Design Of Transmission Line Structures Research Articles

New NESC Extreme Ice Loading

This paper deals with the effects of the National Electrical Safety Code (NESC)-2007 extreme ice with concurrent wind loading conditions, a new loading condition for the design of electric utility structures, hardware, and conductors. This paper provides answers to some of the questions that may be in the minds of utility engineers involved in the design of transmission line structures by comparing the effects of the new extreme ice loading condition with those of the existing NESC weather-related loading conditions. This study evaluates whether structures designed on the basis of the NESC district loading conditions or extreme wind loading conditions could sustain loads resulting from the new extreme ice loading condition and identifies the regions of the United States where the extreme ice loading conditions would not likely control the design of transmission line structures. The new NESC extreme ice loading condition is also compared with the ASCE Std7-05 ice and wind loadings for other structures.

A stochastic model of severe thunderstorms for transmission line design

The importance of wind loading in the design of transmission line structures has been widely recognised. Due to the inherent variabilities of natural phenomena, the modelling of wind loads is a demanding task. Despite the fact that quite extensive research has been carried out in Australia over last 30 years, the wind loads that are generated by high intensive, localised, small-scale wind storms, such as severe thunderstorms, i.e. downbursts are poorly defined. The intention of the present paper is to propose a stochastic model that could realistically and accurately simulate wind loads that are generated by thunderstorm downbursts for transmission line design. The proposed model is then calibrated using existing meteorological records and compared with the results of other similar studies on severe winds. The major advantage of the proposed model for downburst winds is that the size effect of downbursts has been taken into account.

Probabilistic Design of Transmission Line Structures

For many years, electric transmission line structures in the U.S. have been designed in accordance with the minimum load and strength requirements given in the National Electrical Safety Code (NESC). Transmission line designers have recognized certain deficiencies in the NESC and usually specify increased design loading requirements based on conditions in local service areas. This practice has led to a lack of uniformity in design criteria for transmission line structures in the U.S. and points to the need for a uniform design approach based on probabilistic concepts. A load and resistance factor design format is recommended in which the design factors are probability‐based. The design point method for reliability analysis is reviewed and a computer program which applies this method to transmission line structures is described. A calibration example is presented which illustrates the use of this program for establishing the level of reliability in an existing structure and the corresponding design factors...

Reliability‐Based Design of Wood Transmission Line Structures

Several phases of a project seeking to improve the design of wood transmission line structures are presented. Improved information for wood pole strength includes a compilation of results from previous pole tests of new fairly short poles. Strength and stiffness values from a pilot study of transmission-size poles and poles removed from service are also presented. These test show that pole strength is significantly reduced by exposure to typical service conditions. In addition, limited tests of new transmission-size poles show results similar to those of previous tests of new short poles. A load and resistance factor design format with design factors based on reliability concepts is advocated as a practical method to improve design of transmission line structures by achieving a better balance of reliability and economy. The proposed utility use of equations for load and resistance factors containing design quantity variabilities and reliability index values allows the consideration of special conditions and encourages gathering of local data. An illustration of the reliability-based design method is also included.

Probability-Based Wind Loadings for the Design of Transmission Line Structures

A rational method of posing design wind loads for transmission line structures is overviewed. This method uses historical wind data from a utility's service area, a gradient wind model to compute near-surface design wind velocities, a statistical model for transmission structure response to gusty winds, and a probability-based approach to computing the most probable maximum lifetime load as well as minimum acceptable load/strength factors.

Probability-Based Wind Loadings for the Design of Transmission Line Structures

Probability-Based Wind Loadings for the Design of Transmission Line Structures

Discussion on “fundamental considerations governing the design of transmission line structures.” Atlantic city, N. J., June 30, 1908

Discussion on “fundamental considerations governing the design of transmission line structures.” Atlantic city, N. J., June 30, 1908

Discussion on ``Fundamental Considerations Governing the Design of Transmission Line Structures.'' Atlantic City, N. J., June 30, 1908

Discussion on ``Fundamental Considerations Governing the Design of Transmission Line Structures.'' Atlantic City, N. J., June 30, 1908

Fundamental Considerations Governing the Design of Transmission-Line Structures

Before the work of designing a tower or pole for a given transmission line can proceed, a statement must be made setting forth the loads which the structure should be capable of withstanding. This statement is, in general, based on a forecast of the probable extreme weather conditions which may occur in the vicinity of the line, and also on a prediction as to what accidents will probably occur to the conductors of the line.