Phased time-dependent FE analysis of reinforced concrete beams

The structural life of a reinforced concrete beam has previously been defined by several stages which include loading of an intact structure to the serviceability stage, corrosion, load reduction before repair procedures, removal of contaminated concrete, patch repair and finally strengthening. Numerical simulations of this service life cycle without strengthening, where time-dependent effects such as creep and shrinkage were included in the constitutive models, were carried out using the phased analysis in the finite-element software Diana. The results of the simulations showed that the failure load is in good agreement with the failure load corresponding to the upper bound of the 95% confidence interval obtained in a previous probabilistic study based on the experimental results. Initial strains owing to shrinkage of the concrete and the repair material were implemented using the Model Code 1990 model (predefined in Diana) and a model for development of free shrinkage strain in beams exposed to one-side drying. This model was developed by Planas and Elices while the material parameters are based on Model Code 1990 or Eurocode 2. Total strains across the cross-section of the beam calculated in the finite-element analyses are compared with data that are available from the experimental study.