• Wind and Structures
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• v.18 no.5
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• pp.473-495
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• 2014

Localized wind events, in the form of tornadoes and downbursts, are the main cause of the large number of failure incidents of electrical transmission line structures worldwide. In this study, a numerical model has been developed to study the behaviour of self-supported transmission lines under various tornado events. The tornado wind fields used were based on a full three-dimensional computational fluid dynamics analysis that was developed in an earlier study. A three-dimensional finite element model of an existing self-supported transmission line was developed. The tornado velocity wind fields were then used to predict the forces applied to the modelled transmission line system. A comprehensive parametric study was performed in order to assess the effects of the location of the tornado relative to the transmission line under F2 and F4 tornado wind fields. The study was used to identify critical tornado configurations which can be used when designing transmission line systems. The results were used to assess the sensitivity of the members' axial forces to changes in the location of the tornado relative to the transmission line. The results were then used to explain the behaviour of the transmission line when subjected to the identified critical tornado configurations.

• Wind and Structures
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• v.13 no.5
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• pp.451-469
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• 2010

The majority of weather-related failures of transmission line structures that have occurred in the past have been attributed to high intensity localized wind events, in the form of tornadoes and downbursts. A numerical scheme is developed in the current study to assess the performance of transmission lines under tornado wind load events. The tornado wind field is based on a model scale Computational Fluid Dynamic (CFD) analysis that was conducted and validated in a previous study. Using field measurements and code specifications, the CFD model data is used to estimate the wind fields for F4 and F2 full scale tornadoes. The wind forces associated with these tornado fields are evaluated and later incorporated into a nonlinear finite element three-dimensional model for the transmission line system, which includes a simulation for the towers and the conductors. A comparison is carried between the forces in the members resulting from the tornadoes, and those obtained using the conventional design wind loads. The study reveals the importance of considering tornadoes when designing transmission line structures.

• Wind and Structures
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• v.34 no.2
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• pp.215-230
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• 2022

Majority of transmission line system failures at many locations worldwide have been caused by severe localized wind events in the form of tornadoes and downbursts. This study evaluates the structural response of two different transmission line systems under equivalent F2 tornadoes obtained from real incidents. Two multi-span self-supported transmission line systems are considered in the study. Nonlinear three-dimensional finite element models are developed for both systems. The finite element models simulate six spans and five towers. Computational Fluid Dynamics (CFD) simulations are used to develop the tornado wind fields. Using a proper scaling method for geometry and velocity, full-scale tornado flow fields for the Stockton, KS, 2005 and Goshen County WY, 2009 are developed and considered together with a previously developed tornado wind field. The tornado wind profiles are obtained in terms of tangential, radial, and axial velocities. The simulated tornadoes are then normalized to the maximum velocity value for F2 tornadoes in order to compare the effect of different tornadoes having an equal magnitude. The tornado wind fields are incorporated into a three-dimensional finite element model. By varying the location of the tornado relative to the transmission line systems, base shears of the tower of interest and peak internal forces in the tower members are evaluated. Sensitivity analysis is conducted to assess the variation of the structural behaviour of the studied transmission lines associated with the location of the tornado relative to the tower of interest. The tornado-induced forces in both lines due to the three different normalized tornadoes are compared with corresponding values evaluated using the simplified load case method recently incorporated in the ASCE-74 (2020) guidelines, which was previously developed based on the research conducted at Western University.

• Earthquakes and Structures
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• v.17 no.4
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• pp.387-398
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• 2019

On the basis that ground motions may arrive at a structure from any horizontal direction and that different directions of seismic incidence would result in different structural dynamic responses, this paper focuses on orienting the crucial seismic incidence of transmission tower-line systems based on the wavelet energy method. A typical transmission tower-line system is chosen as the case study, and two finite element (FE) models are established in ABAQUS, with and without consideration of the interaction between the transmission towers and the transmission lines. The mode combination frequency is defined by considering the influence of the higher-order modes of the structure. Subsequently, wavelet transformation is performed to obtain the total effective energy input and the effective energy input rate corresponding to the mode combination frequency to further judge the critical angle of seismic incidence by comparing these two performance indexes under different seismic incidence angles. To validate this approach, finite element history analysis (FEHA) is imposed on both FE models to generate comparative data, and good agreement is found. The results demonstrate that the wavelet energy method can forecast the critical angle of seismic incidence of a transmission tower-line system with adequate accuracy, avoiding time-consuming and cumbersome computer analysis. The proposed approach can be used in future seismic design of transmission tower-line systems.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.682-687
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• 2000

In this paper, the simulation methods using transmission lines are studied and realized, which are necessary in design and analysis of hydraulic control systems. The basic idea of this method is that system components are separated by transmission line element for simulation. The PI-controller can keep inductance level as low as desired. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. Parallel hydraulic circuits are simulated using parallel processing algorithm. To shoe that using variable timestep size in each subsystem, simulation time can be reduced. Performance of the simulation results is compared with that of Runge Kutta method.

• Wind and Structures
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• v.34 no.4
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• pp.335-353
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• 2022

The current work numerically investigates the transient force and dynamic response of an overhead transmission tower-line structure caused by the passage of a high-speed train (HST). Taking the CRH2C HST and an overhead transmission tower-line structure as the research objects, both an HST-transmission line fluid numerical model and a transmission tower-line structure finite element model are established and validated through comparison with experimental and theoretical data. The transient force and typical dynamic response of the overhead transmission tower-line structure due to HST-induced wind are analyzed. The results show that when the train passes through the overhead transmission tower-line structure, the extreme force on the transmission line is related to the train speed with a significant quadratic function relationship. Once the relative distance from the track is more than 15 m, the train-induced force is small enough to be ignored. The extreme value of the mid-span dynamic response of the transmission line is related to the train speed and span length with a significant linear functional relationship.

• Journal of Magnetics
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• v.11 no.2
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• pp.90-94
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• 2006

A finite-element method is used to analyze loss generation and electromagnetic noise absorption characteristics of a coplanar waveguide transmission line integrated with a magnetic thin film. Parameters used in the analysis are the electrical resistivity of the magnetic layer and the thickness of both magnetic and insulating layers. The results indicate that L-C resonance is the main loss mechanism of the electromagnetic noise absorption.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.291-303
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• 2019

In the paper the analysis of natural vibrations of the transmission line with use of spectral elements and the laboratory experiments is performed. The purpose of the investigation is to analyze the natural vibrations of the transmission line and compare with the results obtained in the numerical simulations. Particular attention is paid to the hysteretic and aerodynamic damping analysis. Sensitivity of the wave number is performed for changing of the tension force, as well as for the different damping parameters. The numerical model is made using the Spectral Element Method. In the spectral model, for various parameters of stiffness, damping and tension force, the system response is checked and compared with the results of the accelerations obtained in the measurements. A frequency response functions (FRF) are calculated. The credibility of the model is assessed through a validation process carried out by comparing graphical plots of FRF and time history analysis and numerical values expressing differences in acceleration amplitude (MSG), phase angle differences (PSG) and differences in acceleration and phase angle total (CSG) values. The next aspect constituting the purpose of this paper is to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method. The obtained results show good accuracy in the range of both experimental measurements as well as simulation analysis. The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division, tensile strength or material damping can be studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.518-522
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• 2014

This paper is concerned with the dynamic modeling of transmission line undergoing galloping vibrations. To this end, the kinetic and potential energies of a uniform wire vibrating in space are derived. The equations of motion suitable for numerical simulations are derived using the assumed mode method and Lagrange equation. The resulting equations of motion are expressed in matrix form. To cope with bundled transmission line, the spacer was modelled by a spring element. As a numerical example, a two-wire transmission line combined by spacers was considered. Natural vibration characteristics show that the in-plane vibrations of the transmission line appeared in low frequency range, which may lead to galloping.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.589-594
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• 2002

The filter of hairpin type can be designed small but has a demerit which a design method is complex. This paper suggests the method that a hairpin line filter is designed with applying a transmission line method and J inverter circuit, accurately calculated the J value and the b parameter. It is considered about the line have no the mutual coupling element with next line to each other. is calculated a length of electric coupling line about coupling element in each inverter stage from the J value and the b parameter. In order to show the validity of the proposed design method, band pass filter of small hairpin line is designed at center frequency 2.6 GHz, with Serenade 8.0 software tool and the simulation characteristics are compared with design results.