Combined Influence of Cyclic Loads and Corrosion on the Technical Condition of Metal Structures of Metro Escalators

Abstract

This article examines the influence of loads, conventionally divided into static and cyclic ones, and of corrosion acting together on the structural elements of metal structures of metro escalators. The dynamics of corrosion processes are determined by the environment, the degree of influence of which, depending on the geographical location and based on seasonality, can vary from non-aggressive to highly aggressive. This, with simultaneous occurrence of deformations (a stressed state is created in the structure), can lead to fatigue failures. The state of the metal structure of the escalator in this case is the most important element, since the failure of almost any of its structural elements means a complete stop of the escalator.The prerequisites for corrosion fatigue for low carbon steels, as the main material in manufacture of metal structures for metro escalators, are also considered.The main objective of the study is to search for criteria for creating an experimental and computational method for determining the residual life of metal structures of metro escalators with a high degree of reliability. Identification and analysis of criteria for assessing the condition of metal structures was carried out by the authors using experimental research and survey methods, that resulted in a conclusion that the degree of degradation of the main characteristics and properties of metal structure elements is determined not only by the number of loading cycles, but also by the duration of exposure to an aggressive environment.