SIST EN 50341-1:2002 is the Slovenian version of EN 50341-1:2001 that covered overhead electric lines with nominal system voltages exceeding AC 45 kV and with rated frequencies below 100 Hz. It is the first of three parts of EN 50341 and it is common to all countries. Two approaches are used for determination of actions on lines, general and empirical approach. Each country extends the application of first part with the requirements included in the national normative aspect that constitute parts 2 and 3 of the standard. In national normative aspect, country specifies the climatic conditions that allow the application of a general or empirical approach. For Slovenia, this is SIST EN 50341-3-21:2009, which uses an empirical approach for determining actions on transmission tower. EN 50341-1:2012 supersedes EN 50341-1:2002. It is used for overhead electric lines with nominal system voltages exceeding 1 kV and with rated frequencies below 100 Hz. It consists of two parts. The second part (national normative aspect) was not released yet for Slovenia. Unlike its predecessor, EN 50341-1:2012 does not provide guidance for determining actions using empirical approach, but only uses general approach. Therefore, SIST EN 50341-3-21:2009 is not compatible with EN 50341-1:2012. In the master˝s thesis, therefore, characteristic elements of 400 kV transmission tower are analyzed and designed in two ways. In the first part, actions on transmission tower are determined using an empirical approach (SIST EN 50341-1:2002 together with SIST EN 50341-3-21:2009), and in the second part using a general approach (EN 50341-1:2012). The differences between actions and load cases are compared and how this reflects in the axial forces, displacements and reactions. The analysis of the transmission tower is carried out with idealised computing model made in RFEM programme, which uses finite element method for calculation. Since the load - bearing transmission towers are more commonly used in a line than section towers , we consider the case of load – bearing transmission tower.
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