Design Of Tower Structures Research Articles

Effects of Ground Resistivity and Tower Structural Design on Transmission Line Symmetrical Components

Electric power transmission towers are line support that exists in different structural configurations depending on the design. Parameters in consideration for the design include proposed voltage and current ratings to be carried by the tower, weight of aluminum conductor and the weight of concrete foundation on which the tower would be erected. It is often reported that ground resistivity of the ground on which an electric power transmission tower is erected has significant effects on earth faults and transmission losses on the line. This paper presents an investigation of the effects of ground resistivity and tower structural design on transmission line symmetrical components. Symmetrical component parameters’ evaluation of the transmission lines approach is considered the best option. Ten differently structured transmission towers were selected for the case study. The effects of installing these ten towers on each of the available ground resistivity types were examined. A modern computer software was developed in carrying out this investigation. The results are presented and discussed. It was observed that at each location of a tower, ground resistivity plays a vital role in measuring the performance of tower in an electric power supply stability and reliability.

Advanced joint slip model for single-angle bolted connections considering various effects

Latticed structures are commonly used in transmission towers due to lightweight, fast fabrication, and easy installation, but they generally experience more complicated structural behaviors. The full-scale tests on transmission towers have revealed large discrepancies between the numerical simulation and experimental results because the significant joint slip effects have not well considered in the former. The existing joint slip models were so simple that many key parameters had not been taken into account. Thus, a comprehensive joint slip model is proposed in this article for better prediction and design of tower structures. First, a full-detailed finite element model based on ABAQUS incorporating more realistic parameters for a typical joint is developed and calibrated by the experimental data from the literature. Furthermore, the proposed FE model is used for parametric study of joint behaviors with considerations of bolt pretension, friction at contact face, angle sizes and plate thickness, steel and bolt grades, number of bolts, and hole tolerance. Finally, an advanced joint slip model is provided for further incorporation in the second-order direct analysis of transmission towers. This work is limited in the literature and will significantly improve safety and enhance the cost-efficiency of tower design. The proposed model shows high accuracy and can be simply determined by joint details in line with the component method specified in Eurocode 3-1-8.

Optimum design of tower structures using Firefly Algorithm

SUMMARYThe Firefly Algorithm (FA) as a recent new meta‐heuristic optimization algorithm is developed for determining optimum design of tower shaped structures. The FA mimics the social behavior of fireflies, which communicate, search for pray and find mates using bioluminescence with varied flashing patterns. In this paper, an adaptive FA is presented that utilizes the feasible‐based method to handle constraints. This method is effective in improving the convergence and also suitable for expensive optimization tasks such as large‐scale structures. Three tower structures are selected to evaluate the performance of the algorithm. The results are better than the other results proposed in the literature and confirm the validity of the proposed algorithm. Copyright © 2012 John Wiley & Sons, Ltd.

Sensitivity of lightning shielding failure of double-circuit transmission line on tower geometric structures

A numerical calculation method based on the leader propagation model of lightning is proceeded to investigate the effect of overhead line tower geometric constructions to the lightning shielding failure. In this paper, the height and the spacing of the ground wire were changed to study the sensitivity of the shielding effectiveness on tower constructions. As the conclusion, an efficient layout scheme of ground wire and phase wire was proposed. Even if the protecting angle of the ground wire keeps unchanged, if the height of the ground wire is various, the total shielding failure rate is totally different, so we should take into account other factors except for the protection angle during the design of tower structure. This paper compared the total trip out rate of four types of double-circuit towers and concluded that the concave drum-type tower is the best design.

Seismic Design Scope of Tower Structures for UHV Transmission Lines on the Zone of Earthquake Fortification Intensity 8

The seismic action effects of tower structures for ultra-high-voltage(UHV, upon 750KV) overhead transmission lines are much greater than those of 500KV and below, it is necessary to inspect the control load in structural design and specify the seismic design scope of tower structures for these UHV transmission lines. In this paper, the current regulations of seismic design and non-seismic design of tower structures for overhead transmission line were contrasted firstly; then, a series of typical towers including large-crossing towers and cup-towers at soft sites, on the zone of earthquake fortification intensity region of 8, were analyzed. The ratios of seismic action effects and wind load effects for characteristic value were calculated and the control load in structural design of tower structure was investigated. The results show that, although the height and the weigth of tower structures for UHV transmission lines are increasing, the control load in structural design is still the wind load on the zone of earthquake fortification intensity region of 8 and below.

Reliability-Based Robust Optimization Design for Lattice Tower Structure

Reliability Analysis is applied into tower structural design and influence of uncertain factors is considered into the design. The reliability robust optimization mathematical model of tower structure is established by combining the reliability optimization designing theory with the robust design method and injecting reliability sensitivity into the design model. The reliability sensitivity is added to the reliability-based optimization design model and the stiffness reliability-based robust design is reduced to a multi-objection optimization. Take the lattice tower structure for example, after designing, it shows not only lighter weigh, saving in material, simplifying construction, but also improving its safety and stability. The example proves the method to be effective.

Optimal frequency design of tower structures via an approximation concept

The purpose of this paper is to develop a new numerical method via an approximation concept for finding the optimal bending stiffness distribution of a one-dimensional distributed-parameter structure (i.e. beam) under a fundamental natural frequency constraint. The distributed-parameter structure is modeled by an FEM system and the bending stiffness distribution is approximated by a piecewise-linear function. A cubic displacement function is utilized in the FEM system. Then the displacement function is determined so that the optimality condition described at every point would be satisfied only at the element ends. It is shown that the optimal bending stiffnesses can be obtained from a set of simultaneous linear equations which is rearranged from a set of governing equations of the lowest eigenvibration. No iteration is required in determining the optimal displacement functions and bending stiffnesses. A numerical example of a tower structure is presented in order to demonstrate the validity, efficiency and accuracy of this method.