High Wind Pressure Research Articles

Progressive failure of asphalt shingles under high winds: Assessment via full-field deformation measurements on full-scale roof panels

Failures of roof asphalt shingles under high winds have been reported to occur at wind speeds lower than the shingle performance classification. The understanding of the progressive failure mechanisms of shingles subjected to high-wind pressures has been hindered by difficulty in accurately quantifying uplifts and wind-induced pressures with high spatial resolution, especially for large-scale wind test setups that simulate realistic scenarios. This paper reports on an experimental study to assess the use of three-dimensional digital image correlation (‘StereoDIC’) to accurately measure full-field surface deformations of shingles installed on full-scale roof structures and subjected to realistic high winds. Deformation measurements were acquired on shingles installed on typical wood-frame roof panels and subjected to winds with speed up to 257 km/h (160 mph) using an outdoor wind tunnel. The specimens were designed to study the proposed test setup and StereoDIC measurement method for two different combinations of shingle surface coloration (and thus speckle pattern) and field of view. The experiments produced accurate local and full-field shingle deformation measurements. Different datasets were used to gain new insight into the influence of salient aspects of the wind test setup and deformation measurement method on the understanding of the temporal evolution of shingle uplift and failure mechanisms.

Investigation of the Effect of the Wind Speed on the Aerodynamic and Architectural Design of Tall Buildings

The magnitude, speed, direction, and distribution of the wind are known to have a negative impact on high-rise buildings, particularly when the building is extremely tall. As the height of the building increases, the effect of the wind increases significantly. This results in a high wind pressure exerted on the building which causes the wind loads subjected by the buildings to increase considerably. Thus, this study investigates the wind effect on tall buildings and proposes a solution to reduce the aerodynamic drag through a design that meets both architectural and aerodynamic considerations. Investigation of wind effect on tall buildings with different wind speeds, heights and shapes is carried out. Numerical methods are utilized to study the wind pressure, drag coefficient and pressure distribution on different types of buildings. ANSYS Fluent is used for computational fluid dynamics (CFD) simulation to assess the drag coefficient of the buildings. The drag coefficient of the building is determined in Reynold’s number range of 1×106 to 2×106. The study is conducted in low subsonic speed (Ma < 0.3). The result shows that the drag coefficient of the building tends to be constant at low subsonic speeds. Besides, the study found that the drag coefficient increases by 1% to 3% for every 0.1 m increment in the height of the building. The study also found that a cylindrical building has the lowest drag coefficient because of its more streamlined shape. Overall, this study provided guidance and recommendations for wind resistance which can be taken into consideration when designing tall buildings. Hence, the building can be built even taller while maintaining its rigidity and stability.

Research on the Influence Mechanism of Outdoor Wind Environment on Indoor Smoke Exhaust Efficiency in the Super-High-Rise Tower Crown Based on Airpak Simulation

The high wind pressure and velocity of the outdoor environment make super-high-rise tower crown space distinct from general tall through space. This segregation causes the crown space to be particularly prone to smoke short-circuiting influenced by the outside wind environment if a fire occurs indoors, and causes deficient smoke exhaust efficiency in a fire. The goal of this study was to investigate the general principle regarding the effect of the outdoor wind environment on smoke exhaust efficiency of such spaces under the crown space. We measured external wind direction and wind pressure in the smoke exhaust in the tower crown and developed setting plans for the exhaust outlets and make-up air inlet. Airpak was used to create the external wind environment and compare simulations to see if smoke short-circuiting occurred. We analyzed the causes, summarized solutions that did not result in short-circuiting of smoke flow, and made adjustments. We provide an ideal plan for the setting direction and vent velocity of the make-up air inlet and exhaust outlet in the crown spaces of super-tall towers to improve the design of smoke exhaust systems in such spaces.

Association between meteorological factors and elderly falls in injury surveillance from 2014 to 2018 in Guangzhou, China

IntroductionWith rapid increase in the aging population, falls injuries have become an important public health problem. However, limited data have been reported on the associations between meteorological factors and falls injuries in the elderly. This study assessed the epidemiology of falls injuries and explored this association in the elderly in Guangzhou, China. MethodsData on elderly falls injury cases and meteorological variables from 2014 to 2018 in Guangzhou were collected from the Guangzhou Injury Monitoring System and Guangzhou Meteorological Bureau, respectively. The monthly average data on falls injuries and meteorological factors were applied to the data analysis. These correlations were conducted using Pearson correlation analysis. A multiple linear regression model was used to estimate the effects of meteorological factors on falls injuries in the elderly in Guangzhou, China. ResultsAccounting for 49.41% of causes of elderly injury were falls in the Guangzhou Injury Monitoring System from 2014 to 2018, which occupied first place for five consecutive years. The monthly number of elderly falls injury cases was lowest in April and highest in December, and had a positive correlation with monthly mean wind speed (r = 0.187, P < 0.01) and a negative correlation with monthly atmospheric pressure (r = -0.142, P < 0.05). A multiple linear regression model was constructed (F = 10.176, P < 0.01), which explained 23.7% of the variances (R2 = 0.237). Monthly mean wind speed (β = 76.85, P < 0.01) and monthly mean atmospheric pressure (β = −3.162, P < 0.01) were independent factors affecting monthly elderly falls injuries. ConclusionsFalls are the primary cause of injury among elderly people in Guangzhou, China. Meteorological factors are related to falls injuries in the elderly population. Decreasing activity during high wind and low atmospheric pressure weather may help reduce the number of elderly falls injury cases.

Deep learning-based early weed segmentation using motion blurred UAV images of sorghum fields

Weeds are undesired plants in agricultural fields that affect crop yield and quality by competing for nutrients, water, sunlight and space. For centuries, farmers have used several strategies and resources to remove weeds. The use of herbicide is still the most common control strategy. To reduce the amount of herbicide and impact caused by uniform spraying, site-specific weed management (SSWM) through variable rate herbicide application and mechanical weed control have long been recommended. To implement such precise strategies, accurate detection and classification of weeds in crop fields is a crucial first step. Due to the phenotypic similarity between some weeds and crops as well as changing weather conditions, it is challenging to design an automated system for general weed detection. For efficiency, unmanned aerial vehicles (UAV) are commonly used for image capturing. However, high wind pressure and different drone settings have a severe effect on the capturing quality, what potentially results in degraded images, e.g., due to motion blur. In this paper, we investigate the generalization capabilities of Deep Learning methods for early weed detection in sorghum fields under such challenging capturing conditions. For this purpose, we developed weed segmentation models using three different state-of-the-art Deep Learning architectures in combination with residual neural networks as feature extractors.We further publish a manually annotated and expert-curated UAV imagery dataset for weed detection in sorghum fields under challenging conditions. Our results show that our trained models generalize well regarding the detection of weeds, even for degraded captures due to motion blur. An UNet-like architecture with a ResNet-34 feature extractor achieved an F1-score of over 89% on a hold-out test-set. Further analysis indicate that the trained model performed well in predicting the general plant shape, while most misclassifications appeared at borders of the plants. Beyond that, our approach can detect intra-row weeds without additional information as well as partly occluded plants in contrast to existing research.All data, including the newly generated and annotated UAV imagery dataset, and code is publicly available on GitHub: https://github.com/grimmlab/UAVWeedSegmentation and Mendeley Data: https://doi.org/10.17632/4hh45vkp38.4.

Geosynthetic as Sustainable Materials for Earthquake resistant of Masonry Structures

When exposed to simultaneous in-plane and out-of-plane behaviour generated by earthquakes or high wind pressure, unreinforced masonry (URM) walls are vulnerable to failure. The paper presents the performance of brick masonry panels using non-woven geotextile in-plane shear and out-of-plane bending experimentally tested. The panels were reinforced with a diagonal geometric pattern on both sides. From the laboratory assessment, it was determined that geosynthetic enhancement significantly improved the capacity of load carrying, displacement capacity, bending moment, stiffness, diagonal shear, in-plane shear, and flexural strength with higher performance for both cases in the case of the cross pattern. In contrast to the un-strengthened panel, experimental findings have demonstrated a less fragile behaviour. Geosynthetics can therefore be preferably suited for strengthening the brick masonry panel in order to defend brick constructions in seismic populated places.

Electrostatic Air Filtration by Multifunctional Dielectric Heterocaking Filters with Ultralow Pressure Drop.

In air filtration, for creating healthy indoor air, there is an intrinsic conflict between high filtration efficiency and low wind pressure drop. In this study, we overcame this conflict by developing new dielectric heterocaking (HC) filters, in which high relative dielectric constant (εr) materials were heterogeneously loaded on traditional polymer fibers. The dielectric HC filters in an electrostatic polarizing field generate a great amount of charges on their surface, leading to a strong attraction to precharged aerosol particles, and result in high filtration efficiency. Observing via a charged coupled device camera, the migration speed of aerosol smoke particles toward the polarized HC fiber exceeded those toward the unpolarized HC fiber by a factor of 6. We loaded high-εr HCs including manganese dioxide (MnO2), activated carbon, zinc oxide (ZnO), copper oxide (CuO), and barium titanate (BaTiO3) on polyurethane foams using a fast and large-scale roll-to-roll gel squeezing method. Based on the experimental results, when HCs had a εr larger than 5.1, an increased εr did not benefit electrostatic filtration efficiency for aerosol particles much, but resulted in a larger net ozone production. We suggested a MnO2-HC filter for efficient and multifunctional filtration of indoor particles, ambient ozone, and formaldehyde with only 3.8 Pa pressure drop at 1.1 m/s filtration velocity. This efficient and cost-effective dielectric HC filter opens a new avenue for the design of multifunctional filters, which will facilitate its large-scale production and commercial application in the ventilation system for healthy buildings.

Experimental evaluation of permeable cable-supported façades subjected to wind and earthquake loads

In building engineering, non-structural components represent a significant cost of the overall budget of a construction project. However, in many cases their design is essentially based on architectural criteria rather than on structural performance mainly because the structure stability does not necessary rely on them. Among nonstructural elements, façades are one of the most visible and expensive components where innovation is very popular. Permeable cable-supported façades are a recent frontage proposal designed to allow not only flexible exterior finishes, but also the flow of natural light and the apparent building transformation according to the daytime and light; however, their structural performance for wind and earthquake loads is still a subject of research. This paper, for the first time, experimentally evaluates the wind and seismic behavior of these type of façades. A five-step comprehensive approach is proposed for the evaluation of cable-supported masonry facades including field and laboratory tests. In the first step, the individual capacity of the connections and materials of the system is evaluated under standardized and non-standardized procedures. The next step consisted in quantifying the fundamental vibration periods and the modal shapes of the façade system including the effect of the border and hanging conditions. The following phase is to estimate the wind load using computational fluid dynamics (CFD). In order to understand the effect of the wind at the different scales of the structure, simulations are performed starting with few bricks and progressively increasing the size of the computational model until assessing the entire building. These analyses allow understanding how the micro and macro components distribution and geometry can affect the wind in-and-out-flow and the possibility of vortexes. Then, a full-scale experimental sub-assembly specimen of a representative module of the façade is subjected to uniformly distributed pressures; the setup considered the border conditions, tension loads, and actual materials. Finally, the seismic assessment phase includes a simplified non-linear procedure to calculate critical accelerations at the building roof, and shaking-table tests of full-scale specimens subjected to these demands. The proposed methodology is apply to a case study consisting on a 40-m height permeable façade of the 12-story Santafe Foundation Hospital located in Bogota (Colombia). The main conclusions of this study are: (1) the dynamic properties of the system mainly rely on the cable tensioning and mass of the system; (2) fundamental vibration frequencies of the façade are much higher than wind demands, so no wind-related amplifications are expected; (3) the façade porosity avoids that high wind pressures may be developed; and (4) for design level earthquakes no major damage is expected. Overall, results show an appropriate performance of this type of façades.

An Evaluation Of Offshore Wind Renewable Energy Performance In Malaysia

The effort in finding the potential of renewable energy in Malaysia is essential due to the problem of global warming and the rise of energy demand. As time passes, these problems become severe and start to create a significant concern. This study aims to evaluate the performance of wind energy in Malaysia as a step ahead for the application of renewable energy to overcome the problems mentioned above. A software simulation using ANSYS was performed to evaluate wind energy performance by adopting the wind speed profile data for offshore locations in Malaysia. Based on these data, the potential sites for offshore wind energy development were assessed and proposed by the criteria of wind pressure in the rotor, wind velocity in the rotor, and the total power generation. The results show that Kijal, Kuala Terengganu, Kudat and Kota Kinabalu measure the greatest wind energy by the high wind pressure and velocity.&#x0D; Keywords: Offshore wind energy, Offshore Malaysia, Wind energy performance

Dome roofs and domes of orthodox churches

The article studies the shapes of the dome roofs of church monuments of architecture. The presentation is primarily based on the relative comparisons methods. The authors compare the shapes of the dome roofs of church monuments of the Orthodox architecture that relate to different styles and epochs, and emphasize the inviolability of the established canonical church requirements. They analyze the shapes of the dome roofs of Orthodox churches in the Southern Urals. The present paper is aimed at giving recommendations for the restoration of historical churches with a weakened ability of bearing walls, taking into account the improvement of the operation of enclosing structures. The authors study the aerodynamic characteristics of the church dome roofs for determining the most difficult areas (high wind pressure) and taking subsequent correct constructive decisions. Solid works suite-based visualization is used in the study.

Assessment of greenhouse gas emissions of ventilated timber wall constructions based on parametric LCA

The increased use of multi-storey timber buildings can potentially create a significant reduction on the life cycle environmental impact of a building. However, with an increasing height of timber buildings the challenge is to maintain the same expected performance independent of the height; tall buildings are particularly exposed to high wind pressures combined with wind-driven rain. Additionally, tall buildings require longer construction times in which the structural elements are especially exposed to moisture. Furthermore, inspection, maintenance and repair possibilities are limited compared to low-rise buildings. This work develops a parametric life cycle assessment (LCA) methodology to evaluate the consequences (greenhouse gas (GHG) emissions) caused by a potential moisture damage of a failure event (considered as the mould and decay growth) in typical ventilated timber wall constructions from four countries: Germany (DE), France (FR), Norway (NO) and Sweden (SE). The environmental performance is evaluated throughout the life cycle of the wall construction in accordance with the modular system of life cycle stages as defined in EN 15978. Global warming potential (GWP) is used as a proxy for environmental impact. Product specific average environmental product declaration (EPD) is used as a main data source in GHG emission calculation. Three parameters; i) number of windows, ii) extent of damage around the window area and iii) the number of damaged layers; are used to evaluate the potential risk of GHG emission from moisture damage around window connections. A probabilistic-based design methodology is also applied to assess the mould and decay occurrence. The total GHG emission results from different scenarios considered in this study and the magnitude of environmental impact related to probabilistic damage are presented. The results show that GHG emissions increase with increase of the number of windows, the damaged area and the increase in the number of replaced layers. This is due to the additional GHG emissions from the materials used to replace the damaged layers. The probability of failure is sensitive to the defined unacceptable level of mould growth. This affects the risk assessment, where the perturbation derived from the different probabilities of failure for different layers are observed at the corresponding replacement interval. The results also show that the parametric results are sensitive to the variables used to estimate the area of replacement, the number of windows, the number of damaged layers and the considered failure event. This study can be used to evaluate and minimize the potential GHG emission of possible moisture damages scenarios on building envelopes. Furthermore, it can enable to consider various improvement measures that reduce the risk, resulting in a robust construction with good function, longer service life and lower embodied emissions during the building's life time. The study also highlights the need for further analysis of the assumptions and background data used when developing the parametric tool.

Lyα Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions

Abstract To shed more light on the nature of the observed Lyα absorption during transits of HD 209458b and to quantify the major mechanisms responsible for the production of fast hydrogen atoms (the so-called energetic neutral atoms, ENAs) around the planet, 2D hydrodynamic multifluid modeling of the expanding planetary upper atmosphere, which is driven by stellar XUV, and its interaction with the stellar wind has been performed. The model self-consistently describes the escaping planetary wind, taking into account the generation of ENAs due to particle acceleration by the radiation pressure and by the charge exchange between the stellar wind protons and planetary atoms. The calculations in a wide range of stellar wind parameters and XUV flux values showed that under typical Sun-like star conditions, the amount of generated ENAs is too small, and the observed absorption at the level of 6%–8% can be attributed only to the non-resonant natural line broadening. For lower XUV fluxes, e.g., during the activity minima, the number of planetary atoms that survive photoionization and give rise to ENAs increases, resulting in up to 10%–15% absorption at the blue wing of the Lyα line, caused by resonant thermal line broadening. A similar asymmetric absorption can be seen under the conditions realized during coronal mass ejections, when sufficiently high stellar wind pressure confines the escaping planetary material within a kind of bowshock around the planet. It was found that the radiation pressure in all considered cases has a negligible contribution to the production of ENAs and the corresponding absorption.

Effectiveness of a perforated light shelf for energy saving

Light shelves are natural lighting systems, which have been highlighted in various studies as a suitable approach for reducing energy consumption. However, external light shelves are at risk of being destroyed by high wind pressure when used on the upper stories of high-rise buildings. Therefore, this study proposes a perforated light shelf that minimizes the effect of wind pressure. Its effectiveness is verified by comparing its lighting energy saving performance with that of previously tested light shelves in an actual testbed. The results showed that at vent ratios of 29.55%, 32.58%, 34.27%, and 35.35%, the lighting energy consumption of the proposed perforated light shelf (Case 4) increased by 20.6%, 20.6%, 42.9%, and 48.3%, respectively, in comparison with that of a nonperforated light shelf. However, at the same four vent ratios, the perforated light shelf was found to be capable of reducing the lighting energy consumption by 74.0%, 74.0%, 56.0%, and 51.4%, respectively, in comparison with a case without a light shelf (Case 1) and a case with a 0° fixed nonperforated light shelf (Case 2). In Case 4, the lighting energy saving rate of the perforated light shelf may be improved by increasing its width.

Performance Evaluation of Energy Reduction of Light Shelf Applying Punching Plate

Various studies on lighting energy savings are conducted, given that lighting energy consumption accounts 23.5% of building energy consumption. Especially, external type light shelf's efficiency is acknowledged; however, its application is limited in Korea, where high rise building ratio is high, due to high wind pressure. This study delves into natural lighting system to cope with wind pressure, and proposes the punching plate-installed light shelf. This study actually draws lighting energy output, according to whether the punching plate is applied through the test-bed, and verifies the effectiveness of the punching plate-installed light shelf. The conclusion is presented below: First) The result of performance evaluation of light shelf with the punching plate in winter solstice showed that the awning area decreased as the opening ratio increased so that the indoor distributed illumination tended to increase, and <TEX>$-40^{\circ}$</TEX> which was advantageous for awning was determined as the proper angle. Second) The light shelf with the punching plate in spring/autumn equinox shows improved lighting according to the angle, and the appropriate angle of light shelf with the punching plate has increased to <TEX>$15^{\circ}$</TEX> and <TEX>$20^{\circ}$</TEX> according to the opening ratio in comparison to <TEX>$5^{\circ}C$</TEX> which is the appropriate angle of light shelf with no punching plate due to the reflection area reduced by the reflecting plate with holes. Third) The result of performance evaluation of light shelf with the punching plate in summer solstice showed that the lighting performance tended to decrease as the opening ratio increased. 4) The light shelf with the punching plate incurs a 50% energy loss in comparison to the light shelf with no punching plate. However, its effectiveness has been proven in the aspects that it can bring a 50% energy saving in comparison to the case with no installation of light shelf and that it can be designed in response to wind pressure on the high floors.

Pressure distributions on prism-shaped buildings in experimentally simulated downburst

Wind loading is one of the most significant factors in civil engineering that influences the structural design considerably. In this paper, a group of manufacturing equipments for downburst simulation based on impinging jet model was developed for investigating the wind loads on structures: including the centrifugal air bellows to generate airflow, a movable platform to realize multiple locations of the building and a freely rotatable turntable to implement alterable building angles. Hundreds of transducers were used to measure the wind action on all surfaces of the building. The pressure coefficients calculated from the observed data were utilized to evaluate the downburst wind load. Pressure distributions on three prism-shaped building models with different placements and angles were investigated to obtain the maximum wind action and mean pressure coefficients. The results showed that the maximum pressure coefficient would reach 1.0 on the top surface if the downburst just broke out over the edifice. Considering that the building was in the developing field of the downburst, the top and the front surfaces would be under high wind pressure and only the back surface would endure wind suction. When the downdraft happens away from the prismatic building, all surfaces, except the front surface, would subject to suction with different degrees. It was also found that the pressure coefficient on the right surface would get its negative peak at first and then go straight up to 0.6 as the angle changed from 0° to 45° and the wind pressure on the front surface would decrease slightly through the whole process. The assertive results provide elemental data for structural wind-resistant design in civil engineering for the downburst-prone areas.

A study on performance evaluation of punching plate reflecting plate-applied external light shelf according to vent ratio

Global energy consumption shows uptrend each year in the rapidly changing contemporary era. Building energy consumption accounts for 38% of total energy consumption, and lighting takes up high ratio with 22% in the building energy consumption. Lighting is actually applied to various researches and spaces. The light shelves make illuminance balanced by introducing natural light to indoor spaces. Among the light shelf types, external fluorescent light shelves are known to be more excellent in lighting performance, compared to the internal fluorescent light shelves and mixed fluorescent light shelves. However, the light shelves externally protruding by high wind pressure have difficulties in applying them to high rise buildings. This research proposes a punching plate reflecting plate-applied external fluorescent light shelf that can be designed for and applied to high rise buildings. This research verified the lighting performance of the existing light shelves and the circle-shaped punching plate reflecting plate-applied

Out-of-Plane Behavior of URM Walls Strengthened with Fabric-Reinforced Cementitious Matrix Composite

AbstractThe use of unreinforced masonry (URM) walls is common practice in different types of construction, such as interior or exterior walls. URM walls are typically deficient in flexural capacity when subjected to out-of-plane loading caused by high wind pressure or earthquakes. Retrofitting masonry walls with novel materials, such as fiber-reinforced polymer (FRP) composites, has shown enhancement of the flexural capacity and pseudoductility. This study evaluates the feasibility of fabric-reinforced cementitious matrix (FRCM) as an alternative external strengthening technology to improve out-of-plane behavior of URM walls. This paper reports experimental results on flexural capacity of nine clay brick walls of which six were strengthened with two different amounts of FRCM, namely one and four reinforcement fabrics. Experimental evidence shows significant improvements in the structural performance in terms of flexural capacity and stiffness of the strengthened walls. An analysis, disregarding arching ef...

Analysis of Internal Flow Field for Centrifugal Fan in Series

Centrifugal fan in series with high wind pressure is the key facility of pneumatic transport equipment. To consider the impact of changed conditions on performance of centrifugal fan, internal flow of three-stage centrifugal fan at rated speed in different total pressure conditions is analyzed by CFD software FLUENT6.3 in this paper. Flow characteristics are obtained and the differences of total pressure and velocity distribution in each impeller are analyzed under different conditions, velocity distribution on the meridian plane and section of wind guide plates are compared. Finally, curves of P-Q and P-η at 4600 r/min are forecasted through the analysis of the data, which provide references for reducing impact that condition alteration on fan performance and improving the efficiency of the fan.

Dimension stone design – partial safety factors: a reliability based approach

Today's thin stone veneers must be designed to resist, besides their self-weight, high wind pressures and induced seismic forces. They must accommodate hygrometric differential movement, deflection, vibration and creep, etc. When available, code requirements do not provide an accurate or realistic safety factor for the specific type of anchor and or stone used in a project. Global safety factors that are recommended by stone industry associations are imprecise and used as rules of thumb. Limit state design has replaced the older concept of allowable stress design in most forms of civil engineering. As a result, all modern buildings are designed in accordance with a code which is based on limit state theory for all man-made materials, yet there is an astonishing nonexistence of ′natural stone′. In this paper partial factors of safety are proposed depending on the types and on the coefficients of variation of the distributions of resistances. Their values are determined using structural reliability analysis for the load and resistance factor design format according to Eurocode 1990. Aging and stone resistance decay is outside the scope of the article, yet some guidance is provided on the influence of stone durability on stone cladding performance. An application example is used to illustrate both methods, and conclusions are drawn.

A Method for Generating Electricity by Fast Moving Vehicles

A method for generating electricity using high wind pressure generated by fast moving vehicles channeling the induced wind in the direction of the wind turbine; converting the energy of the wind into mechanical energy by using wind turbine; and converting the mechanical energy into electrical energy by using a generating device and can be used for applications.