Time-dependent reliability analysis of railway overhead structures

Abstract

Overhead structures play a vital role in the operation of electrified rail networks. They support overhead electrical wires that provide the necessary power to the operation of trains. Overhead structures are simple steel structures that lack redundancies and failure in a single location may cause significant deformation or complete collapse. Failures of these simple structures have substantial consequences which usually interrupt train service. These steel structures are exposed to the environment and gradual deterioration of steel due to corrosion jeopardizes their strength and serviceability. This paper presents a reliability-based method for strength assessment of portal overhead structures using the first order reliability method. In the resistance formulation, a modified corrosion decay model proposed in this article predicts the thickness loss of wide flange structural steel sections. Meanwhile, load effect formulation follows a structural steel design code and an industry standard. It is found that the bridge-mast connection and the attachment point to drop vertical on the bridge are the most critical parts during the service life of the structure. The reliability analysis presented in this work is an efficient mean for structural engineers to identify critical locations of overhead structure and facilitate asset managers to prioritize inspection and maintenance works for deteriorated overhead structures.