Design Wind Speed Research Articles

Revisiting design wind speed and cyclonic factor for east coast of India

It is very much challenging to estimate the accurate design wind speed for engineering structures of India, those experiencing extreme wind events such as cyclones. However, there are different categories of structures based on their importance level and a trade-off always exists between structural safety and economy. Indian code IS15498 specifies uniform cyclonic factors. However, a wide variation has been found while considering different return periods and threshold wind speeds above which cyclones have been modelled. Accordingly, a cyclonic factor (k4) has been calculated using three distinct approaches. These include the Gumbel distribution with the Generalized Least Squares Method (GLSM), the Generalized Extreme Value distribution with the Least Squares Method, and the Peaks over Threshold approach employing the De Haan method. These methods were applied to the dataset of peak values from all cyclone events to determine the design wind speed and, subsequently, the cyclonic factor. The analysis shows that Gumbel distribution with GLSM provides the best results with 1.03 value of cyclonic factor. Reverse Weibull can also be used to fit the extreme wind speed data. The outcomes from all approaches consistently underscore the necessity of a cyclonic factor for the east coast of India.

Improved Hawaii Basic Design Wind Speed Maps Including Topographic Effects

Improved Hawaii Basic Design Wind Speed Maps Including Topographic Effects

Non-stationary winds effects over large partially-open roofs: A CFD study regarding the role of unsteady aerodynamics

Non-stationary winds are increasingly attracting the attention of the scientific community and, despite not being explicitly considered in current design practice, they are known to produce important damages. In particular, the non-stationarity of such events has important consequences with respect to four main aspects which affect the definition of design wind loads: (i) the design wind speed definition, (ii) the wind profiles, (iii) the calculation of the structural response and (iv) the insurgence of unsteady aerodynamics effects. While the first three aspects already received considerable attention, the last one is still largely unclear and its relevance still to be assessed. In particular, for non-stationary winds such as macro- and micro-downbursts, the ramp-up time might become so short to trigger unsteady aerodynamic effects in the overall flow arrangement, which cannot be inferred from results obtained for stationary cases. In this paper, we propose a first investigation of such matter considering a large stadium roof using Large Eddy Simulations. Results show that, for the considered case, noticeable unsteady aerodynamic effects, which leads to an amplification of wind loads, can be triggered when the wind rump-up time is in the order of 30 s, and quickly decrease in importance for higher rump-up times.

A Conceptual Study of Wind Load With Different Types of Lateral Load Resisting Methods in 15-Storey Structure

Abstract: In order to strengthen rigidity and control the base deflection of a high-rise structure, stabilizers and trusses are typically used. A stabilizing layer on the building's roof efficiently fortifies the structure. Lateral stiffness is increased by each succeeding stabilizer layer, albeit less so than by the preceding stabilizer layer. The essential components in multi-storey buildings that can withstand shear forces are the shear walls. More efficient shear walls are required as building code requirements rise and tall structures and skyscrapers get taller. The ductility, energy dissipation capacity, and deformation capacity of conventional reinforced concrete shear walls are limited. In the field of structural engineering, a damper in a building is a device intended to lessen the impact of dynamic forces like seismic vibrations or oscillations caused by wind. These devices are necessary in tall or flexible constructions where excessive movement may cause structural damage or cause discomfort for the residents. In this research, we prepare four different cases of 15-storey structure. All modeling work performed in ETABS 2016. Material properties use concrete grade M-40 and steel grade Fe375 and Fe250. One case has shear walls on corners, second case have FVD damper on corners and last case have outrigger on corners. For design wind speed data use code IS: 875-(2015).

A corner protrusion strategy for the aerodynamic response mitigation of tall buildings with the aim of using non-structural components

Side protrusion, i.e., the addition of material on the side of a tall building, has been demonstrated as an effective strategy to mitigate the aerodynamic responses under a broad range of design wind speeds. This study investigates the possibility of producing similar behavior of side protrusion via a corner protrusion strategy. The proposed strategy is evaluated using two parameters, which are the gap ratio (GR) and the protrusion ratio (PR). High-frequency force balance (HFFB) wind tunnel testing was carried out to examine the aerodynamic performance of ten models under different wind angles. The results demonstrate that the corner protrusion strategy can achieve similar performance as the side protrusion strategy using nonstructural components (NCs). The reductions of base overturning moment (OTM) for model CP-14–86 are 33%, 39%, 33%, and 24% at the mean hourly design wind speeds (cities) of 42 m/s (San Francisco), 53 m/s (New York), 62 m/s (Houston), and 77 m/s (Miami), respectively. The effectiveness of the corner protrusion strategy occurs when the PR is larger than 6%. The benefits of using NCs to reduce wind responses of tall buildings are discussed, which is expected to be a competitive aerodynamic strategy not only for new buildings but also for retrofitting existing buildings.

Wind Mapping of Malaysia Using Ward’s Clustering Method

Malaysian wind maps used in wind analysis and engineering design are dated back to the last 50 years of wind data. Cotemporally, the mean wind speed was used as the basic wind design and due to changes in the weather condition worldwide, wind monitoring assumption and structure design are jeopardized. Therefore, this study aims to map the wind based on the trend of the highest wind speed recorded. The wind speed was analyzed based on a trend basis. The study included 42 Malaysian Metrological Department weather stations and the annual wind speed was acquired based on the monthly highest wind speed (1990–2019). The data were then processed using the 95% confidence interval method to determine the mean of the month, and the annual wind trendline was obtained. The trendline was then clustered using Ward’s method with the assistance of the high-level programming language, PYTHON v3.11.6. The clustering analysis produced two clusters for the Malaysian Peninsula and two for Sabah and Sarawak. The recommendation is to use the highest wind speed recorded on the map as the design wind speed. The recommendation is expected to help experts to compensate for the uncertainties in wind speed during the design stage and avoid incidents in the field.

Examination of Wind Impacts on RCC Frame Structures in Different Wind Zones

Reinforced refers to a structurally sound assemblage of carefully joined slabs, beams, columns, and foundation components. Through the use of this complex network, loads are systematically transferred from slabs to beams, then to columns, converge at the foundation, and finally travel to the soil beneath. This structural analysis offers a thorough investigation of load-carrying dynamics by examining multiple scenarios for the same structure while accounting for varying wind speeds. A G+9 storey building is subjected to a comparative evaluation in three different wind zones (I, II, and III) with corresponding wind speeds of 33 m/s, 39 m/s, and 44 m/s. The structural behaviour is carefully modelled and examined under the impact of dead load, live load, and wind load using sophisticated STAAD Pro software. This thorough analysis clarifies the structure’s unique reactions to different wind speeds. In order to determine the design loads of a multistorey building, this paper gives a comparative assessment of wind load. Then, using the fundamental wind speed and other local characteristics, the wind load in that zone may also be calculated. The wind speed is time-dependent and random, though. The current study uses the IS 875 code to analyse wind loads in different zones of a multistorey building. The design wind speed of that zone, with a variance, is used to estimate the wind loads.

Wind Loads on Rooftop Solar Panels for a Flat-roof Cubic Building

Objective: Rooftop solar installations may be susceptible to significant damage during strong winds. With the increase in solar photovoltaic generation, most building wind codes need to be updated to provide relevant wind resistance design information. The present study aims to estimate wind loads on rooftop solar panels for a cubic building under the design wind speed specified by the Swiss wind code. Methods: Wind tunnel tests and computational fluid dynamics modeling were carried out to determine lift force coefficients for rooftop solar panels on a cubic building. The tests involved a single panel connected to a force balance, and in a subsequent phase, a panel array with pressure taps located on the upper and lower surfaces of the panels. The computational model was initially validated using measured data, and then wind loads were computed under an atmospheric boundary layer profile for the design wind speed. Results: Lift force coefficients for rooftop solar panels on a cubic building were measured and computed for various building orientations. When the flow directly impinged on the lower face of the panels, maximum lift coefficients as high as 0.7 were computed. Conclusion: Adding shielding backplates, ensuring system porosity, and mounting panels together are effective strategies for reducing loads.

Robustness Evaluation of Aerodynamic Flutter Stability and Aerostatic Torsional Stability of Long-Span Suspension Bridges

Structural robustness is defined by the international engineering community as the capabilities of structural systems that enable them to survive unforeseen or unusual circumstances. In order to highlight the unforeseen and unusual characteristics of wind hazards, this study introduces the concept of structural robustness into the wind-resistant design and evaluation of bridges and proposes the robustness evaluation of aerodynamic flutter and aerostatic torsional stability of long-span bridges. Furthermore, the return period of the design wind speed that a bridge can resist is used to represent wind-resistant robustness. Aiming at the problem of aerodynamic and aerostatic stability, the analysis methods of aerodynamic flutter stability robustness and aerostatic torsional stability robustness of long-span suspension bridges are respectively established. Based on the established methods of aerodynamic flutter stability and aerostatic torsional stability robustness evaluation, robustness analysis is carried out on eight completed long-span suspension bridges and two long-span suspension bridges to be built. The evaluation method proposed in this study makes it possible to measure the ability of bridge structures to resist multiple disasters using the same index.

Bias and variance reduction of high return levels for extreme hazard modelling

AbstractMany existing extremal data span only a few decades that result in large uncertainty in the estimated shape parameter of the extreme hazard model. This in turn leads to potentially large bias and variance of extrapolated extreme values at high return levels. This paper illustrates a statistical method that helps obtain hazard models that produce estimates at high return levels with reduced bias and variance. This method makes use of the maximum recorded values of extremal data that are independently recorded from a number of observational sites or generated by heterogeneous mechanisms. The logarithmically transformed average recurrence interval of the maximum recorded value at a site is shown to follow the Gumbel (Type I extreme value) distribution; therefore, multiple, say $$m$$ m , observational sites provide a sample of size $$m$$ m log-transformed average recurrence intervals, each from a distinct site. The sample can be treated as a sample from a Gumbel distribution, irrespective of the underlying hazard-generating mechanisms or the statistical hazard models. Application of the method is illustrated by analysis of the extreme wind gust data from automatic weather stations in South Australia and shown to lead to significant reduction of 2.9 m/s in potential bias of the mean and a reduction of 98.1% in variance of the 500-year gust speed at Adelaide Airport. The results are compared to the specifications in the Australian standard AS/NZS 1170.2:2021 and indicate that the standard may have overestimated the wind gust hazard; hence, the specified design wind speeds may fall on the conservative side for South Australia.

Influence of reduced drag load on stay cables on the construction cost of cable-stayed bridges: Two study cases

Rain–wind–induced vibrations (RWIVs) can cause the large-amplitude vibration of flexible cables in cable-stayed bridges; such vibration is one of the engineering safety problems that must be resolved. Currently, aerodynamic measures, such as dimples and spirals, are typically used as measures for suppressing vibration in stay cables. By calculating and comparing the equivalent static wind loads (ESWLs) of six typical cable-stayed bridges, the proportion of ESWL acting on the cable to that acting on the entire bridge increases approximately linearly with the bridge span. Hydrophobic coating can effectively suppress RWIVs and evidently relieve the ESWL. Hence, compared with the commonly used aerodynamic measures with surface roughness, this coating has a considerable potential as an alternative for suppressing vibration. Based on the foregoing, the wind resistance design optimization of two actual cable-stayed bridges with main spans of 420 and 1160 m is implemented to investigate the construction costs of cable wind load reduction. After optimization, the structural responses of the main towers are reduced by 4%–12%, and the optimized tower and foundation sizes are reduced by 5%–8%. The optimization for the two bridges exceed 5% and 7%, respectively. The construction investment savings are approximately 2.3 million and 7.2 million USD, respectively. These values further improve with increasing bridge span and design wind speed.

Surrogate-based cyber-physical aerodynamic shape optimization of high-rise buildings using wind tunnel testing

This study proposes a surrogate-based cyber-physical aerodynamic shape optimization (SB-CP-ASO) approach for high-rise buildings under wind loading. Three components are developed in the SB-CP-ASO procedure: (1) an adaptive subtractive manufacturing technique, (2) a high-throughput wind tunnel testing procedure, and (3) a flexible infilling strategy. The downtime of the procedure is minimized through a parallel manufacturing and testing (llM&T) technique. An unexplored double-section setback strategy with various cross-sections and transitions positions is used to demonstrate the performance of the proposed procedure. A total of 173 physical specimens were evaluated to reach the optimization convergence within the reserved testing window. Further analysis of promising shapes considering multiple design wind speeds is suggested to achieve target performance objectives at various hazard levels. Practical information on setback and cross-section modification strategies is discussed based on the optimization results. In comparison with a square benchmark model, the roof drifts for promising candidates with similar building volumes are reduced by more than 70% at wind speeds higher than 50 m/s. This procedure is expected to provide an efficient platform between owners, architects, and structural engineers to identify ideal candidates within a defined design space for real-world applications of high-rise buildings.

Duration of extreme synoptic wind speeds for North America in a changing climate and its engineering implementation

In modern wind engineering practice, wind load effects are often defined as a function of a basic design wind speed, an aerodynamic force coefficient, several multipliers to consider surrounding terrain, topographic effect, and the directionality of the wind climate. Among these variables, the basic design wind speed is associated with an averaging time (also known as gust duration), e.g., 0.02-second, 3-second, 10-minute, or one hour. The design level aerodynamic force coefficients are defined as a specific percentile within a reference period, representing the generic time duration of wind events, i.e., wind duration, which is assumed to be one hour. A recent study showed that the hurricane wind duration could differ from this assumption. There has not been any study that investigated synoptic wind duration and its engineering implementations comprehensively. It is also unclear whether climate change impacts the synoptic wind duration. Historical records, often less than 50 years, are insufficient to calculate the wind duration for threshold wind speeds at a higher return period. Therefore, this study employed 15 long-term hourly wind speed simulations covering most of North America, each of which has 70 years in the past (1050 years in total) and 80 years into a future changing climate (1200 years in total), to investigate the wind durations in the current and future changing climate. It was found that the durations for winds of about 700-year return period are close to the traditionally assumed one hour and have limited effects on the wind loads for the strength design. However, wind durations can be much longer than one hour for the lower return period level wind speeds, which can impact the wind responses for serviceability limit state design and cladding and component (C&C) design.

Characterizing wind-structure interaction for performance-based wind design of tall buildings

Performance-based wind design (PBWD) has been receiving a great deal of attention from the wind and structural engineering communities. This is specifically highlighted with the release of the ASCE pre-standard for PBWD (2019). The PBWD of tall building requires a series of steps one of which is the interaction parameter, i.e. characterizing the interaction of the tall building with the wind field. In the studies involving slender structures-such as tall buildings, it is essential to consider this interaction parameter which is a function of the time-varying aerodynamic loads. The aerodynamic loads consist of the turbulent loads due to fluctuating wind, known as buffeting loads, and the self-excited loads resulting from the interaction of the structural motions with wind, referred as aeroelastic loads. Flexible structures can become unstable at a critical wind speed, known as flutter speed, wherein a diverging motion of the structure occurs. Aerodynamic instability that is caused by self-excited loads generally doesn’t occur in tall buildings within their design wind speeds but certainly needs to be considered in a wind-structure interaction analysis, particularly when tall buildings become increasingly slender and are allowed to enter post-elastic region. This study aims to characterize the interaction parameter in the PBWD of tall buildings by including the self-excited loads in its response analysis corresponding to the three-degree-of-freedom response motions of the building in along-wind, across-wind, and torsional directions. For this purpose, the flutter derivatives that are used to represent the self-excited loads in frequency domain are first obtained from wind tunnel tests of scaled section models of the structure and then converted into approximate coefficients known as Rational Function Coefficients (RFC) as part of Rational Function Approximations (RFA) of the self-excited loads in Laplace or time domain. The wind loads on a structure in time domain are calculated by combining both the buffeting loads and self-excited loads associated with the calculated RFC. The non-linear structural behavior of a 44-story and a 60-story tall building each is studied using nonlinear dynamic time-history analysis in extreme wind conditions and then observed for any flutter-like instabilities. The concept PBWD is applied considering the performance objective involving those associated with occupant comfort and structural or non-structural damages.

Comparative analysis of self supporting steel chimney subjected to wind load by IS: 875 (part-3) – 1987 and IS: 875 (part-3) – 2015

Steel chimneys are used for releasing smoke in various power plants, oil and gas industries. Steel chimneys are generally subjected to static and dynamic loads. Geometry of steel chimney like height, diameter at top and bottom plays key role when structure subjected to lateral loading like wind or earthquake. In this study static analysis is conducted on a self-supporting steel chimney of height 90 m subjected to wind load located in Vijayawada for categories 1, 2, 3 and 4. For comparison of IS: 875 (part-3)-1987 to IS: 875 (part-3)-2015, variation of Terrain, height and structure size factor (K2), Design wind speed (VZ), Design wind pressure (PZ), segment moment with respect to chimney base and corresponding segment base of all categories are considered in this study, as basic dimensions of chimney, basic wind speed (Vb), probability factor (K1) and topography factor (K3) are same for both codes. From the study it is found that K2,VZ,PZ, segment moment with respect to chimney base and segment base of all categories are more for IS: 875 (part-3)-2015 than IS: 875 (part-3)-1987. VZ, PZ, segment moment with respect to corresponding segment base of all categories for IS: 875 (part-3)-2015 increases because of Importance factor for cyclonic region (K4).

Effects of side and corner modification on the aerodynamic behavior of high-rise buildings considering serviceability and survivability

This study explores the complementary effects of side and corner modification on the aerodynamic behavior for high-rise buildings across representative design wind speeds. Twelve doubly-symmetric prismatic models were examined using high-frequency force balance (HFFB) wind tunnel testing at the University of Florida. The effectiveness of the aerodynamic strategies was quantified using roof drift and roof acceleration under different design wind speeds covering serviceability and survivability. The results show that both corner and side modifications can achieve promising aerodynamic performance under high design wind speeds. However, the effectiveness of the aerodynamic strategies is significantly reduced under low design wind speeds. With a corner modification strategy, the vortex shedding frequency is increased, leading to worse across-wind response at lower design wind speeds when compared to the square benchmark model. To address this issue, side modifications (i.e., side protrusions) can be used to preserve the vortex shedding frequency and achieve competitive aerodynamic performance while simultaneously maintaining the floor area and geometry. This research explores new aerodynamic modification options for owners, architects, and structural engineers with the aim of better aerodynamic performance for high-rise buildings without compromising other design objectives.

Local topography factor for design wind speeds near and on the escarpment with gentle slope

Local topography factor for design wind speeds near and on the escarpment with gentle slope

An Integrated Estimating Approach for Design Wind Speed under Extreme Wind Climate in the Yangtze River Inland Waterway

Developing the engineering design standard of wind speed is a key aspect of the climate research in the Yangtze River Inland Waterway (YRIW), which is highly sensitive to extreme weather and climate processes. An engineering design wind speed projection model was established to evaluate the distribution of extreme wind speeds in the YRIW region at spatiotemporal scales from 1979 to 2100, integrating the Weibull distribution and generalized extreme value (GEV) distribution characteristics. We also used high-precision climate model products and integrated analysis methods to predict the evolution of engineering design wind speeds in the study area in the future. The results show that: (1) The maximum wind speed in the study area shows a decline—recovery trend in the historical period in general and a weak increase in Wuhan and Shanghai. (2) The maximum wind speed does not follow the Weibull distribution, and the extracted extreme wind speed types include type I, II, and III GEV distributions. (3) The updated inland port project design wind speed can meet the climatic and topographic characteristics of the YRIW. (4) The model of CNRM-CM6-1-HR product accurately captures the spatial and temporal characteristics of the maximum wind speed. (5) In the future, the design wind speed shows a slight decrease in Shanghai, Jiujiang and Yueyang. These findings provide a scientific theoretical reference and engineering reference for the development of design wind speeds for inland port projects at various cross-sections in the YRIW.

Extreme wind speed prediction in mountainous area with mixed wind climates

In addition to common synoptic wind system, the mountainous terrain forms a local thermally driven wind system, which makes the mountain wind system have strong terrain dependence. Therefore, in order to estimate the reliable design wind speeds for structural safety, the samples for extreme wind speeds for certain return periods at mountainous areas can only come from field measurements at construction site. However, wind speeds measuring duration is usually short in real practice. This work proposes a novel method for calculating extreme wind speeds in mountainous areas by using short-term field measurement data and long-term nearby meteorological observatory data. Extreme wind speeds in mountainous area are affected by mixed climates composed by local-scale wind and large-scale synoptic wind. The local winds can be recorded at construction site with short observatory time, while the extreme wind speeds samples from synoptic wind climate from nearby meteorological station with long observatory time is extracted for data augmentation. The bridge construction site at Hengduan Mountains in southwestern China is taken as an example in this study. A 10-month dataset of field measurement wind speeds is recorded at this location. This study firstly provides a new method to extract wind speed time series of windstorms. Based on the different windstorm features, the local and synoptic winds are separated. Next, the synoptic wind speeds from nearby meteorological stations are converted and combined with local winds to derive the extreme wind speeds probability distribution function. The calculation results shows that the extreme wind speed in the short return period is controlled by the local wind system, and the long-period extreme wind speed is determined by the synoptic wind system in the mountain area. The descending slope of the synoptic wind speed exceeding probability exceeds the local wind by about 20%. If the influence of mixed climate is not considered, and the wind speed samples are not divided by category, the decline slope will be 7% lower.

Experimental study of wind-induced dynamic response and collapse of a mechanically-attached membrane roofing system installed on metal substrate of flat-roofed low-rise steel building

This paper investigates the wind-induced dynamic response at design wind speed and the collapse of a mechanically-attached membrane roofing system installed on metal substrate of flat-roofed low-rise steel building, based on a wind pressure loading test using full-scale assembly specimens. Three kinds of waterproofing membranes with different mechanical properties are tested. The wind loads employed in the test are generated by using the time histories of wind pressure coefficients on the roof of a flat-roofed low-rise building with low parapets, which were obtained from a wind tunnel experiment. Both the temporal and spatial variations of wind pressures are reproduced by using three Pressure Loading Actuators (PLAs). A step-wise pressure loading test commonly employed in the conventional wind-resistant performance evaluation in Japan is also carried out for a comparative purpose. The results indicate that the fasteners connecting the disks with the metal substrate are subjected to not only vertical uplift forces due to negative wind pressures (suctions) but also horizontal forces related to the membrane deformation. The maximum value of horizontal force is nearly equal to that of the vertical force. Although the general correlation between vertical and horizontal forces is not so high, the maximum values of these forces may occur almost simultaneously. Larger the membrane deformation, larger the horizontal forces are. The horizontal forces reduce the failure loads and affect the failure modes significantly. Therefore, the effect of horizontal forces should be considered in the evaluation of wind-resistant performance of mechanically-attached membrane roofing systems. The failure load under step-wise pressure is generally smaller than that under fluctuating wind pressures. Therefore, the conventional step-wise pressure loading test can be used as a simple method for evaluating the failure load of the roofing system on the safer side.