Wind Loading on Catenary Domes

2019 ◽  
Author(s):  
Richard M. van Gool ◽  
Ryan A. Bradley ◽  
Mitchell Gohnert
Keyword(s):  
Pressure Coefficient ◽  
Wind Loading ◽  
Pressure Coefficients ◽  
Hemispherical Dome ◽  
Circular Profile ◽  
Mean Pressure ◽  
Efficient Alternative ◽  
Base Radius ◽  
The Mean ◽  
Layer Flow

<p>Catenary domes are a less conventional, but structurally efficient, alternative to traditional circular-profile domes. Unlike the more common circular forms, there is a dearth of wind loading information for catenary structures. This paper aims to provide some insight in this regard. A series of wind tunnel tests were undertaken to investigate the effects of geometry and Reynolds number on the mean pressure coefficient distributions over catenary domes in a turbulent boundary layer flow. A hemispherical dome was also assessed, and the results compared with that for the catenary shapes. These parameters were evaluated to elucidate their influence on the loading on these structures. Only the results relating to mean pressure coefficients are reported in this paper. An important finding was that the height to base radius (H/R) of the catenary dome had a substantial influence on the mean pressure coefficient distributions over the structure. Finally, the results of the investigation and their implications on the design of catenary domes are discussed. This may be of value to designers because at present no wind loading information exists for catenary domes</p><p>– at least to the author’s knowledge.</p>

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.

Near-Bed Flow Mechanisms Around a Circular Marine Pipeline Close to a Flat Seabed in the Subcritical Flow Regime Using a k-ɛ Model

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Muk Chen Ong ◽  
Torbjørn Utnes ◽  
Lars Erik ◽  
Dag Myrhaug ◽  
Bjørnar Pettersen
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Flow Regime ◽  
Boundary Layer Thickness ◽  
Friction Velocity ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Mean Pressure ◽  
Flow Mechanisms ◽  
The Mean

Flow mechanisms around a two-dimensional (2D) circular marine pipeline close to a flat seabed have been investigated using the 2D unsteady Reynolds-averaged Navier–Stokes (URANS) equations with a standard high Reynolds number k-ɛ model. The Reynolds number (based on the free stream velocity and cylinder diameter) ranges from 1 × 104 to 4.8 × 104 in the subcritical flow regime. The objective of the present study is to show a thorough documentation of the applicability of the k-ɛ model for engineering design within this flow regime by means of a careful comparison with available experimental data. The inflow boundary layer thickness and the Reynolds numbers in the present simulations are set according to published experimental data, with which the simulations are compared. Detailed comparisons with the experimental data for small gap ratios are provided and discussed. The effects of the gap to diameter ratio and the inflow boundary layer thickness have been studied. Although under-predictions of the essential hydrodynamic quantities (e.g., time-averaged drag coefficient, time-averaged lift coefficient, root-mean-square fluctuating lift coefficient, and mean pressure coefficient at the back of the pipeline) are observed due to the limitation of the turbulence model, the present approach is capable of providing good qualitative agreement with the published experimental data. The vortex shedding mechanisms have been investigated, and satisfactory predictions are obtained. The mean pressure coefficient and the mean friction velocity along the flat seabed are predicted reasonably well as compared with published experimental and numerical results. The mean seabed friction velocity at the gap is much larger for small gaps than for large gaps; thus, the bedload sediment transport is much larger for small gaps than for large gaps.

Experimental Investigation of Wind Loads on Fish-Shaped Roof Structures

2013 ◽  
Vol 639-640 ◽  
pp. 434-443
Author(s):  
Ming Liang Zhang ◽  
Qiu Sheng Li
Keyword(s):  
Experimental Investigation ◽  
Lower Surface ◽  
Shape Coefficient ◽  
Pressure Coefficients ◽  
Minimum Pressure ◽  
Mean Pressure ◽  
Wind Actions ◽  
Rigid Model ◽  
The Mean ◽  
Two Sides

Wind tunnel tests of 1:100 rigid model of fish-shaped roof structures were carried out. The mean, fluctuating (RMS) and peak pressure coefficients, the local shape coefficient distributions on fish-shaped roofs were presented and discussed. It was found that negative pressures (suctions) occurred on the most areas on the roofs, and high negative pressure coefficients occurred on the eaves and cantilevered roof parts. When wind flows blew along the corridors under the roofs, the flows enhanced suctions on the surfaces of the roofs, and the suctions on the lower surface were greater than those on the upper surfaces, positive pressures occurred on that area after superposition of wind actions on the two sides. The roof eaves and regions above the corridors experienced the worst RMS pressure coefficients and the worst minimum pressure coefficients. The distribution characteristics of the worst RMS and minimum pressure coefficients were found to be quite similar to those of the mean pressure coefficients. The results obtained from the experimental investigation are expected to be useful in the wind-resistant design of complex roof structures in typhoon-prone regions.

Pressure modes for hyperbolic paraboloid roofs

2020 ◽  
Vol 7 (1) ◽  
pp. 226-246
Author(s):  
Fabio Rizzo ◽  
Cristoforo Demartino
Keyword(s):  
Pressure Coefficient ◽  
Measured Signal ◽  
Hyperbolic Paraboloid ◽  
Pressure Coefficients ◽  
Truncated Svd ◽  
Mean Pressure ◽  
Vertical Displacements ◽  
Value Decomposition ◽  
Experimental Pressure ◽  
Polynomial Surface

AbstractThis paper presents a study on Singular Value Decomposition (SVD) of pressure coefficients hyperbolic parabolic roofs. The main goal of this study is to obtain pressure coefficient maps taking into account spatial non-uniform distribution and time-depending fluctuations of the pressure field. To this aim, pressure fields are described through pressure modes estimated by using the SVD technique. Wind tunnel experimental results on eight different geometries of buildings with hyperbolic paraboloid roofs are used to derive these pressure modes. The truncated SVD approach was applied to select a sufficient number of pressure modes necessary to reconstruct the measured signal given an acceptable difference. The truncated pressure modes are fitted through a polynomial surface to obtain a parametric form expressed as a function of the hyperbolic paraboloid roof geometry. The superpositions of pressure (envelopes) for all eight geometry were provided and used to modify mean pressure coefficients, to define design load combinations. Both symmetrical and asymmetrical pressure coefficient modes are used to estimate the wind action and to calculate the vertical displacements of a cable net by FEM analyses. Results clearly indicate that these load combinations allow for capturing large downward and upward displacements not properly predicted using mean experimental pressure coefficients.

Interference effects of three consecutive wall-mounted cubes placed in deep turbulent boundary layer

2014 ◽  
Vol 756 ◽  
pp. 165-190
Author(s):  
Hee Chang Lim ◽  
Masaaki Ohba
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Coefficient ◽  
Azimuth Angle ◽  
Pressure Variation ◽  
Interference Effects ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Mean Pressure ◽  
The Mean

AbstractIn this study we undertook various calculations of the turbulent flow around a building in close proximity to neighbouring obstacles, with the aim of gaining an understanding of the velocity and the surface-pressure variations with respect to the azimuth angle of wind direction and the gap distance between the obstacles. This paper presents the effects of flow interference among consecutive cubes for azimuth angles of $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\theta = 0$, 15, 30, and $45^{\circ }$ and gap distances of $G = 0.5{h}, 1.0{h}, 1.5{h}$, and $\infty $ (i.e. a single cube), where $h$ is the cube height, placed in a turbulent boundary layer. A transient detached eddy simulation (DES) was carried out to calculate the highly complicated flow domain around the three wall-mounted cubes to observe the fluctuating pressure, which substantially contributes to the suction pressure when there is separation and reattachment around the leading and trailing edges of the cubes. In addition, the results indicate that an increasing azimuth angle increases the pressure variation on the centre cube of the three parallel-aligned cubes. The mean pressure variation can even change from negative to positive on the side face. Owing to interference effects, the mean pressure coefficient of the centre cube of the three parallel-aligned cubes was generally lower than the coefficient of the single cube and tended to increase depending on the gap distance. Furthermore, when the three consecutive cubes are in a tandem arrangement, the gap distance has little influence on the first cube but results in significant interference effects on the second and third cubes.

Field Measurement of Boundary Layer Wind Characteristics and Wind Loads on Super-Tall Building

2011 ◽  
Vol 243-249 ◽  
pp. 5128-5135
Author(s):  
Wen Hai Shi ◽  
Zheng Nong Li
Keyword(s):  
Pressure Coefficient ◽  
Tall Buildings ◽  
Tall Building ◽  
Recent Past ◽  
Comprehensive Investigation ◽  
Pressure Fields ◽  
Mean Pressure ◽  
Wind Characteristics ◽  
The Mean

Significance of full-scale experiments, analyzing wind and pressure fields in the proximity or on tall buildings, is evident from the attention that has been dedicated by researchers to these programs in the recent past. In the south and southeastern regions of China this problem is of particular relevance due to the presence of Typhoons. This paper presents some recent results measured from a super tall building located near the coast of Xiamen, Fujian province, China. In the first part of this study, attention is devoted to the characterization of the wind field atop a super-tall building; a comprehensive investigation on wind velocity and turbulence characteristics during the passage of Typhoon Fanapi is summarized. In the second part, results associated with the mean pressure and mean pressure coefficient were concentrated on the identification of direction-dependent pressure characteristics is analyzed.

scholarly journals Experimental investigation of the aerodynamics of a large industrial building with parapet

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Aly Mousaad Aly ◽  
Matthew Thomas ◽  
Hamzeh Gol-Zaroudi
Keyword(s):  
Flow Pattern ◽  
Separation Bubble ◽  
Industrial Building ◽  
Pressure Coefficients ◽  
Industrial Buildings ◽  
Straight Line ◽  
Mean Pressure ◽  
The Mean ◽  
Wind Pressures ◽  
Peak Pressures

AbstractThe aerodynamic performance of a roof depends significantly on its shape and size, among other factors. For instance, large roofs of industrial low-rise buildings may behave differently compared to those of residential homes. The main objective of this study is to experimentally investigate how perimeter solid parapets can alter the flow pattern around a low-rise building with a large aspect ratio of width/height of about 7.6, the case of industrial buildings/shopping centers. Solid parapets of varied sizes are added to the roof and tested in an open-jet simulator in a comparative study to understand their impact on roof pressure coefficients. Roof pressures were measured in the laboratory for cases with and without parapets under different wind direction angles (representative of straight-line winds under open terrain conditions). The results show that using a parapet can alter wind pressures on large roofs. Parapets can modify the flow pattern around buildings and change the mean and peak pressures. The mean pressure pattern shows a reduction in the length of the separation bubble due to the parapet. The parapet of 14% of the building’s roof height is the most efficient at reducing mean and peak pressures compared to other parapet heights.

Wind Effects of Architectural Details on Gable-Roofed Low-Rise Buildings in Southeastern Coast of China

2014 ◽  
Vol 17 (11) ◽  
pp. 1551-1565 ◽  
Author(s):  
Peng Huang ◽  
Ling Tao ◽  
Ming Gu ◽  
Yong Quan
Keyword(s):  
Pressure Coefficient ◽  
Wind Loads ◽  
Wind Effects ◽  
Drag Coefficients ◽  
Pressure Coefficients ◽  
Southeastern Coast ◽  
Negative Peak ◽  
The Mean ◽  
Net Pressure ◽  
Block Pressure Coefficient

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.

Cavitation in the rotational structures of a turbulent wake

1995 ◽  
Vol 287 ◽  
pp. 383-403 ◽  
Author(s):  
B. Belahadji ◽  
J. P. Franc ◽  
J. M. Michel
Keyword(s):  
Pressure Coefficient ◽  
Three Dimensional ◽  
Turbulent Wake ◽  
Streamwise Vortices ◽  
Near Wake ◽  
Absolute Value ◽  
Cavitation Inception ◽  
Wake Vortices ◽  
Mean Pressure ◽  
The Mean

Experiments show that cavitation, if moderately developed, makes three kinds of vortical coherent structures visible inside the turbulent wake of a two-dimensional obstacle: Bénard–Kármán vortices, streamwise three-dimensional vortices and finally the vortices which appear on the borders of the very near wake. The latter, which are called here near-wake vortices, result by successive pairing in the first ones and there is some indication that they are also the origin of streamwise vortices. Cavitation is not a passive agent of visualization, as can be established on the basis of fundamental arguments, and it reacts with the flow as soon as it appears; when it is developed, it breaks the connection between the elongation rate and the vorticity rate of the vortex filaments. Then the subsequent evolution of a cavitating vortex and its final implosion are rather complicated. Despite its active character, cavitation in rotational structures, if properly interpreted, can give information of interest on the basic non-cavitating turbulent flow. By adapting a simple model due to Kermeen & Parkin (1957) and Arndt (1976), and counting near-wake vortices, it is possible to accurately predict the conditions of cavitation inception: consideration of coherent rotational structures is probably the best approach to explain, in an almost deterministic way, the large difference between the absolute value of the mean pressure coefficient at the obstacle base and the incipient cavitation number.

Sign in / Sign up

Export Citation Format

Share Document