind pressure at edges and corners. Additionally, the reduction rate of spatially averaged wind pressures with area was found to be dependent on the size of tributary area, rather than the shape of tributary area. [ABSTRACT FROM AUTHOR]

This paper studied the loads on the configuration details of low-rise building roofs by the rigid model pressure measurement tests, which were often destroyed in wind disasters. The pressure coefficients and drag coefficients of the ridge, protruding gable wall and eaves gutter were examined, which were of varied heights and with or without the other 2 types of configuration details. The results show that the negative pressure of interior surface ( the leeward surface for the ridge) of the configuration details end varies severely and the amplitude occurs when the wind obliquely blows to the exterior surface (the windward surface for the ridge) , which leads to the very large worst peak net pressure coefficient towards the roof. The worst peak net pressure coefficients of the protruding gable wall, ridge and eaves gutter are about 18.0, 10.5 and 7.0, respectively. However the peak pressure away from the roof ( towards the windward surface for the ridge) is relatively stable. The worst peak net negative pressure of the lower tap is 5 larger than that of the higher tap on the same vertical plan of the protruding gable wall, while that of the lower tap is only O. 8 larger than that of the higher tap for the eaves gutter. When the roof is equipped with the other 2 types of configuration details, the worst peak net negative pressure coefficients of the ridge and protruding gable wall decrease much to 7.5 and 6.0 from 10.5 and 18.0, respectively, while that of the eaves gutter decreases to 6 from 7. The worst peak drag coefficients of the ridge and eaves gutter are not affected by whether the roof is attached with the other 2 types of configuration details or not, while that of the protruding gable wall is smaller when the roof is attached with ridge and eaves gutter. The worst peak drag coefficients of the protruding gable wall and eaves gutter are larger with the increase of each height. [ABSTRACT FROM AUTHOR]

The implementation of the probability analysis method on extreme wind loads considering the directionality and uncertainties of the wind load effect coefficients and wind speeds can yield accurate design wind loads. However, it is difficult to popularize this method among structural designers because its theory and calculation process are complicated. The directional design wind speeds for a given city, which are more suitable in the commonly used simplified method for estimating the wind loads (i.e., the sector-by-sector method), are obtained in this study via multi-parameter optimization. A multiple population genetic algorithm program is established for optimization based on the time histories of the wind pressure coefficients obtained from numerous wind pressure taps of different rigid models. For different structural aerodynamic characteristics, the proposed directional design wind speeds can be combined with the sector-by-sector method to obtain results that are closest to the overall reference values of the design wind pressures of all pressure taps under a certain safety guarantee. The applicability, economy, and safety of the sector-by-sector method with the proposed directional design wind speeds are discussed in comparison to other simplified estimation methods using examples of Des Moines, IA, USA, and Shanghai, China, for non-typhoon and typhoon-prone climates, respectively. • An MPGA (multiple population genetic algorithm) program was proposed to determine the directional design wind speeds. • The results of the MPGA program can significantly improve the effect of the sector-by-sector method. • The use of the results of the MPGA program does not affect the concision of the sector-by-sector method. • The results of the MPGA program can be easily reused to estimate the extreme wind pressures on different buildings. [ABSTRACT FROM AUTHOR]

Due to the fickle distribution characteristics, good approximation of the wind pressure probability density function for an entire roof is challenging, especially for tail region. Maximum entropy model (MEM) can theoretically generate the least biased distribution. However, classical MEM may lead to unreliable estimates of the corresponding integer moments. This study developed a new maximum entropy model with fractional moments. There are several important features: A new translation function is introduced, thus allowing negative data to be modeled. For a good bias-variance trade-off, the constraint number M was fixed as four. After estimating the initial value of the Lagrange multiplier λ by a computationally simple linear equation system, a simple search was carried out to find a better solution. The generalized pattern search was adopted for determining the global optimal solution for the fractional moment orders α. The performance was benchmarked through typical field measurement data of wind pressures on the roof of a low-rise building under typhoon conditions. Compared with common models, the proposed method had better performance and more stable results for the dataset examined for the whole roof. This method is also beneficial for peak value evaluation and the simulation of wind pressures. • A new approach is proposed for PDF estimation of wind pressures by maximum entropy model with fractional moments. • New translation function to allow fractional moments to be applied for wind pressures. • New algorithms to optimize the Lagrange multiplier and the fractional moment orders. • The model performance is investigated using measured wind pressures of a low-rise building during Typhoon Muifa. [ABSTRACT FROM AUTHOR]

Predicting structural responses under joint action of wind and snow loads is important in ensuring the safety of lightweight roof structures in snowy regions. In this paper, a series of similarity parameters that should be satisfied in the wind tunnel test to simulate structural responses under joint action of wind and snow loads are proposed from the perspective of similarity of wind field, particle movement, flow around the building, and structural dynamics. Then, with a double-pitched roof structure as research object, an aeroelastic model test with substituted snow particles is designed and structural responses are obtained through the wind tunnel test. The other two types of tests, namely, aeroelastic model test with additional weights and pressure measurement test, are also conducted; their results are compared with those of the aeroelastic model test with substituted snow particles. The mean and RMS response of the other two types of tests are both significantly lower than those of the aeroelastic model test with substituted snow particles. The preliminary conclusion is that wind-induced structural vibration is influenced by snowdrift and possible asynchronous vibration of the particle layer and roof structure, which could lead to a considerable increase in structural dynamic responses. [ABSTRACT FROM AUTHOR]