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

Precise prediction of the structural capacity of lattice transmission towers under different loads is essential to accurate assessment of the reliability of transmission networks. In doing so, the uncertainties inherent in the modeling parameters of the towers should be taken into account. In this regard, the present paper developed a probabilistic framework to analyze the failure of a 230 kV double-circuit tower in a full-scale type test accounting for the uncertainties including eccentricity at the connections, joint slippage, and initial imperfection in the members. Three loading patterns were applied to the manufactured full-scale tension tower. A finite element model of the tower was established and verified by the test results considering the mentioned uncertainties. The importance vectors derived from reliability analysis showed the effect of each of these parameters on the displacement of the target points as well as the maximum load-carrying capacity of towers members for these load patterns. Further, additional moments resulting from eccentricity at the connections were highlighted through a proposed regression-based equation. The failure probability of the tested tower was then determined for di erent load factors whose results were presented in terms of fragility curves. Finally, the effect of eccentricity on the tower failure was quantified.