Estimation of the residual service life of reinforced concrete beams of an industrial facility taking into account corrosion wear

Abstract

Introduction. Corrosion damage of reinforcement and concrete is an important factor reducing durability of industrial facilities. The article presents the methodology and results of probabilistic calculation of residual life of separate reinforced concrete structures of an industrial building as well as of reinforced concrete structures working in the system. A three-storey open stand with dimensions in terms of 30 × 15 m and 25 m in height is considered. The calculated parameters of the actual state of the structures are obtained on the basis of experimental diagnostic studies.
 
 Materials and methods. According to the results of a full-scale field engineering inspection using standard and non-standard methods of non-destructive testing, the most damaged structures of the framework — reinforced concrete floor beams have been determined. The degree of corrosion damage of working reinforcement and compressed concrete has been determined. The method of probabilistic calculation of a reinforced concrete beam with regard for corrosion deterioration is outlined. The limiting bending moment in the beam section is considered as a nonlinear function of two random arguments — the strength of concrete and the strength of reinforcement. A linear law of corrosion damage accumulation is adopted. The probabilistic characteristics of the limiting bending moment are found by the Monte Carlo method on the basis of the normative method of calculation of a rectangular reinforced concrete section with double reinforcement. The reliability index has been used to determine the numerical values of the probability of failure and operating time.
 
 Results. Statistical characteristics of bending moment limit changing in time from the beginning of concrete protective properties exhaustion to element failure have been obtained. Lifetime before failure for a given guaranteed safety is found out.
 
 Conclusions. The practical application of the probabilistic method combined with field survey data to solve the problem of assessing the residual service life of reinforced concrete beams of a real industrial building is shown.