Calculation of horizontal displacement of conductors under wind loading toward buildings and other supporting structures

1994 ◽  
Vol 30 (2) ◽  
pp. 496-504 ◽  
Author(s):  
A.L. Clapp
Keyword(s):  
Horizontal Displacement ◽  
Wind Loading ◽  
Supporting Structures

Nonlinear dynamic behaviour of guy cables in turbulent winds

2001 ◽  
Vol 28 (1) ◽  
pp. 98-110 ◽  
Author(s):  
Bruce F Sparling ◽  
Alan G Davenport
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Horizontal Displacement ◽  
Wind Loading ◽  
Second Phase ◽  
Nonlinear Coupling ◽  
Wide Range ◽  
Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

A comparison of the gust factor method and the patch load method of analysis of guyed towers

1996 ◽  
Vol 23 (4) ◽  
pp. 862-871 ◽  
Author(s):  
Robert G. Selby ◽  
Robert B. Dryburgh
Keyword(s):  
Dynamic Method ◽  
Wind Loading ◽  
Dynamic Effects ◽  
Gust Factor ◽  
Parametric Studies ◽  
Patch Load ◽  
Load Analysis ◽  
Guyed Towers ◽  
Tower Height ◽  
Supporting Structures

The Canadian standard CAN/CSA-S37-94 "Antennas, towers and antenna supporting structures" (S37) has introduced as an appendix a quasi-dynamic method of analysis. This patch load method yields a more realistic pattern of forces in a guyed tower, but S37 contains no firm guidelines as to when this new method is required over the conventional static gust factor approach. This paper describes various comparative studies that were made to determine the conditions under which the normally used gust factor approach does not give sufficiently acceptable results so that patch load analyses are required. Results of the parametric studies and the analyses of a large number of actual towers showed that leg loads in the upper few spans tended to be about 15% larger on average in a patch load analysis. Face shears at the guy supports were also about 15% higher on average in the patch load method. The studies revealed no strong trends between the patch load and gust factor correlation and the tower parameters, although there were slight trends suggesting that a patch load analysis was warranted if the tower height was greater than 250 m, the aspect ratio was greater than 120, or the drag area exceeded 2.0 m2/m. The presence of a cantilever accentuated the margin between the results of the two methods. Key words: guyed towers, analysis, wind loading, dynamic effects, patch load, gust factor.

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

Abnormalities of the Teeth and Their Supporting Structures

1972 ◽  
Vol 5 (2) ◽  
pp. 249-272
Author(s):  
Leslie Bernstein ◽  
Kenneth S. Keyes
Keyword(s):  
Supporting Structures

The Nature of Mining-Induced Horizontal Displacement of Surface on the Example of Several Coal Mines

2014 ◽  
Vol 59 (4) ◽  
pp. 971-986 ◽  
Author(s):  
Krzysztof Tajduś
Keyword(s):  
Underground Mining ◽  
Mining Industry ◽  
Horizontal Displacement ◽  
Surface Slope ◽  
Proportionality Coefficient ◽  
Model Studies ◽  
Displacement Vectors ◽  
Mining Conditions ◽  
Design Projects ◽  
Academy Of Sciences

Abstract The paper presents the analysis of the phenomenon of horizontal displacement of surface induced by underground mining exploitation. In the initial part, the basic theories describing horizontal displacement are discussed, followed by three illustrative examples of underground exploitation in varied mining conditions. It is argued that center of gravity (COG) method presented in the paper, hypothesis of Awierszyn and model studies carried out in Strata Mechanics Research Institute of the Polish Academy of Sciences indicate the proportionality between vectors of horizontal displacement and the vector of surface slope. The differences practically relate to the value of proportionality coefficient B, whose estimated values in currently realized design projects for mining industry range between 0.23r to 0.42r for deep exploitations, whereas in the present article the values of 0.33r and 0.47r were obtained for two instances of shallow exploitation. Furthermore, observations on changes of horizontal displacement vectors with face advancement indicated the possibility of existence of COG zones above the mined-out field, which proved the conclusions of hitherto carried out research studies (Tajduś 2013).

Fragility Analysis of Transmission Line Subjected to Wind Loading

2019 ◽  
Vol 33 (4) ◽  
pp. 04019044 ◽  
Author(s):  
Xing Fu ◽  
Hong-Nan Li ◽  
Li Tian ◽  
Jia Wang ◽  
Hu Cheng
Keyword(s):  
Transmission Line ◽  
Fragility Analysis ◽  
Wind Loading
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