南方能源建设 (Mar 2023)
Comparative Analysis of Slenderness Ratio Calculation Methods of Cross Bracings for Towers Between China and EU Overhead Transmission Line Standards
Abstract
[Introduction] This paper aims to effectively avoid the design quality problems caused by the difference between domestic and foreign engineering design specifications. The study makes comparative analysis of slenderness ratio of cross bracings for angle steel members of transmission towers according to the current Chinese standard Technical Code for the Design of Tower and Pole Structures of Overhead Transmission Line (DL/T 5486—2020) and the European standard Overhead Electrical Lines Exceeding AC 1 kV (EN—50341—2012). [Method] An example of the typical arrangement pattern of cross bracings with auxiliary materials in projects was given to calculate the slenderness ratio of the poles according to the two standards. [Result] The results we obtained demonstrate that when calculating for the two cross bracings subject to same compression, the Chinese standard adopts the calculation of length correction factor to correct the influence of the joint action of the two cross bracings on the buckling strength of the compression member. The European standard adopts the checking calculation of the sum of buckling strength of the two poles which shall be greater than or equal to the algebraic sum of the loads on the two poles to ensure the buckling strength of the member meets the structural requirement. [Conclusion] In the arrangement pattern of typical cross bracings with auxiliary materials, the calculated buckling strength obtained according to the Chinese standard is less than that obtained according to the European standard under the following three conditions: two poles subject to same compression and equal pressure, two poles subject to same compression and unequal pressure, and two poles with one pole subject to pulling and the other subject to compression.
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