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.

Comparison of Dynamic Analysis Methods in a Cable-Stayed Tower Under Extreme Wind Loads in Cuba

2019 ◽  
Vol 60 (3) ◽  
pp. 210-220
Author(s):  
Ingrid Fernández Lorenzo ◽  
Bruno Jorge Clavelo Elena ◽  
Olivia Ollet Otero ◽  
Vivian Beatriz Elena Parnás
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Method ◽  
Time History ◽  
Wind Loads ◽  
Wind Loading ◽  
Axial Loads ◽  
Wind Speeds ◽  
Extreme Wind ◽  
Patch Load ◽  
Guyed Mast

Several methods and investigations have been conducted in order to dynamically analyze the behavior of guyed mast telecommunication towers subject to wind loading, due to the importance of such structures in current society. Due to their slenderness, flexibility and lightweight, these structures are particularly susceptible to wind loads, being strong hurricane winds the cause of several tower failures in Cuba. This works conducts the study of a 120 meters tall guyed mast, model MAR 2008, facing extreme wind loads in two different locations. The structure is modeled using the computational assisted software SAP2000 and a dynamic analysis is undertaken using two methods: the equivalent static method "Patch Load" and the full dynamic method "Time History" using Direct Integration. The basic wind speeds are determined according to the Method of Independent Storms (MIS) and standard turbulence intensities for cyclonés regions. Synthetic functions are generated for different heights of the tower in order to apply the "Time History" dynamic method. Finally, a comparison is established between the results in terms of axial loads, joint reactions and displacements. The main conclusion of the study is that as the basic speed decreases, there is a higher resemblance in inner forces and displacements between the results obtained for the two studied methods.

Dynamic response of transmission lines guyed towers under wind loading

2010 ◽  
Vol 37 (3) ◽  
pp. 450-465 ◽  
Author(s):  
F. Gani ◽  
F. Légeron
Keyword(s):  
Dynamic Response ◽  
Direct Current ◽  
Transmission Lines ◽  
Wind Loading ◽  
Dynamic Effects ◽  
Transient Dynamic ◽  
Simplified Method ◽  
Loading Case ◽  
Dc Line ◽  
Guyed Towers

The importance of the dynamic response of guyed towers for transmission lines (TLs) under wind loading is evaluated in this article. The objective is to verify if the simplified static-equivalent approach provided in the current TL codes is sufficient for this type of flexible tower. As a comparison, transient dynamic (TD) analyses were performed. Two different guyed tower configurations were investigated: (i) the direct current (DC) line and (ii) the alternating current (AC) line. Loading cases considering bare and iced TL structures were studied. It was found that, depending on the guyed tower configuration and the loading case, the static-equivalent approach may underestimate the possible dynamic response. In addition, a simplified method that allows a better prediction of the dynamic effects is proposed.

scholarly journals Dynamic Effects of a Heliostat to Wind Loading

2014 ◽  
Vol 49 ◽  
pp. 1728-1736 ◽  
Author(s):  
J.M. Terrés-Nícoli ◽  
C. Mans ◽  
J.P.C. King
Keyword(s):  
Wind Loading ◽  
Dynamic Effects

Nonlinear spectral dynamic analysis of guyed towers. Part II: Manitoba towers case study

2004 ◽  
Vol 31 (6) ◽  
pp. 1061-1076 ◽  
Author(s):  
A M Horr ◽  
A Yibulayin ◽  
P Disney
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Complex Geometry ◽  
Spectral Element ◽  
Wind Loading ◽  
Space Structures ◽  
Loading Test ◽  
Large Space ◽  
Post Buckling ◽  
Guyed Towers

Dynamic response of large complex space structures under wind loading is important in terms of performance and safety. Conventional method of wind loading calculation has been used successfully in codes to analyze large space structures. The method can be applied by approximating the air pressure, induced by wind, on the surfaces of structures. Although this replaces a wind loading test using complicated wind tunnel tests for any structural systems, the accuracy of the method, in the case of complex geometry guyed tower structures, is a matter of consideration. Hence, it is desirable to search for a procedure with more accuracy and reliability. In this respect, attention is paid to the advanced spectral element method and the computational fluid dynamics. Using the proposed formulation, a material and geometric nonlinear dynamic analyses have been performed to simulate post-buckling behaviours and also collapse modes for series of Manitoba Hydro's guyed towers under extreme wind loading conditions. Key words: computational fluid dynamics, wind loading, collapse mode, nonlinear analysis, post-buckling.

Wind loading on intermediate height buildings

1992 ◽  
Vol 19 (1) ◽  
pp. 148-163 ◽  
Author(s):  
R. A. Sanni ◽  
D. Surry ◽  
A. G. Davenport
Keyword(s):  
Research Work ◽  
Dynamic Responses ◽  
Wind Engineering ◽  
Wind Loads ◽  
Wind Loading ◽  
Interference Effects ◽  
Data Set ◽  
Minimum Width ◽  
Gust Factor ◽  
Detailed Method

The current gust factor approach in the detailed method of the National Building Code of Canada (NBCC) for the estimation of wind loads on buildings was developed from research work that was largely directed towards very tall and flexible buildings for which resonant responses are very significant; however, the dynamic responses of the majority of intermediate height buildings are dominated by quasi-steady gust loading with little resonant response. This study has been carried out to assess the applicability of the detailed approach of the NBCC to that class of fairly common intermediate height buildings, of which apartment buildings are good examples. For the purposes of this study, these buildings have been defined as buildings whose heights are between 20 and 120 m and whose ratio of height to minimum width is not more than 4. The responses estimated from the detailed approach of the NBCC have been compared with those from wind tunnel tests with a view to verifying and simplifying its application to such intermediate height buildings.Since intermediate height buildings are often arranged in groups, an experimental study of the interference effects between adjacent buildings was also undertaken to assess the effect of an upwind building on the wind-induced overall moments on a downwind building of a similar height. The influence of this interference effect on the member stresses or forces was investigated using the concept of joint action factors.General agreement between the test and the code-estimated responses was obtained in the comparisons. The small resonant responses observed provided a basis for deriving a simplified method for estimating the gust factor in the detailed method without the requirement of knowing the structure's dynamic properties.Significant interference effects were found, particularly for the across-wind and torsional moments on buildings in an open exposure; however, the amplification of the overall wind-induced moments does not necessarily translate into a similar amplification of member forces or stresses. For the buildings studied, the results have shown that for the majority of practical situations, interference effects are not likely to result in amplification of member stresses or forces. A set of additional factors of safety have been proposed, based on the limited experimental data set, to cover load amplification by interference effects for those members that are very sensitive to overall wind-induced torsional moments. Key words: codes, wind loads, wind engineering, intermediate height buildings, interference effects.

Dynamic 3D Foundation–Soil–Foundation Interaction on Stratified Soil

2017 ◽  
Vol 17 (03) ◽  
pp. 1750032 ◽  
Author(s):  
Zejun Han ◽  
Gao Lin ◽  
Jianbo Li
Keyword(s):  
Three Dimensional ◽  
Integration Scheme ◽  
Computational Stability ◽  
Wave Propagation Velocity ◽  
Foundation Soil ◽  
Precise Integration ◽  
Soil Layers ◽  
Parametric Studies ◽  
Soil Foundation ◽  
Supporting Structures

This paper studies the dynamic interaction between two or more adjacent foundations resting on the surface of a stratified soil. The precise integration scheme adopted ensures that the numerical results obtained are highly accurate. Only the interfaces between the foundations and the soil need to be discretized and there is no limit on the thickness or on the number of soil layers to be considered. Numerical examples are provided to verify the accuracy and computational stability of the proposed approach. A series of parametric studies have been carried out to clarify the effects of layer depth, soil damping, spacing between adjacent foundations, masses and moment inertias of supporting structures and the wave propagation velocity on the dynamic behavior of three-dimensional (3D) foundation–soil–foundation interaction (FSFI).

Sign in / Sign up

Export Citation Format

Share Document