scholarly journals Wind Pressure Coefficients on Greenhouse Structures

Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 149 ◽  
Author(s):  
Chrysanthos Maraveas
Keyword(s):  
Structural Engineering ◽  
Experimental Studies ◽  
Measurement Data ◽  
Wind Pressure ◽  
Wind Loads ◽  
Structural Safety ◽  
Strong Wind ◽  
Design Standards ◽  
Pressure Coefficients ◽  
Research Studies

Commercial production greenhouses are widely used to produce plants and crops. From the structural engineering viewpoint, among the loads that act on greenhouses, wind and snow loads are the major ones. This paper focuses on the former, particularly on wind pressure coefficients. Design and construction of greenhouses should consider wind loads in order to ensure seamless operation, overall stability, durability, and safety, even though human occupancy is limited. Classification and design of greenhouses is typically based on European standards, which cover a variety of geometries and conditions. Some recent research studies suggest, however, that greenhouse design standards should be revised to ensure structural safety of greenhouses subject to strong wind loads. Triggered by this recent outcomes, this paper reviews existing literature on the topic: (a) briefly presenting the state of the art methods for determining wind pressures on greenhouses; (b) comparing the EN 13031-1 pressure coefficients with those stemming from recent experimental studies on single-span pitched and arched roof greenhouses in South Korea; and (c) summarizing most recent comparative results for multi-span greenhouses. It concludes that these recent research studies are not enough to justify revision of EN 13031-1, and more measurement data and experimental or numerical studies are necessary to justify such a conclusion.

scholarly journals Study of Wind Loads and Wind Speed Amplifications on High-Rise Building with Opening by Numerical Simulation and Wind Tunnel Test

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Fu-Bin Chen ◽  
Xiao-Lu Wang ◽  
Yun Zhao ◽  
Yuan-Bo Li ◽  
Qiu-Sheng Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Pressure ◽  
Wind Loads ◽  
Structural Safety ◽  
Pressure Coefficients ◽  
High Rise ◽  
High Rise Building ◽  
The Mean

High-rise buildings are very sensitive to wind excitations, and wind-induced responses have always been the key factors for structural design. Facade openings have often been used as aerodynamic measures for wind-resistant design of high-rise buildings to meet the requirement of structural safety and comfort. Obvious wind speed amplifications can also be observed inside the openings. Therefore, implementing wind turbines in the openings is of great importance for the utilization of abundant wind energy resources in high-rise buildings and the development of green buildings. Based on numerical simulation and wind tunnel testing, the wind loads and wind speed amplifications on high-rise buildings with openings are investigated in detail. The three-dimensional numerical simulation for wind effects on high-rise building with openings was firstly carried out on FLUENT 15.0 platform by SST k − ε model. The mean wind pressure coefficients and the wind flow characteristics were obtained. The wind speed amplifications at the opening were analyzed, and the distribution law of wind speed in the openings is presented. Meanwhile, a series of wind tunnel tests were conducted to assess the mean and fluctuating wind pressure coefficients in high-rise building models with various opening rates. The variation of wind pressure distribution at typical measuring layers with wind direction was analyzed. Finally, the wind speed amplifications in the openings were studied and verified by the numerical simulation results.

WIND PRESSURE DISTRIBUTION ON LOW-RISE BUILDINGS WITH CYLINDRICAL ROOFS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Astha Verma ◽  
Ashok Kumar Ahuja
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Wind Tunnel ◽  
Pressure Distribution ◽  
Open Circuit ◽  
Wind Pressure ◽  
Wind Loads ◽  
Wind Loading ◽  
Pressure Coefficients ◽  
Available Information

Wind is one of the important loads to be considered while designing the roofs of low-rise buildings. The structural designers refer to relevant code of practices of various countries dealing with wind loads while designing building roofs. However, available information regarding wind pressure coefficients on cylindrical roofs is limited to single span only. Information about wind pressure coefficients on multi-span cylindrical roofs is not available in standards on wind loads. Present paper describes the details of the experimental study carried out on the models of low-rise buildings with multi-span cylindrical roofs in an open circuit boundary layer wind tunnel. Wind pressure values are measured at many pressure points made on roof surface of the rigid models under varying wind incidence angles. Two cases namely, single-span and two-span are considered. The experimental results are presented in the form of contours of mean wind pressure coefficients. Results presented in the paper are of great use for the structural designers while designing buildings with cylindrical roofs. These values can also be used by the experts responsible for revising wind loading codes from time to time.

Wind Load Characteristics of Tall Building with Atrium

2013 ◽  
Vol 639-640 ◽  
pp. 515-522
Author(s):  
Yong Gui Li ◽  
Q.S. Li
Keyword(s):  
Wind Tunnel ◽  
Critical Role ◽  
Pressure Coefficient ◽  
Tall Building ◽  
Wind Pressure ◽  
Wind Loads ◽  
Design Guideline ◽  
Pressure Coefficients ◽  
Opening Ratio ◽  
Wind Pressures

Wind tunnel test of 1:500 rigid model of tall building with atrium was carried out. Based on the experimental results, characteristics of wind pressures on atrium facades and wind loads on the structure were investigated in detail. The results show that the formation of flow separation on the building top plays a critical role in the generation of wind pressures on the atrium facades. Meanwhile, wind pressure coefficient distributions on the atrium facades are found to be relatively uniform. Moreover, the horizontal and vertical correlations of pressure coefficient exhibit high at most locations on atrium facades. With the increasing of the opening ratio, the mean wind pressure coefficients first decreased and then stabilized, and the fluctuating wind pressure coefficients first decreased and then increased. A design guideline for the wind-resistant design of atrium facades was proposed, and the results predicted by the proposed guideline were in good agreement with those from the wind tunnel tests, indicating that the proposed guideline can be used in engineering applications. When the opening ratio is no more than 5.33%, the effect of the facade pressures within the atrium on the wind loads on the structure can be ignored. For such cases, the wind-resistant design for a tall building with atrium can refer to that of a similar shape tall building without atrium.

Structural design and globalization – the particular case of bridge construction equipment

2019 ◽  
Author(s):  
José M. S. Soares ◽  
Pedro Pacheco ◽  
Hugo Coelho ◽  
André Resende ◽  
Diogo Carvalho ◽  
...  
Keyword(s):  
Structural Design ◽  
Structural Engineering ◽  
Structural Safety ◽  
Construction Equipment ◽  
Bridge Construction ◽  
Design Standards ◽  
Developing Regions ◽  
Satisfactory Outcome ◽  
Major Factors ◽  
Design Construction

<p>Structural safety may be seen as an outcome of 3 major factors: Design, Construction/Erection and Materials. Each of these factors is usually governed by specific standards. In order to reach a satisfactory outcome, the standards should ideally be coherent and complementary. In the regions that led the development of structural engineering (US, Europe, Japan) it took decades to develop articulated standards and this development is still ongoing – for instance, improvement of materials and quality control promote material reduction, safety factors or even incorporation of new materials into design standards.</p><p>As globalization continues to accelerate, structural engineering companies simultaneously face global competition and new global opportunities. Challenges arise in situations in which Design, Construction and Materials’ standards are not governed by a common language or background. The use of large bridge construction equipment such as LG or MSS is widespread in Europe and North America. Increasing implementation of modern bridge construction processes in developing regions not yet familiarized with inherent construction equipment bring new challenges in terms of safety and standard harmonization. Some of these challenges are addressed in this paper. Main conclusions drawn in the end may be generalized to other design and construction activities.</p>

scholarly journals Fluid structure interaction based structure stress and modal analysis of a flat type solar panel supporting system

2021 ◽  
Vol 248 ◽  
pp. 02018
Author(s):  
Handai Liu ◽  
Piao Zhang ◽  
Zhenqiang Lai ◽  
Xiaofeng Dong ◽  
Zhicheng Wang ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Fluid Structure Interaction ◽  
Solar Panel ◽  
Wind Pressure ◽  
Wind Loads ◽  
Strong Wind ◽  
Flat Panel ◽  
Fluid Structure ◽  
Supporting System ◽  
Structure Interaction

Solar panel supporting systems are often affected by strong wind loads, especially in typhoon-intensive areas such as Southeast Asia. This paper focuses on the study of flat-panel solar energy system. The numerical model of solar panel supporting system has been built by using the fluid flow control equations. Firstly, the numerical simulation of aerodynamic characteristics of the solar panel supporting system are conducted, and then the pressure results gained from CFD are loaded and coupled to the front and back of the solar panels. Lastly, the stress, strain and the modal analysis results of the support system under four different directional wind loads are achieved. The conclusions include: (1) under the condition of same wind speed, the wind pressure and distribution of the solar panel are different with different wind directions, and the wind load perpendicular to the solar panel has the greatest influence on the solar supporting system. (2)The modal frequency of flat panel solar supporting system is little affected by wind directions and average wind pressure. In the structure design, low order vibration should be considered mainly in the supporting part of the system, while the high order vibration should be generally considered in vibrating risk of solar panel. (3)The first six modal frequencies coupled with fluid-structure interaction of the flat panel solar supporting system are all slightly lower than the free modal frequencies.

Experimental investigation of wind loads on wind turbine blade under various turbulent flows

2021 ◽  
pp. 136943322110401
Author(s):  
Yi Li ◽  
Qian Song ◽  
Qiu-Sheng Li ◽  
Di-Ling Wang ◽  
Xiao-Peng Wu
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Dynamic Properties ◽  
Turbine Blades ◽  
Wind Farms ◽  
Wind Turbine Blade ◽  
Wind Pressure ◽  
Wind Loads ◽  
Pressure Coefficients

For investigation of the effects of turbulence intensity (TI) on the wind loads on wind turbine blade, a 1:20 scaled model of a typical 3D wind turbine blade is designed and used for the pressure measurement test in a wind tunnel. Five uniform flows with different turbulence intensities are simulated in the wind tunnel test. The mean and root-mean-square (RMS) wind pressure coefficients, base moment coefficients, and their power spectral densities are presented and discussed in detail. Combined with the dynamic properties of the blade structure, wind-induced displacements at the tip of the blade are calculated by the random vibration theory. The results show that the increasing of TI amplifies the aerodynamic loads on the blade in terms of RMS wind pressure coefficients and RMS bending moment coefficients. Large wind-induced displacement of the wind turbine blade may be stimulated by high TI even under the feathering condition. This article aims to further the understanding of wind loads on wind turbine blades and provide useful information for the wind-resistant design of wind farms established in regions with high turbulence levels.

Characteristics of Wind Loads Acting on Complex Long-Span Roof Structure

2013 ◽  
Vol 639-640 ◽  
pp. 523-529
Author(s):  
Fu Bin Chen ◽  
Q.S. Li
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Leading Edge ◽  
Wind Pressure ◽  
Wind Loads ◽  
Pressure Coefficients ◽  
Long Span ◽  
Roof Structure ◽  
Fluctuating Wind

The Shenzhen New Railway Station (SNRS) has roof dimensions of 450 m long and 408 m wide. This paper presents the results of wind loads acting on the large-span roof structure. In the wind tunnel test, wind-induced pressures including mean and fluctuating components were measured from the roof of a 1:200 scale SNRS model under suburban boundary layer wind flow configuration in a boundary layer wind tunnel of HD-2 at Hunan University. Based on the data obtained simultaneously from the wind tunnel tests, the distributions of the mean and fluctuating wind pressure coefficients and the characteristics of probability density functions of wind pressures of typical pressure taps were analyzed in detailed. The outcomes of the experimental study indicate that: (1) The maximum mean negative wind pressure coefficients on the roof occur at the windward leading edge region, where the maximum fluctuating wind pressure coefficients occur also in this region; (2) There are some differences of the maximum mean negative wind pressure coefficients and RMS wind pressure coefficients under conditions with different number of trains inside the station, but such effects on the overall pressure distributions on the whole roof are negligible; (3) There are clearly negative skewed distributions for some pressure taps at the windward leading roof edge and much longer negative tails are observed, which follow Non-Gaussian distributions. The results presented in this paper are expected to be of considerable interest and of use to researchers and professionals involved in designing complex long-span roof structures.

scholarly journals Improvement Dependability of Offshore Horizontal-Axis Wind Turbines by Applying New Mathematical Methods for Calculation the Excess Speed in Case of Wind Gusts

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3085
Author(s):  
Konstantin Osintsev ◽  
Seregei Aliukov ◽  
Alexander Shishkov
Keyword(s):  
Computer Simulation ◽  
Wind Turbines ◽  
Experimental Studies ◽  
Offshore Wind ◽  
Approximation Schemes ◽  
Calculation Error ◽  
Strong Wind ◽  
Mathematical Methods ◽  
Wind Gusts ◽  
Gas Dynamic

The problem of increasing the reliability of wind turbines exists in the development of new offshore oil and natural gas fields. Reducing emergency situations is necessary due to the autonomous operation of drilling rigs and bulk seaports in the subarctic and Arctic climate. The relevance of the topic is linked with the development of a methodology for theoretical and practical studies of gas dynamics when gas flows in a pipe, based on a mathematical model using new mathematical methods for calculation of excess speeds in case of wind gusts. Problems in the operation of offshore wind turbines arise with storm gusts of wind, which is comparable to the wave movement of the gas flow. Thus, the scientific problem of increasing the reliability of wind turbines in conditions of strong wind gusts is solved. The authors indicate a gross error in the calculations when approximating through the use of the Fourier series. The obtained results will allow us to solve one of the essential problems of modeling at this stage of its development, namely: to reduce the calculation time and the adequacy of the model built for similar installations and devices. Experimental studies of gas-dynamic flows are carried out on the example of a physical model of a wind turbine. In addition, a computer simulation of the gas-dynamic flow process was carried out. The use of new approximation schemes in processing the results of experiments and computer simulation can reduce the calculation error by 1.2 percent.

scholarly journals Probability Characteristics, Area Reduction, and Wind Directionality Effects of Extreme Pressure Coefficients of High-Rise Buildings

2021 ◽  
Vol 11 (15) ◽  
pp. 7121
Author(s):  
Shouke Li ◽  
Feipeng Xiao ◽  
Yunfeng Zou ◽  
Shouying Li ◽  
Shucheng Yang ◽  
...  
Keyword(s):  
Probability Distribution ◽  
Pressure Coefficient ◽  
Wind Pressure ◽  
Extreme Pressure ◽  
Distribution Law ◽  
Distribution Fitting ◽  
Pressure Coefficients ◽  
High Rise ◽  
Area Reduction ◽  
The Mean

Wind tunnel tests are carried out for the Commonwealth Advisory Aeronautical Research Council (CAARC) high-rise building with a scale of 1:400 in exposure categories D. The distribution law of extreme pressure coefficients under different conditions is studied. Probability distribution fitting is performed on the measured area-averaged extreme pressure coefficients. The general extreme value (GEV) distribution is preferred for probability distribution fitting of extreme pressure coefficients. From the comparison between the area-averaged coefficients and the value from GB50009-2012, it is indicated that the wind load coefficients from GB50009-2012 may be non-conservative for the CAARC building. The area reduction effect on the extreme wind pressure is smaller than that on the mean wind pressure from the code. The recommended formula of the area reduction factor for the extreme pressure coefficient is proposed in this study. It is found that the mean and the coefficient of variation (COV) for the directionality factors are 0.85 and 0.04, respectively, when the orientation of the building is given. If the uniform distribution is given for the building’s orientation, the mean value of the directionality factors is 0.88, which is close to the directionality factor of 0.90 given in the Chinese specifications.

A New Generation of Tools for the Design of Tall Buildings Subjected to Wind Loads

2008 ◽  
Author(s):  
Emil Simiu ◽  
Rene D. Gabbai
Keyword(s):  
Structural Engineering ◽  
Tall Buildings ◽  
Building Envelope ◽  
Force Balance ◽  
Wind Loads ◽  
Individual Member ◽  
Engineering Practice ◽  
Wind Effects ◽  
Uncertainty Estimates ◽  
Internal Forces

Current approaches to the estimation of wind-induced wind effects on tall buildings are based largely on 1970s and 1980s technology, and were shown to result in some cases in errors of up to 40%. Improvements are needed in: (i) the description of direction-dependent aerodynamics; (ii) the description of the direction-dependent extreme wind climate; (iii) the estimation of inertial wind effects induced by fluctuating aerodynamic forces acting on the entire building envelope; (iv) the estimation of uncertainties inherent in the wind effects; and (v) the use of applied wind forces, calculated inertial forces, and uncertainty estimates, to obtain via influence coefficients accurate and risk-consistent estimates of wind-induced internal forces or demand-to-capacity ratios for any individual structural member. Methods used in current wind engineering practice are especially deficient when the distribution of the wind loads over the building surface and their effects at levels other than the building base are not known, as is the case when measurements are obtained by the High-Frequency Force Balance method, particularly in the presence of aerodynamic interference effects due to neighboring buildings. The paper describes a procedure that makes it possible to estimate wind-induced internal forces and demand-to-capacity ratios in any individual member by: developing aerodynamic and wind climatological data sets, as well as aerodynamic/climatological directional interaction models; significantly improving the quality of the design via rigorous structural engineering methods made possible by modern computational resources; and properly accounting for knowledge uncertainties. The paper covers estimates of wind effects required for allowable stress design, wherein knowledge uncertainties pertaining to the parameters that determine the wind loading are not considered, as well as estimates required for strength design, in which these uncertainties need to be accounted for explicitly.

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