Reliability-Based Approach for Fragility Analysis of Lattice Transmission Tower in the Type Test

Abstract

Precise prediction of the structural capacity of lattice transmission towers under various loads is essential to assess the reliability of the transmission network accurately. In doing so, the uncertainties inherent in the modeling parameters of the towers need to be taken into account. In this paper, a probabilistic framework is developed to analyze the failure of a 230 kV double-circuit tower in full-scale type test accounting for the uncertainties including eccentricity at the connections, joint slippage, and initial imperfection in the members. Three loading patterns are applied to the manufactured full-scale tension tower. A finite element model of the tower with consideration of mentioned uncertainties is built and verified by the test results. The importance vectors derived from reliability analysis clarifiy the effect of each of these parameters on the target points' displacement, as well as the maximum load carrying capacity in towers' members for these load patterns. Besides, the additional moments due to eccentricity at the connections are considered by a proposed regression-based equation. The failure probability of the tested tower is determined for various load factors, and the results are presented in terms of fragility curves. Besides, the effect of eccentricity on the tower’s failure is quantified.