Dynamic response analysis of transmission towers after conductor breakage using ADINA

Dunford, Joseph I. (Joseph Isaac) (2011) Dynamic response analysis of transmission towers after conductor breakage using ADINA. Masters thesis, Memorial University of Newfoundland.

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Abstract

The objective of this research was to (i) assess the peak dynamic and static residual loads on various types of transmission line structures due to conductor rupture, (ii) study the effect of structural flexibility on maximum dynamic impact and static residual conductor loads and (iii) carry out a sensitivity study of various line parameters such as conductor tension, ice load, insulator length and terrain types on the peak dynamic and static residual loads. -- To accomplish these objectives, the following tasks were carried out: -- A number of numerical models of a 30 span transmission line were developed and analyzed using the ADINA finite element software package. The initial results were validated by comparing with the full scale test data. -- Four structure types were considered in the detailed analyses. These were: (1) self-supported steel lattice tower with different leg extensions, (2) guyed-V steel lattice tower, (3) tubular steel pole structure and (4) H-frame wood pole structure. The effect of the structures' flexibility on peak dynamic and static residual conductor tensions was studied, after a conductor rupture -- A sensitivity analysis study was conducted to study the effects of various line design parameters such as initial conductor tension, conductor loading (bare conductor, versus loads due to half an inch and one inch radial ice thicknesses), insulator length and terrain types (e.g. level, hilly and valley terrains). The results from this study are presented in terms of their effect on impact factors. -- The results obtained from the numerical simulation study indicate that the structural flexibility and the span/insulator and the span /sag ratios have considerable effects on the residual conductor tension (hence on the insulator force). However, the peak dynamic tensions are affected not only by the structural flexibility but also by the cross arm mass and the shape of the structures used for line modeling. For stiff structures, cross arm mass has very little effect on the peak conductor tension. For transmission line modeled with rigid structures, the impact factors are not sensitive to the stiffness values, where as for line modeled with flexible structures, the residual ratio depends on both the stiffness values and span/insulator and span/sag ratios. The effect of insulator string length has more effect on residual ratio than peak impact factor. The specific terrain types that were considered in this study had only minimum effects on the impact factors.

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