SELECTION AND PERFORMANCE OF ANCHORS FOR GUYED TRANSMISSION TOWERS

1969 ◽  
Vol 6 (2) ◽  
pp. 119-135 ◽  
Author(s):  
K. E. Robinson ◽  
H. Taylor
Keyword(s):  
Transmission Lines ◽  
Soil Types ◽  
Construction Equipment ◽  
Soil Conditions ◽  
Transmission Towers ◽  
Reasonable Cost ◽  
Soil Exploration ◽  
And Performance ◽  
Design And Construction

This paper presents information on the selection and performance of anchors for guyed EHV transmission towers. The information used was obtained during the design and construction of two transmission lines each over 540 miles (>869 km) long in British Columbia.Five anchors have been designed and tested: (1) buried plate with compacted backfill; (2) buried steel mat or grillage with loose backfill; (3) cast-in-place concrete with loose backfill; (4) power installed helical; and (5) grouted rod anchors.The highly variable soil and access conditions along the line necessitated an anchor that could economically be installed in nearly all soil types and by ordinary construction equipment that could easily move between tower sites in rugged terrain.The simply installed, conservatively designed, cast-in-place concrete anchor was found to satisfy these requirements at reasonable cost. Power-installed helical anchors and grouted rod anchors may provide an economical anchor in more uniform soil conditions and where easier access conditions exist. However, these anchors require more detailed soil exploration and contract inspection than the cast-in-place concrete anchors.

scholarly journals Collapse Analysis of a Transmission Tower-Line System Induced by Ice Shedding

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaxiang Li ◽  
Biao Wang ◽  
Jian Sun ◽  
Shuhong Wang ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Transmission Lines ◽  
Progressive Collapse ◽  
Element Model ◽  
Transmission Tower ◽  
Line System ◽  
Finite Element Software ◽  
Transmission Towers ◽  
Ice Shedding ◽  
The Impact

Ice shedding causes transmission lines to vibrate violently, which induces a sharp increase in the longitudinal unbalanced tension of the lines, even resulting in the progressive collapse of transmission towers in serious cases, which is a common ice-based disaster for transmission tower-line systems. Based on the actual engineering characteristics of a 500 kV transmission line taken as the research object, a finite element model of a two-tower, three-line system is established by commercial ANSYS finite element software. In the modeling process, the uniform mode method is used to introduce the initial defects, and the collapse caused by ice shedding and its influencing parameters are systematically studied. The results show that the higher the ice-shedding height is, the greater the threat of ice shedding to the system; furthermore, the greater the span is, the shorter the insulator length and the greater the dynamic response of the line; the impact of ice shedding should be considered in the design of transmission towers.

Design and Construction of the Concrete Canoe California II

1986 ◽  
Vol 23 (03) ◽  
pp. 271-275
Author(s):  
R. Cengiz Ertekin ◽  
Bradford A. Porter
Keyword(s):  
University Of California ◽  
And Performance ◽  
American Society ◽  
The University ◽  
Design Construction ◽  
Design And Construction ◽  
Civil Engineers

Student chapters of the American Society of Civil Engineers participate annually in a competition for the design, construction and performance of concrete canoes that meet certain minimum rule restrictions. This paper reports on the craft entered in the 1984 competition by students at the University of California/ Berkeley. The Berkeley team came in second in the men's and women's races and placed first in both design and construction.

Personalizing Oncology: Perspectives and Prospects

2013 ◽  
Vol 31 (15) ◽  
pp. 1904-1911 ◽  
Author(s):  
John Mendelsohn
Keyword(s):  
Clinical Trials ◽  
Molecular Targets ◽  
Targeted Drugs ◽  
Genetic Aberrations ◽  
Patients With Cancer ◽  
Reasonable Cost ◽  
Before And After ◽  
Cancer Medicine ◽  
And Performance ◽  
Selection Of

This article provides an overview of the research, beginning a century ago, that has led to the current use of genomically informed methods for selection of targeted therapies to treat individual patients with cancer—so-called precision cancer medicine. Until 1980, most research on cancer therapy was not targeted in the sense we use the word today. Since then, there has been an acceleration in research identifying genetic and molecular targets and in clinical trials using biomarkers that identify the presence of genetic or molecular markers in a patient's cancer to select appropriate targeted therapy. This approach has been made possible by increased knowledge of the genetic pathogenesis of cancer and by increased capacity to sequence genes and genomes in clinically useful timeframes and at a reasonable cost. However, many challenges and pitfalls remain in selecting optimal targets, interpreting data on genetic aberrations, designing effective targeted drugs and antibodies, dealing with resistance to treatments, identifying appropriate combinations of therapies, and performing the complex clinical trials that are required. Future clinical research with experimental targeted agents is likely to be more informative because of appropriate preselection of patients enrolled onto trials and performance of genetic and molecular studies on specimens of a patient's cancer before and after treatment.

scholarly journals Effects of a Crossarm Brace Application on a 275 kV Fiberglass-Reinforced Polymer Crossarm Subjected to a Lightning Impulse

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6248
Author(s):  
Muhammad Syahmi Abd Rahman ◽  
Mohd Zainal Abidin Ab Kadir ◽  
Muhamad Safwan Ab-Rahman ◽  
Miszaina Osman ◽  
Shamsul Fahmi Mohd Nor ◽  
...  
Keyword(s):  
Field Strength ◽  
Simulation Study ◽  
Transmission Lines ◽  
Potential Distribution ◽  
Mechanical Performance ◽  
Swing Angle ◽  
Frp Composite ◽  
Reinforced Polymer ◽  
Transmission Towers ◽  
Lightning Impulse

The crossarm is an important component of transmission towers, providing insulation for transmission lines at different voltage ratings. Recently, composite crossarms were widely used as a composite tower component and were found to be the most favorable choice for replacing old wooden crossarms. Owing to the satisfactory pilot operation and multiple sets of testing, fiberglass-reinforced polymer (FRP) composite crossarms have been used in Malaysia in both 132 and 275 kV transmission lines since the late 1990′s. Since then, some modifications have been proposed to improve the mechanical performance of the crossarm, in order to ensure the reliability of its performance. In this investigation, the effect of a proposed improvement, achieved by installing a brace for the crossarm, was investigated numerically. A simulation study was conducted, with a consideration of the lightning impulse voltage (LIV) and swing angle exhibited by the crossarm. The potential and electric field (E-Field) distribution were analyzed and are presented in this paper. It was found that the potential distribution and E-Field strength for the crossarm and the surrounding air were greatly affected by the installation of the brace.

Physiological and biomass partitioning shifts to water stress under distinct soil types in Populus deltoides saplings

2020 ◽  
Vol 13 (5) ◽  
pp. 545-553
Author(s):  
Senlin Yang ◽  
Jian Shi ◽  
Lianghua Chen ◽  
Jian Zhang ◽  
Danju Zhang ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Drought Stress ◽  
Gas Exchange ◽  
Nitrogen Metabolism ◽  
Populus Deltoides ◽  
Soil Types ◽  
Soil Conditions ◽  
N Assimilation ◽  
Wide Range ◽  
Gas Exchange Rate

Abstract Aims Although soil environments exist extensive heterogeneity for many plants with a wide range of distribution, researches about effects of soil conditions on plants’ tolerance and adaptation are particularly inadequate. In our study, the aims are to reveal physiological strategies of Populus deltoides against drought stress under different soil conditions and to select the most suitable soil type for P. deltoides plantation. Methods Under controlled conditions, we used P. deltoides as a model species to detect differences in gas exchange rate, antioxidative capacity, nitrogen metabolism and biomass accumulation and partitioning in response to drought stress under three mineral soil types with distinct physicochemical characters, i.e. red soil (RS), yellow soil (YS) and yellow-brown soil (BS). Important Findings Exposure to 25% of field water holding capacity in soil for 3 months had significantly decreased biomass of all organs, photosynthetic rate, enzyme activities related to N assimilation, but increased H2O2, malondialdehyde and content of both NO3− and NH4+, when P. deltoides was planted in both RS and YS. In contrast, under BS, there are slightly negative effects exerted by water deficit on total biomass, gas exchange rate, activities of enzymes related to nitrogen metabolism and membrane damage caused by reactive oxygen species, which can be associated with a consistent increase in superoxide dismutase, peroxidase and catalase, and a higher ratio of root mass to shoot mass. It is concluded that, such higher capacity in tolerance and adaptation against drought stress under BS relative to both RS and YS could be accounted for more sufficient nutrient provision in soil parental materials and better soil aeration conditions which play a vital role in plant acclimation to water shortage. Our study also revealed that, distribution areas of BS might be preferable for cultivation of P. deltoides, when compared with those of RS and YS.

Analysis and performance of superconductive coaxial transmission lines

1964 ◽  
Vol 52 (10) ◽  
pp. 1147-1154 ◽  
Author(s):  
R.J. Allen ◽  
N.S. Nahman
Keyword(s):  
Transmission Lines ◽  
And Performance

scholarly journals Modeling and optimizing transmission lines with GIS and Multi-Criteria Decision Analysis

2017 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Joram Schito
Keyword(s):  
Decision Analysis ◽  
Transmission Lines ◽  
Least Cost Path ◽  
Ongoing Research ◽  
Stable Algorithm ◽  
Multi Criteria Decision Analysis ◽  
Transmission Towers ◽  
Cost Surface ◽  
First Results ◽  
Simple Additive Weighting

AbstractIn planning transmission lines with the use of Geographic Information Systems, the use of the Least Cost Path (LCP) algorithm has been established while relevant criteria are modeled using Multi-Criteria Decision Analysis (MCDA). Despite their established use, this combination (MCDA/LCP) often leads to results that do not correspond to realistic conditions. Therefore, the MCDA/LCP computation must usually be optimized on an algorithmic level as well as on the decision model and the underlying data relevant for the MCDA. The current paper presents the state-of-the-art of an ongoing research project that aims to solve these issues. First results are promising since a stable algorithm has been developed that computes a cost surface, a Least Cost Corridor (LCC), a LCP, and the transmission towers' positions by simple additive weighting based on user's weights. Optimizations on the MCDA models have already been implemented and tested. The findings are integrated into a 3D Decision Support System which aims at facilitating the work of TL planners by realistic modeling and by reducing the approval process for new TL.

Sign in / Sign up

Export Citation Format

Share Document