ФУНКЦИЯ НАДЕЖНОСТИ ПРЕДВАРИТЕЛЬНО НАПРЯЖЕННОЙ КОРРОДИРОВАННОЙ ЖЕЛЕЗОБЕТОННОЙ БАЛКИ ПРИ НЕЛИНЕЙНОМ РАСПРОСТРАНЕНИИ КОРРОЗИИ

Abstract

The paper considers the limit state function in the context of reliability analysis of corroded beams. Methods for determining the ultimate load limit for corroded beams are discussed. Various approaches to the determination of the limit state function are considered, including those based on statistical data on corrosion and modelling of stresses in a reinforced concrete beam. A general reliability assessment model for reinforced concrete structures should include corrosion propagation. Most previous studies have focused on one-dimensional diffusion problems with an assumed constant corrosion rate. A nonlinear corrosion rate model, unlike linear models, considers the corrosion current density not constant over the service life of a reinforced concrete structure. An approach to reliability analysis together with a nonlinear corrosion growth model is developed. In this paper, the main problems related to reliability under a nonlinear model of prestressed reinforcement rope corrosion of reinforced concrete beams are discussed. A function for the reduction of reinforcing bar diameter from time is presented. Sensitivity analysis is performed to determine the effect of corrosion growth parameters on the reliability index of reinforced concrete T-beam. The nonlinear corrosion growth model, together with other relevant probabilistic models used to describe random variables, was applied to analyze the reliability of a reinforced concrete crane girder. The expression of corrosion current density shows that the corrosion rate increases exponentially as the value of the design parameter of the model increases. To further evaluate the effect of the proposed time corrosion growth model on the reliability of reinforced concrete beam, two specific cases are considered. The first one is with fixed corrosion current density, and the second one is with fixed corrosion growth at a given time.