Author: Lee, M M K;Kamtekar, A G
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Lee, M M K;Kamtekar, A G
The Structural Engineer, Volume 67, Issue 22, 1989
A finite element method is applied to the study of natural frequencies of electric transmission line structures. The tower has been modelled as a space truss consisting of 3-dimensional truss elements with three translational degrees of freedom at each node. The sagged conductor cable has been assumed to be composed of straight elements. Extensional characteristics of the cable element are fully considered. A parametric study is conducted to determine the influence of various parameters on the spectrum of natural frequencies of a conductor cable, and appropriate non-dimensional curves are presented. These non-dimensional curves give an insight into the general characteristics of a sagged cable, and can be used to predict inplane natural frequencies over a wide range of sagispan ratios. The first few natural frequencies of the transmission linesystem fall in the range 0.05 to 0.5 Hz. Professor M.L. Gambhir
The Tyne Bridge Sir Ralph Freeman and Ralph Anthony Freeman (son and grandson of the first Sir Ralph) have provided us with most interesting comment on the association of the earlier Sir Ralph with this very well-known bridge, which was featured on the cover of The Structural Engineer for 5 September last: We were pleased to see the picture of the Tyne Bridge and to read the positive comments about this famous bridge, now almost 61 years old. Verulam
The Loma Prieta earthquake at 5.04pm on 17 October caused extensive structural damage in San Francisco, in Oakland, and in smaller communities to the south. It measured 6.9 on the Richter scale, which is comparable to the event which devastated parts of Azerbajan nearly a year ago. A major difference was the scope of destruction. While the Armenian disaster caused disruption which resulted in a death toll of over 2000, the fatalities in California were less than one 10th of this.