Methodology for analyzing the reliability characteristics of lattice supports for overhead power lines based on the failure range

Ensuring the reliability of lattice structures of overhead line (OL) supports is the primary task of the designer. If the calculation and design of typical structures of mass construction is carried out in accordance with the current regulatory documents, then the issue of ensuring the guaranteed minimum required level of reliability of OL supports is carried out by using various types of reliability factors. In fact, FORM methods (first-order methods for determining the reliability of building structures) remain, since SORM methods (second-order methods) are extremely difficult to implement. At the same time, current regulatory documents do not provide an unambiguous algorithm for determining the reliability characteristics of OL support structures. Therefore, the design engineer needs a clear and unambiguous method for determining the reliability characteristics of lattice structures of overhead power line supports, which allows for a reasonable provision of a given level of reliability for all structural elements. The article proposes a method for determining the susceptibility of steel structures of power transmission lines to avalanche-like collapse based on a numerically reasonable determination of the excluded elements of the system for forming a secondary calculation scheme. It is based on the calculation based on the finite element method in a geometrically and structurally nonlinear formulation. This method allows for a clear determination of the most critical structural rods, rather than assigning them based on engineering experience or recommendations. A method for determining the numerical reliability characteristics of steel structures of power transmission lines is proposed based on the finite element method in a stochastic formulation. The failure range β serves as the main characteristic. The sought reliability of the system is between the lower value of βmin (the characteristic of one of the most critical elements of the system) and the upper value of βmax (the characteristic for a group of the most critical elements of the system), determined during the analysis of the structure for the tendency to avalanche-like collapse. In order to test the proposed methods, the reliability of the anchor-angle support U220-2+9 was analyzed. Based on the calculation results, insufficient reliability of the structure for the design situation with the maximum of the considered loads was revealed. A methodology has been developed for analyzing the tendency of steel rod structures of power transmission line supports to avalanche-like collapse, which makes it possible to determine the most dangerous elements of the system for a specific type of loading.